joseph ledoux_synaptic self

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SYNAPTIC SELF HOW OUR BRAINS BECOME WHO WE ARE

BY.JOSEPH LeDOUX

ACKNOWLEDGMENTS

The bottom-line point of this book is “You !e "ou! s"npses.# S"npses !e the sp$es bet%een b!in $ells&

but !e mu$h mo!e. The" !e the $hnnels of $ommuni$tion bet%een b!in $ells& n' the mens b" %hi$h most of

%ht the b!in 'oes is $$omplishe'.To p!opose s"npti$ e(plntion of the self& ) h' to 'is$uss in some 'etil ho% the b!in %o!ks. )*+e t!ie'

to 'o this %ithout t!i+ili,in the f$ts it*s not pop ps"$holo"& ho%-to& o! self-help book. /lthouh %!itin bout the

b!in in %" tht %ill be $le! to l" !e'e!s n' t the sme time not insultin to othe! s$ientists is touh& )*m

plese' %ith the !esult.

But ) 'i'n*t $hie+e this ol lone. 0" %ife& 1n$" P!in$enthl& is n !t $!iti$& n' fntsti$ %!ite!. She

$onstntl" u!e' me to use %o!'s e$onomi$ll"& n' to +oi' !epetition. She !e' n' !e!e'& e$h time 2often to m"

nno"n$e3 %ith sh!pene' pen$il in hn'. /n' %hen ) h' finll" met he! $!iti$l pp!o+l& ) tu!ne' the mnus$!ipt

o+e! to 4i$k 5ot& m" e'ito! t 6ikin. )t %s !et to h+e p!o like 4i$k on m" si'e.

) lso %nt to thnk p!esent n' pst membe!s of m" lb. 7ithout thei! $!eti+it" n' h!' %o!k& the s$ien$e

tht inspi!e' me to %!ite Synaptic Self %oul' not e(ist. /n' the %o!k $oul' not h+e been 'one %ithout the ene!ous

suppo!t of the 1tionl )nstitute of 0entl Helth& 1e% Yo!k Uni+e!sit"& the 7 H. 5e$k 8oun'tion& n' the Hen!" n'Lu$" 0oses 8un'.

)*m lso !teful to $olleues %ho !e' $e!tin $hpte!s n' $ommente' on them. Thnks to Y'in Du'i&

J$ek Debie$& 5!im 1'e!& 9!e Sulli+n& n' 4fi Lmp!e$ht. )n ''ition& se+e!l $olleues $onsulte' %ith me on

spe$ifi$ topi$s& in$lu'in Ton" 0o+shon& :!l Sht,& Dn Snes& Je!ome 5n& Tim 7ilson& Stephen Hppel&

1n$e" 0u!ph"& B!!" E+e!itt& 1o!m ;7hite& Sn'! 8ile& Justine 5ent& D+i' Silbe!s%ei& J$k 9o!mn& /m" /m-

sten& Li, Phelps& n' Jonthn :ohen.

7ill :hn %ent bo+e n' be"on' on the 7o!ks :ite' list. /n' 0in Hou n' :lu'i 8!b m'e

in'ispensble $ont!ibutions to the illust!tions.

B!ett 5ell"& 4i$k 5ot*s ssistnt t 6ikin& %s lso +e!" helpful th!ouhout Spe$il thnks to B!b! :mpo

n' :!l Bolte t 6ikin fo! thei! 3!ouhness n' thei! ptien$e %ith m" $o!!e$tions n' to Don Homolk& ele-e"e'

$op" e'ito!.) lso %nt to e(p!ess m" !titu'e to m" ents& 5tink 0tson n' <in B!o$kmn. ) !etl" pp!e$ite

thei! '+i$e n' suppo!t.

8inll"& ) thnk m" $hil'!en& J$ob n' 0ilo. The" inspi!e m" s"npses to ne e+e!" '".

7!itin book is humblin e(pe!ien$e. You $ome to !eli,e ho% mn" ins "ou thouht "ou un'e!stoo'

but !ell" 'i'n*t& t lest not %ell enouh e(plin them $le!l". ) le!ne' t!emen'ous mount %hile %!itin SynapSelf

n' hope "ou 'o too %hile !e'in it.



CHAPTER ONE

THE B)9 O1E

D/D& 7H/T )S THE 0)1D= )S )T JUST / SYSTE0 O8 )0PULSES O4 SO0ETH)19 T/19)BLE=

-- B!t Simpson

“) 'on*t kno%& so m"be )*m not&# the T-shi!t si'. H' it been nothe! time o! pl$e& ) p!obbl" %oul'*+e

$hu$kle' n' mo+e' on. But ) %s on Bou!bon St!eet %hen this postmo'e!n home to Des$!tes*s p!o$lmtion& “)

think& the!efo!e ) m&# ppe!e' on "oun mn %e+in to%!' me. ) h' >ust h' 'inne! in the 8!en$h ?u!te! fte!

lon '" of 't 'iestion n' s$hmoo,in t the So$iet" of 1eu!os$ien$e :onfe!en$e& n nnul et-toethe! of

thi!t" thousn' o! so b!in !ese!$he!s f!om !oun' the %o!l'. The soun' of Di(ieln' tunes& the !om of stle bee!&

n' the siht of s$ntil" $l' %omen 'n$in on !un%"s insi'e '!k b!s h' me $ontempltin the "e!s n' life

$hnes tht h' $ome n' one sin$e ) m"self h' %e+e' 'o%n Bou!bon St!eet 'u!in m" $ollee '"s in

Louisin. ) he'e' b$k to m" hotel& !efle$tin on m" pst n' p!esent life n' %on'e!in bout %ht& ll of su'-

'en& seeme' to me to be the bi @uestion b!in !ese!$he!s shoul' be skinA

“;7ht mkes us %ho %e !e=#

1eu!os$ien$e hsn*t "et 'el+e' 'eepl" into this pu,,lin issue. )t hs& fo! oo' !eson& fo$use' on ho%

spe$ifi$ p!o$esses& like pe!$eption& memo!"& o! emotion& %o!k in the b!in& but mu$h less on ho% ou! b!ins mke us

%ho %e !e. )*' +entu!e uess tht if !n'om smple of neu!os$ientists %e!e

e'& “7ht 'o %e kno% bout the b!in me$hnisms of the self n' pe!soniit"=# the p!e'ominnt ns%e!

%oul' be “1ot mu$h.#

But m"be %e kno% mo!e thn %e think. 0"be some o! e+en mn" pie$es of the pu,,le h+e l!e'" been

'is$o+e!e'& n' >ust h+e to be ssemble' into $ohe!ent %hole. /$tull"& ) belie+e this miht be the $se. / lot of

info!mtion is +ilble bout ho% the b!in %o!ks& n' %hile it m" not "et be suffi$ient to full" e(plin pe!sons& it

shoul' $e!tinl" en$ou!e us to bein thinkin bout the p!oblem.

0" notion of pe!sonlit" is p!ett" simpleA it*s tht "ou! “self&# the essen$e of %ho "ou !e& !efle$ts ptte!ns of

inte!$onne$ti+it" bet%een neu!ons in "ou! b!in. :onne$tions bet%een neu!ons& kno%n s s"npses& !e the min

$hnnels of info!mtion flo% n' sto!e in the b!in. 0ost of %ht the b!in 'oes is $$omplishe' b" s"npti$

t!nsmission bet%een neu!ons& n' b" $llin upon the info!mtion en$o'e' b" pst t!nsmission $!oss s"npses.

9i+en the impo!tn$e of s"npti$ t!nsmission in b!in fun$tion& it shoul' p!$ti$ll" be t!uism to s" tht

the self is s"npti$. 7ht else $oul' it be=*

1ot e+e!"one& ho%e+e!& %ill be hpp" %ith this $on$lusion. 0n" %ill su!el" $ounte! tht the self is

ps"$holoi$l& so$il& mo!l& estheti$& o! spi!itul& !the! thn neu!l& in ntu!e. 0" s"npti$ theo!" of the self is not

p!opose' s n lte!nti+e to these +ie%s. )t is& !the!& n ttempt to po!t!" the %" the ps"$holoi$l& so$il& mo!l&

estheti$& o! spi!itul self is !eli,e'.

)*ll stte unshme'l" f!om the st!t tht %e $n*t& t this point& o ll the %" in fo!multin $omplete



s"npti$ theo!" of pe!sonlit". But e+en p!til un'e!stn'in of the s"npti$ bsis of %ho %e !e is& fo! me& n

$$eptble ol. 8o! seekin kno%le'e bout the b!in is not onl" +li' s$ientifi$ pu!suitC it $n lso imp!o+e the

@ulit" of life& s %hen it un$o+e!s ne% %"s of t!etin neu!oloi$l o! ps"$hit!i$ 'iso!'e!s.

SYNAPTIC NATURE

Let*s st!t %ith f$tA People 'on*t $ome p!essemble'& but !e lue' toethe! b" life. /n' e$h time one of

us is $onst!u$te'& 'iffe!ent !esult o$$u!s. One !eson fo! this is tht %e ll st!t out %ith 'iffe!ent sets of enesC

nothe! is tht %e h+e 'iffe!ent e(pe!ien$es. 7ht*s inte!estin bout this fo!multion is not tht ntu!e n' nu!tu!e

both $ont!ibute to %ho %e !e& but tht the" $tull" spek the sme lnue. The" both ultimtel" $hie+e thei!

mentl n' beh+io!l effe$ts b" shpin the s"npti$ o!ni,tion of the b!in. The p!ti$ul! ptte!ns of s"npti$

$onne$tions in n in'i+i'ul*s b!in& n' the info!mtion en$o'e' b" these $onne$tions& !e the ke"s to %ho tht

pe!son is.

The eneti$ bluep!int beins to unfol' in the ne%l" fe!tili,e' e. 9enes $tull" 'o t%o thins in the

b!o'est bioloi$l senseA the" mke us ll the sme 2%e*!e ll humns3& n' the" lso 'istinuish us f!om one

nothe! 2e$h of us hs uni@ue eneti$ mkeup tht $ont!ibutes to ou! in'i+i'ulit"3. 7hen t%o people et toethe!

n' mke bb"& the" l%"s en' up %ith $!etu!e tht looks n' $ts like humn n' not like monke"& 'o& o!

fish. The $ommon eneti$ he!ite of ou! spe$ies 'i$ttes tht the bsi$ s"stems n' mole$ules in m" b!in !e the

sme s those in "ou!s& n' the bsi$ mentl n' beh+io!l !epe!toi!e +ilble to me is lso +ilble to "ou. 7e ll

%lk up!iht& spek th!ouh ou! mouths& luh& $!"& n' le!n f!om e(pe!ien$es. But s $hil'!en of p!ti$ul! set of

p!ents& %ho !e themsel+es p!o'u$ts of p!ti$ul! eneloi$l histo!"& %e e$h lso h+e enes tht i+e ou!

b!ins uni@ue @ulities n' 'i!e$t the spe$ifi$ mnne! in %hi$h the ene!l mentl n' beh+io!l $h!$te!isti$s of

ou! spe$ies !e e(p!esse'. 9eneti$ f$to!s !e in f$t kno%n to influen$e +!iet" of in'i+i'ul o! pe!sonlit"

$h!$te!isti$s& in$lu'in ho% outoin& fe!ful& o! !essi+e one is& s %ell s the likelihoo' tht one %ill 'e+elop

'ep!ession& n(iet"& o! s$hi,oph!eni.

Just ho% 'o enes ffe$t in'i+i'ul beh+io!= )n the simplest te!ms& the" 'o so b" mkin p!oteins tht

shpe the %" neu!ons et %i!e' toethe!. The!e !e mn" steps& to s" the lest& bet%een enes n' thei!

e(p!ession in $tul beh+io!& but eneti$ s$ulptin of the s"npti$ o!ni,tion of neu!l s"stems is the ke" to the

p!o$ess. /niml b!ee'e!s h+e lon kno%n tht it tkes onl" fe% ene!tions of mtin mon $!efull" sele$te'

in'i+i'uls to bein influen$in beh+io!l t!its of thei! offsp!in& su$h s ho% tme o! fie!$e i+en line of 'os is.

7hen b!ee'e!s t!" to $ustomi,e beh+io! in this fshion& the" in f$t !e often %o!kin %ith the s"npti$ o!ni,tion

of the b!in. / fe% e(t! $onne$tions he!e& little mo!e o! little less neu!ot!nsmitte! the!e& n' nimls bein to $t

'iffe!entl". On$e %e !eli,e tht the bsi$ %i!in pln of the b!in is un'e! eneti$ influen$e& it*s es" to see ho% not

onl" nimls but lso people $n h+e +e!" simil! b!ins n' "et be so 'iffe!ent& !iht f!om the st!t of thei! li+es.

9eneti$ fo!$es& ope!tin on the s"npti$ !!nement of the b!in& $onst!in& t lest to some e(tent& the %" %e $t&

think& n' feel. The hopes of some& n' the fe!s of othe!s& su!!oun'in the issue of humn $lonin ob+iousl" hine

on the impo!tn$e of enes in !eultin not onl" ho% %e look& but lso %ho %e !e.

8o! oo' !eson& then& @uite lot of ttention is bein pi' to enes these '"s. 7i'el" !e' utho!s&

in$lu'in 4i$h!' D%kins& E. O. 7ilson& n' Ste+en Pinke!& h+e !ue' fo!$efull" tht ke" spe$ts of min' n'

beh+io! !e inhe!ite'. Still& it*s impo!tnt to !e$oni,e tht enes onl" shpe the b!o' outline of mentl n'

beh+io!l fun$tions& $$ountin fo! t most pe!$ent of i+en t!it& n' in mn" instn$es fo! f! less.

)nhe!itn$e m" bis us in $e!tin 'i!e$tions& but mn" othe! f$to!s 'i$tte ho% one*s enes !e e(p!esse'.

8o! e(mple& if %omn $onsumes e($essi+e l$ohol 'u!in p!enn$"& o! $hil' hs 'iet 'efi$ient in

$e!tin nut!ients& b!in eneti$ll" 'estine' fo! b!illin$e $n inste' tu!n out to be $oniti+el" impi!e'. Like%ise&

fmil" histo!" of e(t!+e!sion $n be s@uel$he' in n o!phne !un %ith n i!on fist& >ust s ntu!l ten'en$" to be

sh" n' %ith'!%n $n be $ompenste' fo! to some 'e!ee b" the suppo!ti+e en$ou!ement of p!ents.* E+en if it



be$omes possible to $lone $hil' %ho hs 'ie' t ten'e! e& it*s p!obble tht the look-like& h+in his o%n set of

e(pe!ien$es& is oin to $t& think& n' feel 'iffe!entl".

7e he! lot these '"s bout ho% i'enti$l t%ins& !e!e' p!t b" sep!te 'opti+e p!ents& $n h+e

simil! hbits n' t!its.* 7e he! less bout the mn" %"s the" 'iffe!. The min out$ome of Ju'ith 4i$e H!!is*s

$ont!o+e!sil FFG book& The Nurture Assumption, in %hi$h she p!opose' tht p!ents h!'l" mtte!& %s p!obbl"

the eme!en$e of $le!e! i'es bout >ust ho% impo!tnt& n' un'e! %ht $on'itions& p!ents do mtte!.

The pe!-sonlit" 'iso!'e!s of $hil'!en !ise' in b!utl 4omnin o!phnes !e sho$kin testimon" to the f$t tht

e(pe!ien$es $n h+e p!ofoun' effe$ts on beh+io!.* 9enes !e impo!tnt& but not ll-impo!tnt.

NURTURING NATURE

The pu,,le of ho% ntu!e n' nu!tu!e shpe %ho %e !e is simplifie' b" the !eli,tion tht s"npses !e the

ke" to the ope!tions of both. 7hethe! "ou! p"$he$k is 'eposite' to "ou! bnk $$ount utomti$ll" o! "ou hn' it

o+e! to the telle! in pe!son& it oes to the sme pl$e. 1tu!e n' nu!tu!e fun$tion simil!l"A the" !e simpl" t%o

'iffe!ent %"s of mkin 'eposits in the b!in*s s"npti$ le'e!s.

8o! e(mple& in life 2n' not >ust in $!toons3 !o'ents !ell" !e f!i' of $ts. This is t!ue of !ts n' mi$e

li+in in the %il'& but lso of the !ts stu'ie' in lbo!to!ies. /lthouh lb !ts $ome f!om b!ee'in $olonies tht h+ebeen isolte' f!om $ts fo! mn"& mn" ene!tions& n" one of them& upon seein $t fo! the fi!st time& %ill “f!ee,e#

'e' in its t!$ks. This is 0othe! 1tu!e t %o!k& sin$e the !t 2n' his imme'ite n$esto!s3 ne+e! h' the op-

pe!tunit" to le!n f!om pe!sonl e(pe!ien$e tht $ts !e 'ne!ous. This be .+io! is not >ust spe$ifi$ to !ts o! e+en

nimls& fo! people lso f!ee,e %hen $e' %ith 'ne!. 4e$ll the mteu! +i'eotpe of the bombin t the FF Alnt

Summe! Ol"mpi$s sho%n o+e! n' o+e! on :11. 7ithin se$on'

Ithe e(plosion& e+e!"one in the +i$init" %s $!ou$hin motionless.#

7h" 'i' f!ee,in be$ome eneti$ll" h!'%i!e' beh+io!= Ob+iousl"& e!e*s no %" to kno% fo! su!e& sin$e

%e h+e no fossil !e$o!' t!$in the e+o.tion of beh+io!l o! mentl $p$ities.u Ho%e+e!& !esonble h"pothesis

tht f!ee,in is benefi$il !esponse %hen f$e' %ith p!e'to!. P!e'to!s& p!iml 'ne! fo! most nimls& !espon'

to n' !e e($ite' b" mo+ement. eepin still in the f$e of 'ne! is often the best thin fo! the p!e" to 'o. e$use

millions of "e!s o nimls %ho 'i' so %e!e mo!e likel" to su!+i+e& 3'" it*s %ht most nimls 'o& t lest s ninitil line of 'efense. 8!ee,in not $hoi$e but n utomti$ !esponse& p!ep!o!mme' %" of 'elin ;ith 'ne!.

)t sometimes b$kfi!es& ho%e+e!& s %hen 'ee! is f!o,en in the e'lihts of n on$omin $!. Like most

e+olution!il" bse' st!teies& it*s oo' fo! mn" nimls mu$h of the time& but not fo! ll nimls ll of the time.

7ht*s inte!estin is tht f!ee,in lso o$$u!s if !t 2o! othe! niml3 $le!l" he!s soun' tht p!e$e'e'

n +e!si+e stimulus 2 mil' ele$t!i$l o$k of its feet3 on some p!io! o$$sion.* The!e*s no p!e'to! !oun' in this

se& so ho% is the $onne$tion fo!me'= The soun' is %!nin sinl. /n" !t Eit su!+i+es n en$ounte! %ith $t o!

othe! p!e'to! shoul' sto!e in its !in s mu$h bout the sitution s possible so tht the ne(t time the soun's sihts

o! smells tht p!e$e'e' the !!i+l of the $t o$$u!& those stimuli $n e tten'e' to in o!'e! to in$!ese its $hn$es of

st"in li+e. )n the $se of he ele$t!i$l sho$k& pin !e$epto!s !e $ti+te' n' this substitutes fo! $lose en$ounte!

of the h!mful kin' %ith p!e'to!& mkin it possible fo! the timuli tht p!e$e'e' the sho$k to be sto!e' s if the"

%e!e those tht p!eAe'e' $t.

The!e !e t%o bsi$ %"s in %hi$h these kin's of p!o$esses miht h+e een %i!e' up in the b!in. 8i!st&

t%o-s"stem ope!tion miht e(ist& %ith me s"stem fo! !espon'in to spe$ies-t"pi$l 2innte o! eneti$ll" p!oC!mme'3

'ne!s n' nothe! fo! le!nin bout no+el ones e(pe!ien$e' b" n'i+i'uls in thei! li+es. O! the!e miht >ust be one

s"stem tht tkes $!e of oth situtions. )n f$t& e(pe!iments sho% tht the ltte! is the %" the b!in i$tull" %o!ks

Dme to !eion of the b!in $lle' the m"'l elimintes the ten'en$" fo! !ts to f!ee,e to both the $t

n' to the soun'. The m"'l is p!t of the b!in s"stem tht $ont!ols f!ee,in beh+io! n' othe! 'efensi+e

!esponses in th!etenin situtions. )ts s"npses !e %i!e' b" ntu!e to !espon' to the $t& n' b" e(pe!ien$e to



!espon' in the sme %" to 'ne!s tht !e le!ne' bout. )t*s %on'e!full" effi$ient %" to 'o thinsA

!the! thn $!ete sep!te s"stem to $$ommo'te le!nin bout ne% 'ne!s& >ust enble the s"stem

tht is l!e'" e+olution!il" %i!e' to 'ete$t 'ne! to be mo'ifible b" e(pe!ien$e. The b!in $n& s !esult& 'el

%ith no+el 'ne!s b" tkin '+nte of e+olution!il" fine-tune' %"s of !espon'in. /ll it hs to 'o is $!ete

s"npti$ substitution %he!eb" the ne% stimulus $n ente! the $i!$uits tht the p!e%i!e' ones use'.

8o! the pst t%ent" "e!s& )*+e been t!"in to fiu!e out ho% b!ins le!n bout 'ne!s. )n m" p!e+ious book&The Emotional Brain, ) 'es$!ibe' mu$h of %ht is kno%n bout the o!ni,tion of the b!in s"stem in+ol+e'& n' li'

out the impli$tions fo! un'e!stn'in emotions. The bsi$ %i!in pln is simpleA it in+ol+es the s"npti$ 'eli+e!" of

info!mtion bout the outsi'e %o!l' to the m"'l& n' the $ont!ol of !esponses tht $t b$k on the %o!l' b"

s"npti$ outputs of the m"'l. )f the m"'l 'ete$ts somethin 'ne!ous +i its inputs& then its outputs !e

ene'. The !esult is f!ee,in& $hnes in bloo' p!essu!e n' he!t !te& !elese of ho!mones& n' lots of othe!

!esponses tht eithe! !e p!ep!o!mme' %"s of 'elin %ith 'ne! o! !e spe$ts of bo'" ph"siolo" tht suppo!t

'efensi+e beh+io!s. Th!ouhout m" pst !ese!$h& )*+e m'e use of the f$t tht the fe! s"stem n le!n n' sto!e

info!mtion bout stimuli tht %!n of impen'in bo'il" i!m o! othe! 'ne!s. 4e$entl"& thouh& m" lb hs tu!ne' to

stu'ies of e(L$tl" ho% fe! le!nin tkes pl$e t the s"npti$ le+el. This ne% %o!k& 'e$!ibe' in this book& she's liht

on ho% s"npti$ mo'ifi$tions in the fe! C"stem& p!ti$ul!l" in the m"'l& llo% us to benefit f!om pst en$ounte!s

+ith 'ne!.

0ost s"stems of the b!in !e plsti$& tht is& mo'ifible b" e(pe!ien$e& 1hi$h mens tht the s"npses

in+ol+e' !e $hne' b" e(pe!ien$e. But& s Ahe fe! e(mple sho%s& le!nin is not the fun$tion tht those s"stems

o!iinll" %e!e 'esine' to pe!fo!m. The" %e!e built inste' to $$omplish $e!tin Asks 2like 'ete$tin 'ne!& fin'in

foo' n' mtes& he!in soun's& o! mo+

in limb to%!' some 'esi!e' ob>e$t3. Le!nin 2s"npti$ plsti$it"3 is >ust fetu!e tht helps them 'o thei!

>ob bette!.

Plsti$it" in ll the b!in*s s"stems is n inntel" 'ete!mine' $h!$te!isti$. This m" soun' like ntu!e-

nu!tu!e $ont!'i$tion& but it is not. /n innte $p$it" fo! s"npses to !e$o!' n' sto!e info!mtion is %ht llo%s

s"stems to en$o'e e(pe!ien$es. )f the s"npses of p!ti$ul! b!in s"stem $nnot $hne& this s"stem %ill not h+e

the bilit" to be mo'ifie' b" e(pe!ien$e n' to mintin the mo'ifie' stte. /s !esult& the o!nism %ill not be ble to

le!n n' !emembe! th!ouh the fun$tionin of tht s"stem. /ll le!nin& in othe! %o!'s& 'epen's on the ope!tion of

eneti$ll" p!o!mme' $p$ities to le!n. Le!nin in+ol+es the nu!tu!in of ntu!e.

LEARNING WHO WE ARE

The stu'" of le!nin n' memo!" p!o$esses in the b!in hs '+n$e' !pi'l" in the lst fe% 'e$'es. This

book is in l!e p!t bse' upon this ne% un'e!stn'in of en$o'in n' sto!e n' thei! o!iin in s"npti$ fun$tion.

Le!nin& n' its s"npti$ !esult& memo!"& pl" m>o! !oles in luin $ohe!ent pe!sonlit" toethe! s one oes

th!ouh life. 7ithout le!nin n' memo!" p!o$esses& pe!sonlit" %oul' be me!el" n empt" impo+e!ishe' e(p!ession

of ou! eneti$ $onstitution. Le!nin llo%s us to t!ns$en' ou! enes& o!& s the no+elist Slmn 4ush'ie si'& “Life

te$hes us %ho %e

Ou! enes m" bis the %" %e $t& but the s"stems !esponsible fo! mu$h of %ht %e 'o n' ho% %e 'o it

!e shpe' b" le!nin. /lthouh !t is b" ntu!e f!i' of $ts& it %ill li+e lone! if it le!ns %he!e in its p!ti$ul!

%o!l' $ts !e most likel" to be en$ounte!e' n' %ht kin's of soun's n' smells !e p!esent %hen $ts !e ne!b".

/ !t tht hs sto!e' this info!mtion in its fe! s"stem is mo!e %o!l'l"& n' mu$h bette! off& thn one tht hs not.

Somethin simil! o$$u!s in mn" if not most othe! b!in s"stemsA the info!mtion the" en$o'e n' sto!e to'" %ill

$ont!ibute impo!tntl" to ho% the" fun$tion tomo!!o%.

Ou! kno%le'e of %ho %e !e& of the %" %e think bout ou!sel+es& of %ht othe!s think of us& n' of ho%

%e t"pi$ll" $t in $e!tin situtions is in l!e p!t le!ne' th!ouh e(pe!ien$e& n' this info!mtion is $$essible to

us th!ouh memo!". 7ithout le!nin n' memo!"& %e %oul'nt kno% if the pe!son %e !e to'" >ibes %ith the one %e



%e!e "este!'" o! the one %e e(pe$t to be tomo!!o%. 7ithout le!nin n' memo!"& pe!son %oul' h+e the b!e-

bones pe!sonlit" p!o+i'e' b" enes& but %oul'n*t kno% mu$h bout it.

But& s %e %ill see th!ouhout this book& le!nin n' memo!" lso $ont!ibute to pe!sonlit" in %"s tht

e($ee' e(pli$it self-kno%le'e. The b!in& in othe! %o!'s& le!ns n' sto!es mn" thins in net%o!ks tht fun$tion out-

si'e of $ons$ious %!eness. These le!ne' ten'en$ies ffe$t ll spe$ts of min' n' beh+io!& n' !e p!obbl" t

lest s impo!tnt fo! '"-to-'" fun$tionin s %ht %e kno% bout ou!sel+es $ons$iousl".

THE BIG ONE, OR IS IT?

0" %lk 'o%n Bou!bon St!eet ot me thinkin bout the o!iins of the self s the ke" o+e!!$hin p!oblem

tht neu!os$ien$e shoul' im to sol+e. 0n" othe! b!in s$ientists& ho%e+e!& miht be in$line' to s" tht

$ons$iousness is the bi one.

1eu!os$ientists t!'itionll" h+e +oi'e' $onf!ontin $ons$iousness. The topi$ %s one tht !eti!e'

neu!os$ientists& f$in thei! o%n mo!tlit"& %oul' tlk bout& but "oun b!in !ese!$he!s kne% bette!. E+en >okin

bout it $oul' i+e "ou b' !eputtion. But times h+e $hne' n' 'is$ussions of $ons$iousness b"

neu!os$ientists !e on the !ise. The" h+e e+en been the bsis of n in'i$tment of s$ien$e. )n The End of Science,

John Ho!n& so$il $!iti$ tu!ne' s$ien$e >ou!nlist tu!ne' s$ien$e $!iti$& nnoun$e' tht neu!os$ien$e %s& like

othe! s$ien$es& 'e'. But unlike some othe! 'is$iplines& he !ue'& neu!os$ien$e %s en'in not be$use it h'

sol+e' its bi @uestion ho% 'oes $ons$iousness %o!k=but be$use it ne+e! %oul'.

) think it*s oo' tht s$ientists !e no% inte!este' in $ons$iousness& but ) lso belie+e it*s bein

o+e!emphsi,e'. Suppose ne(t %eek %e fin' out tht fte! 'e$'es of flse st!ts n' file' p!omises& n

in'eftible neu!os$ientist finll" hs sol+e' the $ons$iousness p!oblem. 7oul' tht !ell" tell us %ht mkes people

ti$k= 7oul' %e no% un'e!stn' %h" s$hi,oph!eni eme!es in one pe!son but not his t%in b!othe!C %h"& %hen t%o

people !e f$e' %ith bo'il" h!m& one is p!l",e' b" his fe! %hile the othe! fihts b$kC %h" n e($essi+el" sh"

$hil' is likel" to be$ome n n(ious 'ultC %h" some people !e +eet!ins n' othe!s en>o" !e' metC %h" met-

ete! sometimes o!'e!s +eet!in 'ishC %h" m" ki's $n*t stn' the musi$ ) listen toC o! %h" ) like thei!s= The

ns%e! to e$h of these is $le!l" 1o

The @uestion Synaptic SeKKsks is not “Ho% 'oes $ons$iousness $ome out of the b!in=# but !the! “Ho%

'oes ou! b!in mke us %ho %e !e=#

7ht pe!son is& n' %ht he o! she thinks& feels& n' 'oes& is b" no st!et$h of the imintion influen$e'

onl" b" $onS$iOUsneSs. 0n" of ou!

thouhts& feelins& n' $tions tke pl$e utomti$ll"& %ith $ons$iousness onl" $omin to kno% them s

the" hppen& if t ll. 8iu!in out the me$hnism of $ons$iousness %oul' su!el" be m>o! s$ientifi$ $oup& but it

%oul'n*t e(plin ho% the b!in %o!ks& o! ho% ou! b!ins mke us the in'i+i'uls %e !e.

/n un'e!stn'in of the m"ste!" of pe!sonlit" $!u$ill" 'epen's on fiu!in out the un$ons$ious fun$tions of

the b!in. nconscious is $tull" noto!iousl" mbiuous %o!'. Some people m" think it !efe!s to 8!eu'in

!ep!esse' memo!ies& othe!s tht it is %ht hppens in $om& o! fte! bein hit on the he'& o! '!inkin too mu$h.

1one of these 'efinitions is %ht ) h+e in min'. )nste'& %ht ) men b" the te!m is the mn" thins tht the b!in

'oes tht !e not +ilble to $ons$iousness. 27e $n be thnkful this is the %" %e fun$tion& fo! if %e h' to

$ons$iousl" pln e$h mus$le $ont!$tion& ou! b!in %oul' be so bus" %e %oul' p!obbl" ne+e! en' up $tull" tkin

step o! utte!in senten$e.3

:ons$iousness& t lest the kin' of $ons$iousness %e men %hen %e tlk bout ou! o%n mentl sttes& +e!"

likel" 'e+elope' in the b!in !e$entl" in e+olution!" histo!"& l"e!e' on top of ll the othe! p!o$esses tht l!e'" e(-

iste'>o Un$ons$ious ope!tion of the b!in is thus the !ule !the! thn the e($eption th!ouhout the e+olution!"

histo!" of the niml kin'om.# )t*s linuisti$ @ui!k& o! !e+elin $ultu!l ssumption& tht the ol'e! 2un$ons$ious3

p!o$esses !e 'efine' s netions of the ne%e! one 2$ons$iousness3. Lnue isn*t pe!fe$t.

7ht& then& !e ll these un$ons$ious p!o$esses= /$tull"& the" in$lu'e lmost e+e!"thin the b!in 'oes&



f!om stn'!' bo'" mintenn$e like !eultin he!t !te& b!ethin !h"thm& stom$h $ont!$tions& n' postu!e& to

$ont!ollin mn" spe$ts of seein& smellin& beh+in& feelin& spekin& thinkin& e+lutin& >u'in& belie+in& n'

iminin 7e $n be n' often !e %!e of %ht %e !e 'oin %hen these thins hppen& but mu$h of the time

$ons$iousness is info!me' fte! the f$t. 7hen someone speks to "ou& fo! e(mple& "ou 'e$o'e senten$e menin

on the bsis of the soun' of the %o!'s 2phonolo"3& the menin of the %o!'s 2semnti$s3& the !mmti$l !eltions

bet%een the %o!'s 2s"nt(3& n' "ou! kno%le'e bout the %o!l' 2p!mti$s3. You usull" !e not %!e ofpe!fo!min these ope!tions& but simpl" 'o them. 7hile "ou en' up $ons$iousl" kno%in %ht the pe!son si'& "ou

'on*t h+e $ons$ious $$ess to the p!o$esses tht llo%e' "ou to $omp!ehen' the senten$e. Simil!l"& %hen "ou

"ou!self utte! senten$es& "ou o th!ouh the sme p!o$esses& often %ithout $ons$ious thouht& but this time s the

ene!to! !the! thn the !e$ei+e!. Ou! bilities to pe!$ei+e the %o!l'& tten' to ob>e$ts n' e+ents& !emembe!&

imine& n' think ll ope!te p!ett" mu$h in this fshion. :olle$ti+el"& these p!o$esses h+e been $lle' the

ps"$holoi$l o! $oniti+e un$ons$ious n' the" $$ount fo! mu$h of mentl life.

Does tht men %e*ll kno% %ht pe!son is %hen %e fiu!e out the ope!tions of these +!ious $ons$ious

n' un$ons$ious fun$tions= 7hile unlo$kin the s"npti$ me$hnisms un'e!l"in e$h of these p!o$esses is itself

oin to be @uite $hllene& %e nee' to o be"on' the me!e e(plntion of ho% e$h %o!ks in isoltion. 7e nee' to

un'e!stn' ho% the mn" p!o$esses inte!$t& n' ho% the p!ti$ul! inte!$tions tht tke pl$e insi'e n in'i+i'ul*s

b!in i+e !ise to n' mintin %ho he o! she is. 0" im in this book is to sho% ho% it is possible& t lest in p!in$iple&

to bein to un'e!stn' the self in te!ms of su$h s"npti$ inte!$tions.

P!e+ious ttempts to !elte the self to the b!in h+e mostl" 'one so +i the $ons$ious self. 4e$entl"&

thouh& it ppe!s the ti'e is beinnin to tu!n. /ntonio Dmsio*s book& The Feelin! of "hat #appens, 'is$usses the

protoself kin' of $o!e self tht e(ists outsi'e of $ons$iousness& n' in The $inds% Past 0i$hel 9,,ni

emphsi,es the impo!tn$e of un$ons$ious p!o$esses in the p!o'u$tion of $ons$iousness. Thus& $ons$iousness&

fte! lon bein nele$te' in b!in s$ien$e& is finll" ettin the ttention it 'ese!+es& but it is lso bein put in its

pl$es p!t of& but not $omp!isin the enti!et" of& the mentl te!!in. /lthouh these othe! books 'el %ith the self

n' the b!in& the" 'o not e(plo!e the bioloi$l me$hnisms b" %hi$h the b!in mkes the self. This is %ht Synaptic

Self'oes.

/s %e bein to un'e!stn' ou!sel+es in s"npti$ te!ms& %e 'on*t h+e to s$!ifi$e othe! %"s of

un'e!stn'in e(isten$e. The i'e tht the self is $!ete' n' mintine' b" !!nements of s"npti$ $onne$tions&

in othe! %o!'s& 'oesn*t 'iminish %ho %e !e. )t inste' p!o+i'es simple n' plusible e(plntion fo! ho% the

eno!mousl" $omple( ps"$ho-spi!itul-so$io$ultu!l p$ke of p!otoplsm %e $ll ou! self is possible.

CHAPTER TWO

SEE5)19 THE SEL8



51O7 THYSEL8.

O!$le t Delphi

SEL8-51O7LED9E )S / D/19E4OUS TH)19.

Lo> 4eeo

Befo!e %e o lookin fo! the essen$e of pe!son in the b!in& it %oul' help to h+e some $on$eption of %ht

%e !e seekin. The!e*s $e!tinl" no sho!te of opinion bout %ht te!ms like personality o! the self miht men.

7illim Jmes& fo! e(mple& p!opose'A &In its 'idest possi(le sense)), a man*s%Self is the sum total of all that he CANcall his, not onl" his bo'" n' his ps"$hi$ po%e!s& but his $lothes n' his house& his %ife n' $hil'!en& his n$esto!s

n' f!ien's& his !eputtion n' %o!ks& his ln's n' ho!ses& n' "$ht n' bnk-$$ount.

)f the" %( n' p!ospe!& he feels t!iumphntC if the" '%in'le n' 'ie %"& he feels $st 'o%n&not

ne$ess!il" in the sme 'e!ee fo! e$h thin& but in mu$h the sme %" fo! ll.#*

)n f$t& %hole !e of ps"$holo" is 'e+ote' to the stu'" of pe!sonlit" n' the self. /n' theoloins&

philosophe!s& no+elists& n' poets h+e lso h' mu$h to s" on the sub>e$t. 7hile seeminl" 'eep t!uths h+e

sometimes eme!e' f!om these musins& it is not $le! ho%& if t ll& these insihts miht !elte to the %o!kins of the

b!in. /fte! ll& fo! mn" people& the b!in n' the self !e @uite 'iffe!ent. ) hope to sho% he!e tht this is not the $se.

To 'o so& ) fi!st nee' to 'es$!ibe %" of thinkin bout the self tht is $omptible %ith $u!!ent un'e!stn'in of b!in

fun$tion.

“SOUL SERENADE”

/ fe% months fte! st!tin this book& ) tten'e' $onfe!en$e on the !eltion bet%een the b!in n' the soui&

sponso!e' b" 2fittinl" enouh3 the 6ti$n. The spe$ifi$ topi$ %s “1eu!os$ien$e n' Di+ine /$tion&# n' the theolo-

ins %ho o!ni,e' this meetin %e!e t!"in to !e$on$eptuli,e :hu!$h te$hins in %" tht %oul' mke sense in

liht of $u!!ent s$ientifi$ un'e!-stn'in of ho% the %o!l' %o!ks. )n p!ti$ul!& the" %e!e ttemptin to 'ete!mine ho% it

is possible fo! 9o' to influen$e people*s li+es %ithout +ioltin the l%s of ph"si$s. ) $n*t p!esent the full !ne of

+ie%s e(p!esse'& but one tht stoo' out %s the notion tht 9o' interacts but 'oesn*t inter+ene)

The bsi$ i'e oes somethin like thisA )n the beinnin& 9o' set the uni+e!se up in $e!tin %" 2tht is&

he $!ete' the l%s of ph"si$s3 n' hs subse@uentl" left it lone& t lest fo! the most p!t. On t"pi$l '"&

the!efo!e& 9o' 'oesn*t $ont!ol the position of st!s n' plnets& mo+e mountins& p!t ses& $hne %ethe!

$on'itions& o! mke people 'o thins the" %oul'n*t othe!%ise 'o 2in othe! %o!'s& he 'oesn*t usull" inte!+ene3& but he

'oes $ommuni$te %ith people 2he inte!$ts3.

Ou! $on$e!n he!e is not %ith the theoloi$l !uments fo! n' inst noninte!+entionist +ie% of 9o' but

!the! %ith the possibilit" 2o! impossibilit"3 of s$ientifi$ +ie% of inte!$tion. 9i+en tht people li+e ph"si$l e(isten$e

in the ph"si$l %o!l'& n' tht 9o' is not p!t of the ph"si$l %o!l'& the @uestion isA Ho% $n 9o' inte!$t %ith

people= )f "ou belie+e in the e(isten$e of nonmte!il soul& then ll "ou nee' to ssume is tht %hen 9o' %s

$!etin the uni+e!se& he %o!ke' out some %" of inte!$tin %ith the soul. Sin$e both 9o' n' the soul !e

nonmte!il& tht inte!$tion %oul' lso be nonmte!il& n' the l%s of ph"si$s %oul' the!efo!e be un+iolte' %hen



inte!$tions o$$u!.

0u$h to m" su!p!ise& ho%e+e!& mn" of the theoloins tten'in this meetin 'i'n*t belie+e in $lssi$

nonmte!il soul 2this %oul' p!obbl" be n e+en bie! su!p!ise to the fithful the" !ep!esent3. )nste'& the" seeme'

to $$ept the p!in$iple tht the min' is ine(o!bl" tie' to the b!in& n' the" $onse@uentl" belie+e' in soul tht is

p!ett" mu$h one n' the sme s the neu!ll" me'ite' min'& p!t of the ph"si$l %o!l' tht must b" its ntu!e obe"

the l%s of ph"si$s.Theoloins %ho link the soul to the ph"si$l %o!l' $tull" h+e histo!" on thei! si'e. 7hile mn" :h!istins

to'" $ontinue to belie+e in soul tht is sep!te f!om the bo'" n' tht su!+i+es 'eth& this i'e 'i'n*t !ell" be-

$ome p!ominent in :h!istinit" until the 0i''le /es. E!l" :h!istin te$hins emphsi,e' the !esu!!e$tion

of the bo'" itself on Ju'ment D" !the! thn me!el" the su!+i+l of nonmte!il soul. /$$o!'in to 0!k FAMN&

Jesus si'& “)t is bette! fo! "ou to et into the 5in'om of 9o' %ith but one e"e thn to be th!o%n into 9ehenn %ith

both e"es.# This lesson %s pp!entl" not ment s"mboli$ll" but inste' !efle$te' the e!l" Ju'i$ notion tht %e

tke into the fte!life the bo'il" stte %ith %hi$h %e le+e this life.2This e(plins %h" Je%s n' :h!istins& n'

0uslims& h+e $emete!ies on the %este!n slopes of 0ount Oli+e& f$in the Este!n 9te of the Ol' :it" in Je!uslemA

the $lose! thei! bo'ies !e bu!ie' to the Este!n 9te& %hi$h is %he!e the 8inl Ju'ment is e(pe$te'& the soone! the"

%ill be !ise'.3 /n$ient E"ptins lso seem to h+e belie+e' tht the bo'"& n' not >ust the spi!it& $!!ies on in some

%" fte! 'eth. )n the Tomb of 0enen& fo! e(mple& foe of the !o"l fmil" $hisele' off thei! f$es to ensu!e tht

the" %ent into the ne(t life ph"si$ll" $hllene'.

)f the soul is in'ee' ph"si$l in ntu!e& p!t of the 'ilemm bout ho% to sustin belief in both ph"si$s n'

9o' %oul' be sol+e' 2the p!t bout ho% the soul meshes %ith the bo'"3. Ho%e+e!& the tho!ouhl" mo'e!n theolo-

ins %oul' still be in bit of @untum pi$kle. )f the soul is e@ui+lent to the min'& n' the min' 'epen's on the

fun$tionin of the b!in& ho% $n 9o' inte!$t %ith people %ithout ph"si$ll" ffe$tin thei! neu!ons n'& thus&

inte!+enin= /n' %he!e is the soul hnin out %hile the bo'" 'e$"s in the inte!im bet%een 'eth n' Ju'ment

D"= 1ot su!p!isinl"& the 6ti$n $onfe!en$e en'e' in$on$lusi+el". 1o mtte! ho% ll the pie$es of the pu,,le %e!e

mo+e' !oun'& the" 'i'n*t fit toethe! to mke $ohe!ent pi$tu!e. /s the philosophe! D+i' Hume si' lon o& loi$

n' !esonin 2n' p!esumbl" s$ien$e3 $nnot e(plin the immo!tlit" of the soul. Eithe! "ou belie+e o! "ou 'on*t.

0" !eson fo! 'is$ussin this $onfe!en$e n' the issues it !ise' is not so mu$h to !ue the point tht it

%oul' be 'iffi$ult& n' m"be impossible& to fin' s$ientifi$ solutions to theoloi$l !i''les& but !the! to 'emonst!te

tht spi!itul +ie% of the self isn*t 2o! 'oesn*t h+e to be3 completely in$omptible %ith bioloi$l one. 7hte+e!

else %e !e n' !en*t& mu$h of %ht %e !e is $$ounte' fo! b" %ht oes on in ou! b!ins. Some theoloins& s

%e+e seen& h+e $ome to $$ept this. But e+en people %ho belie+e in n immte!il soul tht su!+i+es 'eth h+e

$kno%le'e' the f$t tht the no!ml fun$tionin of the soul 'epen's on the b!in. Shkespe!e emb!$e' this

notion %hen he $lle' the b!in the soul*s f!il '%ellin / fe% minutes %ith m" mothe!& 'e+out :tholi$ %ith

/l,heime!*s 'isese& mkes it pinfull" $le! >ust ho% f!ile the soul*s '%ellin is.

THE LIMITS OF LOGIC

Theoloins !en*t the onl" ones %ho h+e $on$e!ne' themsel+es %ith inte!$tions bet%een bo'" n' soul.

The @uestion is lso one of the m>o! pu,,les tht hs o$$upie' philosophe!s th!ouh the es. )n the se+enteenth

$entu!"& the 8!en$h mthemti$in 4en Des$!tes 'e+ise' %" of thinkin bout bo'" n' soul tht hs shpe'

philosophi$l 'ebte on this topi$ e+e! sin$e.* Like the $ontempo!!" theoloins 'es$!ibe' bo+e& Des$!tes souht

mens of !e$on$ilin s$ien$e n' fith. His solution %s to p!opose tht “the mentl# n' “the ph"si$l# %e!e

sep!te substn$es tht met n' inte!$te' t spe$il pl$e in the b!in.

Histo!ins seem to !ee tht the e!liest 9!eek philosophe!s 'i' not h+e $le!l" 'istinuishe' notions of

bo'" n' soul.# Lte!& thouh& some philosophe!s $me to +ie% bo'" n' soul s sep!te. Plto& fo! e(mple&

belie+e' tht the intelle$tul essen$e of n in'i+i'ulhis ps"$he o! soulsu!+i+es 'eth.* )n f$t& Plto looke'

fo!%!' to 'eth so tht he $oul' be f!ee of his bo'" n' ll its nee's n' pssions n' finll" be $pble of pu!e



thouht.* 8o! /!istotle& in $ont!st& bo'" n' soul %e!e so inte!ll" !elte' tht the" $oul' not be sep!te'& thouh

the" $oul' be 'istinuishe' $on$eptull".* B" the 0i''le /es& philosophe!s 'opte' $ombintion of these notions&

+ie%in bo'" n' soul s t%o unifie' ;substn$es* 2like /!istotle3 but !e!'in the soul s ete!nl 2like Plto3.

/@uins& fo! e(mple& belie+e' tht the intelle$tul& nonmte!il @ulities of min' +e the soul immo!tlit"C n' tht

the bo'" %s !esu!!e$te' n' !eunite' %ith the soul on Ju'ment D".*

This %s the intelle$tul b$k'!op inst %hi$h Des$!tes pl"e' his influentil 'is$ussion of bo'" n'min'. Like Plto& he +ie%e' the mentl n' ph"si$l s sep!te substn$esA “0" soul& b" %hi$h ) m %ht ) m ... is

enti!el" n' bsolutel" 'istin$t f!om m" bo'"& n' $n e(ist %ithout it.# )n fusion of fith n' ps"$holoi$l theo!"&

Des$!tes e@ute' the soul %ith $ons$iousness& n' si' onl" humns h+e $ons$ious $ont!ol of thei! beh+io!.

The!efo!e& onl" humn souls $n in o! lose $$ess to he+en b" thei! $tions. The beh+io!s of othe! nimls %e!e&

in Des$!tes*s s$heme& !efle(i+e o! utomti$& n' $!!ie' out %ithout thouht. So& fo! Des$!tes& if it %sn*t

$ons$ious& it %sn*t mentl. Des$!tes 'i'n*t e($tl" 'en" the e(isten$e of un$ons$ious p!o$esses& but simpl"

!elete' them to the ph"si$l %o!l'& p!oposin tht the" fun$tion in humns the %" the" 'o in min'less 2soulless3

nimls.

But if ;the ph"si$l* n' ;the mentl* !e $ompletel" 'iffe!ent entities& ho% $n the $ons$ious soul 2the mentl3

be !esponsible fo! the ph"si$l bo'"= Des$!tes*s solution %s tht the $ons$ious soul substn$e $n inte!$t %ith

the mte!il bo'" b" mens of smll !eion of the b!in $lle' the pinel ln'. ;:fhile most p!ts of the b!in e(ist

in 'upli$te& the pinel ln' is sinul! n' $ent!ll" lo$te'& %hi$h sueste' to Des$!tes tht it must be the set

of min'-bo'" inte!$tion pl$e %he!e $ommn's f!om the soul $n influen$e the bo'"& n' %he!e info!mtion f!om

the bo'" 2eithe! bout the outsi'e %o!l' o! the bo'" itself3 $n ente! the soul s pe!$eptions& emotions& n'

kno%le'e.

)n Des$!tes*s s$heme& the nonph"si$l soul substn$e $tull" se!+e' the 'ul fun$tion of $ommuni$tin

%ith the ph"si$l bo'" s %ell s %ith 9o'. This inte!pl" bet%een ph"si$l n' nonph"si$l substn$es is p!e$isel"

the kin' of solution to the p!oblem of ho% 9o' inte!$ts %ith people tht the theoloins t the 6ti$n $onfe!en$e

%e!e t!"in to mo+e be"on'. Ou! inte!est he!e& ho%e+e!& is not in the theoloi$l @uestion 2Ho% 'oes 9o' inte!$t

%ith the soul=3& but in the philosophi$l one 2Ho% 'oes the min' inte!$t %ith the bo'"=3. Des$!tes*s f!min of the

philosophi$l @uestion& n' his p!ti$ul! ns%e! to it 2 min'-bo'" inte!$tion in the b!in3& set up the $onun'!um

kno%n s the min'-bo'" p!oblem& %hi$h philosophe!s h+e st!ule' %ith e+e! sin$e. ) %nt to mke t%o points

bout this sub>e$t tht !e !ele+nt to the p!esent 'is$ussion.

8i!st& in e@utin the min' %ith $ons$iousness& Des$!tes f!me' the min'-bo'" p!oblem in te!ms of the

!eltion bet%een $ons$iousness n' the b!in. /s su$h& the min'-bo'" p!oblem& in its t!'itionl $on$eption& $on$e!ns

n aspect of the min' !the! thn the %hole min'. 0ost of %ht the b!in 'oes is not& in f$t& p!t of the t!'itionl

min'-bo'" 'ebte. Some $ontempo!!" philosophe!s tke b!o'e! +ie% thn Des$!tes n' $$ept tht $e!tin

non$ons$ious spe$ts of b!in fun$tion lso $ont!ibute to mentl life.* Ho%e+e!& the" !e!' su$h non$ons$ious

spe$ts s “es" p!oblems# tht !e not !ell" the $on$e!n of philosoph". /s %ill be$ome pp!ent lte! in this

$hpte!& ) belie+e tht these impli$it o! un$ons$ious spe$ts of the self lso pl" n impo!tnt !ole& in f$t n essentil

one& in shpin %ho %e !e n' e(plinin %h" %e 'o %ht %e 'o.

Se$on'& it*s impo!tnt to 'istinuish the philosophi$l min'-bo'" p!oblem f!om the neu!os$ientifi$ p!oblem

bout ho% the b!in $!etes the min'. Philosophe!s& b" 'efinition& seek philosophi$l solutions to p!oblems 2in$lu'in

the min'-bo'" p!oblem3 n' 'is$uss the possible !eltions& the loi$& tht miht e(ist bet%een fun'mentl

substn$es in ntu!e 2mtte! n' min'3. 1eu!os$ientists& b" $ont!st& t"pi$ll" st!t %ith the ssumption tht the

mte!ilist +ie% of the min'-bo'" p!oblem is $o!!e$t 2tht the min' is p!o'u$t of the b!in3& n' then t!" to

un'e!stn' ho% the b!in mkes the min' possible.* )n f$t& mn" philosophe!s to'" $$ept some +e!sion of m-

te!ilism& but e+en if the ti'es shoul' shift in the $omin "e!s n' 'ulism 2the belief tht min' n' bo'" !e

sep!te substn$es3 shoul' tke o+e! philosoph"& neu!os$ientists %ill not be out of >obs. B!in !ese!$he!s !e& fte!

ll& stu'"in the b!in& not philosoph". This 'oes not men tht the pths of the neu!os$ientist n' philosophe! ne+e!



$!oss. The" often 'o& n' %hen the" 'o& e$h !oup hs sometimes been enlihtene' 2n' sometimes en!e'3 b"

the othe!. But& ultimtel"& be$use philosophe!s n' b!in s$ientists !e pu!suin 'iffe!ent $on$e!ns& p!o!ess in one

fiel' 'oes not ne$ess!il" sinl n '+n$e o! 'efet in the othe!.

)n spite of m" o%n $ontention tht $ons$iousness is not the be-ll n' en'll of min' n' beh+io!& )

ne+e!theless h+e $onsi'e!ble s"mpth" fo! the belief tht neu!os$ien$e %ill $ome to e(plin $ons$iousness.

Des$!tes %s $o!!e$t in thinkin bout un$ons$ious mentl p!o$esses in ph"si$l te!msC he e!!e'& ho%e+e!& in$on$ei+in of $ons$iousness s nonph"si$l. Tht the b!in me$hnisms un'e!l"in $ons$ious e(pe!ien$e h+en*t

been fiu!e' out "et 'oesn*t men tht the" %ill !emin obs$u!e fo!e+e!. )n f$t& !e$ent !ese!$h hs beun to mke

some he'%" in un'e!stn'in the b!in me$hnisms of $ons$iousness& n' %e*ll tke look t this %o!k lte! in

the book.

OUR BODIES, OUR SELVES

/lthouh the min'-bo'" p!oblem is the f+o!ite topi$ of philosophe!s %ho %o!k in the !e $lle' the

philosoph" of the min'& some of these philosophe!s h+e othe! thins on thei! min's. One tht is p!ti$ul!l" !ele+nt

to us& n' tht is $losel" inte!t%ine' %ith the min'-bo'" p!oblem& is the issue of %ht $onstitutes pe!son. )s pe!son

bo'"& min'& min' in bo'"= Does pe!son h+e to be humn= /!e ll humns pe!sons= :oul' $!etu!e f!om

nothe! plnet be pe!son= :n humn lose pe!sonhoo' s !esult of b!in 'me& insnit"& o! mo!l

t!ns!essions= 7hen 'u!in life 'oes pe!sonhoo' st!t n' stop= )s n emb!"o o! n infnt pe!son= 7ht bout

someone %ho line!s fo! months in $om f!om %hi$h he %ill& b" me'i$l p!e'i$tion&

ne+e! !e$o+e!= The ltte! @uestions h+e %i'e-!nin so$il n' lel impli$tions& but onl" if the fo!me!

ones $n be ns%e!e' in some !esonble %". )f %e $n*t estblish p!e$isel" %ht pe!son is& it mtte!s little

%hethe! %e !e one o! not. John Lo$ke h' somethin like this in min' %hen he si'& hun'!e's of "e!s o& tht

person is “fo!ensi$ te!m& pp!op!itin $tions n' thei! me!itC n' so belons onl" to intellient ents& $pble of

l%& n' hppiness n' mise!". . . . This pe!sonlit" e(ten's itself be"on' p!esent e(isten$e to %ht is pst& onl" b"

$ons$iousness.

Pete! St!%son is pe!hps the best-kno%n mo'e!n philosophe! in this !e. His mu$h-$ite' ppe! “Pe!sons

st!ts %ith Lu'%i 7ittenstein*s sse!tion tht bo'ies !e not in possession of the sttes of $ons$iousness tht $ome

out of themA “The ) o$$u!s in philosoph" th!ouh the f$t tht the ;%o!l' is m" %o!l'. The philosophi$l ) is not the

mn& not the humn bo'"& o! the humn soul . . . but the metph"si$l sub>e$t& the limitnot p!t of the %o!l'.#

You*ll p!obbl" be hpp" to kno% tht St!%son& too& %s pu,,le' b" these %o!'s& %hi$h he $lle' imp!essi+e but

obs$u!e.

St!%son %s moti+te' b" 7ittenstein*s !$ne sttements to t!" to e(plin the i'e of somethin tht is

both sub>e$t of e(pe!ien$es 2tht is& is $ons$ious3 n' is p!t of the %o!l' 2tht is& is 'epen'ent on bo'"3. He

%nte' to un'e!stn' the !eltion bet%een t%o @uestionsA 7h" 'o %e s$!ibe sttes of $ons$iousness to ou! bo'ies&

n' %h" 'o %e s$!ibe sttes of $ons$iousness to n"thin t ll= Des$!tes h' !ise' the fi!st %hen he si'& “) m

not lo'e' in m" bo'" like pilot in +essel&# n' 7ittenstein the se$on' %ith his sttement tht “The thinkin&

p!esentin sub>e$tthe!e is no su$h thin.#

/$$o!'in to St!%son& be$use %e $n tt!ibute ou! o%n sttes of $ons$iousness to ou!sel+es& othe!s like

us must lso h+e simil! sttes of $ons$iousness. )f %e $n fiu!e out ho% to i'entib3! those %ho !e like us& %e $n

kno% to %hom $ons$iousness shoul' be tt!ibute'in othe! %o!'s& %e $n kno% %ho is pe!son. To 'o this& he

'istinuishe' bet%een t%o kin's of sttementsA those tht ob+iousl" $n be pplie' to mte!il bo'ies tht lso e(hibit

$ons$iousness 2“is in pin&# “is thinkin&# “belie+es in 9o'#3 n' those tht $n be pplie' e@ull" to mte!il bo'ies

tht !e $ons$ious n' tht !e not 2“is he+"# “is tll&# “is h!'#3.

Like Lo$ke n' St!%son& mn" philosophe!s h+e tken the +ie% tht pe!sonhoo' is $h!$te!isti$ of

intellient& $ons$ious $!etu!es& tht $ons$iousness is& in f$t& the @ulit" tht 'efines pe!sonhoo'. But othe!s 'emn'

mo!e& in the fo!m of mo!l element. This %s impli$it in Lo$ke& s %ell s in the %!itins of 5nt. Dniel Dennett



$ombine' the thouht of Lo$ke n' 5nt& n' othe! philosophe!s& p!oposin tht the!e !e t%o inte!!elte' notions of

pe!son& one mo!l n' one metph"si$l. The metph"si$l pe!son is thinkin& feelin& intellient& $ons$ious

ent& %hile the mo!l pe!son is one %ho is $$ountble fo! his $tions. Dennett sks %hethe! bein pe!son in the

metph"si$l sense utomti$ll" mkes one pe!son in mo!l sense& o! 'oes it me!el" mke mo!l $p$it"

possible. He oes on to list se+e!l $on'itions of pe!sonhoo'. / bein is pe!son if it is !tionl& +e!bl& $ons$ious&

n'& in f$t& self-$ons$ious& $pble of bein $te' to%!' in $e!tin %"& n' $pble of !e$ip!o$tin %hen $te'to%!' in this %". Dennett*s list lso bo!!o%e' f!om John 4%ls& %ho !ue'& “To !e$oni,e nothe! s pe!son one

must !espon' to him n' $t to%!'s him in $e!tin %"s&# n' f!om Thoms 1el& %ho ffi!me' tht “e(t!emel"

hostile beh+io! to%!'s nothe! is $omptible %ith t!etin him s pe!son.# But Dennett& in the en'& $on$lu'es tht

these !e ne$ess!" but not suffi$ient $on'itions fo! 'efinin pe!sontht the!e is& fun'mentll"& no %" to set

pssin !'e fo! pe!sonhoo' tht is not !bit!!".

The $on$ept of the self& %hi$h is of utmost impo!tn$e to us he!e& is $losel" !elte' to the philosophi$l

notion of pe!son. 7ithin philosoph"& the!e hs& in f$t& been !o%in inte!est in the self& n out$ome of %hi$h hs

been the eme!en$e of 'istin$tions bet%een 'iffe!ent spe$ts of the self. One mu$h-'is$usse' 'istin$tion is bet%een

the minimum n' the n!!ti+e self.* The fo!me! is n imme'ite $ons$iousness of one*s self& n' the ltte!

$ohe!ent self-$ons$iousness tht e(ten's %ith pst n' futu!e sto!ies tht %e tell bout ou!sel+es. The n!!ti+e self

be!s some !eltion to the postmo'e!n notion tht the self is so$ill" $onst!u$te'. 7hile so$il $onst!u$tion is often

+ie%e' s 'imet!i$ll" oppose' to s$ientifi$ +ie% of mn& the t%o !e not ne$ess!il" t o''s %ith e$h othe! sin$e

b!ins& in the en'& !e !esponsible fo! both the beh+io!s tht $olle$ti+el" $onstitute the so$il milieu& n' fo! the

!e$eption b" e$h in'i+i'ul of the info!mtion $on+e"e' b" this milieu.

)n fo$usin on $ons$iousness s the le'in metph"si$l fetu!e of %ho %e !e& philosophe!s inte!este' in

the @uestion of pe!sonhoo' n' the self le+e out mu$h of %ho %e !ell the non$ons$ious spe$ts. /n' in 'i+i'in

the %o!l' into mte!il ob>e$ts n' $ons$ious sel+es o! pe!sons& s St!%son 'i'& nonhumn nimls !e pl$e' in

kin' of ontoloi$l limbo& sin$e nonhumn niml $nnot be pe!son.

/lthouh othe! nimls !e not $ons$ious in the humn sense& the" !e not simpl" ob>e$ts& like !o$ks o!

$hi!s. The" !e li+in $!etu!es %ith ne!+ous s"stems tht mke it possible fo! thei! bo'ies to inte!$t %ith n'

$hne the mte!il %o!l' in %"s tht !o$ks n' $hi!s $nnot. The $on$ept of pe!son& $ons$ious self& %hile

useful s %" of e+lutin issues !elte' to bein humn& is thus less +luble s ene!l-pu!pose $on$ept fo!

un'e!stn'in e(isten$e in the $onte(t of ou! niml n$est!". /n' be$use %e must pu!sue mn" spe$ts of ho%

the b!in %o!ks th!ouh stu'ies of nonhumn o!nisms& %e nee' $on$eption of %ho %e !e tht !e$oni,es the

e+olution!" !oots of the humn bo'"& in$lu'in the b!in.

Thouh not s %i'el" 'is$usse' s $ons$ious spe$ts of the self& non$ons$ious spe$ts !e ne+e!theless

impo!tnt. The" !e essentil to the Bu''hist ttempt to eliminte the $ons$ious self& to i'es bout multiple sel+es b"

7illim Jmes n' othe!s s %ell s to notions of p!imiti+e& non$on$eptul& o! e$oloi$l self tht e(ists outsi'e of

$ons$ious %!eness. On$e %e $$ept tht the self of humn $n h+e $ons$ious n' non$ons$ious spe$ts& it

be$omes es" to see ho% othe! nimls $n be thouht of s h+in sel+es& so lon s %e !e $!eful bout %hi$h

spe$ts of the self %e !e s$!ibin to e$h spe$ies in @uestion.

The self& then& is notion tht $n be $on$ei+e' of lon n e+olution!" $ontinuum. 7hile onl" humns $n

h+e the uni@ue spe$ts of the self m'e possible b" the kin' of b!ins tht humns h+e& othe! nimls h+e the

kin's of sel+es m'e possible b" thei! o%n b!ins. To the e(tent tht mn" of the s"stems tht fun$tion

non$ons$iousl" in the humn b!in fun$tion simil!l" in the b!ins of othe! nimls& the!e is $onsi'e!ble o+e!lp in

the non$ons$ious spe$ts of the self bet%een spe$ies. Ob+iousl"& the mo!e simil! the b!ins& the mo!e the o+e!lp.

The e(tent to %hi$h othe! nimls h+e n" kin' of $ons$iousness is& unfo!tuntel"& impossible to kno%. 7e

$n spe$ulte& but be$use the humn min' $nnot be$ome $t& 'o& bi!'& li,!'& f!o& o! fish min'& %e $nnot

kno% %ith $e!tint" ho% su$h @uestion shoul' be ns%e!e'. Des$!tes*s !etest $ont!ibution %s pe!hps his

$on$lusion tht the onl" thin he $oul' kno% %ith $e!tint" %s his o%n min'. So lon s %e !e tlkin bout othe!



nimls %ith b!ins like ou! o%n 2tht is& othe! humns3& %e $n h+e some $onfi'en$e tht thei! mentl sttes !e

like ou!s. But %e $nnot %ith n" 'e!ee of $e!tint" e(t!polte f!om ou! o%n mentl sttes to those of othe! spe$ies.

)n spite of h+in otten this f! %ith some ke" $on$epts f!om philosoph"& the f$t is tht philosoph" %ill

p!obbl" not i+e us the kin' of foun'tion %e nee' to pu!sue the !eltion bet%een the self n' the b!in.3 To stte

tht min'& o! pe!son& o! self is ll ph"si$l& o! ll mentl& o! p!tl" ph"si$l n' p!tl" mentl& o! somethin else

ltoethe! 2like the p!o'u$t of so$ill" $onst!u$te' !eltions bet%een people3& l"s out the te!!ito!" in %" tht is use-ful fo! nl",in b!o' $teo!ies of e(pe!ien$e %ithin n' bet%een spe$ies& but 'oes not tell us mu$h bout ho% to

pu!sue me$hnisms in the b!in. )f %e !e oin to fiu!e out ho% it is tht ou! b!ins mke us %ho %e !e& %e nee'

%" of linkin fi!l" 'etile' $on$eption of %ho %e !e to neu!l fun$tions. Ps"$holo" m" be mo!e !ele+nt to tht

pu!pose.

MIND SCIENCE

Ps"$holo" %s $tull" b!n$h of philosoph" until the lte nineteenth $entu!"& %hen 7ilhelm 7un't&

9e!mn ph"sioloist& ben 'oin e(pe!iments to un'e!stn' the %" the min' %o!ks !the! thn >ust spe$ultin

bout it. He n' his follo%e!s& kno%n s int!ospe$tionists& took the ke" steps !e@ui!e' to $on+e!t ps"$holo" into n

e(pe!imentl s$ien$e. Thei! min topi$ of in+estition %s $ons$ious e(pe!ien$e& %hi$h the" e(plo!e' b" e(minin

thei! o%n e(pe!ien$es& ttemptin to b!ek them into essentil& i!!e'u$ible elements.

But e!l" in the t%entieth $entu!"& some ps"$holoists ben to !ue tht this %s no %" to $on'u$t

s$ientifi$ !ese!$h& sin$e one*s $ons$ious e(pe!ien$es $n onl" be kno%n pe!sonll"& n' $nnot be +e!ifie' b"

othe!s. This i'e $uht on n' e+entull" sp%ne' beh+io!ism& %hi$h %s bse' on the p!emise tht

s$ientifi$ll" +li' ps"$holo" h' to fo$us on obse!+ble e+ents 2beh+io!l !esponses3 !the! thn inte!nl sttes.

Some of its 'he!ents %e!e metho'oloi$l beh+io!ists& %hi$h ment the" 'i'n*t ne$ess!il" !e>e$t the e(isten$e of

$ons$iousness& but simpl" belie+e' it $oul'n*t be stu'ie'. 4'i$l beh+io!ists& in $ont!st& $tull" 'enie' tht

$ons$iousness e(iste'. 8o! them& mentl sttes %e!e illusions $!ete' b" ten'en$ies to $t in one %" o! nothe!.

Philosophe!s like 9ilbe!t 4"le 'opte' !'i$l beh+io!ism s !esolution to the min'-bo'" p!oblem& elimintin the

min' enti!el"& le+in onl" the ph"si$l bo'" to be e(pline' in ph"si$l te!ms. 4"le $lle' mentl sttes “hosts in

the m$hine&# fte! the “'eus e( m$hin# of 9!eek t!e'"& o' tht %s lo%e!e' onto the ste f!om bo+e to

sol+e the p!oblems of mo!tls.

To%!' the mi''le of the $entu!"& it '%ne' on some s$ientists tht the ope!tions 2$omputtions3 pe!fo!me'

b" $ompute!s %e!e not unlike %ht humn 'oes %hen sol+in p!oblem. This notion %s emb!$e' b" some

f!sihte' ps"$holoists like Je!!" B!une! n' 9eo!e 0ille!& n' the $oniti+e pp!o$h to ps"$holo"&

%hi$h emphsi,e' inte!nl me$hnisms tht p!o$ess info!mtion& %s bo!n. This %s n tt!$ti+e lte!nti+e to

min'less beh+io!ism& n' e+entull" the $oniti+e mo+ement 'eth!one' beh+io!ism n' b!ouht the min' b$k to

ps"$holo".

The min' tht !etu!ne'& thouh& %s not e($tl" the one tht the beh+io!ists h' 'ispose' of Beh+io!ists

h' ob>e$te' to the emphsis of int!ospe$tionists on mentl $ontent 2the e(pe!ien$e of the $olo! !e'& fo! e(mple3.

:oniti+e s$ientists& ho%e+e!& %e!e stu'"in mentl processes !the! thn the $ontent of $ons$iousness. The" %e!e

mo!e $on$e!ne' %ith ho% $olo!s !e 'ete$te' n' 'is$!iminte' thn in %ht it is like $tull" to e(pe!ien$e them.

)t is no% %i'el" !e$oni,e' tht %e $n h+e $ons$ious $$ess to the out$ome of $oniti+e p!o$esses& but

%e !e not usull" %!e of the p!o$esses tht %e!e in+ol+e' in ene!tin tht $ontent. Ou! pe!$eptions& memo!ies&

n' thouhts ene!ll" %o!k in hpp" ino!n$e of the p!o$esses tht mke them possible. 8o! $oniti+e s$ientists&

n' in st!k $ont!st to Des$!tes& min' n' $ons$iousness !e not t ll the sme.

The $oniti+e mo+ement h' t!emen'ous imp$t on ps"$holo"& but its influen$e 'i' not stop the!e.

)nfo!mtion-p!o$essin $on$epts %e!e lso 'opte' b" %o!ke!s in linuisti$s& nth!opolo"& n' othe! so$il s$ien$es&

s %ell s mthemti$s n' ph"si$s. /n' >ust s ps"$holoists %e!e $on$ei+in of min's in te!ms of $ompute!

ope!tions& $ompute! s$ientists n' mthemti$ins %e!e pu!suin the notion tht $ompute!s miht pe!fo!m min'like



ope!tions& n i'e tht le' to the fiel' of !tifi$il intellien$e 2/L3. Ultimtel"& $oniti+e s$ien$e eme!e' s n

inte!'is$iplin!" pp!o$h to un'e!stn'in ho% the min' %o!ks. )t $me to be $lle' “the ne% s$ien$e of min'.#

The f$t tht $oniti+e p!o$esses !e not 'epen'ent on $ons$iousness 2$tull"& $ons$iousness 'epen's on

unconscious $oniti+e p!o$esses3 mens tht the mentl +s. ph"si$l 'ilemm 'oes not h+e to be o+e!$ome in o!'e!

to stu'" the b!in me$hnisms of $onition. )n'ee'& mn" of the p!o$esses stu'ie' b" $oniti+e s$ientists !e lso

topi$s of !ese!$h pu!sue' b" so-$lle' $oniti+e neu!os$ientists. Le' b" b!ekth!ouhs in un'e!stn'in the ps"-$holo" of $onition& $oniti+e neu!os$ientists h+e been +e!" su$$essful in !eltin pe!$eption& ttention& memo!"&

n' thinkin to un'e!l"in me$hnisms in the b!in.

:oniti+e ps"$holo"& n' its siste!& $oniti+e neu!os$ien$e& %oul' thus seem to be tkin us e+e! $lose!

to%!' ps"$holoi$l n' neu!obioloi$l un'e!stn'ins of the self. Ho%e+e!& this is not e($tl" the $se. Thouh %e

un'e!stn' ho% spe$ifi$ $oniti+e p!o$esses %o!k ps"$holoi$ll" n' neu!oloi$ll"& $oniti+e pp!o$hes fll sho!t

%hen it $omes to e(plinin the self.

8i!st of ll& b" its +e!" 'efinition& $oniti+e s$ien$e is s$ien$e of onl" p!t of the min'the $oniti+e p!t

n' not s$ien$e of the %hole min'. T!'itionll"& s %e*ll see in $hpte! N& the min' hs been +ie%e' s t!ilo"&

$onsistin of $onition& ffe$t 2emotion3& n' $ontion 2moti+tion3. The f$t tht emotion n' moti+tion !e not

stu'ie' b" $oniti+e s$ien$e mkes sense if $oniti+e s$ien$e is !e!'e' s s$ien$e of $onition& but is t!oublin if

the fiel' is suppose' to be the s$ien$e of min'. / min' %ithout feelins n' st!i+ins 2the kin' of min' t!'itionll"

stu'ie' in $oniti+e s$ien$e3 miht be ble to sol+e $e!tin p!oblems i+en it b" $oniti+e ps"$holoist& but it 'oesn*t

st$k up %ell s the mentl foun'tion of self The kin' of min' mo'ele' b" $oniti+e s$ien$e $n& fo! e(mple& pl"

$hess +e!" %ell& n' $n e+en be p!o!mme' to $het. But it is not plue' %ith uilt %hen it $hets& o! 'ist!$te' b"

lo+e& ne!& o! fe!. 1eithe! is it self-moti+te' b" $ompetiti+e st!ek& o! b" en+" o! $ompssion. )f %e !e to

un'e!stn' ho% the min'& th!ouh the b!in& mkes us %ho %e !e& %e nee' to $onsi'e! the 'hole min'& not >ust the

p!ts tht subse!+e thinkin.

/ se$on' sho!t$omin of $oniti+e s$ien$e is tht it hs not !pple' su$$essfull" %ith ho% +!ious $oniti+e

p!o$esses inte!$t to fo!m the min'. :onsi'e!ble p!o!ess hs been m'e in un'e!stn'in ho% pe!$eption&

memo!"& n' thinkin %o!k& but not bout ho% the" %o!k toethe!. /n' in liht of the t!ip!tite ntu!e of the min'& n

un'e!stn'in of the self is oin to !e@ui!e tht %e not onl" fiu!e out ho% +!ious $oniti+e p!o$esses inte!$t& but

lso tht %e in$lu'e emotions n' moti+tions in the mi( n' fiu!e out ho% the" inte!$t %ith one nothe!& s %ell s

ho% the" inte!$t %ith $oniti+e p!o$esses. Ou! hopes& fe!s& n' 'esi!es influen$e ho% %e think& pe!$ei+e& n'

!emembe!. / s$ien$e of min' nee's to $$ount fo! n' un'e!stn' these $omple( p!o$esses.

/n'& finll"& $oniti+e s$ien$e 'els %ith the %" the min' t"pi$ll" %o!ks in most of us& !the! thn the %" it

%o!ks uni@uel" in n" one of us. 7hile %e ll h+e bsi$ll" the sme mentl p!o$esses me'ite' b" the sme b!in

me$hnisms& the %" these p!o$esses n' me$hnisms ope!te is 'ete!mine' b" ou! p!ti$ul! eneti$ b$k!oun'

n' life e(pe!ien$es.

)t %oul' be h!' to o+e!stte the impo!tn$e of $oniti+e s$ien$e. )t hs been e(t!emel" su$$essful s

!ese!$h p!o!m& n' hs !e+olutioni,e' the %" %e $on$ei+e of the min'. So %hen ) sinle out the sho!t$omins of

the

fiel'& ) 'o so not to $on'emn it& but inste' to simpl" point out tht it*s in$omplete %hen it $omes to

un'e!stn'in %ht mkes us %ho %e !e.

THE PERSONALITY CONTEST

Ps"$holo"& s %e kno% it to'"& is n impe!fe$t m!!ie bet%een t%o 'istin$t pp!o$hes to the %o!kins

of the min' tht eme!e' in the lte nineteenth $entu!". One is the e(pe!imentl pp!o$h& %hi$h emphsi,es the

%" spe$ifi$ mentl p!o$esses& like pe!$eption o! memo!"& t"pi$ll" %o!k. This is the pp!o$h tht +e !ise to

$oniti+e ps"$holo". The othe! pp!o$h is mo!e $on$e!ne' %ith ho% %ell-'>uste' people !e n' ho% the" miht

$hne thei! beh+io! to imp!o+e thei! ps"$holoi$l %ell-bein. )t fo$uses on in'i+i'uls n' thei! i'ios"n$!ti$ t!its&



hbits& feelins& n' thouhts& !the! thn on the %" thins %o!k in most people most of the time. The +!ious fo!ms

of ps"$hothe!p" in use to'" !e out!o%ths of this pp!o$h& %hi$h hs lso been fountinhe' fo! theo!ies of

pe!sonlit". This is the kin' of ps"$holo" tht is po!t!"e' in films n' no+els n' is %ht people usull" h+e in

min' %hen the" think of %ht ps"$holoist is.

)'es bout pe!sonlit" !e p!obbl" s n$ient s i'es. /!oun' M B.:.& Hippo$!tes& fo! e(mple&

p!opose' tht one*s helth n' $h!$te! %e!e 'ete!mine' b" the inte!$tion mon fou! bo'il" humo!s 2bloo'&phlem& bl$k bile& n' "ello% bile3& e$h of %hi$h& in tu!n& !efle$te' fou! $osmi$ elements 2e!th& %te!& i!& n' fi!e3.

Si( hun'!e' "e!s lte!& 9len e(pn'e' the theo!"& p!oposin tht e($ess in one o! nothe! humo! +e people 'is -

tin$ti+e pe!sonlities. 2E($ess bloo' le' to snuine& enthusisti$ pe!sonlit"C too mu$h bl$k bile m'e one

meln$holi$C bun'n$e of "ello% bile le' to i!!itble o! $hole!i$ tempe!mentC n' o+e!p!o'u$tion of phlem +e

!ise to slo%& ptheti$& o! phlemti$ pe!son.3

/lthouh +ie%s of pe!sonlit"& tempe!ment& $h!$te!& n' the self $ontinue' to be 'e+elope' o+e! the

$entu!ies& mo'e!n pp!o$hes essentill" ben %ith 8!eu'*s ps"$honl"ti$ theo!". Subse@uent theo!ies h+e fo!

the most p!t been +!itions on o! !e$tions to 8!eu'& n' fll into se+e!l b!o' $teo!ies. These in$lu'e neo-

8!eu'in ps"$ho'"nmi$ theo!ies& o!nismi$ o! self theo!ies& t!it theo!ies& beh+io!l o! le!nin theo!ies& n'

$oniti+e theo!ies.

Pe!sonlit" theo!ists $le!l" h+e h' +luble insihts into the %o!kins of the humn min'& n' h+e

ui'e' the!pists in thei! effo!ts to help people '>ust to life*s $hllenes. But the +!ious theo!ies !e often 'i!e$tl"

$ont!'i$to!". The!e %e!e feu's %ithin ps"$honl"sis e+en in 8!eu'*s '" 2Jun& fo! e(mple& b!oke %" f!om st!i$t

8!eu'inism3. Lte!& the neo-8!eu'ins h' 'isputes s %ell. 8o! e(mple& some mintine' 8!eu'*s emphsis on !e-

p!esse' se(ul u!es s the !oot of n(iet"C %hile othe!s !epl$e' se(ulit" %ith so$il n'Ko! $ultu!l f$to!s s the

$o!e ps"$honl"ti$ $on$ept. Ps"$honl"ti$ theo!" to'" is p!obbl" best +ie%e' s fmil" of theo!ies !the! thn

sinle %ell-'efine' +ie% of ho% the min' %o!ks n' ho% it b!eks 'o%n in ps"$hoptholo".

But 'iffe!en$es %ithin ps"$honl"ti$ theo!" ple $omp!e' to 'iffe!en$es bet%een ps"$honl"ti$ n' othe!

pe!sonlit" theo!ies. Some theo!ies fo$us on ps"$hoptholo"& %hile othe!s !e mo!e $on$e!ne' %ith the ntu!e of

the %ell-'>uste' pe!son. Un$ons$ious moti+tion pl"s ke" !ole in some theo!ies& %hile othe!s o in the opposite

'i!e$tion n' fo$us lmost e($lusi+el" on $ons$ious st!i+ins. Beh+io! is moti+te' in multiple %"s in mn" theo!ies&

%he!es in othe!s& sinle moti+e is emphsi,e' 2e..& se(ul !tifi$tion o! self-$tuli,tion3. So$il $onsi'e!tions

!e impo!tnt in some but !e less $!u$il in othe!s. Bioloi$l f$to!s& espe$ill" enes& !e belie+e' to un'e!lie

stble pe!sonlit" t!its o+e! one*s life spn fo! some theo!ists& but othe!s emphsi,e the !ole of le!nin n'

situtionl 2espe$ill" so$il3 f$to!s in 'ete!minin beh+io!l n' mentl sttes.

One possible e(plntion fo! the 'i+e!sit" of pe!sonlit" theo!ies is tht the topi$ is simpl" so 'iffi$ult tht no

one hs @uite fiu!e' it out "et. /lte!nti+el"& the!e m" h+e not been $le! %inne! in this pe!sonlit" $ontest not

be$use the +!ious theo!ies p!opose' to 'te !e ll %!on& but be$use mn" !e t lest p!tl" $o!!e$t. )f this is

t!uen' ) belie+e this is the $sethen the best %" to $onst!u$t +ie% of the self miht be not to pit the +!ious

theo!ies inst one nothe! but !the! to s"nthesi,e $!oss them.

A VIEW OF THE SELF

So f!& )*+e use' the te!ms personality n' the self !the! loosel". 1o% it*s time to et mo!e spe$ifi$. 8!om

he!e on& %hen ) use the te!m the self ) m !efe!!in to the totlit" of the li+in o!nism. This notion subsumes the

i'e of pe!sonlit" n' is simil! to %ht 7illim Jmes h' in min' %hen he 'es$!ibe' the self s the sum totl of

%ho one is 2see the openin p!!ph of this $hpte!3. But in o!'e! fo! this +ie% of the self to be useful to ou! pu!suit

of ho% the b!in mkes the self possible& %e nee' to !efine it $onsi'e!bl".

)n mo'e!n pe!sonlit" theo!"& s in philosoph"& the notion of the self t"p

i$ll" !efe!s to the $ons$ious self& in the sense of h+in self-kno%le'e& self-$on$ept& n' self-esteemC of

bein self-%!e& self-$!iti$lC of feelin self-impo!tntC n' of st!i+in to%!' self-$tuli,tion. :!l 4oe!s& pionee!



ps"$holoist of the self& summe' up this +ie%& 'efinin the self s “the o!ni,e'& $onsistent $on$eptul estlt

$ompose' of pe!$eptions of the $h!$te!isti$s of the ;)* o! ;me.* “2&O 8o! 4oe!s& these pe!$eptions !e +ilble to

%!eness& thouh not ne$ess!il" in %!eness.# 0o'e!n self ps"$holoists like H,el 0!kus h+e simil! fo$us

on self $ons$iousness.# These ps"$holoists 'o not 'en" tht some spe$ts of mentl life o$$u! un$ons$iousl"& but

inste' minimi,e the impo!tn$e of the un$ons$ious $omponents of the min' in f+o! of the notion of self s n

$ti+e ent in the $ont!ol of mentl sttes n' beh+io!.)n spite of this lon t!'ition of emphsis on the self s $ons$ious entit"& the self tht %e !e %!e of& o!

$n be %!e of& is not the enti!et" of %ht the te!m the self!efe!s to. The ps"$holoist 4uth 0un!oe& fo! e(mple&

!ues fo! mo!e fun'mentl +ie%. She points out tht “ sense of self %hi$h de+elops in the $ou!se of li+in is too

f! $onfuse' %ith the t!ul" ne$ess!" o!nismi$ self.# 0un!oe is @uestionin %hethe! the “sense of self# tht 'e+elops

o+e! time is the %hole self. )n othe! %o!'s& she is !uin tht the self tht %e !e %!e of n' st!i+e to imp!o+e& the

self tht %e h+e sense of& the self tht mn" pe!sonlit" theo!ists h+e been enth!lle' %ith& is too n!!o% +ie% of

%ht the self !ell" is.

The e(isten$e of self is fun'mentl $on$omitnt of bein n niml. /ll nimls& in othe! %o!'s& h+e

self& !e!'less of %hethe! the" h+e the $p$it" fo! self-%!eness. /s !esult& the self $onsists of mo!e thn %ht

self-%!e o!nisms !e $ons$iousl" %!e of. )n'ee'& !e$ent !ese!$h in so$il ps"$holo" hs emphsi,e' tht

mn" impo!tnt spe$ts of humn so$il beh+io!& in$lu'in 'e$ision-mkin s %ell s the %" %e !e$t to membe!s

of !$il n' ethni$ !oups& !e me'ite' un$ons$iousl".# These 'iffe!en$es %ithin o!nisms 2$ons$ious +s.

un$ons$ious spe$ts3 n' bet%een o!nisms 2$!etu!es %ith n' %ithout $ons$iousness3 !e not $ptu!e' b" n

un'iffe!entite' notion of the self& but $n be $$ounte' fo! b" 'istinuishin bet%een e(pli$it n' impli$it spe$ts of

the self.

Thins %e $ons$iousl" kno% bout %ho %e !e mke up the eplicit spe$ts of the self. These !e %ht %e

!efe! to b" the te!m self%a'are n' $onstitute %ht %e $ll ou! self-$on$eptC the" !e %ht the self ps"$holoists !e

inte!este' in. The implicit spe$ts of the self& b" $ont!st& !e ll othe! spe$ts of %ho %e !e tht !e not imme'itel"

+ilble to $ons$iousness& eithe! be $use the" !e b" thei! ntu!e in$$essible& o! be$use the" !e $$essible but

not bein $$esse' t the moment. /ll nimls h+e impli$it sel+es& but onl" nimls tht h+e the $p$it" fo!

$ons$ious self-%!eness h+e e(pli$it sel+es 2this is %h" the e(isten$e of pe!sonlit" in pet 'oes not ne$ess!il"

men tht the pet is $ons$ious in the humn sense3.

This +ie% of the self $ont!sts %ith the i'e of pe!son s elbo!te' b" philosophe!s like St!%son&

Dennett& n' othe!s. Onl" humns $n be pe!sons& but ll nimls $n h+e sel+es& espe$ill" %hen %e llo% fo! the

'istin$tion bet%een impli$it n' e(pli$it sel+es. One miht %nt to b!o'en the notion of pe!son to $$ount fo!

e(pli$it n' impli$it spe$ts. This %oul' sol+e one p!oblem 2the f$t tht the!e*s mo!e to pe!son thn %ht tht pe!-

son is $ons$ious of3 but %oul' le+e nothe! un''!esse' 2the !eltion bet%een pe!sons n' othe! nimls3.

Tht e(pli$it n' impli$it spe$ts of the self e(ist is not p!ti$ul!l" no+el i'e. )t is $losel" !elte' to

8!eu'*s p!tition of the min' into $ons$ious& p!e$ons$ious 2$$essible but not $u!!entl" $$esse'3& n' un$ons$ious

2in$$essible3 le+els. Ho%e+e!& 8!eu'*s te!ms $!!" mu$h theo!eti$l lue tht ) %nt to le+e behin'.

The te!ms implicit n' eplicit !e themsel+es not $ompletel" neut!l. The" !e bo!!o%e' f!om the stu'" of

memo!"& %he!e it is no% %i'el" !e$oni,e' tht the b!in s"stem in+ol+e' in fo!min e(pli$it& $ons$iousl" $$essible

memo!ies is 'istin$t f!om +!iet" of othe! s"stems tht !e $pble of le!nin n' sto!in info!mtion impli$itl"&

%hi$h is to s" %ithout $ons$ious %!eness. /$tull"& sin$e most b!in s"stems !e plsti$& n' %o!k outsi'e of

$ons$iousness& the" $n be thouht of s impli$it memo!" s"stems o!& bette! "et& s s"stems tht !e ble to sto!e

spe$ifi$ kin's of info!mtion impli$itl". To the e(tent tht ou! life*s e(pe!ien$es $ont!ibute to %ho %e !e& impli$it n'

e(pli$it memo!" sto!e $onstitute ke" me$hnisms th!ouh %hi$h the self is fo!me' n' mintine'. Those spe$ts

of the self tht !e le!ne' n' sto!e' in e(pli$it s"stems $onstitute the e(pli$it spe$ts of the self. To be self-%!e is

to !et!ie+e f!om lon-te!m memo!" ou! un'e!stn'in of %ho %e !e n' pl$e it in the fo!ef!ont of thouht. )n

$ont!st& those spe$ts of the self tht !e le!ne' n' sto!e' in impli$it s"stems mke up the impli$it spe$ts of the



self. 7e use this info!mtion bout ou! sel+es ll the time& e+en thouh %e m" not be $ons$iousl" %!e of it. The

%" %e $h!$te!isti$ll" %lk n' tlk n' e+en the %" %e think n' feel ll !efle$t the %o!kins of s"stems tht

fun$tion on the bsis of pst e(pe!ien$e& but thei! ope!tion tkes pl$e outsi'e of %!eness. ) %ill h+e mu$h to s"

in lte! $hpte!s bout the %o!kins of e(pli$it n' impli$it memo!" fun$tions of the b!in.

The self is unit& in the sense tht o!nisms o to !et pins to keep themsel+es li+e n' %ell. Ph"si$l

'me to one*s ppe!n$e is not tken lihtl" 2!emembe! the h!m tht f$e !emo+l f!om the E"ptin tomb %sment to $hie+e3& no! !e insults to one*s $h!$te!. Both impli$it n' e(pli$it s"stems !e utili,e' to $$omplish this

unit" in humns. But self-p!ese!+tion is uni+e!sl moti+e& in'epen'ent of %hethe! the o!nism is %!e tht it is

%o!kin to%!' this ol. / $o$k!o$h $n s$mpe! %" %hen humn foot pp!o$hes %ithout bein e(pli$itl"

%!e of bein in 'ne!& the sme %" tht sinle-$ell b$te!ium $n 'ete$t n' mo+e %" f!om h!mful mole-

$ules in its $hemi$l %o!l'.

The self is not stti$. )t is ''e' to n' subt!$te' f!om b" eneti$ mtu!tion& le!nin& fo!ettin& st!ess&

in& n' 'isese. This is t!ue of both impli$it n' e(pli$it spe$ts of the self& %hi$h m" be influen$e' simil!l" o!

'iffe!entl" t n" one point. 8o! e(mple& mil' $ompliment m" onl" be !eiste!e' n' sto!e' in e(pli$it memo!"& but

lo%in p!ise& !eiste!e' e(pli$itl"& miht le' to the !ousl of emotion s"stems tht then lso sto!e spe$ts of the

e(pe!ien$e impli$itl". On the othe! hn'& st!ess is kno%n to impi! e(pli$it memo!" %hile t the sme time enhn$in

the impli$it memo!" fun$tions of emotion s"stems.

/s impo!tnt s le!nin is& not ll spe$ts of the self !e le!ne'. Some !e 'ue to ou! eneti$ he!ite. /ll

of the $p$ities tht %e h+e s #omo sapiens, in$lu'in ou! $p$ities to le!n n' !emembe!& !e m'e possible

b" the eneti$ mkeup of ou! spe$ies. 7ht %e pl$e in ou! in'i+i'ul memo!" s"stems is fun$tion of ou! uni@ue

e(pe!ien$e& but the e(isten$e n' bsi$ mo'e of ope!tion of these s"stems !e 'ue to ou! spe$ies*s enes. /t the

sme time& %e e$h h+e fmil" eneti$ histo!" tht is +!ition on the theme of bein humn& n' pe!sonl

set of enes tht is +!ition on ou! fmil"*s& n' these +!itions lso influen$e %ho %e !e.

The most %ell-!ti$ulte' +ie% of the !ole of enes in shpin beh+io!l n' mentl $h!$te!isti$s $omes

f!om bioloi$l t!it theo!ies of pe!sonlit"& %hi$h p!opose tht one*s en'u!in @ulities !e 'ue to one*s eneti$ b$k-

!oun'. :onsi'e!ble e+i'en$e hs been msse' to suppo!t the +ie% tht some t!its& su$h s the e(tent to %hi$h

one is e(t!o+e!te' 2!e!ious3 +s. int!o+e!te' 2sh"& fe!ful& %ith'!%n3& !e hihl" influen$e' b" one*s eneti$ histo!".

1e+e!theless& the!e !e t%o impo!tnt $+ets to eneti$ theo!" of pe!sonlit"

8i!st& enes h+e been foun' to $$ount fo! onl" bout pe!$ent of p!ti$ul! pe!sonlit" t!it. 7ht this

sttement mens is tht enes $$ount t most fo! hlf of i+en t!it& not tht hlf of ll of pe!sonlit" is $$ounte'

fo! b" enes. 8o! some t!its& eneti$ influen$e is far less n' is often not mesu!ble. )nt!o+e!sion is p!obbl" the

t!it %ith the st!onest eneti$ influen$e. /lthouh mn" e(t!emel" sh"& int!o+e!te' $hil'!en ten' to be$ome n(ious&

'ep!esse' 'ults& some 'o >ust fine. )s this be$use the eneti$ influen$e in the ltte! !oup %s tempo!!"& o!

be$use the eneti$ ten'en$" %s s@uel$he'= The f$t tht %hen e(t!eme int!o+e!sion is $uht e!l"& it $n be

!e+e!se' to some e(tent b" suppo!ti+e fmil" en+i!onment suests tht enes 'o not full" 'i$tte ps"$holoi$l

'estin". Life*s e(pe!ien$es& in the fo!m of le!nin n' memo!"& shpe ho% one*s enot"pe is e(p!esse'. E+en the

most !'ent p!oponents of eneti$ 'ete!mintion of beh+io! 'mit tht enes n' en+i!onment inte!$t to shpe t!it

e(p!ession. )t*s mtte! of ho% mu$h& not %hethe!& both $ont!ibute.

The se$on' $+et to the eneti$ $$ount of pe!sonlit" stbilit" $omes f!om !ese!$h sho%in tht people

!e not l%"s t!ue to thei! so-$lle' pe!sonlit" t!its. One m" be sh" t %o!k o! in so$il !oups& fo! e(mple& but

'ominee!in t home. )n f$t& %hen ps"$holoists h+e e(mine' the $onsisten$" of beh+io! $!oss situtions& the

!esults h+e not suppo!te' the +ie% tht people $t $onsistentl" in 'iffe!ent situtions. Obse!+tions su$h s these

suest to 7lte! 0is$hel tht beh+io!l n' mentl sttes !e not 'i$tte' b" $onstitutionl f$to!s but inste' !e

situtionll" 'ete!mine'. 0is$hel !ues tht the bilit" to p!e'i$t beh+io! 'epen's upon kno%in bout pe!son*s

thouhts& moti+tions& n' emotions !elti+e to p!ti$ul! set of $i!$umstn$es. He 'es$!ibes these s “if... then

!eltions.# “)f# "ou !e in sitution /& “then# "ou 'o X& but “if# in sitution B& “then# "ou 'o Y. /$$o!'in to 0is$hel&



people 'on*t possess stble pe!sonlit" t!its o+e! time& but stble “if. . . then# p!ofiles.

/s %ith most pol!i,e' !uments in ps"$holo"& the!e is t!uth in both the situtionl n' the t!it +ie%s. The

st!one! the eneti$ $ont!ibution to p!ti$ul! $h!$te!isti$& the mo!e likel" it %ill be e(p!esse' unifo!ml" in 'iffe!ent

situtions. /t the sme time& situtions +!" in the e(tent to %hi$h the" 'i$tte the %" %e $t. / !e' t!ffi$ liht %ill

$use most people to stop& !e!'less of %hethe! the" !e ene!ll" !essi+e o! timi'& %he!es "ello% liht llo%s

mo!e ltitu'e fo! ten'en$ies like !ession o! timi'it" to be e(p!esse'A* 7e*ll +isit @uestions bout eneti$s n'pe!sonlit" in in $hpte! M& %hen %e e(plo!e ho% the b!in is built.

)n p!oposin tht the self e(ists& ) !un the !isk of !eif"in somethin tht is& ultimtel"& not !el. Bob D"ln& fo!

e(mple& si'& “) $hne 'u!in the $ou!se of '". ) %ke n' )*m one pe!son& n' %hen ) o to sleep ) kno% fo!

$e!tin tht )*m someone else. ) 'on*t kno% %ho ) m most of the time. )t 'oesn*t e+en mtte! to me.# /n'& $$o!'in

to Philip 4oth& “/ll ) $n tell "ou %ith $e!tint" is tht )& fo! one& h+e no self& n' tht ) m un%illin o! unble to

pe!pet!te upon m"self the >oke of self.# 0!k Epstein& %ho hs t!ie' to inte!te ps"$honl"sis n' Bu''hism&

points out tht the eo*s ime of itself 2its ob>e$t ime3 is l%"s l$kin s n $$ount of the sub>e$t 2the self3&

impl"in tht mu$h of the self is& in essen$e& impli$it. 7hile the %hole self is not usull" en$ounte!e' b" the in'i+i'ul

%ho possesses it 2%ho is it3& o! b" othe!s& it ne+e!theless e(ists.

;7ht then is it= )n m" +ie%& the self is the totlit" of %ht n o!nism is ph"si$ll"& bioloi$ll"&

ps"$holoi$ll"& so$ill"& n' $ultu!ll". Thouh it is unit& it is not unit!". )t in$lu'es thins tht %e kno% n' thins

tht %e 'o not kno%& thins tht othe!s kno% bout us tht %e 'o not !eli,e. )t in$lu'es fetu!es tht %e e(p!ess n'

hi'e& n' some tht %e simpl" 'on*t $ll upon. )t in$lu'es %ht %e %oul' like to be s %ell s %ht %e hope %e ne+e!

be$ome.

The f$t tht ll spe$ts of the self !e not usull" mnifest simultneousl"& n' tht 'iffe!ent spe$ts $n

e+en be $ont!'i$to!"& m" seem to p!esent hopelessl" $omple( p!oblem. Ho%e+e!& this simpl" mens tht 'iffe!ent

$omponents of the self !efle$t the ope!tion of 'iffe!ent b!in s"stems& %hi$h $n be but !e not l%"s in s"n$. 7hile

e(pli$it memo!" is me'ite' b" sinle s"stem& the!e !e +!iet" of 'iffe!ent b!in s"stems tht sto!e info!mtion

impli$itl"& llo%in fo! mn" spe$ts of the self to $oe(ist. /s 7illim Jmes si'& “1eithe! th!ets no! ple'ins $n

mo+e mn unless the" tou$h some one of his potentil o! $tul sel+es.# )n -rlando, 6i!ini 7oolf pointe' out& “/

bio!ph" is $onsi'e!e' $omplete if it me!el" $$ounts fo! si( o! se+en sel+es& %he!es pe!son m" %ell h+e s

mn" thousn'.# O! s the pinte! Pul 5lee e(p!esse' it& the self is “'!mti$ ensemble.#

THE SELF AND THE BRAIN

Theo!ies of the self n' pe!sonlit" !e not usull" f!me' in %"s tht !e $omptible %ith ou!

un'e!stn'in of b!in fun$tion. Ho%& then& $n %e !elte the $omple( $onstelltion )*+e $lle' the self to the s"stems

n' s"npses of the b!in=Bo The ol of the !est of the book is to ns%e! this @uestion. Ho%e+e!& b!ief p!e+ie% is

in o!'e!.

The self $n be un'e!stoo' in te!ms of b!in s"stems in+ol+e' in le!nin n' sto!in info!mtion& in e(pli$it

n' impli$it s"stems& bout thins tht !e sinifi$nt in people*s li+es. The p!o$essin b" these s"stems l%"s

o$$u!s in ph"si$l n' so$il $onte(t 2 sitution3 n' is pe!fo!me' b" net%o!ks tht fun$tion the %" the" 'o

be$use of both eneti$ inhe!itn$e n' pst e(pe!ien$es. Put this %"& in o!'e! to un'e!stn' the self& %e nee' to

e(plin ho% b!in s"stems un'e!l"in thinkin& emotion& n' moti+tion 2the men tl t!ilo"3 'e+elop un'e! the

influen$e of ntu!e n' nu!tu!e& n' ho% these s"stems mke it possible fo! us to tten' to& pe!$ei+e& le!n bout&

n' sto!e n' !et!ie+e e(pe!ien$es. 7e espe$ill" nee' to e(plin ho% 'iffe!ent s"stems inte!$t %ith n' influen$e

one nothe!. 7ithout these inte!$tions& n' the mentl inte!tion the" enen'e!& e$h of us %oul' simpl" be

$olle$tion of isolte' mentl fun$tions !the! thn $ohe!ent pe!son.

The point& thouh& is not simpl" to stte tht le!ne' n' innte inte!$tions bet%een $oniti+e& emotionl&

n' moti+tionl p!o$esses mke us %ho %e !e& but inste' to e(plin ho' these inte!$tions %o!k. /n' the

e(plntion tht ) %ill pu!sue in the !emin'e! of this book in+ol+es neu!l& espe$ill" s"npti$& me$hnisms. ) belie+e&



in sho!t& tht n ns%e! to the @uestion of ho% ou! b!ins mke us %ho %e !e $n be foun' in s"npti$ p!o$esses

tht llo% $oope!ti+e inte!$tions to tke pl$e bet%een the +!ious b!in s"stems tht !e in+ol+e' in p!ti$ul!

sttes n' e(pe!ien$es& n' fo! these inte!$tions to be linke' o+e! time. )t is p!obbl" not t ll ob+ious %ht this

sttement mens t this point in the book. Befo!e it %ill bein to mke sense& %e nee' to $o+e! mo!e !oun'.

CHAPTER THREE

THE 0OST U1/::OU1T/BLE O8 0/:H)1E4Y

0Y O71 B4/)1 )S TO 0E THE 0OST U1/::OU1T/BLE O8 0/:H)1E4Y /L7/YS BU)19&

HU00)19& SO/4)19 4O/4)19 D)6)19& /1D THE1 BU4)ED )1 0UD. /1D 7HY= 7H/T*S TH)S P/SS)O1

8O4=

6i!ini 7oolf

0ost of us !e s m"stifie' b" ou! b!ins s 6i!ini 7oolf& thouh pe!hps less elo@uent in ou! ino!n$e.

Still& e+e!"one hs he!' fe% thins bout the %!inkle' blob in the noinfo! instn$e& tht %e use onl" io pe!$ent

of it. But %ho $me up %ith this numbe!= /n' %h" %oul' %e e+en h+e the !est if it %e!en*t useful= E+olution 'oesn*t

usull" mke o!ns in su$h %" tht the" mostl" o unuse'& >ust in $se someone fiu!es out one '" %ht to 'o

%ith the e(t! mte!il. )t*s h!' to imine ho% F pe!$ent of the b!in& l$kin in +lue fo! most of us most of the

time& $oul' h+e e+e! $ome into e(isten$e. 4ese!$he!s h+e been lookin into %ht the b!in 'oes fo! mn" "e!s

no%& n' f!om %ht the" h+e 'is$o+e!e'& it 'oesn*t seem tht most of it is& in f$t& !estin i'l".

People lso ten' to $!!" !oun' %ith them one o! both of t%o ''itionl e!!oneous beliefs bout the b!in.

The fi!st is tht fun$tions of the b!in& like pe!$eption& memo!"& o! emotion& !e lo$te' in spe$ifi$ !es. The othe! is

tht $hemi$ls flotin !oun' in the b!in 'ete!mine ou! mentl sttes. Unlike the io pe!$ent m"th& these !e $tull"

p!t t!uths tht& tken out of $onte(t& !e ptentl" flse. 7e kno%& t lest in ene!l sense& ho% the b!in %o!ks&

n' it*s not b" isln's of b!in tissue o! b" isolte' $hemi$ls ope!tin in'epen'entl". P!ti$ul! !es !e impo!tnt&

but not on thei! o%nA the" p!ti$ipte in fun$tions b" %" of thei! s"npti$ $onne$tions %ith othe! !es. :hemi$ls are

lso impo!tnt& but minl" be$use of thei! %o!k t s"npses %ithin fun$tionl s"stems.



This $hpte! %ill i+e n $$ount 2lbeit n bb!e+ite' one3 of this “most un$$ountble of m$hine!"&#

'es$!ibin some bsi$ f$ts tht !e ne$ess!" to un'e!stn' the b!in*s s"npti$ s"stems. /lthouh the 'is$ussion

%ill h+e to et bit te$hni$l lon the %"& this info!mtion is essentil to m" t tempt to !elte the self to s"npses.

Be$use )*+e kept thins simple& those l!e'" in the kno% m" %ish to skip he'. Ho%e+e!& the no+i$e %ill et

$!sh $ou!se on %ht neu!ons !e& ho% s"npses $onne$t them toethe!& n' %h" s"npti$ $onne$tions !e the ke"

to b!in fun$tion.

BRAINS: SO DIFFERENT, YET ALL THE SAME

7e mmmls belon to the !oup of nimls $lle' +e!teb!tes& subph"lum %e sh!e %ith othe!

b$kbone' $!etu!es& in$lu'in bi!'s& !eptiles& mphibins& n' fish. 0mmls n' bi!'s sep!tel" 'es$en'e' f!om

!eptiles millions of "e!s o. )n spite of this $ommon n$est!"& the b!ins of !eptiles& bi!'s& n' mmmls look +e!"

'iffe!ent. Beneth these 'issimil!ities& thouh& the!e*s $ommon pln tht*s !io!ousl" 'he!e' to.

E+e!" +e!teb!te b!in $n be 'i+i'e' into th!ee b!o' ,onesA the hin'-b!in& mi'b!in& n' fo!eb!in. )n the

e!l" "e!s of the t%entieth $entu!"& neu!os$ientists 'is$o+e!e' tht 'me to e$h ,one h' 'iffe!ent p!e'i$tble

$onse@uen$e.* 8o! e(mple& in stu'ies of $ts& it %s foun' tht pu!poseful& +olunt!" beh+io! n' p!oblem-sol+in

bilit" %e!e impi!e' %hen the fo!eb!in %s 'me'. 1e+e!theless& e+en %ith mssi+e in>u!ies to the fo!eb!in&

some sembln$e of no!ml $oo!'inte' beh+io! !emine'. Su$h $omp!omise' nimls $oul' o!ient to%!' noise

o! %ith'!% thei! p% f!om het& n' $oul' %lk& et& n' !oom. The" $oul' e+en 'ispl" full-blo%n emotionl

!esponses& espe$ill" those t"pi$ll" e(p!esse' in ne! o! fe!& if the h"pothlmus& smll !eion situte' t the

bse of the fo!eb!in& %s sp!e'. 7hen l!e! lesions %e!e m'e tht !emo+e' ll of the fo!eb!in& in$lu'in the

h"pothlmus& onl" !u'iment!" !esponses !emine'. These nimls& %hen $hllene' %ith intense stimultion& $oul'

hiss& b!e thei! teeth& unshethe thei! $l%s& o! s%ipe p%& but $oul' not mne to put ll of these beh+io!s

toethe! into $oo!'inte' 'efense o! tt$k !esponse. 7hen the mi'b!in %s 'me'& the niml %s essentill"

$omtose

li+e ph"si$ll"& but not beh+io!ll" o! ps"$holoi$ll". /n' %hen the hin'-b!in %s 'est!o"e'& life itself

$ese'.

8!om these $!u'e e(pe!iments& it %s $on$lu'e' tht the hin'b!in $ont!ols +e!" bsi$ fun$tions& those

ne$ess!" fo! st"in li+eC the mi'b!in is in+ol+e' in mintinin %kefulness n' $o!se& isolte' beh+io!l

!e$tionsC n' the fo!eb!in $oo!'intes $omple( beh+io!l n' mentl p!o$esses. )t shoul' not be su!p!isin& i+en

these effe$ts of b!in 'me& tht the fo!eb!in 2ne$ess!" fo! thinkin n' p!oblem-sol+in3 is the !eion tht 'iffe!s

the most bet%een mmmls n' othe! +e!teb!tes n' the hin'b!in 2ne$ess!" fo! life3 the lest. 1e+e!theless& ll

th!ee le+els !e !ep!esente' in ll +e!teb!tes& n' e+en the e+olution!il" '+n$e' fo!eb!in is st!u$tu!e' $$o!'in

to $ommon un'e!l"in o!ni,tionl pln tht is ppli$ble to e+e!" +e!teb!te spe$ies.

8o! e(mple& the humn fo!eb!in $onsists of se+e!l sub'i+isions& one of %hi$h is the %!inkle' oute! l"e!&

the neo$o!te(. This is the p!t of the fo!eb!in tht mkes possible mn" of ou! hihe! mentl fun$tions. The 'esin-

tion neo !efle$ts the f$t tht this b!in !eion %s& fo! mn" "e!s& belie+e' to be e+olution!il" ne%& h+in eme!e'

%hen mmmls e+ol+e' f!om !eptiles. Othe! +e!teb!tes %e!e thouht to h+e p!imo!'il o! ol'e! $o!te( but not

mmmlin o! neo$o!te(. This +ie% ben to $hne& thouh& in the lte Fs n' e!l" FNs& %hen ne%

te$hni@ues fo! stu'"in the b!in be$me +ilble. Bse' on the ptte!ns of $hemi$l stinin n' ne!+e

$onne$tions 'is$o+e!e' %ith these te$hni@ues& the o!ni,tion of the b!in $me to be bette! pp!e$ite'& n'

!ese!$he!s %e!e ble to use this info!mtion to fin' the e@ui+lent 2o! t lest the sembln$e3 of neo$o!te( in both

bi!'s n' !eptiles& suestin both tht it %sn*t so ne% fte! ll n' tht it $e!tinl" %sn*t uni@ue to mmmls. The

!eson this $o!te( h' not been foun' in these nimls e!lie! %s be$use of its unusul lo$tion& bu!ie' beneth

othe! b!in !es& inste' of !estin on top& s it 'oes in mmmls.

7hile t the le+el of o+e!ll b!in st!u$tu!e simil! o!ni,tionl pln pplies to mn" 'iffe!ent nimls& it

is not the $se tht ll b!ins !e the sme. / i+en b!in !e $n +!" eno!mousl" in si,e n' $omple(it" bet%een



'iffe!ent spe$ies& llo%in some nimls to 'o thins tht othe!s $nnot. )n mphibins& fo! e(mple& n !e in the

mi'b!in $lle' the !e$tum is espe$ill" %ell 'e+elope'& mkin it possible fo! most f!os to th!ust thei! tonue into the

fliht pth of n inse$t n' $ptu!e it& fet most people $n*t $$omplish. Bts n' !ts $n he! thins tht %e

$nnot& n' bees use mneti$ sense& %hi$h %e 'o not h+e& to ui'e thei! mo+ements. Diffe!ent spe$ies h+e

been sub>e$te' to 'iffe!ent e+olution!" p!essu!es n' thei! b!ins !efle$t thei! uni@ue histo!ies.N

The most ob+ious 'iffe!en$e bet%een the mmmlin n' othe! +e!teb!te b!ins is the e(tent to %hi$h the$o!te( hs e(pn'e'. /lthouh& s %e h+e seen& !eptiles n' bi!'s !e no% kno%n to h+e some neo$o!te(& the

mmmlin neo$o!te( is f! mo!e elbo!te thn the e@ui+lent !es in these othe! spe$ies. /n' %ithin mmmls&

the!e !e 'istin$tions s %ellA the neo$o!te( is bie! n' mo!e 'iffe!entite' in p!imtes thn in !o'ents& n' in

humns mo!e so thn in monke"s. These $hnes in $o!ti$l si,e n' $omple(it" !e& ho%e+e!& supe!impose' on

bsi$ neo$o!ti$l pln. 8o! e(mple& in ll mmmls& p!o$esses !elte' to senstion 2+ision& u'ition& tou$h3 !e

!ep!esente' in the !e! n' p!o$esses in+ol+e' in $ont!ollin mo+ement in the f!ont of the $o!te(.

7ithin i+en spe$ies& the simil!ities of $o!ti$l o!ni,tion !e st!ikin. E!l" ntomists 'is$o+e!e' tht

the m>o! ptte!ns of $o!ti$l %!inkles& %hi$h ppe! to be !n'oml" !!ne' to the uninitite' e"e& !e m,inl"

$onsistent f!om pe!son to pe!son& n' $n be use' s ln'm!ks to i'entif" +!ious !eions of the neo$o!te(. 7ht*s

!em!kble is tht these pu!el" st!u$tu!l p!$els& 'efine' b" the %!inkles& tu!n out to $o!!espon' to fun$tionl

'i+isions& !es tht p!ti$ipte 2b" %" of thei! s"npti$ $onne$tions %ith othe! $o!ti$l n'Ko! sub$o!ti$l !es3 in

'iffe!ent spe$ts of mentl life n' beh+io!.#* 8o! e(mple& the !e of the $o!te( in+ol+e' in $ont!ollin p!e$ise

mo+ements of +!ious bo'" p!ts is lo$te' >ust in f!ont of the $ent!l sul$us& one of the m>o! %!inkles in the $o!te(&

%hile tou$h& he!in& n' +isul !es !e 'efine' b" thei! o%n %!inkles& s !e !es in+ol+e' in lnue

$omp!ehension n' spekin. On $!eful e(mintion& some +!ition in the o!ni,tion of $o!ti$l o! othe! b!in

!es is e+i'ent in 'iffe!ent people& but the bsi$ o+e!ll !$hite$tu!l pln of the b!in is p!ett" mu$h the sme in n"

t%o in'i+i'uls.

)n spite of the t!emen'ous simil!it" of ou! b!ins& %e ll $t 'iffe!entl"& h+e uni@ue bilities& n' h+e

'istin$t p!efe!en$es& 'esi!es& hopes& '!ems& n' fe!s. The ke" to in'i+i'ulit"& the!efo!e& is not to be foun' in the

o+e!ll o!ni,tion of the b!in& but !the! in the fine-tunin of the un'e!l"in net%o!ks. To un'e!stn' the 'efinin

@ulities of e$h pe!son& %e nee' to o be"on' the supe!fi$il o!ni,tion of the b!in 2its 'i+ision into b!o' !eions

n' !es %ithin these3 n' tu!n to the mi$!os$opi$ st!u$tu!e n' fun$tion of neu!l s"stems& n' espe$ill" to the

$ells n' s"npses tht $onstitute them.

THE CELL WAR

/ll o!ns n' tissues of the bo'" !e $ompose' of $ells. But unlike the $ells in othe! bo'" p!ts& b!in $ells&

o! neu!ons& 'i!e$tl" $ommuni$te %ith one nothe!. The!e*s nothin mi$l bout the p!o$essneu!ons !e simpl"

built in %" tht llo%s them to e($hne info!mtion %ith one nothe! in %"s tht othe! $ells $nnot.# :ommon

ptte!ns of $ommuni$tion bet%een neutons ensu!e tht ll humn b!ins %o!k in bsi$ll" the sme %"& %he!es

subtle 'iffe!en$es in these ptte!ns of $ommuni$tion i+e !ise to the 'istin$ti+e @ulities tht %e e$h h+e.

The e(isten$e of $ells in the b!in n' othe! p!ts of the bo'" is tken fo! !nte' to'"& but this kno%le'e

%s onl" m'e possible b" the fu!the! 'e+elopment of the mi$!os$ope in the nineteenth $entu!". /!oun' GQN&

0tthis S$hlei'en& 9e!mn botnist& fi!st p!opose' tht plnts %e!e m'e up of 'is$!ete units& o! $ells. The

follo%in "e!& his f!ien' Theo'o! S$h%nn e(ten'e' the notion to nimls& n' the!eb" b!ouht botn" n' ,oolo"

toethe! in sinle theo!"& the so-$lle' $ell theo!"&* %hi$h !ue' tht ll li+in thins !e $ompose' of $ells.

7hethe! $ell theo!" %s ppli$ble to the b!in %s topi$ tht %s fie!$el" 'ebte' fo! 'e$'es. 7hen

e!l" b!in ntomists e(mine' b!in tissue un'e! mi$!os$ope& the" 'i' see st!u$tu!es !esemblin $ells. But unlike

$ells in othe! o!ns& b!in $ells h' fine fibe!s e(ten'in out of thei!. Some s$ientists $on$lu'e' tht this ment tht



the b!in

uni@uenot $ompose' of 'is$!ete $ells but inste' m'e up of n entnle$ mesh o! !eti$ulum of

$ontinuousl" $onne$te' elements. Othe!s& thouh& ! ue' tht the fun'mentls of $ell theo!" pplie' e@ull" to the

b!in.

T%o of the m>o! fiu!es in the 'ebte %e!e Sntio 4mRn " :>l o Spin n' the )tlin ntomist

:millo 9oli. 9oli& %o!kin in hi kit$hen& in+ente' metho's fo! stinin the b!in tht llo%e' bette! +isuli ,tion ofits mi$!os$opi$ ntom". He f+o!e' the !eti$ul! theo!". )!oni$ll" on the bsis of the metho's pionee!e' b" 9oli&

:>l !ue' fo!$efull" fo the ppli$tion of the $ell theo!" to the b!in& n' %on mn" $on+e!ts. On of these %s

7ilhelm 7l'e"e!& %ho in GF publishe' ppe! in %hi$h h sueste' tht b!in $ells be $lle' neu!ons. )n this

ppe!& he lso $oine' th ph!se the neuron doctrine to $$ount fo! the ppli$tion of the $ell theo! to the b!in. :>l

pp!entl" $onsi'e!e' the 'o$t!ine his& t lest in spin if not nme& n' %s not hpp" to h+e h' his thun'e! stolen

b" 7l'e"e!. But the loss in sttu!e& if n"& %s tempo!!". E+e!" !'ute stu'ent in neu!os$ien$e to'" kno%s %ho

:>l %s& %he!es fe% h+e e+e! he!' of 7l'e"e!.

One of the e!l" n' l!el" un!e$oni,e' sol'ie!s in the neu!on %! %s the "oun Simun' 8!eu'. /fte!

$ompletin his me'i$l t!inin in 6ienn& 8!eu' $$epte' position s fmulus& o! !ese!$h s$hol!& n' stu'ie'

the ne!+ous s"stem of fish n' $!"fish.* /s e!l" s GGQ& lon befo!e the neu!on 'o$t!ine %s $o'ifie'& he p!omote'

the i'e tht ne!+e $ells !e ph"si$ll" sep!te' f!om one nothe!. This $on$ept lte! fiu!e' p!ominentl" in one of

his e!liest fo!"s into ps"$holoi$l theo!". )n Pro.ect for a Scientific Psycholo!y, %!itten in GF but unpublishe' fo!

mn" 'e$'es 8!eu' stte' tht “the ne!+ous s"stem $onsists of 'istin$t n' simil!l" $onst!u$te' neu!ones. . . %hi$h

te!minte upon one nothe!.# He int!o'u$e' the te!m con%

tact (arriers to 'es$!ibe the points %he!e neu!ons but& n' sueste' tht inte!$tions bet%een neu!ons

$!oss $ont$t b!!ie!s mke possible memo!"& $ons$iousness& n' othe! f$ets of the min'. /lthouh these notions

%e!e m,inl" sophisti$te' fo! thei! time& 8!eu' felt tht p!o!ess in un'e!stn'in the b!in %oul' be too slo% fo!

his tste n' so bn'one' neu!l theo!" of the min' in f+o! of pu!el" ps"$holoi$l one. The !est is histo!".

T%o "e!s fte! 8!eu' %!ote his Pro.ect, Si! :h!les She!!inton p!opose' 'iffe!ent te!m fo! the

$onne$tions bet%een neu!ons. She!!inton h' been %o!kin on the !efle( p!oblem.* / !efle( is the simplest kin' of

neu!l $i!$uit tht $ont!ols beh+io!. 7hen "ou! ph"si$in tps "ou on the knee& "ou! le >e!ks be$use the tp eli$its

senstions tht !e t!nsmitte' lon sensory ne!+es tht o!iinte in "ou! knee n' t!+el to "ou! spinl $o!'. The

messes in the senso!" ne!+es t!ie! $ti+it" in motor ne!+es tht $ome out of the spinl $o!' n' en' in "ou! le

mus$les& le'in to the >e!k. She!!inton !eli,e' tht the p bet%een the senso!" n' moto! neu!ons h' to be

b!i'e' someho% if info!mtion $!!ie' b" the senso!" ne!+es %s to be t!nsfe!!e' to the moto! ne!+es. He %s

p!obbl" un%!e of 8!eu'*s $ont$t b!!ie!s& n' $hose to $ll the ps s"npses& 'e!i+e' f!om the 9!eek %o!'

menin to $lsp& $onne$t& o! >oin* The notion of s"npses s points of $ommuni$tion bet%een $ells is one to %hi$h

%e still 'he!e& n' %hi$h is essentil to ou! effo!ts to un'e!stn' %ho %e !e in te!ms of b!in me$hnisms.

)n F& :>l n' 9oli sh!e' the 1obel P!i,e fo! thei! !oun'b!ekin !ese!$h on b!in ntom".

/lthouh the neu!on 'o$t!ine h' ine' $onsi'e!ble suppo!t b" then& 9oli $lun bitte!l" to the !eti$ul! theo!" t

the %!' $e!emon".# Still& 'efiniti+e p!oof tht the ne!+ous s"stem is $ompose' of $ells 'i' not $ome until mn"

"e!s lte!. 7ith the in+ention of the ele$t!on mi$!os$ope in the Fs& s$ientists $oul' finll" e(mine the b!in in

suffi$ient !esolution to see tht the tin" fibe!s e(ten'in out of neu!on 'o not t"pi$ll" mke 'i!e$t ph"si$l $ont$t

%ith neihbo!in $ells. )n'ee'& the" !e sep!te' b" tin" sp$es& s"npti$ sp$es& $!oss %hi$h the b!in 'oes its

business.

WHAT MAKES NEURONS SPECIAL?

B" kno%in the fun$tion pe!fo!me' b" fe% $ells of most o!ns in the bo'"& %hethe! the li+e!& ki'ne"& o!

ll bl''e!& "ou $n 'e'u$e the o!n*s o+e!ll fun$tion. This is not t!ue of the b!in& ho%e+e!& %he!e $ells

p!ti$ipte in m"!i' $ti+ities& f!om seein n' he!in to thinkin n' feelin& f!om %!eness of self to the



in$omp!ehension of infinit". The !$hite$tu!e of neu!on helps us bein to un'e!stn' %h" the b!in is so

multifun$tionl& %hile o!ns like the pn$!es n' spleen !e not.

1eu!ons h+e t%o m>o! p!ts. The fi!st is the $ell bo'"& %hi$h is in+ol+e' in impo!tnt housekeepin

fun$tions& su$h s sto!in eneti$ mte!il n' mkin p!oteins n' othe! mole$ules tht !e ne$ess!" fo! the $ell*s

su!+i+l. The $ell bo'" 'oes mu$h the sme %o!k in neu!ons s it 'oes in othe! $ells. The m>o! st!u$tu!l 'iffe!en$e

bet%een neu!ons n' othe! $ells lies in the spe$il ppen'es tht neu!ons h+ethe ne!+es. These fibe!s& %hi$he(ten' out of the $ell bo'"& !e %ht $use' ll the $onfusion in the nineteenth $entu!" bout %hethe! the b!in %s&

like othe! o!ns& $ompose' of 'is$!ete $ells.

1e!+e fibe!s !e so!t of like telephone %i!es. The" llo% neu!ons in one p!t of the b!in to $ommuni$te %ith

neu!ons in nothe!. B" %" of these $onne$tions& $ommunities of $ells tht %o!k toethe! to $hie+e p!ti$ul! ol

$n be fo!me' $!oss sp$e n' time in the b!in. This $p$it" un'e!lies ll of the b!in*s $ti+ities n' is bsent in

othe! o!ns.

The!e !e t%o +!ieties of ne!+e fibe!s& (ons n' 'en'!ite. /(ons !e output $hnnels& n' 'en'!ites !e

input $hnnels. /n (on $!!ies messes to othe! $ells. )t $n en' ne!b"& llo%in $ommuni$tion %ith its $lose

neu!onl neihbo!s& o! it $n st!et$h o+e! +e!" lon 'istn$es& s mu$h s se+e!l feet. )f "ou !e stn'in still n'

'e$i'e to tke step& the mo+ement of "ou! le on the bsis of "ou! 'e$ision in+ol+es (ons tht o!iinte in $ell bo'-

ies lo$te' in the mo+ement $ont!ol !eions in the f!ontl $o!te( 2>ust behin' "ou! fo!ehe'3 n' tht t!+el

uninte!!upte' to the bse of the spinl $olumn 2in the !eion of "ou! lo%e! b$k3.

The en' of the (on& $lle' the te!minl& is the point t %hi$h the sen'in neu!on $ommuni$tes %ith

!e$ei+in neu!ons. /lthouh te!minls most often fo!m $onne$tions %ith 'en'!ites& the" $n lso $ont$t $ell bo'ies o!

othe! (ons. Den'!ites& too& sometimes $ommuni$te bet%een one nothe!. )n o!'e! fo! the lon (ons 'es$en'in

f!om "ou! f!ontl $o!te( to "ou! spinl $o!' to $use "ou! le to mo+e& the te!minl hs to $ont$t 'en '!ites of the

!e$ei+in $ells in the spinl $o!'. The (ons of these !e$ei+in $ells then e(ten' out n' te!minte t mus$les in "ou!

le. The !!i+l of sinls t the mus$le le's to $ont!$tion& n' thus mo+ementJN

0n" 'en'!ites h+e little knobs $lle' spines e(ten'in f!om them. These !e !e'il" seen %hen b!in

tissue is stine' %ith the metho's 'e+elope' b" 9oli. Spines !e espe$ill" impo!tnt s !e$ei+e!s of messes f!om

(ons& n' pl" ke" !ole in b!in 'e+elopment& s %ell s in le!nin n' memo!"C s %e %ill see lte!.

0ost neu!ons h+e onl" one (on. Ho%e+e!& e$h (on b!n$hes mn" times befo!e it en's& llo%in

sinle neu!on to sp%n mn" te!minls. The !esult is tht the messes sent out f!om one $ell $n ffe$t mn"

othe!s. This is $lle' 'i+e!en$e. /t the sme time& e$h neu!on $n !e$ei+e inputs f!om nume!ous othe!s. This is

$lle' $on+e!en$e.

The point t %hi$h the sen'in n' !e$ei+in elements of neu!ons meet is ou! st!& the s"npse. Be$use

info!mtion usull" flo%s $!oss the s"npse st!tin f!om the (on te!minl& this si'e is si' to be p!es"npti$& n'

the !e$ei+in si'e& often o$$upie' b" 'en'!iti$ spine& posts"npti$. /s She!!inton note'& be$use s"npse is

sp$e bet%een the sen'in n' !e$ei+in $ells& somethin hs to $!oss the s"npti$ sp$e in o!'e! fo! the t%o $ells to

$ommuni$te.

GALVANIZED FROG LEGS

The @uestion of ho% info!mtion is e($hne' bet%een neu!ons $!oss the s"npti$ sp$e is tie' in $losel"

%ith tht of ho% info!mtion is t!nsfe!!e' lon ne!+e fibe! of sinle neu!on. Befo!e %e $onsi'e! s"npti$

t!nsmission& %e the!efo!e nee' to $onsi'e! ne!+e $on'u$tion.

)n the NNos& /nton 0esme!& 6iennese ph"si$in& h' been usin i!on mnets to t!et +!iet" of

ph"si$l n' mentl ml'ies& until he foun' he $oul' h+e the sme effe$t %ithout the mnets %hen he looke' into

ptient*s e"es n' %+e' his hn's o+e! the ffli$te' bo'" p!t. This %s the bi!th of mesme!i,tion& o! h"pnosis.

0esme! belie+e' tht some m"ste!ious& mneti$ll" sensiti+e flui' %s p!esent th!ouhout the uni+e!se& in$lu'in



the humn bo'"& n' tht he $oul' help his ptients b" usin his o%n niml mnetism to lte! this flui'. /t the

time& little %s kno%n bout the ph"siolo" of the ne!+ous s"stem& n' n" theo!"& in$lu'in one s %$k" s niml

mnetism& seeme' possible.

/ fe% "e!s lte!& the )tlin Luii 9l+ni noti$e' tht the mputte' le of f!o hun f!om n i!on t!ellis

%ith b!ss hook t%it$he' 'u!in lihtnin sto!m. He lso foun' he $oul' mke f!o le ki$k t n" time he

%ishe' if he tou$he' the ne!+es %ithin the %oun' %ith one metl n' the foot %ith nothe!. This %s& in effe$t& the fi!stbtte!". 9l+ni& in the t!'ition of 0esme!& $on$lu'e' tht the metls %e!e $on'u$tin +itl spi!its f!om the f!o. So-

$lle' niml ele$t!i$it" %s n o$$ult !the! thn s$ientifi$ phenomenon.

Se+e!l 'e$'es lte!& :!lo 0tteu$$i& nothe! )tlin& m'e the fi!st mesu!ements of enuine ele$t!i$l

$ti+it" in ne!+es. )n 9e!mn"& Johnnes 0ulle! n' Emil Du Bois-4e"mon'& !eli,in the impo!tn$e of this obse!-

+tion& ben !ese!$h p!o!m tht !es$ue' ele$t!i$l $on'u$tion in ne!+es f!om the %o!l' of m"sti$ism n' tu!ne'

it into th!i+in s$ientifi$ !ese!$h fiel'.

/t the time& the ssumption %s tht ne!+es $on'u$te' ele$t!i$it" like %i!es. But one of Du Bois-4e"mon'*s

stu'ents& He!mnn +on Helmholt,& 'i' n e(pe!iment tht sueste' othe!%ise. He $l$ulte' the spee' of ele$t!i$l

$on'u$tion in f!o ne!+e fibe!s b" mesu!in ho% mu$h time elpse' befo!e i+en mus$le t%it$he' %hen ne!+es of

'iffe!ent lenths %e!e ele$t!i$ll" stimulte'. /lthouh $on'u$tion time %s fstbout M mete!s pe! se$on'

2!ouhl" M mph3it %sn*t s fst s ele$t!i$it"& %hi$h $n un'e! $e!tin $on'itions flo% th!ouh %i!e t bout the

spee' of liht.

8!om these simple but info!mti+e e(pe!iments it be$me $le! tht ne!+es 'o $on'u$t ele$t!i$it"& but in

spe$il %". Ele$t!i$it" 'oes not flo% pssi+el" th!ouh ne!+e s it 'oes th!ouh %i!e. 4the!& impulses $on'u$te'

th!ouh ne!+es !e (iolo!ically p!opte'& mo+e' lon b" ele$t!o$hemi$l !e$tions& p!o$ess tht tkes lot

lone! thn pssi+e ph"si$l $on'u$tion.

The bioloi$ll" p!opte' impulse in ne!+e is $lle' n $tion potentil. This '!mti$ ele$t!i$l e+ent is

no!mll" initite' t the point %he!e the (on eme!es f!om the $ell bo'". On$e t!ie!e'& it t!+els like !ollin %+e

'o%n the (on to%!' the te!minl. The p!option o$$u!s s kin' of neu!o'omino effe$tn ele$t!i$l $hne in

one p!t of the (on memb!ne p!o'u$es simil! $hne in '>$ent p!ts& n' so on& ll the %" 'o%n to the

te!minl. /$tion potentils $n be t!ie!e' !tifi$ill" b" ele$t!i$l stimultion& %hi$h mkes them es" to stu'"& but

no!mll" the" o$$u! in $ell %hen o!'e!s $ome f!om s"npti$ inputs.

7o!k b" mn" pionee!in neu!os$ientists estblishe' the bsi$ p!in$iples of ele$t!i$l p!option in (ons&

%hi$h be$me the foun'tion fo! mu$h of %ht %e no% kno% bout the %o!kin of neu!ons. / oo' 'el of this !e-

se!$h %s pe!fo!me' usin the int (ons of s@ui's& the shee! si,e of %hi$h m'e it esie! to in+estite ele$t!i$l

$on'u$tion. Espe$ill" note%o!th" %e!e the stu'ies pe!fo!me' in the FMs b" /ln Ho'kin n' /n'!e% Hu(

le" in Enln'. Buil'in on Ohm*s l% of ele$t!i$it" 2%hi$h sttes tht +olte is e@ul to $u!!ent times

!esistn$e3& the" $h!$te!i,e' in p!e$ise mthemti$l fo!m the bsi$ fetu!es of ele$t!i$l t!nsmission in (ons.

The Ho'kin-Hu(le" e@utions !e still use' to'" to $l$ulte $u!!ent& +olte& n' !esistn$e in (ons.

SYNAPTIC CHATTER

The e(isten$e of ele$t!i$l $on'u$tion in ne!+es sueste' to lte-nineteenth-$entu!" s$ientists tht ele$t!i$l

impulses pl"e' $!iti$l !ole in the no!ml fun$tions pe!fo!me' b" the b!in. / ke" !elte' @uestion %s %hethe!

ele$t!i$l p!option %s suffi$ient to e(plin ho% the b!in %o!ke'. She!!inton*s stu'ies of !efle(es 'ete!mine' tht

it %s not.

Ele$t!i$l impulses in senso!" n' moto! ne!+es $le!l" seeme' in+ol+e' in !efle(esA %hen senso!" ne!+es

'ete$t tp on "ou! knee& the" $on'u$t ele$t!i$l impulses tht& in tu!n& le' to ele$t!i$l impulses in moto! ne!+es&

n' to the >e!k. But ho% 'oes the senso!" ne!+e $ommuni$te %ith the moto! neu!on= She!!inton 'emonst!te' tht

%hile ele$t!i$l stimultion of senso!" ne!+e eli$ite' n ele$t!i$l !esponse in the moto! ne!+e& stimultion in the

moto! ne!+e 'i' not e+oke !esponse in the senso!" ne!+e. He $on$lu'e' tht the >un$tion bet%een $ells& the



s"npse& h' +l+elike p!ope!t"it onl" t!nsmitte' in one 'i!e$tion& f!om senso!" to moto! ne!+es. This %s

p!ti$ul!l" sinifi$nt mmunition inst the !eti$ul! theo!"& fo! if neu!ons %e!e $ontinuousl" $onne$te' n'

$ommuni$te' onl" b" ele$t!i$l $on'u$tion& then moto! ne!+es shoul' h+e s si,ble n effe$t on senso!" ne!+es s

the othe! %" !oun'. 1eu!ons must the!efo!e $ommuni$te %ith one nothe! b" some mens othe! thn me!e

ele$t!i$l $on'u$tion.

Subse@uent !ese!$h !e+ele' tht the one-%" $on'u$tion bet%een neu!ons is 'ue to the f$t tht s"npti$t!nsmission in+ol+es the !elese of $hemi$ls f!om sto!e sites in the p!es"npti$ (on te!minl. These mole$ules

!e !elese' %hen $tion potentils p!opte' f!om the $ell bo'" !e$h the te!minl. The !elese' $hemi$ls then

'!ift $!oss the li@ui'-fille' s"npti$ sp$e n' $ome in $ont$t %ith spines o! othe! po!tions of the posts"npti$ $ell.

Be$use the $hemi$l sto!e sites usull" !e p!esent in the p!es"npti$ te!minl n' not in the posts"npti$

'en'!ite& t!nsmission onl" o$$u!s in one 'i!e$tion. These $hemi$ls !e $lle' neu!ot!nsmltte!s& sin$e the" llo%

neu!ons to $ommuni$te $!oss the s"npti$ pthe" t!nsmit bet%een neu!ons.

The $hemi$l ntu!e of neu!onl t!nsmission %s suspe$te' f!om stu'ies in the e!l" FS sho%in tht

the effe$ts of ele$t!i$l stimultion of ne!+es $oul' be mimi$ke' o! blo$ke' b" $e!tin $hemi$l ents. But it 'as n

inenious e(pe!iment b" Otto Loe%i in the Fs tht p!o+i'e' the ultimte p!oof. He !emo+e' the he!ts f!om t%o

f!os& le+in the ne!+es $onne$te' to one he!t but not the othe!& n' infuse' e$h %ith slt%te! solution 2simil!

to no!ml bo'" flui'3. He then ele$t!i$ll" stimulte' the ne!+es on one& %hi$h $hne' the bet !te of the he!t 2the

he!t is posts"npti$ to these ne!+es3. 7hen he !emo+e' the solution f!om the stimulte' he!t n' in>e$te' it into the

othe!& the he!tbet $hne' in the unstimulte' he!t& mu$h s if it h' been stimulte'& in'i$tin tht some

$hemi$l tht h' been !elese' in the stimulte' he!t %s t!nsfe!!e' in the solution to the othe!.

7hile Loe%i*s e(pe!iments in+ol+e' the $onne$tion bet%een ne!+e n'

mus$lethe he!t& in this $seessentill" the sme thin hppens %hen the $onne$tion is bet%een t%o

neu!ons. Tht is& the !!i+l of the $tion potentil in the p!es"npti$ te!minl le's to the !elese of neu!ot!nsmitte!

into the s"npti$ sp$e.

The !elese of neu!ot!nsmitte! mole$ules f!om the p!es"npti$ te!minl is mens& not n en'. )ts ol is to

ene!te n ele$t!i$l !esponse in the post-s"npti$ $ell. /lthouh it is often the 'en'!ites tht !e the posts"npti$

benefi$i!ies of the $hemi$l messe& the ele$t!i$l $hne p!o'u$e' in the 'en'!ite hs to be p!opte' to the $ell

bo'"& n' then to the (on& befo!e n $tion potentil $n o$$u!. This is so be$use the $tion potentil is ene!te'

in the initil p!t of the (on %he!e it $onne$ts %ith the $ell bo'".

The !!i+l of t!nsmitte! f!om sinle p!es"npti$ te!minl is t"pi$ll" not suffi$ient to p!o'u$e n $tion

potentil in the posts"npti$ $ell. Onl" if the posts"npti$ $ell is bomb!'e' %ith t!nsmitte! mole$ules f!om mn"

p!es"npti$ te!minls t bout the sme time%ithin millise$on's %ill n $tion potentil !esult3.

/ i+en posts"npti$ $ell is belie+e' to !e$ei+e !elti+el" fe% s"npti$ $ont$ts f!om n" one p!es"npti$

neu!on. /s !esult& mu$h of the $on+e!en$e tht '!i+es posts"npti$ $ell to%!' $tion potentils $omes f!om the

$on+e!en$e of 'iffe!ent p!es"npti$ $ells onto the posts"npti$ neu!on 2tht is& the ne!-simultneous !!i+l of

neu!ot!nsmitte! f!om 'iffe!ent p!es"npti$ neu!ons3. )n o!'e! fo! the inputs to !!i+e in the posts"npti$ $ell bo'" t

bout the sme time& $tion potentils h+e to h+e been t!ie!e' in the +!ious ptes"npti$ $ells t bout the sme

time. The timin hs to be '>uste' fo! 'iffe!ent lenths of (ons& sin$e& s Helmholt, 'emonst!te'& the lone! the

(on& the lone! it tkes fo! the $tion potentil to t!+el 'o%n it. 5eepin time in the ne!+ous s"stem is +e!"

$omple( >ob.

On$e the posts"npti$ $ell ene!tes n $tion potentil& its !ole shifts f!om tht of !e$ei+e! to sen'e!. )t

no% be$omes p!es"npti$ neu!on tht helps fi!e $tion potentils in othe! $ells.

The full se@uen$e of $ommuni$tion bet%een neu!ons is thus usull" ele$t!i$l$hemi$l ele$t!i$l electrical

sinls $omin 'o%n (ons et $on-+ette' into chemical messes tht help t!ie! electrical sinls in the ne(t $ell.

The!e !e lso s"npses th!ouh %hi$h $ommuni$tion bet%een p!es"npti$ n' posts"npti$ sites is pu!el"

ele$t!i$l& but $hemi$l t!nsmission is the mo!e p!e+lent fo!m. Thus& mu$h of %ht the b!in 'oes in+ol+es



ele$t!i$lt!o $hemi$l. to ele$t!i$l $o'in of e(pe!ien$e. /s h!' s it m" be to imine& ele$t!o$hemi$l

$on+e!stions bet%een neu!ons mke possible ll of the %on'!ous 2n' sometimes '!e'ful3 $$omplishments of

humn min's. You! +e!" un'e!stn'in tht the b!in %o!ks this %" is itself n ele$t!o$hemi$l e+ent.

FROM CELLS TO CIRCUITS AND SYSTEMS

E+e!" humn b!in hs billions of neu!ons tht toethe! mke t!illions of s"npti$ $onne$tions mon one

nothe!. :hemi$ls !e oo,in n' sp!ks fl"in $onstntl"& 'u!in %kefulness n' 'u!in sleep& 'u!in

thouhtfulness n' 'u!in bo!e'om. /t n" one moment& billions of s"npses !e $ti+e.

)mine l!e $o$ktil p!t" t %hi$h hun'!e's of people !e stn'in !oun' n' $httin %ith one

nothe!. )f "ou %e!e to pl$e mi$!ophone in the $hn'elie! t the $ente! of the !oom hih bo+e the $!o%'& "ou

p!obbl" %oul'n*t be ble to mke out %ht %s bein si'& fo! the mn" un!elte' $on+e!stions %oul' blen'

toethe! in the mi$!ophone. You*' le!n mo!e b" listenin in on smll !oups thn b" e+es'!oppin on the %hole

!oom t on$e. )n the sme +ein& it*s not p!ti$ul!l" inst!u$ti+e to sk %ht ll of the b!in*s billions of neu!ons n'

t!illions of $onne$tions !e up to $olle$ti+el" t n" one time. Diffe!ent !oupins of $ells !e 'oin 'iffe!ent thins& so

ttemptin to tke !e'in of them ll toethe! 'oesn*t tell "ou mu$h. )t %oul' be mo!e info!mti+e to e(mine the

ope!tion of spe$ifi$ $i!$uits o! s"stems.

/ circuit is !oup of neu!ons tht !e linke' toethe! b" s"npti$ $onne$tions. / system is $omple( $i!$uit

tht pe!fo!ms some spe$ifi$ fun$tion& like seein o! he!in& o! 'ete$tin n' !espon'in to 'ne!. Seein& fo! e(-

mple& in+ol+es the 'ete$tion of liht b" $i!$uits in the !etin& %hi$h sen's sinls& b" %" of the opti$ ne!+e& to the

+isul thlmus& %he!e the +isul info!mtion is p!o$esse' b" $i!$uits tht !el" thei! output to the +isul $o!te(& %he!e

''itionl $i!$uits ene in fu!the! p!o$essin& ultimtel" $!etin +isul pe!$eptions. The +isul s"stem& like othe!

b!in s"stems& $n thus be thouht of s se!ies of hie!!$hi$ll" !!ne' $i!$uits linke' toethe! b" s"npti$

$onne$tions to pe!fo!m some fun$tion.

S"npti$ inte!$tions bet%een t%o t"pes of neu!ons& $lle' p!o>e$tion neutons n' inte!neu!ons& !e ke" to

un'e!stn'in ho% $i!$uits n' s"stems fi.!n$tion. P!o>e$tion neu!ons h+e !elti+el" lon (ons tht e(ten' out of

the !e in %hi$h thei! $ell bo'ies !e lo$te'. )n hie!!$hi$l $i!$uit& thei! min >ob is to tu!n on the ne(t p!o>e$tion

$ell in the hie!!$h". The" 'o this b" !elesin $hemi$l t!nsmitte! tht in$!eses the likelihoo' tht theposts"npti$ $ell& the ne(t p!o>e$tion $ell& %ill fi!e its o%n $tion potentil. P!o>e$tion $ells ten' to $ti+te o! e($ite

posts"npti$ $ells.

)nte!neu!ons& lso $lle' lo$l $i!$uit $ells& sen' thei! sho!t (ons to ne!b" fl:U& often p!o>e$tion neu!ons&

n' !e in+ol+e' in info!mtion p!o$essin %ithin i+en le+el of hie!!$hi$l $i!$uit. One of thei! min >obs is to

!eulte the flo% of s"npti$ t!ffi$ b" $ont!ollin the acti+ity of p!o>e$tion neu!ons. )nhibito!" inte!neu!ons !elese

t!nsmitte! f!om thei! te!minls tht 'e$!eses the likelihoo' tht the posts"npti$ $ell %ill fi!e n $tion potentil.

These neu!ons pl" n impo!tnt !ole in $ounte!bln$in the e($itto!" $ti+it" of p!o>e$tion $ells.

P!o>e$tion $ells ten' to be i'le in the bsen$e of inputs f!om othe! p!o>e$tion $ells. )nhibito!" inte!neu!ons&

thouh& !e often toni$ll" $ti+e& %hi$h mens the" !e fi!in ll the time. P!t of the !eson %h" p!o>e$tion $ells !e

in$ti+e %hen not bein stimulte' is tht the" !e$ei+e toni$ inhibition f!om

inte!neu!ons. /s !esult& %hen e($itto!" inputs t!" to tu!n on p!o>e$tion $ell& p!ee(istin inhibition of thep!o>e$tion $ell hs to be o+e!$ome. The bln$e bet%een e($itto!" n' inhibito!" inputs to neu!on 'ete!mines

%hethe! it %ill fi!e.

The mount of inhibition ffe$tin $ell $n $hne f!om moment to moment& 'epen'in on othe! f$to!s.

8o! e(mple& %hen p!o>e$tion $ells in one !e of hie!!$hi$l $i!$uit sen' enouh $on+e!ent inputs t bout the

sme time to $ti+te p!o>e$tion $ells in the ne(t !e& the le+el of inhibition in the se$on' !e usull" oes up s

%ell. This hppens be$use the e($itto!" inputs to n !e often $ti+te inte!neu!ons s %ell s p!o>e$tion neu!ons.

The moment!" in$!ese in e($itto!" inputs to inte!neu!ons le's to moment!" in$!ese in thei! inhibito!"



beh+io!& %hi$h in tu!n p!o'u$es moment!" inhibition of the p!o>e$tion neu!ons. So-$lle' eli$ite' inhibition

$ont!sts %ith toni$ inhibition. Be$use !pi'l" $hnin sttes of e($ittion n' inhibition 'i!e$t the flo% of t!ffi$

th!ouh the b!in& it*s es" to un'e!stn' ho% b!ek'o%n in the flo% of impulses $oul' le' to neu!l !i'lo$k.

:onsi'e! n e(mple tht %ill help illust!te ho% eli$ite' n' toni$ inhibition !eulte e($ittion. )mine

$i!$uit $onsistin of t%o p!o>e$tion neutons 2/ n' B3 linke' toethe! in se!ies. ;7hen / is $ti+e& B fi!es. )f the >ob of

the $i!$uit %e!e to mke B fi!e $tion potentils s often s possible s lon s / is $ti+e& these t%o neu!ons %oul'be suffi$ient to 'o the >ob. But suppose its >ob inste' is to tke b!!e of $tion potentils in / n' tu!n them into

fe%e! $tion potentils in B& somethin tht $tull" o$$u!s @uite often in the b!in. This $oul' be $hie+e' b" i+in

neu!on B n inhibito!" pl"mte 2)3. This lo$l $i!$uit neu!on& like B& !e$ei+es the outpui of / n' then $onne$ts %ith B.

So %hen / fi!es& it tu!ns on B n' )& n' e$l p!o'u$es n output. The output of B helps tu!n on the ne(t $ell in the

$i!$uit %hile the output off tu!ns B off. /s !esult& B no% p!o'u$es fe%e! $tion tentils %hen it is fi!e' b" /.

1o% suppose tht the inte!neu!on ) is $onstntl" inhibitin the p!o>e$tio $ell B. 7ith this toni$ inhibition ''e'

in& it is oin to be mu$h h!'e! ft the input f!om / to t!ie! the p!o>e$tion $ell. )f %e put mo!e e($itto!" net tons in

%ith / to '!i+e B& n' time !!i+l >ust so& the toni$ inhibition $n ) o+e!$ome. The $ell $n no% be $ontinuousl"

$ti+te'. But bein stu$k fst-fo!%!' is not oo' fo! neu!ons& %hi$h $n be 'me' o! e+en ' st!o"e' b"

un$he$ke' e($ittion. E$h bu!st of e($ittion thus nee's to $ounte!e' %ith nothe! !oun' of inhibition. Tht*s

%he!e eli$ite' inhibiti$ like tht 'es$!ibe' bo+e& $omes in. 7hen n e($itto!" su!e o+e!$omes toni$ inhibition&

eli$ite' inhibition $n !ein in the e($ittion& !esettin the $i!$uit& p!ep!in it fo! ne% inputs. The!e !e mn" +!itions

on this theme of toni$ n' eli$ite' inhibition& but the s$en!io >ust 'es$!ibe' i+es n i'e of ho% inhibition in ene!l

%o!ks.

)nhibition is +e!" useful 'e+i$e in neu!l $i!$uits. )t ''s t!emen'ousl" to the spe$ifi$it" of info!mtion

p!o$essin& filte!in out !n'om e($itto!" inputs& p!e+entin them f!om t!ie!in $ti+it". Onl" if the e($itto!" inputs

!!i+e simultneousl" $n the" o+e!$ome the inhibition n' eli$it $ti+it". /n' on$e $ti+it" is eli$ite'& inhibition is

impo!tnt fo! keepin the e($ittion in $he$k n' !esettin the $i!$uit.

/lthouh mn" lo$l $i!$uit $ells !e inhibito!"& some !e e($itto!". Just s inhibito!" inte!neu!ons $n be

thouht of s filte!s& e($itto!" inte!neu!ons $n be +ie%e' s mplifie!s. /in imine $i!$uit $onsistin of neu!ons

/

n' B $onne$te' in se!ies. /s befo!e& B is sso$ite' %ith n inte!neu!on& but in this $se it*s n e($itto!"

inte!neu!on 2E3& n' the (on of / b!n$hes n' $ont$ts both B n' E. 7hen / tu!ns on B& the inte!neu!on E is lso

$ti+te'& n' its output $uses fu!the! e($ittion of B. /s !esult& the output of B is mplifie' b" n e($itto!"

inte!neu!on >ust s it %s !e'u$e' b" the inhibito!" inte!neu!on. But& s %e*+e seen& ll this e($ittion ultimtel" hs to

be !eulte' both to mintin no!ml fun$tions n' to p!e+ent in>u!".

THE CHEMICAL BROTHERS

The >ob of p!o>e$tion neu!on& s %e no% kno%& is to tu!n on the ne(t p!o>e$tion $ell in the $i!$uit. This

mens tht $tion potentils in the (ons of p!o>e$tion $ells h+e to t!ie! the !elese of $hemi$ls tht $!oss the

s"npse n' $ont!ibute to the fi!in of n $tion potentil in the posts"npti$ $ell. P!o>e$tion $ells thus nee' to use

$hemi$l neu!ot!nsmitte! tht hs t%o p!ope!ties. The t!nsmitte! fi!st must be ble to $t @ui$kl" t posts"npti$

sitesothe!%ise& ou! pe!$eptions n' othe! mentl sttes $oul' not keep up %ith !pi'l" $hnin e+ents. /n' it must

lso be ble to $hne the ele$t!i$l stte of the posts"npti$ $ell in su$h %" tht the o$$u!!en$e of n $tion

potentil is mo!e likel" to o$$u!. Both !e@ui!ements 2spee' n' e($ittion3 !e fulfille' b" the mino $i'

neu!ot!nsmitte! lutmte& %hi$h is the min t!nsmitte! in p!o>e$tion neu!ons th!ouhout the b!in.

9lutmte $tull" hs t%o !oles in bo'" fun$tion. )n ''ition to se!+in s neu!ot!nsmitte! in the b!in& it

lso pl"s m>o! p!t in bsi$ lifesustinin metboli$ p!o$esses tht o on $ontinuousl" th!ouhout the bo'". 8o!

e(mple& it is buil'in blo$k in the $onst!u$tion of pepti'es n' p!oteins& %hi$h !e bsi$ in!e'ients of li+in

tissues. /n'& in the b!in& it helps 'eto(if" mmoni& %hi$h is ntu!l b"-p!o'u$t of $e!tin $hemi$l !e$tions.



/lthouh lutmte is no% kno%n to be ubi@uitous e($itto!" t!nsmitte! in the b!in& its !ole in t!nsmission %s fo!

lon time h!' to 'isso$ite f!om its so-$lle' metboli$ fun$tions.

)n $ont!st& inhibito!" neu!ons& espe$ill" inhibito!" inte!neu!ons& often !elese the mino $i' 9/B/ 2sho!t

fo! mm-minobut"!i$ $i'3 f!om the te!minls of thei! sho!t (ons. )n $ont!st to lutmte& this inhibito!"

t!nsmitte! !e'u$es the likelihoo' of n $tion potentil bein ene!te' in the posts"npti$ $ell. B" sen'in (ons to

ne!b" p!o>e$tion neu!ons& 9/B/ inte!neu!ons the!eb" !eulte the flo% of t!ffi$ th!ouh i+en !e.9/B/ $tull" %s i'entifie' s neu!ot!nsmitte! lon befo!e lutmte. Be$use it %s %ell estblishe'

tht lutmte %s one of the essentil $hemi$l $omponents in+ol+e' in the s"nthesis of 9/B/& its metboli$ !ole in

9/B/ p!o'u$tion hmpe!e' the 'is$o+e!" tht lutmte %s itself neu!ot!nsmitte!.

9lutmte n' 9/B/ !e toethe! !esponsible fo! mu$h of the neu!ot!nsmission business in the b!in. )f

"ou un'e!stn' the %o!k 'one b" these t%o $hemi$ls& "ou %ill un'e!stn' @uite lot bout ho% s"npses fun$tion.

These n' ll othe! t!nsmitte!s %o!k b" tt$hin to mole$ules $lle' !e$epto!s on the posts"npti$ $ell. 4e$epto!s

sele$ti+el" !e$oni,e n' bin' 2lite!ll"& hol' on to3 t!nsmitte! mole$ules. 9lutmte !e$epto!s !e$oni,e n' bin'

lutmte& but ino!e 9/B/C 9/B/ !e$epto!s !e >ust s sele$ti+e. Ho%& then& 'oes the bin'in of lutmte n'

9/B/ mole$ules to thei! !e$epto! mole$ules le' to e($ittion n' inhibition=

/ll $ells in the bo'" !e $ompletel" en$lose' b" memb!ne& %hi$h 'efines the boun'!" of n in'i+i'ul

$ell. The memb!ne is like fo!mfittin b& spn'e( suit& in %hi$h the $ell is $ontine'. )n neu!ons& it $o+e!s the

(ons n' 'en'!ites s %ell s the $ell bo'". The sp$e outsi'e the memb!ne bet%een neu!ons is $lle' the

e(t!$ellul! sp$e. The f$t tht the e(t!$ellul! sp$e is fille' %ith li@ui' hs t%o impo!tnt $onse@uen$es.

8i!st of ll& this li@ui' is me'ium tht llo%s t!nsmitte! mole$ules to $!oss the e(t!$ellul! sp$e bet%een

p!es"npti$ n' posts"npti$ sitesthe s"npse. T!nsmitte!s 'o this b" 'iffusin out f!om the te!minl. The 'istn$e

the" h+e to t!+el is +e!" smll 2it*s mesu!e' in tin" units $lle' nst!oms& one of %hi$h e@uls one ten-millionth of

millimete!3& mkin the posts"npti$ site $lose n' es" t!et.

The se$on' point is tht e(t!$ellul! li@ui' $ontins ll so!ts of $hemi$ls& mn" %ith ele$t!i$ $h!es& tht

influen$e $ellul! fun$tion. The $ell memb!ne keeps $hemi$ls tht !e insi'e n' outsi'e the $ell sep!te. /t !est

2%hen the $ell is not bein influen$e' b" inputs3& the $hemi$l $omposition of the insi'e of the $ell is mo!e neti+el"

$h!e' thn the flui' outsi'e& 'ue to the kin's of ions tht !e p!esent on the othe! si'e of the $ell memb!ne.

1eu!os$ientiSts h+e mesu!e' the 'iffe!en$e in ele$t!i$l $h!e bet%een the insi'e n' outsi'e of ne!+e $ell. )n

ene!l& the insi'e of neu!on tht is not bein stimulte' is bout milli+olts 2 one-thousn'ths of +olt3 mo!e

neti+e thn the outsi'e. )n othe! %o!'s& the !estin potentil of the $ell is bout m6.

8o! ou! pu!poses& the $tul +olte is not tht impo!tnt. /ll %e nee' to keep in min' is the f$t tht the

memb!ne potentil is fi!l" neti+e t !est. 7hen neu!on is stimulte' b" e($itto!" inputs f!om othe! neu!ons&

ho%e+e!& the memb!ne potentil be$omes mo!e positi+e. The !eson fo! this is !elte' to the %" tht lutmte

%o!ks s neu!ot!nsmitte!.

9lutmte !e$epto! mole$ules spn the $ell memb!ne& %ith p!t f$in insi'e the $ell n' p!t f$in

outsi'e. 7hen lutmte 2!elese' f!om p!es"npti$ te!minl3 bin's to the outsi'e p!t of posts"npti$ !e$epto!&

psse opens up th!ouh the !e$epto!& llo%in positi+el" $h!e' ions in the e(t!$ellul! flui' to mo+e insi'e the

$ell& %hi$h $hnes the $hemi$l bln$e bet%een outsi'e n' insi'e. )f enouh lutmte !e$epto!s !e o$$upie' on

the posts"npti$ $ell t bout the sme time& n' the +olte insi'e be$omes suffi$ientl" positi+e& then n $tion

potentil o$$u!s.

)n $ont!st& %hen 9/B/ !e$epto!s !e o$$upie'& the insi'e of the $ell be$omes mo!e neti+e 2'ue to the

influ( of neti+e ions& espe$ill" $hlo!i'e& th!ouh psse in the 9/B/ !e$epto!3. This mkes it h!'e! fo!

lutmte !elese' f!om othe! te!minls to $hne the $on$ent!tion of the positi+e ions in the posts"npti$ $ell

suffi$ientl" to t!ie! n $tion potentil. 7hethe! n $tion potentil o$$u!s& then& 'epen's on the !eltion bet%een

lutmte 2e($ittion3 n' 9/B/ 2inhibition3. /n' sin$e n" one $ell !e$ei+es mn" e($itto!" n' inhibito!" inputs

f!om mn" othe! $ells& the likelihoo' of fi!in t n" one moment 'epen's on the net bln$e bet%een e($ittion n'



inhibition $!oss ll of the inputs t tht p!ti$ul! time.

9lutmte !e$epto!s ten' to be lo$te' out on the 'en'!ites& espe$ill" in the spines& %he!es 9/B/

!e$epto!s ten' to be foun' on the $ell bo'"& o! on the p!t of 'en'!ites $lose to the $ell bo'". )n o!'e! fo! lutmte-

me'ite' e($ittion to !e$h the $ell bo'" to help t!ie! n $tion potentil& it hs to et pst the 9/B/ u!'.

E($ittion $omin 'o%n 'en'!ite n' he'e' fo! the $ell bo'" $n be e(tinuishe' b" 9/B/.

7ithout 9/B/ inhibition& neu!ons %oul' sen' out $tion potentils $ontinuousl" un'e! the influen$e oflutmte& n' %oul' e+entull" lite!ll" fi!e themsel+es to 'eth. This effe$t hs been 'emonst!te' in e(pe!iments

%he!e the $tion of 9/B/ is blo$ke' !tifi$ill"& o! %he!e po%e!ful 'oses of lutmte-!elte' $ompoun's& too st!on

to be inhibite' b" ntu!l le+els of 9/B/& !e 'ministe!e'. O+e!$ti+it" of lutmte& n' the !esultin in>u!" to

neu!ons& $tull" pl"s n impo!tnt !ole in st!oke n' othe! +s$ul! 'iso!'e!s of the b!in& s %ell s in epileps" n'

possibl" /l,heime!*s 'isese. Some people h+e e(pe!ien$e' mil' +e!sions of lutmte to(i$it" fte! etin :hinese

foo'. 0onoso'ium lutmte 20S93& sometimes use' s n ''iti+e in this $uisine& $n in$!ese the mount of

lutmte in the bo'" to the point of $usin he'$hes& !inin e!s& n' othe! ph"si$l s"mptoms. 4eultion of

9/B/ inhibition is one of the %"s tht ps"$ho$ti+e '!us %o!k. 8o! instn$e& the ntin(iet" '!u 6lium %o!ks b"

enhn$in 9/B/*s ntu!l bilit" to !eulte lutmte. E($itto!" inputs tht %oul' no!mll" eli$it n(iet" b" fi!in

$tion potentils in fe! $i!$uits !e less ble to 'o so in the p!esen$e of 6lium n' !elte' '!us.

MOD SQUADS

)nte!$tions bet%een lutmte n' 9/B/ !e ke" to un'e!stn'in info!mtion p!o$essin b" the b!in& but

these substn$es 'o not %o!k lone o! in isoltion. 8o! e(mple& %hen !e$epto!s in the e"e 'ete$t ptte!ns of liht&

the" sen' messes th!ouh the (ons of the opti$ ne!+e to the b!in. 7hen the ele$t!i$l sinl !e$hes the (on

te!minl& lutmte is !elese'. 2Jhethe! the posts"npti$ $ell fi!es 'epen's not onl" on the $ounte!bln$in fo!$e of

9/B/ inhibition& but lso on othe! $hemi$ls tht !e p!esent t the time. These !e $lle' mo'ulto!s.

0o'ulto!s !e neu!ot!nsmttte!s in the sense tht the" p!o+i'e $hemi$l link bet%een the site f!om %hi$h

the" !e !elese' n' the lo$tion of the

!e$epto!s upon %hi$h the" $t. But in $ont!st to lutmte n' 9/B/& the" !e less 'i!e$tl" in+ol+e' in the

t!nsfe! of info!mtion f!om point to point in hie!!$hi$l $i!$uits. The %" mo'ulto! is 'istinuishe' f!om

t!nsmitte! is 'iffe!ent fo! 'iffe!ent kin's of mo'ulto!s& s %e*ll see soon. /n' sometimes& the 'istin$tion is mu!k" But

one impo!tnt 'iffe!en$e is !elte' to thei! spee'. 9lutmte n' 9/B/ !e fst-$tinA the" $use n ele$t!i$l

$hne in the posts"npti$ $ell %ithin millise$on's of bein !elese' f!om the p!es"npti$ te!minl& n' thei! effe$t is

o+e! in mtte! of millise$on's. 0o'ulto!s& on the othe! hn'& h+e slo%e! n' lone!-lstin effe$ts.

7e*ll $onsi'e! th!ee $lsses of mo'ulto!sA pepti'es& mines& n' ho!mones. E$h $n h+e e($itto!" o!

inhibito!" effe$ts& 'epen'in on the spe$ifi$s of thei! p!ti$iption in fun$tionl $i!$uits.

Pepti'es !ep!esent l!e $lss of slo%-$tin mo'ulto!" substn$es foun' th!ouhout the b!in. The" !e

m'e up of mn" mino $i's& n' !e l!e! mole$ules thn simple mino $i's like lutmte o! 9/B/. Be$use

pepti'es !e often p!esent in the sme (on te!minl s lutmte o! 9/B/ 2but in thei! o%n sep!te sto!e

$omp!tments3& the" !e !elese' %ith the fst t!nsmitte! %hen n $tion potentil $omes 'o%n the (on. But

pepti'es bin' to 'istin$t posts"npti$ !e$epto!s n' $n& s !esult& ument o! !e'u$e the effe$t of the fst

t!nsmitte! %ith %hi$h the" !e !elese'. Ho%e+e!& sin$e pepti'es !e slo% to ffe$t the posts"npti$ site& n' thei!

effe$ts !e lon-lstin& the" ten' to h+e mo!e of n effe$t on subse@uent s@ui!ts of fst t!nsmitte!. 7hile lutmte

n' 9/B/ $n h+e slo% effe$ts s %ell s fst ones& 'epen'in on the !e$epto!s in+ol+e'& pepti'es t"pi$ll" onl"

h+e slo% mo'ulto!" $tions. The" $n ffe$t '!mti$ll" the bilit" of $ell to be fi!e' b" othe! inputs& but $nnot

'o so %ith p!e$ise timin.

The!e !e mn"& mn" pepti'es tht p!ti$ipte in %i'e +!iet" of bo'il" fun$tions. Ou! inte!est is

in the neu!o$ti+e pepti'es& those tht $t in the ne!+ous s"stem. The best kno%n of these !e the opites



en'o!phins n' enkephlins. These !e t!ie!e' b" pin n' st!ess n' bin' to thei! spe$il !e$epto!s& lte!in pin

senstions n' moo'. “Joe!*s hih# is si' to be n opite effe$t. 0o!phine ene!tes its effe$ts b" bin'in to these

!e$epto!s.

The monomines& nothe! $lss of mo'ulto!s& in$lu'e substn$es like se!otonin& 'opmine& epineph!ine&

n' no!epineph!ine. Unlike most othe! t!nsmitte!s n' mo'ulto!s& the $ells tht p!o'u$e monomines !e foun' in

onl" fe% !es& mostl" in the b!in stem& but the (ons of these $ells e(ten' to %i'esp!e' !es th!ouhout theb!in 2fis. Q.G n' Q.3. )n this %"& smll numbe! of hihl" lo$li,e' neu!ons mkin monomines $n influen$e

$ells in mn" othe! lo$tions. 0onomines $hie+e thei! effe$ts b" f$ilittin o! inhibitin the $tions of lutmte o!

9/B/ 2n' the pepti'es tht !e !elese' %ith them3. Be$use the (ons !e so %i'el" 'ist!ibute'& monomines

h+e !elti+el" nonspe$ifi$ effe$ts. The" !e thus not in+ol+e' in p!e$ise !ep!esenttion of stimuli in spe$ifi$ $i!$uits.

)nste'& monomines p!o'u$e lobl stte $hnes in mn" b!in !es simultneousl"& su$h s the hih 'e!ee of

!ousl o$$u!!in th!ouhout the b!in %hen %e en$ounte! su''en 'ne! o! the lo% 'e!ee of !ousl !e@ui!e'

%hen %e !e oin to sleep.

0n" '!us use' in the t!etment of ps"$hit!i$ 'iso!'e!s %o!k b" lte!in monomines. P!o,$& fo!

e(mple& p!e+ents the !emo+l of se!otonin f!om the s"npti$ sp$e. 1o!mll"& s p!t of the p!o$ess b" %hi$h

t!nsmitte! $tion is !eulte'& neu!ot!nsmitte!s !e su$ke' b$k into the te!minls tht !elese them. B" p!e+entin

the !emo+l of se!otonin& llo%in mo!e to st" !oun' lone!& P!o,$ mplifies its effe$ts. One theo!" hol's tht the!e

is 'efi$ien$" of se!otonin in 'ep!esse' o! n(ious b!ins& %hi$h P!o,$ helps $o!!e$t. The e($t mens b" %hi$h

the in$!ese in se!otonin le+els !elie+es n(iet" o! 'ep!ession is not kno%n.

/nti'ep!essnt '!us 2like monomine o(i'se inhibito!s n' t!i$"$li$ nti'ep!essnts3 n' ntips"$hoti$s

2like $hlo!p!om,ine o! phenothi,ine3 lso %o!k b" lte!in monomine le+els. /!nines !e lso t!ets of

!e$!etionl '!usA $o$ine n' mphetmine ffe$t no!epineph!ine n' 'opmine le+els& %hile LSD $ts on

se!otonin !e$epto!s.

/nothe! monomine is $et"l$holine& %hi$h fun$tions s fst t!nsmitte! %hen it %o!ks %ith one !e$epto!

n' s mo'ulto! %ith 'iffe!ent !e$epto!. Dis!uption of $et"l$holine in the neo$o!te( is belie+e' to pl" !ole in

/l,heime!*s 'isese& n' mn" '!us tht h+e been teste' s t!etments fo! /l,heime!*s lte! $et"l$holine

fun$tion.so /$et"l$holine is lso +e!" impo!tnt t!nsmitte! in the bo'"& in+ol+e' %ith ne!+es su$h s those tht

$ont!ol mus$le mo+ements n' he!t !h"thm. 1e!+e s %o!ks b" 'is!uptin $et"l$holine t!nsmission t mus$les&

espe$ill" mus$les !e@ui!e' fo! no!ml b!ethin. 0n" inse$ti$i'es h+e simil! effe$ts in bus.

Ho!mones !e the lst $lss of mo'ulto!s %e %ill $onsi'e!. T"pi$ll"& the" !e !elese' f!om bo'il" o!ns

2like the '!enl& pituit!"& o! se( ln's3 into the bloo'st!em %he!e the" t!+el to the b!in. The!e the" $n& like

othe! mo'ulto!s& lte! the effi$$" of lutmte o! 9/B/ t!nsmission b" bin'in to spe$ifi$ !e$epto!s on $ells. 8o!

e(mple& $o!tisol& ste!oi' ho!mone !elete' f!om the '!enl ln' 'u!in st!ess& is kno%n to lte! info!mtion

t!nsmission in +!iet" of $i!$uits in+ol+e' in memo!" n' emotionl p!o$esses& in p!t b" lte!in the bilit" of

9/B/ to inhibit lutmte. Se( ho!mones& su$h s testoste!one n' est!oen& lso $n h+e p!ofoun' effe$ts on

neu!l t!nsmission n' othe! b!in fun$tions. The moo'-lte!in effe$ts of monthl" +!ition in est!oen le+els in

femles !e %i'el" 'is$usse'& n' est!oen !epl$ement the!p" 'u!in n' fte! menopuse is belie+e' to $ounte!

some of the effe$ts of in on b!in fun$tions. Be$use ho!mones !e$h the b!in th!ouh the bloo'st!em& the"

$n influen$e mn" !eions simultneousl". Ho%e+e!& sin$e onl" $e!tin !es& n' onl" $e!tin $i!$uits in those

!es& possess the !ele+nt !e$epto!s& $onsi'e!ble spe$ifi$it" $n be $hie+e' b" ho!monl mo'ultion.

GOLCI AND THE GAP

/s impo!tnt s $hemi$l s"npti$ t!nsmission is in the b!in& nothe! fo!m& $lle' ele$t!i$l t!nsmission&

lso o$$u!s. /lthouh the e(tent to %hi$h ele$t!i$l s"npses ope!te is not kno%n& it is be$omin mo!e n' mo!e p



p!ent tht the" !e sinifi$nt fo!$es fo! us to 'el %ith s %e $on$ei+e b!in ftmn$tion.

)n o!'e! fo! t%o neu!ons to $ommuni$te ele$t!i$ll"& thei! memb!nes h+e to fuse in su$h %" s to llo%

the 'i!e$t flo% of ele$t!i$it" f!om one to the othe!. These points of fusion !e $lle' p >un$tions. 4e$ent stu'ies h+e

sho%n tht in some b!in !es& like the hippo$mpus !eion impo!tnt fo! the fo!mtion of e(pli$it memo!ies& 9/B/

2inhibito!"3 $ells !e linke' toethe! o! ele$t!i$ll" $ouple'& b" p >un$tions. )n this %"& %hen 9/B/ $ells !e

$ti+te'& e($ittion $n sp!e' bet%een them in su$h %" s to $ti+te mn" of the inte!$onne$te' $ells t on$e.The $ells then fi!e toethe!& in s"n$h!on"& n' the!eb" $n !eulte $ti+it" of p!o>e$tion $ells th!ouhout the !eion.

The e(isten$e of p >un$tions i+es p!til +in'i$tion to 9oli*s !eti$ul! theo!" of the b!in& in the sense

tht some neu!ons $n $ommuni$te 'i!e$tl" b" %" of ph"si$l fusion. 0u$h !emins to be le!ne' bout them& n'

thei! $ont!ibution to s"npti$ t!nsmission nee's to be bette! inte!te' %ith ou! kno%le'e of $hemi$l t!nsmission.

CIRCUITS IN ACTION

The sme bsi$ t!nsmitte!s& mo'ulto!s& n' ho!mones $n be in+ol+e' in +e!" 'iffe!ent fun$tions. Ou!

bilities to see& he!& !emembe!& fe! 'ne!& n' 'esi!e hppiness ll in+ol+e e($itto!" 2lutmte3 s"npti$

t!nsmission !eulte' b" inhibito!" 29/B/3 s"npses n' mo'ulte' b" pepti'es& mines& n' ho!mones. 7ht

mkes soun' 'iffe!ent f!om siht& memo!" 'iffe!ent f!om pe!$eption. fe! 'iffe!ent f!om 'esi!e is not so

mu$h the $hemist!" in+ol+e' but inste' the spe$ifi$ $i!$uits in %hi$h the $hemi$ls $t. /s %" of illust!tin ho%

lutmte& 9/B/& n' mo'ulto!s %o!k& let us $onsi'e! thei! !ole in the 'ete$tion of 'ne! b" the m"'l.

The m"'l 'ete$ts 'ne! b" +i!tue of its position in s"npti$ll" $onne$te' s"stem. )n its simplest

fo!m& this s"stem $n be 'es$!ibe' in te!ms of th!ee-le+el e($itto!" $hin of $ells tht !eleses lutmte

p!o>e$tion $ells in senso!" s"stems $ti+te p!o>e$tion $ells in the m"'l& %hi$h $ti+te p!o>e$tion $ells in moto!

$ont!ol !es. This s$heme le+es mu$h out& but %e*ll h+e the oppo!tunit" to embellish it lte!.

/m"'l $ells !e$ei+e inputs f!om the senso!" %o!l' $onstntl"& but the" ino!e the m>o!it" of them. )n f$t&

the" ten' to be @uies$ent most of the time. The" 'o et %o!ke' up& thouh& %hen the !iht kin' of stimulus is p!esent

one tht sinifies 'ne! o! some othe! bioloi$ll" sinifi$nt e+ent. This hs been sho%n to be t!ue in stu'ies of

both lo%e! nimls n' humns3 So %ht keeps p!o>e$tion $ell in the m"'l f!om fi!in in !esponse to

meninless stimuli= The ns%e!& s "ou*+e p!obbl" uesse'& is 9/B/.

/s %e*+e seen& the !estin memb!ne potentil of $ells in mn" b!in !es is bout m6. )n the

m"'l& ho%e+e!& some $ells $n be s neti+e s G m6& 'ue to sustine' o! toni$ inhibition b" 9/B/. 7ith

9/B/ !e$eptots on m"'l p!o>e$tion $ells o$$upie' n' pssin $hlo!i'e& the insi'e of the $ells be$omes mo!e

neti+e& %hi$h mens it tkes e(t! e($ittion to tu!n the m"'l on. /s !esult& not n" ol' stimulus %ill 'o the

t!i$k. The stimulus hs to h+e spe$il @ulities tht llo% it to o+e!$ome the toni$ inhibition p!o'u$e' b" 9/B/.

Stimuli tht !e inhe!entl" 'ne!ous 2the siht o! smell of p!e'to!3 o! unplesnt 2intense stimuli& like

lou' noises o! stimuli tht $use pin3 !e ble to o+e!$ome the toni$ inhibition& s !e stimuli tht h+e emotionl !es-

onn$e $@ui!e' th!ouh pst le!nin. Thus& n othe!%ise meninless soun' of mo'est intensit" tht p!e+iousl"

o$$u!!e' in sso$ition %ith pin hs the sme effe$t s ntu!l 2innte3 fo!m of 'ne!. Both innte 2h!'-%i!e'3

n' le!ne' 'ne! sinls $use m"'l $ells to fi!e !pi'l" fo! sustine' pe!io'& n' !e thus ble to o+e!$ome

the 9/B/ u!'.

E+en fte! fe!-!ousin stimuli et pst toni$ inhibition n' $use m"'l $ells to fi!e& ho%e+e!& the" !e

still sub>e$t to 9/B/ $ont!ol. The inputs to the m"'l $ti+te 9/B/ $ells s %ell s p!o>e$tion neu!ons. /s !e-

sult& s the inputs be$ome mo!e $ti+e& the eli$ite' inhibition in the m"'l buil's up& %hi$h in tu!n beins to shut

'o%n the $ti+it" of m"'l $ells.

)f the bilit" of 9/B/ to keep meninless stimuli f!om tu!nin on the m"'l is $omp!omise' fo! some

!eson 2eithe! be$use the p!o>e$tion $ells $ome to fi!e mo!e esil" o! be$use the 9/B/ $ells fi!e less esil"3& stimuli



tht !e not 'ne!ous $ome to be !espon'e' to s thouh the" %e!e. This m" o$$u! in $e!tin fe! n' n(iet"

'iso!'e!s. B" the sme loi$& thins tht mke p!o>e$tion $ells fi!e less !e'il" o! tht mke 9/B/ $ells fi!e mo!e

!e'il" shoul' !e'u$e fe! n' n(iet". )n'ee'& one of the most popul! me'i$tions e+e! in+ente' fo! the t!etment of

n(iet" is 6lium& %hi$h %o!ks b" f$ilittin 9/B/ t!nsmission. /lthouh '!us tken o!ll" !e$h mn" sites in the

b!in& it is likel" tht t lest some of thei! effe$ts on fe! n' n(iet" !e $hie+e' b" enhn$in inhibition in the

m"'l& n' the!eb" mkin it h!'e! fo! e(te!nl o! inte!nl stimuli to eli$it fe! !esponses b" $ti+tin m"'l$i!$uits.

The m"'l lso !e$ei+es mo'ulto!" inputs of +!ious t"pes. 8o! e(mple& se!otonin fibe!s te!minte

the!e& n' %hen the mount of se!otonin !ises in the m"'l the $ti+it" of e($itto!" p!o>e$tion $ells is inhibite'.

The inhibition in this $se is not 'ue to the f$t tht se!otonin 'i!e$tl" ffe$ts p!o>e$tion $ells& but !the! tht se!otonin

e($ites 9/B/ $ells& n' thus in$!eses the 'e!ee to %hi$h the" inhibit p!o>e$tion neu!ons.

D!us like P!o,$ %o!k b" in$!esin the mount of se!otonin +ilble t s"npses. B" enhn$in se!otonin

t!nsmission t 9/B/ s"npses in the m"'l& n' the!eb" !e'u$in the $ti+it" of p!o>e$tion neu!ons& P!o,$

m"& like 6lium& help $ont!ol n(iet" b" !e'u$in the bilit" of inputs to the m"'l to $ti+te fe! $i!$uits.

The m"'l is lso the t!et of mn" ho!mones. One of these is $o!nsol& %hi$h is !elese' f!om the

'!enl $o!te( 'u!in fe!-!ousin n' othe!-%ise st!essful e+ents. The f$ilittion of 9/B/ inhibition of m"'l

p!o>e$tion $ells b" se!otonin is mo'ulte' b" $o!tisol. Se!otonifl*S bilit" to f$ilitte inhibition b" e($itin 9/B/ $ells

thus 'epen's on the bin'in of $o!tisol to !e$epto!s lo$te' on m"'l neu!ons. :o!tisol is ele+te' in +!iet" of

ps"$hit!i$ 'iso!'e!s& n' $o!tisol in$!eses the intensit" of fe! !e$tions. D!us like P!o,$ m" !e'u$e

e(e!te' fe! n' n(iet" in ps"$hit!i$ 'iso!'e!s b" enhn$in the bilit" of se!otonin to f$ilitte 9/B/ inhibition

in the p!esen$e of ele+te' $o!tisol.

The fe! s"stem thus ni$el" illust!tes the bsi$ elements of neu!l t!nsmission in the b!in n' its

!eultion b" mo'ulto!" $hemi$ls. 7e %ill buil' upon these points t +!ious times in lte! $hpte!s.

ARE SYNAPSES ENOUGH?

0" emphsis on the impo!tn$e of s"npses in b!in fun$tion is not inten'e' to minimi,e the !ole of othe!

f$to!s. 8o! e(mple& the !te t %hi$h $ell fi!es spontneousl" is fun$tion of $e!tin ele$t!i$l n' $hemi$l

$h!$te!isti$s of the $ell. These !e $lle' int!insi$ p!ope!ties to 'istinuish them f!om e(t!insi$ influen$es f!om othe!

$ells me'ite' b" s"npti$ t!nsmission n' mo'ultion. / $ell*s int!insi$ p!ope!ties& %hi$h m" h+e st!on eneti$

$omponent& %ill !etl" influen$e e+e!"thin tht $ell 'oes& in$lu'in its p!ti$iption in s"npti$ t!nsmission. But

be$use ps"$holoi$l n' beh+io!l fun$tions !e me'ite' b" !etes of $ells >oine' b" s"npses n' %o!kin

toethe! !the! thn b" in'i+i'ul neu!ons in isoltion& the $ont!ibution of the int!insi$ p!ope!ties of $ell to mentl life

o! beh+io! o$$u!s onl" b" %" of the !ole of tht $ell in $i!$uits. 7hile s"npses themsel+es 'on*t $$ount fo!

e+e!"thin the b!in 'oes& the" 'o p!ti$ipte $!u$ill" in e+e!" $t o! thouht tht %e h+e& n' in e+e!" emotion %e

e(p!ess n' e(pe!ien$e. S"npses !e ultimtel" the ke" to the b!in*s mn" fun$tions& n' thus to the self.

CHAPTER FOUR



BU)LD)19 THE B4/)1

E/:H :H)LD )S /1 /D6E1TU4E )1TO / BETTE4 L)8E/1 OPPO4TU1)TY TO :H/19E THE OLDP/TTE41 /1D 0/5E )T 1E7.

Hube!t H. Humph!e"

The b!in*s billions of neu!ons !e int!i$tel" $onne$te' in %"s tht mke possible the mun'ne 2su$h s

the !eultion of b!ethin3 n' the m!+elous 2the belief in n i'e3. But ho% 'o $ells in the 'e+elopin emb!"o

be$ome neu!ons& n' ho% 'o the" en' up in >ust the !iht pl$es= Ho% 'o the (ons of ll these $ells fin' thei! %" to

thei! t!et !es= /n' on$e h+in !e$he' them& ho% 'o the te!minls fiu!e out e($tl" %hi$h neu!ons to mke

s"npses %ith= Be$use the +!ious steps tke time& n' be$use 'iffe!ent $i!$uits o th!ouh these steps on

'iffe!ent s$he'ules& ou! beh+io!l n' mentl !epe!toi!e unfol's !'ull"& n' une+enl"& 'u!in $hil'hoo'. Some-

ho%& thouh& it ll $omes toethe!& n' pe!son& self %ith ll its spe$ts& eme!es.

B!in 'e+elopment is the m>o! bttlefiel' of the ntu!e-nu!tu!e $onfli$t. )n its simplest fo!m& the 'ebte is

bout %hethe! mentl n' beh+io!l $h!$te!isti$s !e 'ete!mine' mo!e b" enes o! b" en+i!onment. To the e(tent

tht mentl n' beh+io!l $h!$te!isti$s !e fun$tions of the b!in& n' s"npti$ll" $onne$te' $i!$uits un'e!lie b!in

fun$tions& the ntu!e-nu!tu!e 'ebte essentill" !e'u$es to @uestions bout ho% $i!$uits !e built 'u!in 'e+elopment.

1o one to'" se!iousl" p!oposes tht the b!in is blnk slte t bi!th& %itin to be %!itten on b"

e(pe!ien$e& o!& lte!nti+el"& tht it is eneti$ll" p!e'ete!mine'& un$hneble !eposito!" of ten'en$ies to $t& think&

n' feel p!ti$ul! %". )nste'& it is %i'el" belie+e' tht b!in $i!$uits $ome bout th!ouh $ombintion of eneti$

n' noneneti$ influen$es& n' the 'ebte no% hines less on the 'i$hotom" thn on the mnne! in %hi$h ntu!e n'

nu!tu!e $ont!ibute to b!in $onst!u$tion.

The 'i$hotom"& in f$t& beins to 'issol+e %hen it is !eli,e' tht& !e!'in @uestions of min' n' beh+io!&

ntu!e n' nu!tu!e !e !ell" t%o %"s of 'oin the sme thin%i!in up s"npsesn' both !e nee'e' to et the

>ob 'one. 7e $ommonl" think of e(pe!ien$es s le+in thei! m!k on the b!in th!ouh the !e$o!' of memo!"& n'&

s %e*ll see in lte! $hpte!s& memo!" is p!o'u$t of s"npses. )t is less $ommon& but no less pp!op!ite& to think of

enes s lso influen$in us in the fo!m of memo!". )n this $se& thouh& the s"npti$ memo!" $omes bout s

!esult of n$est!l !the! thn pe!sonl histo!". The shpin of s"npti$ $onne$tions in e!l" life b" enes n'

e(pe!ien$e is the topi$ of this $hpte!.

FIRST STEPS

The e!liest e+ents in emb!"oni$ b!in 'e+elopment !e l!el" $ont!olle' b" enes& thei! p!o'u$ts n' the

lo$l $hemi$l en+i!onment in %hi$h the" e(ist. The >ob of enes is to mke p!oteins& %hi$h !eulte mn" spe$ts of



b!in 'e+elopment. Some p!oteins !e en,"mes tht t!ie! $hemi$l !e$tions& othe!s in'u$e ''itionl enes to

mke ''itionl p!oteins& some fo!m b!!ie!s tht ui'e n' !est!i$t the mn" $ell mo+ements tht tke pl$e& n' still

othe!s p!o+i'e 'hesi+e su!f$es on $ells to %hi$h othe! $ells $lin %hile mkin thei! %" to thei! finl 'estintions.

7hen %e spek of eneti$ influen$es on b!in 'e+elopment& %e !e essentill" 'es$!ibin the effe$ts of p!oteins n'

thei! $hemi$l spin-offs.

The "oun emb!"o& l$kin senso!" s"stems& is l!el" isolte' f!om 'i!e$t pe!$eptul $ont$t %ith thee(te!nl en+i!onment. But e+en in the e!liest stes of 'e+elopment& enes 'o not ope!te $ompletel" in'epen'entl"

of the outsi'e %o!l'. The $hemi$l en+i!onment of the emb!"o is& b" ne$essit"& in 'i!e$t $ont$t %ith the bo'"

$hemist!" of the mothe!. The emb!"o $nnot mke on its o%n the mino $i's tht !e use' to ssemble the p!oteins

tht !e !e@ui!e' fo! b!in n' bo'" 'e+elopment. The" h+e to be obtine' f!om the mothe!& %ho ets them f!om the

foo' she ets. The mothe!*s 'iet $n lso be the sou!$e of less 'esi!ble substn$esto(ins n' $hemi$l ''iti+es

in foo's& fo! e(mples $n the i! she b!ethes& '!us she tkes 2p!es$!iption

n' !e$!etionl3& n' $i!ettes she m" smoke. The mothe!*s le+el of st!en %ill ffe$t he! ho!monl stte&

%hi$h $n influen$e the emb!"o& s $n ntibo'ies she mkes to fiht off infe$tions. /lthouh the m>o! fetu!es of th

b!in !e 'i$tte' b" eneti$ pln 2%hi$h u!ntees tht ll humn b!in look n' %o!k mu$h the sme3& this pln

!e@ui!es $e!tin $on'itions in th inte!nl $hemi$l en+i!onment in %hi$h neu!ons %ill !o%. )f this ene-inte!nl

en+i!onment inte!$tion is pe!tu!be'& so& too& %ill be the no!ml 'e+elopment of the b!in. 1tu!e n' nu!tu!e inte!$t

f!om the st!t.

B!in 'e+elopment beins in the e$to'e!m& %hi$h& toethe! %ith the meso'e!m n' en'o'e!m& mke up the

th!ee m>o! p!ts of the emb!"o These i+e !ise to the +!ious !eions n' o!ns of the bo'". / thi$kenin p!t of

the e$to'e!m fo!ms the neu!l plte& %hi$h fol's to fo!m the neu! tube& out of %hi$h the b!in beins to be

$onst!u$te'.

)n the neu!l tube& nonneu!l p!e$u!so! $ells 'i+i'e n' i+e !ise to neu!ons. )n humns& the +st m>o!it" of

neu!ons !e m'e in the months >usl p!i$! to bi!th. /t the pek p!o'u$tion point& bout & neu!ons !e be in

ene!te' pe! minute. This p!o$ess is $ont!olle' b" ho!mones tht 'iffus up into the neu!l tube f!om un'e!l"in

tissues n' tu!n on enes tht mke p!oteins& %hi$h& in tu!n& !eulte neu!on p!o'u$tion b" p!e$u!so! $ells. 2Th

ho!mones themsel+es !e ene p!o'u$ts m'e in nonneu!l p!ts of the emb!"o.3 )f p!o'u$tion of neu!ons is

inte!fe!e' %ith 'u!in this e!l" pe!io' 2s"& b" $onsumption of l$ohol o! '!us3& bi!th 'efe$ts& su$h s spin bifi'i o!

nen$ephl"& $n !esult. Ho%e+e!& not ll bi!th 'efe$ts !e 'ue to '!u oi l$ohol $onsumption& n' '!u o! l$ohol

$onsumption 'oes not l%"s le' to bi!th 'efe$ts.

/$$o!'in to $on+entionl %is'om& no ne% b!in $ells !e fo!me' in 'uli mmmlsthe b!in $ells "ou

$@ui!e in e!l" life !e p!ett" mu$h the ones "ou 'ie %ith& minus the ones "ou lose fo! +!ious !esons o+e! the

$ou!se oi "e!s. Ho%e+e!& !e$ent stu'ies b" 8e!nn'o 1ottebohm n' B!u$e 0$E%en of 4o$kefelle! Uni+e!sit"&

Eli,beth 9oul' of P!in$eton& n' othe!s h+e $hllene' the $on+entionl +ie%& 'emonst!tin tht neu!ons $ontinue

to

ene!te' in some !es of the 'ult b!in3* /t this point& it is not kno%n ho% %i'esp!e' the bi!th of ne%

neu!ons is& n' it m" be fi!l" !!e. Ho%e+e!& this fin'in offe!s t lest the limme! of hope tht b!in s$ientists

mihi some'" be ble to 'e+elop the!pies foste!in the !o%th of ne% neu!ons foi l!el" unt!etble neu!oloi$l

'iso!'e!s& su$h s spinl $o!' in>u!ies& st!oke& n' /l,heime!*s 'isese. )t*s impo!tnt to mke 'istin$tion he!e

bet%een neu!oenesisthe bi!th of ne% neu!onsn' s"nptoenesisthe $!etion of ne% s"npses bet%een

e(istin neu!ons. S"nptoenesis is $ommon phenomenon& one tht p!obbl" o$$u!s up until the moment of 'eth.

/s %e %ill see in this $hpte!& s"npses $hne '!mti$ll" 'u!in e!l" life& n' in the ne(t t%o $hpte!s& %e*ll see

ho% s"npses !e $hne' e+e!" time ou! b!in !e$o!'s n e(pe!ien$e.

Soon fte! thei! bi!th& neu!ons bein to se!ete& %ith $ells 'estine' to be p!t of the hin'b!in& mi'b!in&

n' fo!eb!in tkin up 'iffe!ent te!!ito!ies in the !o%in neu!l tube. Se!etion is un'e! the 'i!e$t $ont!ol of spe-

$il set of enes $lle' homeoti$ enes& %hi$h mke p!oteins tht $ont!ol the pl$ement of $ells& p!o+i'in boun'!ies



tht ui'e n' !est!i$t $ell mo+ement& n' 'hesi+e su!f$es tht llo% $ells to $luste! toethe!. Some s$ientists

belie+e tht utism miht be 'ue to muttion of homeoti$ enes tht le's to fult" b!in $onst!u$tion n'

$onne$tion3 The fun$tion of homeoti$ enes %s 'is$o+e!e' in stu'ies of f!uit flies& n' is bein elbo!te' on in

stu'ies of flies n' %o!ms& espe$ill" the %o!m C ele!ans) )t m" be 'iffi$ult to belie+e tht %e h+e mu$h in $ommon

%ith flies n' %o!ms& but the f$t is tht these enes& s %ell s numbe! of othe!s& h+e been p!ese!+e' th!ouh

mn" le+els of e+olution!" histo!".Se!ete' $ells e+entull" 'iffe!entite& %hi$h mens tht the" tke on 'iffe!ent shpes n' si,es& n' en'

up %ith 'iffe!ent t!nsmitte!s n' mo'ulto!s. This is ho%& fo! e(mple& p!o>e$tion n' inte!neu!ons $ome to 'iffe!.

Diffe!entition is un'e! eneti$ $ont!ol but is not st!i$tl" eneti$ll" 'ete!mine' p!o$ess. Stu'ies h+e sho%n tht if

$ells f!om one b!in !eion !e t!nsplnte' to 'iffe!ent !eion in nothe! niml p!io! to 'iffe!entition& the" tke on

the $h!$te!isti$s e(pe$te' of $ells in the !eion of the host !the! thn tht of the 'ono!. :hemi$l f$to!s in the

lo$l en+i!onment ppe! to 'ete!mine the ultimte t"pe of $ell tht %ill be e(p!esse'. Ho%e+e!& the s%it$h $n onl"

o$$u! in +e!" "oun $ells& in'i$tin tht on$e $ell*s t"pe is 'ete!mine'& its fte is sele'. This suests tht $ell

t"pe is not !ii'l" 'i$tte' b" enes n' is st!onl" influen$e' b" the en+i!onment& lbeit in this $se the lo$l

$hemi$l en+i!onment tht su!!oun's the $ell !the! thn the en+i!onment tht is e(te!nl to the o!nism s %hole.

The lo$l $ues in+ol+e'& thouh& !e p!oteins tht h+e themsel+es been eneti$ll" $o'e'& so the noneneti$

$ont!ibutions to $ell 'iffe!entition !e not too f! !emo+e' f!om eneti$ ones.

/s 'e+elopment p!o$ee's& the neu!l tube e(pn's n' ben's& e+entull" ssumin shpe tht beins to

!esemble the b!in. 7hile se!etion initill" pl$es $ells 'estine' to be in the sme b!in !eions toethe! in the

neu!l tube& s the tube !o%s& the $ells h+e to mi!te out f!om thei! se!ete'

!estin pl$e to !e$h thei! finl 'estintions in the !o%in b!in. 0i!tion& fo! e(mple& llo%s the mn"

!eions tht mke up the 'ult neo$o!te( to !e$ei+e f!om the neu!l tube the $o!!e$t numbe!s n' t"pes of $ells tht

%ill be nee'e' fo! those !es to pe!fo!m thei! fun$tions.

/lthouh the e($t mnne! in %hi$h mi!tin $ells fin' thei! 'estintions is not $ompletel" un'e!stoo'& %o!k

on the 'e+elopment of the $o!te( b" Psko 4ki$ of Yle suests tht the p!o$ess in+ol+es the buil'in of s$ffol's

o! $hemi$l t!ils tht mi!tin $ells follo%. These t!ils !e fo!me' b" lil $ells 2nonneu!l $ells foun' in the b!in

tht $ont!ibute in impo!tnt %"s to 'e+elopment n' othe! spe$ts of b!in fun$tion3. The li !e themsel+es ui'e'

b" lo$l $hemi$l $ues& m'e b" enes n' thei! b"-p!o'u$ts& tht se!+e s mole$ul! sinposts& $!etin b!!ie!s tht

!est!i$t mo+ement n' p!o+i'in 'hesi+e su!f$es. /s the eme!in b!in e(pn's in si,e& the t!+elin li !o%

fibe!s tht e(ten' out f!om the p!olife!ti+e ,one 2the pl$e %he!e the p!e$u!so! $ells !e mkin neu!ons n' li3

to%!' the b!in su!f$e 2%he!e the neu!ons nee' to o to fo!m the $o!te(3. B" $!%lin lon the lil t!il& the "oun

neu!ons fin' thei! %" to thei! t!et.

The lil t!il mkes it possible fo! some of the neu!ons li+in ne(t to e$h othe! in the se!ete' neu!l

tube to en' up ne(t to e$h othe! in the $o!te(. This $$ounts in p!t fo! ho% $o!ti$l !es $ome to h+e the $ells

the" 'o those '>$ent to e$h othe! in the tube t!+el toethe! lon the sme lil fibe!s n' ten' to en' up in the

sme $o!ti$l lo$tion. Ho%e+e!& the mnne! in %hi$h $o!ti$l o! othe! b!in !es !e ssemble' is not full"

un'e!stoo'. One possibilit" is tht the fun$tion of $ell 2%hethe! it %ill be in+ol+e' in siht +s. tou$h senstions& fo!

e(mple3 is spe$ifie' eneti$ll"& so tht it is 'estine' to en' up in spe$ifi$ !es 'e+ote' to spe$ifi$ fun$tion befo!e

it le+es the neu!l tube. /nothe! possibilit" is tht $ells le!n %ht to 'o f!om the $onte(t in %hi$h the" en' up. )n

suppo!t of the se$on' possibilit" is the f$t tht if pie$e of +isul $o!te( is !emo+e' n' t!nsplnte' into the lo$tion

of the somtosenso!" 2tou$h3 $o!te(& it %ill $$ept somtosenso!" (ons f!om lo%e! sttion in the b!in 2the

somtosenso!" thlmus3 n' then fun$tion s somtosenso!" $o!te(. N This suests tht $ells 'pt to the lo$l

sitution 2the $hemi$l en+i!onment n' the (ons tht !e $omin into it3 in the p!o$ess of tkin on thei! fun$tion.

Suppo!t fo! the fi!st possibilit" 2tht the fun$tionl fte of $ell is eneti$ll" 'ete!mine'3 $omes f!om !e$ent stu'"

sho%in tht un'e! $e!tin $on'itions %he!e (ons !e p!e+ente' f!om !o%in into the $o!te(& the $ells in the $o!te(

still $ome to possess the $hemi$l mole$ules tht $h!$te!i,e tht !eion. This suests tht the $hemi$l sintu!e



of the $ell is 'ete!mine' b" the $ell itself& likel" b" its enes. Ho%e+e!& f!om the point of +ie% of b!in fun$tion& the >ob

pe!fo!me' b" pie$e of $o!te( is often mo!e 'epen'ent on its s"npti$ $onne$tions thn on the mole$ules p!esent. /s

!esult& e+en if the $hemi$l sintu!e of !eion is fi(e' b" enes& the fun$tion of the !eion %ill in ll likelihoo' be

mo!e 'ete!mine' b" its s"npti$ $onne$tions. :ells t!+elin lon the lil t!il thus seem to be mbi+lent

fun$tionll"& t lest to some e(tent.

On$e neu!ons !e$h thei! 'estintions& the" bein to sp!out (ons. These fle'lin fibe!s then h+e to fin'thei! %" to thei! t!ets& the neu!ons %ith %hi$h the" %ill fo!m s"npses. The t!ets $n be lo$te' ne!b" o! in

f!%" !es& o! both. Thei! so-$lle' pthfin'in 'epen's on

!o%th $ones& st!u$tu!es shpe' like Jpnese fns tht e(ten' f!om the en's of !o%in (ons. The tips of

the !o%th $ones h+e $hemi$l ffinities %ith spe$ifi$ p!oteins in the su!!oun'in sp$ethe" onl" tt$h to $e!tin

p!oteins& n' !e !epelle' b" othe!s. 7hen one of the tips of !o%th $one fin's the !iht substn$e& it tt$hes. )f the

othe! tips !e not tt$he'& the !o%th $one is t%iste' in the 'i!e$tion of the tt$hment& n' the (on follo%s. 4e$ent

stu'ies h+e sho%n tht the sme p!otein $n be both n tt!$tnt n' !epellent fo! n (on& 'epen'in on the

$hemi$l stte of the (on. Slo%l"& step b" step& the !o%th $one $!%ls lon the $hemi$l t!il& pullin the (on

fo!%!'& until it !e$hes its 'estintion. Some sinl& the ntu!e of %hi$h is still not full" un'e!stoo'& then $uses the

!o%th to stop. The fi!st (on lon the t!il& the pionee!& le's the %"& mkin pth tht othe! ne!+e fibe!s f!om the

sme !e $n follo%. Pthfin'in b" fibe!s is not unlike mi!tion lon the lil t!il b" $ells.

7hen (ons !e$h thei! t!et& n' !e$ei+e the sinl to stop !o%in& !o%th $ones i+e %" to (onl

te!minls& %hi$h bein to fo!m s"npti$ $onne$tions %ith posts"npti$ $ells. The initil $onne$tions& like the othe! e!l"

e+ents in b!in 'e+elopment l!e'" 'is$usse'& !e l!el" estblishe' b" eneti$ n' othe! int!insi$ f$to!s. But the

b!in is not $ompletel" built f!om the insi'e out. The finl steps in its $onst!u$tion& espe$ill" the steps th!ouh %hi$h

$onne$tions !e fine-tune' in %" tht enbles them to 'o thei! >obs& !e@ui!e mo!e.

PRO-CHOICE

The humn enome $ontins inst!u$tions fo! bo'" 'e+elopment& in$lu'in& s %e*+e seen& the 'e+elopment

of the o+e!ll st!u$tu!e of the b!in. Some%he!e bet%een n' N pe!$ent of ll enes in the humn bo'" !e

belie+e' to be in the b!in. 1e+e!theless& %e p!obbl" 'on*t h+e enouh enes to $$ount fo! the %i!in of e$h of

the b!in*s t!illions of s"npti$ $onne$tions.#

P!ett" mu$h e+e!"one !ees tht the t!nsition f!om the un$ommitte'& immtu!e initil $onne$tions of the

"oun b!in to the mtu!e n' +e!" spe$ifi$ $onne$ti+it" tht $h!$te!i,es tht of the 'ult !e@ui!es neu!l $ti+it"&

tht is& t!nsmission $!oss s"npses. The e($t !ole of neu!l $ti+it"& thouh& is hete'l" 'ebte'& %ith the min

issue of $ontention bein %hethe! $ti+it"& espe$ill" $ti+it" initite' b" en+i!onmentl stimultion& helps $!ete the

mtu!e $onne$tions o! >ust sele$ts f!om the initil set of int!insi$ll" estblishe' $onne$tions those tht %ill be

!etine'. This inst!u$tion +s. sele$tion 'ebte $uts 'eep into the he!t of humn ntu!eA )s the self s$ulpte' f!om

p!ee(istin set of s"npti$ $hoi$es& o! 'oes e(pe!ien$e inst!u$t n' '' to the s"npti$ bsis of the self s %e o

th!ouh e!l" life= /s %e %ill see& sin$e en+i!onmentll" t!ie!e' neu!l $ti+it" is in+ol+e' in both inst!u$tin n'

sele$tin $onne$ti+it"& this is not so mu$h 'ebte bout enes +s. en+i!onmentl e(pe!ien$e s one bout the

p!e$ise $ont!ibution of e(pe!ien$e.

Sele$tionist i'es o!iinte' in e+olution!" 2D!%inin3 biolo"& %e!e 'opte' n' 'pte' b" the fiel' of

immunolo"& n' %e!e then pplie' to b!in fun$tion. 1iels Je!ne& 1obel P!i,e !e$ipient in immunolo"C int!o'u$e'

sele$tionist thinkin to the stu'" of the b!in in the lte )Fs. Je!ne pointe' out tht the histo!" of biolo" is fille' %ith

instn$es of inst!u$tionl i'es i+in %" to sele$tionist ones. )n his o%n fiel' of immunolo"& fo! e(mple& it %s

on$e thouht tht fo!ein ntiens ente! $ells n' inst!u$t them to mke ntibo'" mole$ules. Tht mo'el is no%

kno%n to be in$o!!e$t. To 'o this& $ell %oul' h+e to be ble to i'entif" fo!ein ntiens. Sin$e the !e$onition of

ntiens is the business of ntibo'ies& the onl" %" to mke n n-

tibo'" to no+el ntien %oul' be to l!e'" h+e the ntibo'". Je!ne s% the fll$" in this loi$& n'



subse@uent !ese!$h sho%e'& s he p!e'i$te'& tht fo!ein ntiens sele$t p!e$u!so! mole$ules f!om p!ee(istin

pool tht $n be ssemble' into l!e +!iet" of ntibo'ies.

Je!ne lte! pplie' his ntibo'" loi$ to the topi$ of le!nin. He ob>e$te' to the inst!u$tionl impli$tions of

John Lo$ke*s se+enteenth-$entu!" empi!i$ist h"pothesis tht the min' is blnk slte fille' in b" e(pe!ien$e& n' in-

ste' si'e' %ith the 9!eek Sophists& %ho belie+e' tht le!nin& s su$h& is impossible. He sueste' tht the i'e of

le!nin f!om e(pe!ien$e 2inst!u$tion3 be !epl$e' %ith the $on$ept tht e(pe!ien$e >ust sele$ts f!om p!ee(istin ltentkno%le'e. P!ph!sin So$!tes& Je!ne note' tht “le!nin $onsists of bein !emin'e' of %ht is l!e'" in the

b!in.#

/ fe% "e!s fte! publi$tion of Je!ne*s h"pothesis& Jen-Pie!!e :hneu(& p!ominent 8!en$h

neu!os$ientist& use' sele$tionist p!in$iples to e(plin $e!tin fin'ins he h' obtine' !e!'in the !ole of neu!l

$ti+it" in the 'e+elopment of s"npti$ $onne$tions bet%een ne!+es n' mus$les. He $on$lu'e' tht neu!l $ti+it"

“'oes not $!ete no+el $onne$tions but& !the!& $ont!ibutes to the elimintion of p!e-e(istin ones.

Pe!hps the most +o$l $ontempo!!" p!$titione! of neu!l sele$tionism is 9e!l' E'elmn& %ho like Je!ne

!e$ei+e' 1obel P!i,e fo! his %o!k on the immune s"stem. )n Neural /ar'in ism, E'elmn !ue' tht s"npses in

the b!in& like nimls in thei! en+i!onments& $ompete to st" li+e. S"npses tht !e use' $ompete su$$essfull" n'

su!+i+e& %hile those tht !e not use' pe!ish. /$$o!'in to E'elmn& “The ptte!n of neu!l $i!$uit!"... is neithe! es-

tblishe' no! !e!!ne' inst!u$ti+el" in !esponse to e(te!nl influen$es. E(te!nl influen$es& inste'& sele$t

s"npses b" inititin n' !einfo!$in $e! tm ptte!ns of neu!l $ti+it" tht in+ol+e them.

Sele$tionists ssume tht eneti$ n' noneneti$ f$to!s inte!$t t e' step of b!in 'e+elopment.

Sele$tion ope!tes on p!ee(istin $onne$tions se up b" enes 2%hi$h mke p!oteins tht help ui'e (ons to the !iht

!es %o!kin in $on$e!t %ith noneneti$ f$to!s 2$hemi$ls f!om the mothe!& fo e(mple3. But enes n' the

$hemi$l en+i!onment !e not %holl" !esponsi ble fo! estblishin the initil $onne$tions. Sele$tionists lso ssume

th the!e*s oo' 'el of !n'omness in+ol+e'te!minls n' 'en'!ites th hppen to be in the sme +i$init" tke

the oppo!tunit" to fo!m s"npti$ $on ne$tions& in'epen'ent of the o+e!ll ui'n$e pln spe$ifie' b" enes. /s

su)t& in Spite of ene!l eneti$ll" p!o!mme' pln& the p!ee(istin $onne$tions upon %hi$h sele$tion

ultimtel" ope!tes lso h+e uni@ue& if 'i+i'ulisti$ ntu!e& f!om %hi$h e(pe!ien$e then 'oes the sele$tin. Be$use

e$h pe!son*s e(pe!ien$es !e 'iffe!ent& 'iffe!ent ptte!ns of $onne$ti+it" !e sele$te'. 9enes thus 'i$tte tht %e %ill

ll h+e humn kin' of b!in %ith !ouhl" the sme kin's of $i!$uits& but !n'om in'i+i'ul 'iffe!en$es %ill e( ist& n'

the $onne$ti+it" of the $i!$uits& sele$te' b" s"npti$ $ti+it"& %ill shpe the in'i+i'ul b!in.

SYNAPTIC MATH

Th!ee of the min tenets of neu!l sele$tionism !e 'es$!ibe' b" the te!ms eu(erance 2mo!e s"npses !e

m'e thn !e kept3& use 2the s"npses tht !e kept !e the ones tht !e $ti+e3& n' su(traction 2$onne$tions not

use' !e eliminte'3. Buil'in the ne!+ous s"stem in this fshion is thouht to p!o+i'e mens of $opin %ith the

pu$it" of info!mtion +ilble to the b!in f!om othe! sou!$es& su$h s the outsi'e %o!l'& 'u!in e!l" 'e+elopment.N

)f the sele$tionists !e !iht& the $onne$tions %e en' up %ith s 'ults !e those tht %e!e not subt!$te'the self&

the" %oul' s"& is not $onst!u$te'& it is sele$te' f!om p!ee(istin possibilities.

Pionee!in stu'ies b" 6ikto! Hmbu!e! n' 4it Le+i-0ontl$ini in the FQs sho%e' tht subt!$ti+e o!

!e!essi+e e+ents 'o o$$u! in the ne!+ous s"stem& +ie% tht is no% %i'el" $$epte'. Du!in 'e+elopment& $ells !e

m'e n' then !e kille' offC $hemi$ls $ome n' oC fun$tions $hne. Ou! min $on$e!n he!e is %ith s"npti$

!e!ession& the p!unin b$k of e(ube!nt& unuse' p!o>e$tions 'u!in e!l" 'e+elopment.

E+i'en$e fo! s"npti$ !e!ession %s p!o+i'e' in %i'el" $ite' stu'" b" Psko 4ki$ n' his $olleuesio

%ho foun' tht the numbe! of s"npses in se+e!l !es of the p!imte $o!te( !ises n' then flls 'u!in the fi!st "e!



of life. Ho%e+e!& follo%-up stu'" in+ol+in mo!e 'etile' nl"sis of one $o!ti$l !e in'i$te' tht the 'e$!ese

'i'n*t o$$u! until pube!t". 9i+en tht $oniti+e 'e+elopment is $lose to $ompletion b" pube!t"& 'e$!ese in

s"npses tht 'oesn*t o$$u! until pube!t" $n*t $$ount fo! the mtu!tion of the min'i. /lthouh fe% su$h

in+estitions h+e been pe!fo!me' in humns& one %i'el" $ite' stu'" suests tht $!oss the $o!te( the !etest

numbe! of s"npses !e p!esent t !oun' t%ent"-fou! months of e 2ob+iousl" lon befo!e pube!t"3& but %ith

'iffe!ent !es !e$hin thei! pek t 'iffe!ent times.:e!tinl"& mu$h mo!e %o!k is nee'e' to 'ete!mine the e(tent to %hi$h s"npse elimintion o$$u!s& %hen it

o$$u!s in spe$ifi$ neu!l $i!$uits& %hethe! the!e !e sinifi$nt spe$ies 'iffe!en$es& n' ho% su$h 't shoul' be inte!-

p!ete'. The ke" issue is not %hethe! s"npses !e eliminte' 'u!in 'e+elopment 2the" $le!l" !e3 but inste'

%hethe! the 'e$!eses tht 'o o$$u! p!o+i'e $on$lusi+e suppo!t fo! the st!on +e!sion of sele$tionismthe +e!sion

tht $lims tht $ti+it" only p!e+ents the elimintion of s"npses. This tkes us to the se$on' p!tthe “use it o! lose

it# p!tof the sele$tionist !ument.

USE IT OR LOSE IT

Tht use p!e+ents s"npti$ 'emise %s sueste' b" set of $lssi$ stu'ies st!te' in the Fs b" D+i'

Hubel n' To!sten 7iesel on +isul s"stem 'e+elopment.*N Like most othe! senso!" s"stems& the +isul s"stem uses

!e$epto!s ne! the bo'" su!f$e 2in this $se& $ells in the p!t of the e"e $lle' the !etin3 to tke in info!mtion f!om

the en+i!onment. 4etinl $ells i+e !ise to (ons tht te!minte in se+e!l posts"npti$ t!ets& the m>o! one of

inte!est he!e bein the +isul thlmus. Thlmi$ $ells& in tu!n& sen' thei! (ons to !es of the +isul $o!te(& %he!e&

to stte it most simplisti$ll"& ou! +isul pe!$eptions eme!e.

1eo$o!ti$l !es& b" 'efinition& h+e si( l"e!s. )n the +isul $o!te(& the (ons f!om the thlmus en' mostl"

in the mi''le l"e!s n' !e 'ist!ibute' to the !est of the +isul $o!te( f!om the!e. 2/(ons f!om !eions othe! thn the

thlmus en' in othe! l"e!s.3 )n stu'ies of mtu!e $ts& Hubel n' 7iesel foun' tht $ells in these mi''le l"e!s

ten'e' minl" to fi!e $tion potentils %hen stimulte' +isull" th!ouh one e"e o! the othe!& %ith fe%e! $ells !e-

spon'in to stimultion of both e"es. The e"e-spe$ifi$ $ells ten'e' to $luste! toethe! in sep!te pt$hes& le'in to

!es %ith $ells !esponsi+e to onl" one e"e. But %hen the" pe!fo!me' the sme stu'" on +e!" "oun $ts& most $ells

!espon'e' to stimultion of both e"es. This le' them to su!mise tht initill"& $o!ti$l $ells must !e$ei+e s"npti$ inputs

f!om e$h e"e& n' then& 'u!in lte! 'e+elopment& inputs f!om one e"e %e!e eliminte'& le+in onl" the inputs f!om

the othe!.

To test %hethe! thei! hun$h %s $o!!e$t& Hubel n' 7iesel $lose' one e"e of thei! e(pe!imentl sub>e$ts

e!l" in life befo!e the e"e se!etion took pl$e in the +isul $o!te(. The e"e %s opene' %hen the nimls be$me

'ults. B" then& !elti+el" fe% if n" $ells !espon'e' to +isul stimultion of the p!e+iousl" $lose' e"e. 1e+e!theless&

the $ells tht %oul' h+e no!mll" !espon'e' to the $lose' e"e %e!e still fun$tionlbut no% the" onl" !espon'e' to

the e"e tht h' been left open. The open e"e& in othe! %o!'s& !etine' $$ess not onl" to its o%n $ells but lso to the

$ells no!mll" 'e+ote' to the othe! e"e. :losu!e of n e"e in n 'ult $t h' no su$h effe$ts& suestin tht the

$o!te( onl" hs this $p$it" to !eo!ni,e 'u!in e!l" 'e+elopment. Hubel n' 7iesel $on$lu'e' tht the

'e+elopment of s"npti$ $onne$tions is $ompetiti+e p!o$ess& one in %hi$h the $onne$tions tht !e use' !e kept

n' those tht o unuse' !e eliminte'.

These fin'ins& %hi$h h+e been $onfi!me' n' elbo!te' on b" mn" in+estito!s o+e! the "e!s&F !e

$e!tinl" $onsistent %ith the sele$tionist p!in$iple tht 'ult s"npses !e pi$ke' f!om p!ee(istin set b" $ti+it".

Ho%e+e!& sin$e this e!l" stu'" %s $on'u$te'& the tools +ilble fo! e(plo!in ho% the b!in %o!ks h+e '+n$e'

$onsi'e!bl"& llo%in neu!os$ientists to no% sk mo!e sophisti$te' @uestions. 0i$hel St!"ke! n' his $olleues&

fo! e(mple& stu'ie' the issue usin mo!e e($tin mesu!e of the effe$ts of

s"npti$ $ti+it".#* 4the! thn mesu!in the o+e!ll $luste!in of e"e-spe$ifi$ $ells in !eion& the" ske'

%ht hppens to in'i+i'ul (on te!minls n' the s"npses the" mke 'u!in 'e+elopment. )n'i+i'ul $ells in the

thlmus %e!e in>e$te' %ith $hemi$l t!$e! t 'iffe!ent times.# The t!$e! then sp!e' th!ouhout the neu!on& ll the



%" to the (on te!minl n' its p!es"npti$ en'ins in the $o!te(. The" foun' tht s 'e+elopment p!o$ee'e'&

mn" (ons 'i' in'ee' !et!$t 2$onsistent %ith sele$tionist +ie%3& but tht the !eminin (ons lso in$!ese' in

$omple(it" 2$onsistent %ith n inst!u$tionl +ie%3. /$ti+it" thus le's to n in$!ese in s"npti$ $omple(it" !the! thn

me!el" stbili,tion of the p!ee(istin ptte!n$ti+it" the!efo!e is $pble of inst!u$tin the fo!mtion of ne%

s"npti$ $onne$tions.

/$ti+it" lso ppe!s to help 'efine the 'em!$tion bet%een !es of the $o!te(. 8o! e(mple& the (onsf!om the +isul thlmus no!mll" sp!e' into !es of the u'ito!" $o!te(& n' +i$e +e!s& in e!l" life. /s

'e+elopment p!o$ee's& the st!" $onne$tions !e p!une' b$k& sin$e the $ells in i+en !e !e mo!e st!onl"

$onne$te' %ith one s"stem o! the othe!& n' the st!one! inputs $ompete mo!e su$$essfull" fo! the ttention of the

posts"npti$ $ells. This $n be seen %ith $onenitll" 'ef 'ults& in %hom the !eion of the $o!te( !esponsi+e to

+isul stimultion in$lu'es the !e tht %oul' t"pi$ll" be o$$upie' b" the u'ito!" $o!te(. )t is the bsen$e of $ti+it"

in the u'ito!" !e tht hs llo%e' the +isul fibe!s to $ompete fo! those s"npses.

7hile %e %oul' ten' to ssume tht s"npti$ $ti+it" in senso!" s"stem& like the +isul s"stem& is 'ue

e($lusi+el" to en+i!onmentl stimultion& stu'ies b" :!l Sht, n' othe!s suest tht b!o'e! +ie% of su$h

$ti+it" is nee'e'3 )n $ont!st to $ts n' some othe! nimls& p!imtes h+e e"e-spe$ifi$ pt$hes p!esent in the

$o!te( t bi!th. Se+e!l %eeks befo!e bi!th& $ells in the !etin !e spontneousl" fi!in $tion potentils in these

nimls3. Be$use mn" $ells in i+en e"e fi!e simultneousl"& %+e of s"n$h!oni,e' $ti+it" is t!nsmitte' to the

b!in f!om e$h e"e. Ho%e+e!& the %+es $omin out of the t%o e"es !e not in s"n$ n'& in f$t& t"pi$ll" o$$u! t

'iffe!ent times. This suests tht en'oenous $ti+it" ene!te' in the t%o e"es in'epen'ent of e(te!nl +isul

stimultion miht be suffi$ient to p!o+i'e the $ompetiti+e $ti+it" in the $o!te( to $!ete e"e-spe$ifi$ $luste!s of $ells.

)n'ee'& if this en'oenous $ti+it" is blo$ke' $hemi$ll"& the $luste!s fil to 'e+elop.

)t*s impo!tnt to mke $l!ifi$tion t this point. 1e% $onne$tions fo!me' b" $ti+it" !e not $!ete' s

enti!el" ne% entities but !the! !e ''e' to int!insi$ll" 'ete!mine' p!ee(istin $onne$tions. /''e' $onne$tions !e

the!efo!e mo!e like ne% bu's on b!n$h !the! thn ne% b!n$hes. /$ti+it" thus 'oes not p!o'u$e %holesle

!e%i!in of the b!in. /fte! ll& most of the $onne$tions in m" b!in n' "ou!s !e the sme. /$ti+it" ''s those little

'>ustments tht mke "ou n' me 'iffe!ent.

)n !e+ie%in the e+i'en$e on the !ole of $ti+it" in the estblishment of the 'ult ptte!n of s"npses& t%o

le'e!s in the fiel'& L!!" 5t, n' :!l Sht,& !e$entl" note' tht “neu!l $ti+it" is likel" p!o+i'in $ues tht '!i+e

the fo!mtion of ne% s"npses n' (on b!n$hes& s %ell s $ues tht $t to sele$t n' stbili,e e(istin ones.#

7hile it m" seem tht su$h n “e+e!"bo'" %ins# summ!" sttement implies tht nothin hs been $$omplishe' in

the fiel'& this %oul' be the %!on $on$lusion. )t hs tken t!emen'ous mount of %o!k to 'emonst!te tht $ti+it"

both inst!u$ts the fo!mtion of ne% $onne$tions n' sele$ts use' ones f!om p!ee(istin pool. 7hile $ti+it" m" not

be ne$ess!" fo! the estblishment of ll $i!$uits& the f$t tht it pl"s ke" !ole in $onst!u$tin t lest some of them

suests tht pu!el" sele$tionist +ie% of b!in 'e+elopment is not +ible. /t the sme time& the f$t tht $ti+it"

inst!u$ts the !o%th of $onne$tions 'oes not !ule out its !ole in sele$tin n' elimintin s"npses. /$ti+it" is in+ol+e'

in both p!o$esses.

)t is p!obbl" best to think of inst!u$tion n' sele$tion s t%o $omplement!" mens b" %hi$h $i!$uits $n be

$onst!u$te' !the! thn s mutull" e($lusi+e theo!ies of b!in 'e+elopment. Unfo!tuntel"& the onl" %" to 'ete!mine

the p!e$ise $ont!ibution of e$h to the $onst!u$tion of p!ti$ul! $i!$uit is to 'o the e(pe!iments. Sin$e onl" fe%

$i!$uits h+e been stu'ie' in this 'e!ee of 'etil& 'e+elopmentl b!in !ese!$he!s !e not likel" to be bo!e' n" time

soon.

WIRING BY FIRING

1e% $onne$tions m'e b" neu!l $ti+it" !e >ust s sub>e$t to the “use it o! lose it# !ule s ol' ones tht

h+e been sele$te' f!om the initil pool of s"npses. :Jhen ne% $onne$tions !e m'e& onl" some su!+i+ethose

tht o on to be use'. But ho% e($tl" 'oes “use# p!e+ent loss= 7ht o$$u!s bet%een posts"npti$ $ell n' its



p!es"npti$ te!minl to ensu!e $onne$tion*s su!+i+l= O!& stte' mo!e positi+el"& ho% 'oes $ti+it" st!enthen

$onne$tions=

)n FMF& Donl' Hebb& :n'in ps"$holoist& p!opose' tht if t%o neutons !e $ti+e t the sme time&

n' one is p!es"npti$ to the othe!& then the $onne$tion bet%een them %ill be st!enthene'. )n Hebb*s %o!'s&

““.XJhen n (on of $ell / is ne! enouh to e($ite $ell B o! !epete'l" n' $onsistentl" tkes p!t in fi!in it& some

!o%th p!o$ess o! metboli$ $hnes tke pl$e in one o! both $ells su$h tht /*s effi$ien$"& s one of the $ells fi!inB& is in$!ese'.# The essen$e of Hebb*s i'e is $ptu!e' b" the slon “:ells tht fi!e toethe! %i!e toethe!.#

/lthouh Hebb o!iinll" p!opose' his fi!e-n'-%i!e theo!" to $$ount fo! the ntu!e of le!nin n' memo!"&

it hs been use' to e(plin othe! spe$ts of s"npti$ fun$tion& espe$ill" the $onst!u$tion of s"npses 'u!in 'e+elop-

ment. :onsi'e! in the estblishment of +isul $o!te( $onne$ti+it". /s %e*+e seen& in p!imtes& the %eeks befo!e

bi!th !e n impo!tnt pe!io' fo! +isul s"stem 'e+elopment& s %+es of spontneous $ti+it" f!om the t%o e"es set

up ptte!ns of $ti+it" tht !esult in the p!efe!entil $ti+tion of $e!tin $o!ti$l $ells b" one e"e o! the othe!. Be$use

$ells in the !etin of one e"e !e mo!e likel" to fi!e spontneousl" t the sme time& n' !e mu$h less likel" to fi!e t

the sme time s $ells in the othe! e"e& $hn$es !e tht %hen posts"npti$ $o!ti$l $ell is $ti+te' b" p!es"npti$

inputs f!om one e"e& p!es"npti$ inputs f!om othe! $ells in the sme e"e %ill be !!i+in mo!e o! less simultneousl".

/$$o!'in to Hebb*s !ule& this $on$u!!ent $ti+it" in p!es"npti$ n' posts"npti$ $ells then le's to st!enthenin of

the $onne$tions f!om tht e"e to the posts"npti$ $ell.

?uite lot hs been 'is$o+e!e' bout the neu!ot!nsmitte! me$hnisms tht un'e!lie Hebbin plsti$it"C

espe$ill" in the $onte(t of le!nin n' memo!". 7e %ill e(mine this %o!k in 'etil in $hpte! . 8o! no%& %e $n

s" tht the best-un'e!stoo' fo!m of Hebbin plsti$it" in+ol+es the !elese of lutmte f!om p!es"npti$ te!minls&

n' the bin'in of the !elese' t!nsmitte! to t%o kin's of posts"npti$ !e$epto!s. One of these !e$epto!s !e$o!'s tht

the posts"npti$ $ell %s $ti+e& n' the othe! !e$o!'s %hi$h p!es"npti$ te!minls $ont$tin the posts"npti$ $ell

%e!e $ti+e t the sme time. )n this %"& the posts"npti$ $ell is ble to 'ete$t the $o-o$$u!!en$e of p!es"npti$ n'

posts"npti$ $ti+it"& n' the!eb" help link the posts"npti$ $ell %ith ll of the p!es"npti$ te!minls tht %e!e $ti+e

%hen the posts"npti$ $ell fi!e' n $tion potentil.

Hebb sueste' tht in o!'e! fo! the in$!ese' effi$ien$" of the $onne$tion bet%een the p!es"npti$ n'posts"npti$ $ell to be mintine'& somethin like ne% !o%th nee's to o$$u!. /lthouh the!e %s little e+i'en$e of itt the time& $ti+it"-in'u$e' !o%th hs no% been obse!+e' in mn" 'iffe!ent $i!$umstn$es. 8o! e(mple& St!"ke!*s

!esults 'es$!ibe' e!lie! sho%e' tht $ti+e (ons b!n$h n' sp!out ne% $onne$tions. /lso& stu'ies of E!i$ 5n'eln' $olleues t :olumbi h+e 'emonst!te' tht ph"sioloi$l plsti$it" is $$ompnie' b" (on b!n$hin n'ne% s"npse fo!mtion both 'u!in 'e+elopment n' follo%in le!nin. On$e this o$$u!s& i+en $tion potentil$omin 'o%n the (on %ill be mo!e effe$ti+e in fi!in the posts"npti$ $ell be$use it $ti+tes mo!e s"npses on tht$ell.

The mnne! in %hi$h $ti+it" p!omotes !o%th 'u!in e!l" 'e+elopment is bein $ti+el" !ese!$he'. One of

the ke" pl"e!s is $lss of posts"npti$ !e$epto!s fo! the e($itto!" t!nsmitte! lutmte 2see $hpte! Q3. These

spe$il !e$epto!s& kno%n s 10D/ !e$epto!s& ppe! to be p!ti$ul!l" impo!tnt in tht the" !e ble to 'ete$t the

mt$h bet%een $ti+it" in the p!es"npti$ n' posts"npti$ neu!on. 7hen these !e$epto!s !e blo$ke' o! othe!%ise

inte!fe!e' %ith& no!ml 'e+elopment is 'is!upte'. 7e %ill h+e mu$h to s" bout the !ole of 10D/ !e$epto!s in

plsti$it" in $hpte! . 8o! no%& it is minl" impo!tnt to kno% tht me$hnisms e(ist tht $n in'ee' llo% Hebb*s

mi$ to be %o!ke'.

/nothe! impo!tnt set of mole$ules !e neu!ot!ophins& spe$il toni$s tht p!omote the su!+i+l n' !o%th of

neu!ons. 7hen n $tion potentil o$$u!s in posts"npti$ $ell& neu!ot!ophins !e !elese' f!om the $ell n' 'iffuse

b$k%!' $!oss the s"npse& %he!e the" !e tken up b" p!es"npti$ te!minls. Un'e! the influen$e of

neu!ot!ophins& the te!minls bein to b!n$h n' sp!out ne% s"npti$ $onne$tions. Sin$e onl" those p!es"npti$ $ells

tht %e!e >ust $ti+e 2tht >ust !elese' t!nsmitte!3 tke up the mole$ules& onl" the" sp!out ne% $onne$tions. /$ti+it"

thus in'u$es !o%th& n' the !o%th tht o$$u!s is !est!i$te' to the $ti+e te!minls.

)n ''ition to this !ole in the $ti+e $onst!u$tion of $i!$uits& neu!ot!ophins !e lso in+ol+e' in s"npse

sele$tion. The ntu!l fte of mn" $ells 'u!in 'e+elopment is n e!l" e(it. So-$lle' p!o!mme' $ell 'eth is one



of the !e!essi+e e+ents tht help shpe the finl ptte!n of $onne$ti+it". :ell 'eth is p!e+ente' if p!es"npti$

te!minl !e$ei+es life-sustinin shot of neu!ot!ophins f!om its posts"npti$ p!tne!. The su!+i+l !te of neu!ons is

in this %" !eulte' b" the limite' +ilbilit" of neu!ot!ophins. Onl" those $ells tht $ompete su$$essfull" fo!

neu!ot!ophins 2those tht !e $ti+e3 su!+i+e. )n the p!esen$e of neu!ot!ophins& the su!+i+in te!minls 2those tht

%e!e $ti+e3 lso bein to sp!out ne% $onne$tions. Sele$tion $n be step lon the pth to%!' $ti+it"-inst!u$te'

!o%thin othe! %o!'s& sele$tion n' inst!u$tion !e p!tne!s in s"npti$ 'e+elopment.

WHAT ABOUT INNATENESS?

The t%o min %"s $i!$uits !e kno%n to et builtsele$tion n' inst!u$ tionboth ssume tht the

s"npti$ $onne$tions tht ultimtel" 'ete!mine %ht $i!$uit %ill 'o n' ho% it %ill 'o it !e %i!e' up epieneti$ll"&

tht is& b" inte!$tions bet%een enes n' en+i!onment 2in$lu'in both the inte!nl n' e(te!nl en+i!onment3. 7he!e

'oes this le+e innteness& the i'e tht $e!tin fun$tions me'ite' b" the b!in miht 'e+elop minl" un'e! eneti$

$ont!ol=

The topi$ of innteness often $omes up in the $onte(t of ps"$holoi$l 2mentl n' beh+io!l3 'e+elopment.

To the e(tent tht ps"$holoi$l $h!$te!isti$s !e me'ite' b" s"npses in the b!in& the ps"$holoi$l n' s"npti$

le+els !e intimtel" !elte'. The @uestion !ise' in the p!e$e'in p!!ph $n the!efo!e be !eph!se'A 7he!e 'oes

the epieneti$ ntu!e of s"npti$ 'e+elopment le+e the s"npti$ bsis of innteness= )n o!'e! to $onsi'e! this

@uestion meninfull"& %e nee' to mke 'istin$tion bet%een the t%o 'iffe!ent menins of innteness. One is the

i'e tht enes mke us ll the sme& i+in us t!its tht %e sh!e %ith othe! membe!s of ou! spe$ies. The othe! is

tht enes mke us uni@ue.

INNATENESS I: SPECIES SPECIFICITY

8o! lon time& innteness %s the business of etholoists& bioloists like 5on!' Lo!en, n' 1iko

Tinbe!en %ho stu'ie' beh+io!.# / %i'e !ne of beh+io!s in +!iet" of 'iffe!ent nimlsf!om nest-buil'in&

mte!nl $!e& n' fo!in to p!e'tion n' 'efense%e!e si' to be innte n' thus %e!e belie+e' to eme!e

'u!in e!l" life in'epen'ent of le!nin n' othe! en+i!onmentl influen$es. Le!nin %s 'eeme' to be impo!tnt in

shpin the in'i+i'ul& but mn" of the $h!$te!isti$s tht mke membe!s of spe$ies $t like %e!e thouht to be

f!ee f!om en+i!onmentl influen$e& o! t lest mo!e 'epen'ent on ntu!e thn nu!tu!e.

The $lssi$ metho' use' b" etholoists to test innteness %s to sho% tht beh+io! %s p!esent t bi!th

o! sho!tl" the!efte!& o!& mo!e ene!ll"& tht it eme!e' in the bsen$e of n oppo!tunit" fo! the o!nism to h+e

le!ne' f!om en+i!onmentl stimultion. But in the Fs& Dniel Leh!mn& n /me!i$n niml ps"$holoist&

$on+in$inl" !ue' tht e+en un'e! the most st!inent isoltion $on'itions& the o!nism is ne+e! $ompletel" isolte'

f!om noneneti$ influen$es& su$h s thins tht hppene' p!entll" o! sho!tl" f

te! bi!th. /s !esult& the epieneti$ ntu!e of beh+io! 'e+elopment $me to be $$epte' b" etholoists& %ho

shifte' %" f!om te!ms like innate n' instinctual n' to%!' species%typical in thei! effo!ts to un'e!stn' the

'e+elopment of the uni@ue beh+io!l !epe!toi!es of 'iffe!ent spe$ies.#

)!oni$ll"& >ust s etholo" %s $omin to $$ept epieneti$ $ont!ibutions to spe$ies-t"pi$l beh+io!&

ps"$holo" 2espe$ill" /me!i$n ps"$holo"3 tu!ne' to%!' n emphsis on innteness. To'"& the innteness of

$e!tin mentl $p$ities in humns n' othe! spe$ies is emphsi,e' b" mn" ps"$holoists. Belo%& %e*ll e(mine

%he!e this t!en' o!iinte' n' %he!e it is oin.

THE DEMISE OF UNIVERSAL LEARNING

Th!ouh the mi'-t%entieth $entu!"& /me!i$n ps"$holo" pi' little ttention to spe$il $p$ities of in'i-

+i'ul spe$ies. Un'e! the influen$e of beh+io!ists like John 7tson& B. 8. Skinne!& n' :l!k Hull& beh+io! $me to



be un'e!stoo' s 'epen'ent on %ht o!nisms le!ne' f!om thei! e(pe!ien$es. 8o! beh+io!ists& le!nin %s

uni+e!sl $p$it" tht %o!ke' mo!e o! less the sme !e!'less of %hi$h niml %s 'oin the le!nin n' %ht

%s bein le!ne'.# )f one %nte' to un'e!stn' ho% humns le!n lnue& mth& telephone numbe!s& tennis& o!

%ht someone looks like& stu'ies of the %" tht ke"-pe$kin in pieon o! b!-p!essin in !t %s !einfo!$e' b"

foo' %e!e >ust s +li' s n"thin else.

Thins ben to $hne in the Fs& %hen the linuist 1om :homsk" $hllene' the notion of uni+e!slle!nin $p$it". He p!opose' tht ntu!l lnue is uni@ue to humns& n' tht lnue $@uisition is 'iffe!ent

f!om othe! le!nin $p$ities tht humns h+e. His i'es bout !ules n' !ep!esenttions in ou! use of lnue

helpe' sp!k the $oniti+e !e+olution in ps"$holo"& n' his $on$eption of uni+e!sl !mm! en$o'e' in the humn

enome hs e+e! sin$e been $o!ne!stone of $oniti+e nti+ism& %hi$h ssumes tht $e!tin ps"$holoi$l $p$ities

!e innte.

The plin +nill +ie% of le!nin %s lso $hllene' %hen niml ps"$holoists in the Fs ben to

!eli,e tht the beh+io!ists* “l% of le!nin# 'i'n*t ppl" to ll fo!ms of le!nin. 8o! e(mple& John 9!$i*s

'is$o+e!" tht some stimuli 2those tht mke "ou si$k to "ou! stom$h3 $n be sso$ite' %ith tstes& but not %ith

soun's o! sihts& %s in$onsistent %ith the beh+io!ist notion tht n" i+en stimulus $oul' be sso$ite' %ith n"

othe! one& thouh it mkes pe!fe$t sense f!om bioloi$l point of +ie%. This n' othe! fin'ins sueste' tht the!e

miht be bioloi$l $onst!ints on le!nin& f$to!s tht tilo! the %o!kins of the le!nin p!o$ess to the spe$ifi$

le!nin tsk n' to the p!ti$ul! le!nin !e@ui!ements of the spe$ies. / uni+e!sl le!nin me$hnism %s $le!l"

not suffi$ient& n' the stu'" of niml beh+io! b" /me!i$n ps"$holoists be$me mo!e etholoi$l.

THE RISE OF EVOLUTIONARY NATIVISM

E+entull"& bioloi$l $onst!ints $me to pl" n impo!tnt !ole in i'es not >ust bout niml beh+io! but

lso bout humn thouht. 8o! e(mple& the ps"$holoist Ste+en Pinke! hs !e$entl" blen'e' the :homsk" nti+ist

t!'ition& %hi$h +ie%s lnue s spe$il $p$it" of humns& %ith i'es bout e+olution& sse!tin tht humns

h+e lnue instin$t& s %ell s +!iet" of othe! innte mentl o!ns 2$p$ities3. These !e belie+e' to h+e

!esulte' f!om D!%inin ntu!l sele$tion n' “o%e thei! bsi$ 'esin to ou! eneti$ p!o!m. Tht lnue m" be

innte is suppo!te' b" stu'ies of pi'in lnue& simple& $!u'e fo!m of +e!bl $ommuni$tion mon people %ho

spek 'iffe!ent lnues but li+e toethe! n' h+e to $ommuni$te %ith one nothe!. Pi'in l$ks !mm! %hen it

is initill" pie$e' toethe!& but b" the se$on' ene!tion& it beins to tke on !mmti$l st!u$tu!e& suestin tht

the un'e!l"in innteness of !mm! ultimtel" eme!es. The innteness of lnue& thouh not uni+e!sll"

!ee' upon& is suppo!te' ''itionll" b" $e!tin eneti$ $on'itions tht h+e been linke' to spe$ifi$ $h!omosomes&

in$lu'in the sp!e' lnue bilities in spite of othe! mentl 'iffi$ulties in $hil'!en %ith 7illims s"n'!ome& n' the

lnue impi!ment in spite of othe!%ise int$t mentl bilities in spe$ifi$ lnue impi!ment 2SL)3. /lthouh the

e+i'en$e fo! innteness is st!onest fo! lnue n' emotionl e(p!essions& innteness hs been postulte' to

$$ount fo! mn" mentl $p$ities. 8o! e(mple& it hs been p!opose' tht humns h+e innte kno%le'e bout

numbe!s& ph"si$s& n' e+en bout ho% othe! humn min's %o!k.No

The !e$ent !oun's%ell of inte!est in the ntu!l sele$tion of mentl fun$tions hs nmee+olution!"

ps"$holo"A The im of this 'is$ipline is to t!" to 'ete!mine %ht f$to!s miht h+e '!i+en the e+olution& b" ntu!l

sele$tion& of ou! +!ious mentl $p$ities. Tkin $lue f!om 5iplin& $!iti$s like Stephen J" 9oul' $ll the

e(plntions p!opose' b" e+olution!" ps"$holoists “Just So Sto!ies#A the" m" soun' oo'& but %hethe! the" !e

t!ue o! not $n*t be kno%ni* /fte! ll& the!e is no fossil !e$o!' of the min'& n' e+olution!" e(plntions bout the

min' !e bsi$ll" untestble. 9oul' suests& in $ont!st& tht lnue n' pe!hps othe! mentl fun$tions tht !e

bein toute' s innte !e not e+olution!" 'pttions& t!its tht %e!e sele$te' fo!& but !the! !e e(pttions&

fetu!es tht enhn$e ou! fitness but



tht %e!en*t o!iinll" 'esine' to 'o %ht %e use them fo!.# 8o! e(mple& bi!'s p!obbl" 'e+elope' fethe!s

s mens of $ont!ollin bo'" tempe!tu!e& n' onl" lte! use' them to fl". /s 9oul' notes& “On$e "ou buil' $om-

ple( m$hine& it $n pe!fo!m so mn" unnti$ipte' tsks. Buil' $ompute! ;fo!* p!o$essin $he$ks t the plnt& n' it

$n lso..& %hip n"one*s ss 2o! t lest tie them pe!petull"3 in ti$-t$-toe. /nothe! $!iti$ of the e+olution!"

e(plntion of lnue is the ps"$holoist D+i' P!em$k& pionee! in the stu'" of $himp lnue. /s he notes&

“Humn lnue is n emb!!ssment fo! e+olution!" theo!" be$use it is +stl" mo!e po%e!ful thn one $n$$ount fo! in te!ms of sele$ti+e fitness. E+olution!" ps"$holoists h+e !espon'e' to su$h tt$ksi pointin out&

mon othe! thins& tht the!e !e b' e+olution!" e(plntions 2those tht !e in'ee' “Just So Sto!ies#3 but lso

oo' ones 2those tht !e bette! !oun'e'3. The p!oblem is the!e*s !et 'el of !oom 2m"be too mu$h3 fo!

inte!p!ettion in the 'e$ision bout %ht $onstitutes oo' s oppose' to b' e+olution!" ps"$holoi$l e(pln-

tion. / mo!e ene!l $!iti@ue of e+olution!" ps"$holo" $n be foun' in Alas, Poor /ar'in, !e$ent $olle$tion of

ess"s put toethe! b" Hil!" n' Ste+en 4ose 2Ste+en is neu!os$ientist %ho stu'ies memo!" n' +o$l opponent

of nti+ist ps"$holo"3 P 4e!'less of ho% this onoin 'ebte en's& ho%e+e!& fo! no% nti+ists !e en>o"in oo'

!i'e 2thouh not f!ee one3 in ps"$holo".

E+en if e+olution!" ps"$holo" tu!ns out to be 'e' %!on 2n' thouh ) 'on*t think tht*s the $se& ) m

$on$e!ne' bout %hethe! its e(plntions $n be put to !io!ous s$ientifi$ tests3& it %oul'n*t men tht nti+ism is lso

$ompletel" %!on. )t*s impo!tnt to 'istinuish bet%een the @uestion “)s the fun$tion X innte=# n' the @uestion “7h"

'i' the innte fun$tion X e+ol+e=# The fo!me! is @uestion bout eneti$s& %hi$h $n potentill" be ns%e!e'& %hile

the ltte! $on$e!ns histo!i$l f$ts tht !e not esil" +e!ifie' s$ientifi$ll". /s 9oul'*s e(pttion !ument points out&

somethin $n be innte 2psse' on eneti$ll"3 e+en if the !ole it pl"s to'" is not the one fo! %hi$h it e+ol+e'.

LEARNING DOMAINS

:lssi$ nti+ism& 'tin b$k to the 9!eeks& ssume' the e(isten$e of p!io!i kno%le'e& of innte i'es&

su$h s i'es bout 9o'& numbe!s& n' othe! so-$lle' uni+e!sl t!uths. 0o'e!n nti+tsts 'o not !ue so mu$h tht

%e h+e p!io!i kno%le'e pe! se but !the! tht %e h+e innte p!e'ispositions to $@ui!e 2le!n bout3 spe$ifi$

kin's of en+i!onmentl info!mtion.# 8o! e(mple& lthouh nti+ists +ie% lnue s n innte $p$it" in humns&

the" 'o not ssume tht %e utomti$ll" kno% %o!'s n' !ulesA to $@ui!e spe$ifi$ lnue %e h+e to be

e(pose' to people %ho spek tht lnue. Ho%e+e!& the info!mtion obtine' f!om listenin to othe!s is& on its o%n&

insuffi$ient to full" $$ount fo! lnue $@uisition 2espe$ill" the use of !mm!3it is this “po+e!t" of the stimulus#

!ument tht is ke" to the nti+ist ssumption tht lnue is innte.So 1ti+ists fu!the! ssume tht the innte

$oniti+e pp!tus tht mkes lnue $@uisition possible 'oes not help us le!n othe! thins& %hi$h !e mne'

b" othe! in'epen'ent innte mentl mo'ules. The $p$ities un'e!l"in innte mentl mo'ules h+e been 'es$!ibe'

s 'omin-spe$ifi$ o! info!mtion-spe$ifi$ le!nin bises& “spe$ili,e' st!u$tu!es tune' to le!n p!ti$ul! kin' of

kno%le'e. The nti+ists* mo'ul! +ie% of le!nin is ob+iousl" in$onsistent %ith the beh+io!ist notion of uni+e!sl

le!nin $p$it" p!esent in ll spe$ies n' use' fo! ll +!ieties of le!nin.

7e no% kno%& n' %ill see in 'etil in lte! $hpte!s& tht the b!in 'oes in'ee' le!n 'iffe!ent thins usin

'iffe!ent s"stems& n' tht 'iffe!ent nimls $n h+e 'iffe!ent le!nin $p$ities& %hi$h is $onsistent %ith the nti+ist

+ie% of innte le!nin mo'ules n' in$onsistent %ith the beh+io!ist notion of uni+e!sl le!nin fun$tion. )t seems

possible& m"be e+en likel" 2thouh not "et p!o+en3& tht the o+e!ll 'esin of these s"stems is to l!e 'e!ee

p!o!mme' eneti$ll". This %oul' $$ount fo! %h" membe!s of spe$ies sh!e $p$ities& n' %h" some

$p$ities 'iffe! bet%een spe$ies. /t the sme time& %hile the +!ious le!nin s"stems m" %ell h+e uni@ue eneti$

histo!ies& t the le+el of $ells n' mole$ules it ppe!s& s %e*ll see in the ne(t t%o $hpte!s& tht !elti+el" fe%

solutions !e use' to $hie+e le!nin both %ithin n' $!oss spe$ies. This implies tht 'eep 'o%n the!e is kin' of

uni+e!slit" to le!nin. 7e*+e en$ounte!e' one of these me$hnisms l!e'"& Hebbin plsti$it"& n' %ill h+e mo!e



to s" bout it n' !elte' fo!ms of plsti$it" in subse@uent $hpte!s.

0ost s"stems in the b!in $n le!n f!om e(pe!ien$e& %hi$h mens tht the t!nsmission p!ope!ties of thei!

s"npses $n be lte!e' b" e(pe!ien$e. )n this sense& le!nin itself is not the spe$ifi$ fun$tion tht $i!$uits %e!e built

2b" e+olution3 to pe!fo!m. Le!nin is inste' $p$it" of s"npses& somethin tht $ont!ibutes to the %" $i!$uits

%o!k. The 'efense $i!$uit in+ol+in the m"'l& fo! e(mple& e(ists to 'ete$t n' !espon' to 'ne!. Le!nin is

+e!" useful fetu!e in $i!$uit like this& llo%in it to !espon' to stimuli tht !e not in themsel+es 'ne!ous but thth+e $ome to be sso$ite' %ith 'ne! in the pstthe soun' m'e b" p!e'to! p!io! to n tt$k& fo!

mple. 7ithout the $p$it" to le!n f!om e(pe!ien$e& the fe! s"stem %oul' still be ble to 'o its >ob 2tht is&

to 'ete$t n' !espon' to 'ne!3 but %oul' be limite' in tht it $oul' onl" !espon' to p!ep!o!mme' 'ne!s.

SELECTIONIST NATIVISM VS INSTRUCTIONAL CONSTRUCTIONISM

Ho%& then& miht n innte $i!$uit& one use' fo! le!nin $e!tin kin' of kno%le'e& be %i!e' 'u!in

'e+elopment= /s %e*+e seen& sele$tion n' inst!u$tion !e the t%o min $hoi$es. Ps"$holoi$l o! $oniti+e nti+ists

!e>e$t on p!in$iple the i'e tht the en+i!onment “inst!u$ts# the min'& n' the!efo!e !e>e$t en+i!onmentl inst!u$tion of

$i!$uits s %ell. /s !esult& the" ten' to be Sele$tionists. 0ssimo Pittelli-Plm!ini& fo! e(mple& buil's upon Je!ne&

:hneu(& n' E'elmn in 'enoun$in the empi!i$ist impli$tions of inst!u$tion& n' !ues tht “the!e is no su$h

thin s le!nin.# He is not @uestionin “le!nin# in the ene!l sense of the te!m but in the beh+io!ist sense of

bein stmpe' in b" the en+i!onment. He oes onA “The!e is no kno%n p!o$ess& eithe! in biolo" o! in $onition& tht

lite!ll" mounts to le!nin in the t!'itionl ;inst!u$ti+e* sense& tht is& to t!nsfe! of info!mtionf!om the

en+i!onment to the o!nism. . . . ll the me$hnisms of $@uisition . . . !e 'ue to p!o$ess of inte!nl sele$tion.# )n

simil! +ein& J$@ues 0ehle! hs stte' tht kno%le'e $omes f!om “unle!nin&# impl"in tht %e $ome to kno%

thins b" p!o$ess of elimintion.

1ti+ist ps"$holoists ssume tht ll humn $p$ities !e p!esent in the e(ube!ntl" %i!e' b!in& %itin to

be pi$ke'& o! p!mete!i,e' 2to use PittelliPlm!ini*s te!m3. Ho%e+e!& s %e*+e seen& s"npti$ sele$tion lone $n*t

full" e(plin b!in 'e+elopmentinst!u$te' !o%th lso pl"s n impo!tnt !ole.

1ti+ists miht t this point $ounte! tht the e+i'en$e fo! $ti+it"-in'u$e' !o%th is st!onest fo! senso!"

s"stems& le+in open the possibilit" tht the b!in s"stems in+ol+e' in hihe! $oniti+e p!o$esses 2the mentl

mo'ules of inte!est to nti+ists3 miht be built b" sele$tion. Ho%e+e!& until it $n be sho%n tht hihe! $oniti+e

fun$tions !e built b" sele$tion lone 2tht $ti+it" 'oes not in'u$e !o%th in !es in+ol+e' in hihe! $onition3& %e

h+e to ssume tht the bsi$ p!in$iples 'is$o+e!e' so f! fo! senso!" s"stems ppl" to othe! s"stemstht $ti+it"-

in'u$e' !o%th is +ible possibilit" in $oniti+e s"stems.

1ot ll $oniti+e s$ientists !e nt>+istssome& in f$t& st!onl" oppose nti+ism. 8o! e(mple& in FFN& t%o

influentil publi$tions tt$ke' nti+ism he'-on. One %s 0ethin1in! Innateness, book b" Jeff!e" Elmn n' $ol-

leuesC the othe! %s >ou!nl !ti$le b" Ste+en ?u!t, n' Te!!" Se>no%ski title' “The neu!l bsis of $oniti+e

'e+elopmentA $onst!u$ti+iSt mnifesto. Both publi$tions !ue' fo! constructi+ist pp!o$h to neu!l

'e+elopment& one tht pl$es inst!u$te' !o%th in the spotliht n' emphsi,es $o!ti$l plsti$it" !the! thn $o!ti$l

spe$ifi$it". 7hile $onst!u$ti+ists !e espe$ill" oppose' to the i'e of innte kno%le'e 2innte mentl $ontent& like

%o!'s o! $on$epts3& the" !e ene!ll" 'isplese' %ith most notions of innteness& in$lu'in the innteness of

$p$ities 2like the $p$it" to le!n lnue3.

/ m>o! tenet of $onst!u$ti+ism is the i'e tht the %i!in of $onition in the neo$o!te( $n be $hie+e' on

the bsis of e(t!insi$ inputstht neo$o!ti$l $i!$uits $n be $onst!u$te' b" e(t!$tin st!u$tu!e f!om the senso!" en-

+i!onment. :onst!u$ti+ists $$ept the p!in$iple tht enes buil' the o+e!ll st!u$tu!e& n' tht !e!essi+e e+ents like

s"npti$ sele$tion tke pl$e& but the" !ue tht epieneti$ p!e%i!in n' sele$tion lone $nnot e(plin $onition. )n

''ition to $itin e+i'en$e fo! $ti+it"-in'u$e' !o%th of s"npses& the" !efe! to stu'ies sho%in tht 'me to !es



in+ol+e' in lnue p!o$essin in the b!in of $hil' le's to onl" mino! 'efi$it& if n"& %he!es the sme lesion in

n 'ult $uses se+e!e p!oblems in usin lnue. Thus& in e!l" life& befo!e $o!ti$l $i!$uits !e finli,e'& !es

no!mll" not in+ol+e' in lnue $n tke on lnue fun$tions. Simil!l"& the" $ite the t!nsplnttion stu'ies

'is$usse' e!lie! in %hi$h pie$es of $o!te( !e !emo+e' in "oun nimls n' put in 'iffe!ent lo$tion in nothe!

niml*s b!in. 24e$ll tht the !elo$te' bit of $o!te( then $@ui!es the mentl p!ope!ties of the host.3 8in'ins like

these le' $onst!u$ti+ists to $on$lu'e tht $i!$uits !e not eneti$ll" p!o!mme' but $@ui!e thei! fun$tions f!om theneu!l $ti+it" tht the en+i!onment eli$its in them. /t the sme time& $onst!u$ti+ists $$ept tht the!e !e $onst!ints

on ho% s"npse $onst!u$tion %o!ks in the $o!te(. 8o! e(mple& $o!ti$l !es 'e+elop in $on>un$tion %ith sub$o!ti$l

$i!$uits& %hi$h !e belie+e' to be mo!e sub>e$t to innte ssembl" thn $o!ti$l ones.

The $onst!u$ti+ist position $$ounts fo! oo' 'el of the 't on $o!ti$l plsti$it" n' is $onsistent %ith the

notion tht le!nin m" be $$omplishe' in fi!l" uni+e!sl %"s t the $ellul! le+el. /lthouh ) h+e $onsi'e!ble

s"mpth" fo! mu$h of the $onst!u$ti+ist !ument& ) feel tht it& too& hs se+e!l limittions. 8i!st& it ssumes tht

mentl 'e+elopment $n be un'e!stoo' mo!e o! less e($lusi+el" f!om the point of +ie% of the $o!te(C non$o!ti$l

$ont!ibutions& thouh $kno%le'e'& !e +ie%e' s mostl" h!'%i!e'& n' not i+en mu$h $onsi'e!tion. Ho%e+e!&

be$use $o!ti$l !es 'epen' on sub$o!ti$l !es fo! the !el" of en+i!onmentl info!mtion& h!'%i!in

in sub$o!ti$l $i!$uit %ill st!onl" influen$e %ht hppens in !elte' $o!ti$l !e& espe$ill" if the

sub$o!ti$l $i!$uit mtu!es e!lie!& s is often the $se. The info!mtion ultimtel" e(t!$te' b" the $o!te( is thus s

mu$h 'ue to the o!ni,tion of the sub$o!ti$l $i!$uit s to the st!u$tu!e of the en+i!onment. Se$on'& in !uin

inst the innteness of some $p$ities& espe$ill" lnue& the $onst!u$ti+ists m" be th!o%in the bb" out %ith

the bth%te! fo! the ske of $onsisten$". Sub$o!ti$l $i!$uits !e $le!l" mo!e likel" to be h!'%i!e' thn $o!ti$l

ones& but %e shoul'n*t !e>e$t out!iht the possibilit" tht some $o!ti$l $i!$uits m" lso be h!'%i!e'. 28o! e(mple& it

hs been p!opose' tht the pe!$eption of f$il e(p!essions of emotion is pe!fo!me' b" spe$ies-spe$ifi$ f$e

pe!$eption mo'ule in the p!imte& in$lu'in humn& $o!te(.3 Thi!'& in p!oposin tht the $o!te( is ene!l-pu!pose

$oniti+e le!nin 'e+i$e& not enouh $!e'it is i+en to the multipli$it" of s"stems 2both $o!ti$l n' sub$o!ti$l ones3

tht ene in le!nin. This th!o%b$k to uni+e!sl le!nin >ust %on*t 'o. 8ou!th& in emphsi,in the bilit" of

pie$e of $o!te( to 'pt to ne% $i!$umstn$es 2'ue to 'ep!i+tion o! 'me o! su!i$l t!nsplnttion3&

$onst!u$ti+ists o+e!look the f$t tht the 'pttion tht !esults f!om su$h unusul $on'itions m" !e+el bno!ml

!the! thn no!ml fun$tionA >ust be$use the $olo!-p!o$essin p!t of the p!imte $o!te( $n tke on ne% fun$tion

%hen the $olo!-p!o$essin !e of the thlmus is 'me' o! !emo+e' 'oes not $ont!'i$t the possibilit" tht $olo!

+ision is n innte spe$ili,tion of p!imtes. Plsti$it"& in& is fetu!e of b!in s"stems& not thei! e+ol+e'

fun$tion.

/ BOTTO0 L)1E. :le!l"& mo!e !ese!$h !the! thn mo!e spe$ultion is in o!'e! t this point. Ho%e+e!&

!me' %ith the info!mtion %e*+e $onsi'e!e'& let*s !etu!n to the @uestion pose' e!lie!A 7he!e 'oes the epieneti$

ntu!e of s"npse 'e+elopment le+e innteness= )t seems tht the!e is no oo' !eson to !e>e$t the possibilit" tht

the o+e!ll fun$tion of some $i!$uits is mo!e o! less inntel" 'ete!mine' b" eneti$ $o'in& espe$ill" if %e !e tlkin

bout innte p!e'ispositions to $@ui!e $e!tin kin's of info!mtion !the! thn bout innte kno%le'e pe! se. /t the

sme time& the!e seems to be no !eson to ssume tht the epieneti$ e(p!ession of n innte fun$tion hs to in+ol+e

only sele$tion f!om p!ee(istin s"npses in finli,in the $i!$uitA sele$tion n' inst!u$tion p!obbl" %o!k toethe! to

shpe the finl $onne$tions of most $i!$uits. The innteness of spe$ies-t"pi$l $h!$te!isti$s is thus not t ll in-

$omptible %ith the epieneti$ ntu!e of b!in 'e+elopment 2tht is& the f$t tht eneti$ n' noneneti$ f$to!s

inte!$t3& so lon s %e 'o not insist tht spe$ifi$ kno%le'e is innte o! tht noneneti$ f$to!s 2like en+i!onmentll"

'!i+en neu!l $ti+it" in neu!l s"stems3 influen$e onl" the sele$tion of p!ee(istin s"npses. 8u!the!& %e h+e to

!emembe! tht %hile innteness 2eneti$ $o'in of n e(istin fun$tion3 $n men 'pttion 2ntu!l sele$tion of tht

fun$tion3& this is not l%"s the $se.



INNATENESS II: INDIVIDUALITY

One loi$l ssumption miht be tht if $p$it" is innte t the le+el of the spe$ies& in'i+i'ul 'iffe!en$es

in tht $p$it" shoul' lso be innte. Suppose& fo! e(mple& tht fte! tho!ouh nl"sis of the p!oblem& s$ientists

%e!e to $ome to the $on$lusion tht humns h+e spe$ifi$ $p$it" $lle' intellien$e& n' tht this $p$it" is

inntel" $o'e' in the humn enome 2b" the %"& neithe! of these p!opositions is ene!ll" $$epte'3. 7oul' %e then

be >ustifie' in ssumin tht 'iffe!en$es in intellien$e bet%een in'i+i'uls o! bet%een !oups of people !e 'ue to

eneti$ +!ition bet%een in'i+i'uls= 1ot ne$ess!il"

The $omple( !eltion bet%een the innteness of in'i+i'ul n' spe$ies $h!$te!isti$s is ni$el" illust!te' b"

stu'" pe!fo!me' on t%o !oups of !te! snkes li+in in :lifo!ni.Fo The snkes !e membe!s of the sme

spe$ies& but some li+e in the m!sh" $ostl !es n' othe!s in the '!ie! inln' !eions. The $ostl snkes et

slusC the inln' ones 'on*t. Ste+en /!nol' %s inte!este' in %hethe! this 'iffe!en$e in foo' p!efe!en$e %s 'ue to

eneti$ o! en+i!onmentl $uses.F He took es f!om snkes li+in in both !eions& n' %hen the bbies ht$he'& he

imme'itel" put them in sep!te $es& isolte' both f!om litte!mtes n' mothe! n' f!om thei! ntu!l hbitt. /

fe% '"s lte!& he offe!e' slus to snkes f!om the t%o !oups. The $ostl bbies te the slus& %hile the inln'

ones ino!e' them. He then pl$e' essen$e of slu on $otton s%bs n' mesu!e' ho% often the snkes fli$ke' thei!

tonues t the s%bs. 2Tonue-fli$kin is ho% snkes tke in smells.3 )solte' $ostl snkes fli$ke' thei! tonues

+io!ousl"& %hile the inln' ones sho%e' little inte!est. E+en %ithin e$h !oup& ho%e+e!& the!e %s some +!ition

f!om in'i+i'ul to in'i+i'ul. /!nol' the!efo!e e(mine' the he!itbilit" of the %ithin-!oup t!it b" $omp!in tonue-

fli$kin s$o!es of siblins to see if the" %e!e mo!e like one nothe! thn un!elte' snkes. )f !elte' in'i+i'uls %e!e

mo!e like thn un!elte' ones& then enes %oul' be impli$te'. )t tu!ne' out tht fmil" !eltions h' little to 'o %ith

the %" the snkes !espon'e'. Slu p!efe!en$e 'ithin the popultion is thus not 'ue to eneti$ $uses. /!nol' then

$!ossb!e' $ostl n' inln' snkes n' foun'

tht this le' to mo!e +!ibilit" in the beh+io! of the offsp!in thn in the “pu!e !oups. 0i(in the enes of

the t%o popultions !e'u$e' the eneti$ influen$e on the beh+io!& suestin tht the 'iffe!en$es in the beh+io! (e%

t'een the !oups is eneti$ in o!iin. Toethe!& these fin'ins le' to the $on$lusion tht enes help in the

e(plntion of the beh+io!l 'iffe!en$e (et'een !oups but not 'ithin !oups& t lest in this $se.

The snke stu'" suests tht e+en if ou! $p$it" fo! some mentl fun$tion like intellien$e o! lnue o!

emotion is innte& %e !e not ne$ess!il" ble to e(plin 'iffe!en$es bet%een people in these $p$ities in te!ms of

enes. 9enes m" pl" n essentil !ole in pl$in fun$tion in the b!in of e+e!" humn& n' t the sme time mke

!elti+el" smll $ont!ibution to 'iffe!en$es in the %" tht fun$tion is %i!e' in in'i+i'uls. The onl" %" to kno% fo!

$e!tin is to 'o the p!ope! e(pe!iments. )n'ee'& fo! some beh+io!s in some spe$ies& $!ossb!ee'in n' he!itbilit"

stu'ies 'o sho% sinifi$nt !eltion in the beh+io! of siblins& in$lu'in those !e!e' sep!tel"& %hi$h suests

2but& s %e*ll see belo%& 'oes not $on$lusi+el" p!o+e3 eneti$ $ont!ibution to beh+io! t the le+el of in'i+i'uls n'

thei! fmilies.

:le!l"& the most $ompellin $se fo! !ole of enes in in'i+i'ul humn beh+io! $omes f!om stu'ies of

i'enti$l t%ins sep!te' t bi!th. Be$use thei! $ommon postntl en+i!onmentl influen$es !e miniml& this

sitution is belie+e' to be the best test fo! !ole of enes in shpin pe!sonlit" t!its of n in'i+i'ul. Some

!em!kble obse!+tions h+e been m'e. 8o! e(mple& one pi! of i'enti$l t%ins sep!te' sho!tl" fte! bi!th en'e'

up in +e!" 'iffe!ent situtionsone !e% up s :tholi$ in 1,i 9e!mn"& n' the othe! li+e' s Je% on

:!ibben isln'. )n spite of bein !ise' un'e! +stl" 'iffe!ent en+i!onmentl $on'itions& the pi! en'e' up %ith

pe$uli! sh!e' t!its& in$lu'in !e'in m,ines b$k to f!ont& n' keepin !ubbe! bn's on thei! %!ists.

Thouh inte!estin& it*s h!' to e(t!polte f!om these i'ios"n$!ti$ fin'ins. Ho%e+e!& l!e stu'ies of mn"

pi!s of t%ins h+e been $on'u$te' to ssess thei! simil!it" in pe!sonlit" t!its n' intellien$e. This %s 'one b"

$omputin he!itbilit" s$o!es& %hi$h estimte ho% mu$h of i+en t!it is 'ue to en+i!onment n' ho% mu$h to enes&

fo! the 'iffe!ent mesu!es. Su$h stu'ies h+e sho%n tht %hile i'enti$l t%ins& li+in toethe! o! p!t& !e mo!e



simil! thn f!te!nl t%ins o! nont%in siblins& the" !e b" no mens in'istinuishble. )n f$t& the $o!!eltion bet%een

pi!s on n" p!ti$ul! mesu!e %s t most onl" bout . fo! i'enti$l t%ins li+in toethe!& n' %s bit less fo!

those li+in p!t& suestin tht enes $$ount fo! t most hlf of i+en t!it.

)t hs been !ue' tht the $ont!ibution of enes is o+e!estimte' in t%in stu'ies in t lest t%o %"s. 8i!st&

n ssessment of the eneti$ $omponent of he!itbilit" 'oes not 'istinuish the 'i!e$t effe$ts of enes f!om in'i!e$t ef-

fe$tsA $hil'*s inhe!ite' timi'it" m" le' his p!ents to !essu!e him $onstntl"& his pee!s to pi$k on him& n' histe$he!s to ino!e him& e$h of %hi$h miht in tu!n !einfo!$e his timi'it" o! b!in bout othe! beh+io!s.

Se$on'& he!itbilit" s$o!es 'o not $$u!tel" $ont!st enes %ith en+i!onment& fo! thins tht !e simil! in

the en+i!onments in %hi$h sep!te' t%ins li+e ine+itbl" et mi(e' in %ith the eneti$ $ont!ibution. The!e !e mn"

oppo!tunities fo! t%ins to h+e sh!e' e(pe!ien$es of one kin' o! nothe!. The !eno%ne' 'e+elopmentl ps"$holoist

Ho%!' 9!'ne! notes the follo%inA “8o! t lest nine $!u$il months& the t%ins sh!e the sme en+i!onmentthe

%omb of the bi!th mothe!. ... Then& too& the" m" not h+e been sep!te' !iht t bi!th. 2/n' un'e! %ht

e(t!o!'in!" $i!$umstn$es 'oes su$h sep!tion o$$u!=3 The" m" o! m" not h+e been !ise' fo! %hile b"

fmil" membe!s. The $hil'!en !e not !n'oml" pl$e'C in ne!l" ll $ses the" !e !ise' %ithin the sme $ultu!e n'

+e!" often in the sme $ommunit"& %ith simil! so$il settins. /lso& infnts %ho look the sme n' beh+e the sme

m" eli$it simil! !esponses f!om 'ults.

)n the e!liest '"s of life& s %e*+e seen& the min en+i!onmentl f$to!s tht $oul' ffe$t the 'e+elopin

t%ins !e $hemi$ls psse' f!om the mothe!*s bloo'st!em to the fetush!'l" t!i+il influen$es. /lso& mn"

$onne$tions fo!m in the b!in p!entll"& llo%in the t%in fetuses to bein to !e$ei+e info!mtion f!om the e(te!nl

en+i!onment in ute!o. 8o! e(mple& b" the thi!tieth %eek of p!enn$"& the he!t !te of the fetus $hnes %hen

soun's o$$u! in the en+i!onment The fetl b!in $n e+en 'is$!iminte en+i!onmentl e+ents n' $n le!n n'

!etin info!mtion bout en+i!onmentl stimuli. /n' fte! bi!th& s 9!'ne! note'& the" !e often not sep!te' im-

me'itel"& n' f!e@uentl" en' up in simil! en+i!onments& %he!e ten'en$ies to look o! $t like $oul' help $on+e!t

subtle into mo!e po%e!ful simil!ities. The $se of the t%ins 'es$!ibe' bo+e sho%s tht this is not l%"s t!ue& but

he!itbilit" stu'ies li+e n' 'ie on !oup +e!es& not on inte!estin obse!+tions of in'i+i'uls. 7hen i'enti$l t%ins&

sep!te' t bi!th& en' up sh!in $h!$te!isti$s s 'ults& %e nee' to %on'e! %hethe! this is 'ue to thei! $ommon

eneti$ he!ite& to $ommon influen$es %ithin the %omb& o! to subtle en+i!onmentl simil!ities tht shpe the

'e+elopment of thei! s"npti$ $onne$tions. /t the sme time& %e lso nee' to pl$e the simil!ities in the $onte(t of

the mn" %"s in %hi$h t%ins 'iffe! f!om one nothe!.

)n su$h @untitti+e nl"ses of !oups& the ol hs been to 'ete!mine ho% the +!ibilit" of t!it !eltes to

eneti$ simil!it" 2i'enti$l +s. f!te!nl t%ins& f!te!nl t%ins +s. siblins& $hil'!en +s. p!ents3 in the ene!l popul-

tion& !the! thn in in'i+i'uls. But in the lst fe% "e!s& !ese!$h on enes hs e(plo'e'& n' ne% pp!o$hes !e

tkin o+e!. The ol'e! beh+io!l eneti$s pp!o$h h' s its im 'istinuishin the $ont!ibution of the en+i!onment

f!om tht of enes 2tht is& of ll enes tken toethe!3. :omple( mthemti$l nl"ses %e!e use' to e(t!$t subtle

'iffe!en$es in the $ont!ibutions of eneti$ n' en+i!onmentl f$to!s to +!ition in t!it in l!e !oups. This

pp!o$h is i+in %" to effo!ts to i'entif" specific enes tht miht be in+ol+e' in spe$ifi$ t!its. The enti!e enome

hs been mppe' in some nimls& in$lu'in humns& %hi$h opens the 'oo! fo! some +e!" sophisti$te' stu'ies of

the !ole of p!ti$ul! enes !the! thn of enes in ene!l. 8o! e(mple& eneti$ll" lte!e' mi$e $n be $!ete' tht

h+e sinle ene missin. Depen'in on %ht ene is kno$ke' out& '!mti$ 'iffe!en$es in beh+io! $n !esult.

Elimintion of the ene fo! $e!tin en,"me use' in !eultin the effe$ts of $l$ium o! othe! mole$ules insi'e b!in

$ells& fo! e(mple& $n inte!fe!e %ith Hebbin plsti$it" t s"npses n' the!eb" 'is!upt lon-te!m memo!"& s %e %ill

see in $hpte! .

But s impo!tnt s enes !e& the" !e usull" $ont!ibuto!s to t!its !the! thn 'i$tto!s. /n' sel'om is n"

b!in fun$tion s $omple( s those in+ol+e' in beh+io!l o! mentl p!o$esses un'e! the $ont!ol of onl" one ene.

The f$t tht 'is!uption of one ene $n le' to memo!" 'efi$it 'oes not men tht memo!" is 'ue to tht ene

lone. /ll effe$ts of enes !e e(p!esse' epieneti$ll"& b" %" of inte!$tions in the inte!nl $hemi$l en+i!onment



bet%een the p!oteins m'e b" multiple enes& o! b" %" of e(te!nl en+i!onmentl stimultion tht eli$its s"npti$

$ti+it" tht then in'u$es enes to mke p!oteins. The p!oteins m'e b" enes $n in tu!n mo'ulte neu!l $ti+it" t

s"npses. /ssembl" of the in'i+i'ul is bi >ob& n' enes h+e lots of p!tne!s in the p!o$ess.

TIMES FOR LEARNING?

0n" ps"$holoi$l theo!ies of 'e+elopment p!opose tht the $hil' mtu!es in stes. 8!eu' 'i+i'e' them

into the nl& o!l& phlli$& n' enitl. Piet tlke' bout senso!imoto!& p!eope!tionl. $on$!ete ope!tion& n'

fo!ml ope!tion stes& %hile othe! theo!ists h+e p!opose' 'iffe!ent te!ms. Un'e!l"in the unfol'in of n" of these

'e+elopmentl stes in beh+io!l n' mentl p!o$esses must be neu!l $hnes. /n'& s 'is$usse' e!lie!& the!e*s

plent" of e+i'en$e tht the b!in 'oes o th!ouh ll so!ts of $hnes 'u!in 'e+elopments"npse numbe!s !e

!isin n' fllin& $ells !e bein bo!n n' '"in& 'en'!ites !e !o%in& b!in ene!" use 2metbolism3 in$!eses. The

p!oblem is tht it is not $le! ho% the $hnes t the neu!l le+el !elte to those t the ps"$holoi$l le+el.

/ mo+ement $lle' b!in-bse' e'u$tion ttempts to use info!mtion bout b!in 'e+elopment n' fun$tion

to ui'e e'u$tion poli$" n' p!$ti$e. One of its bsi$ p!in$iples is tht the!e !e spe$il times fo! le!nin $!iti$l

pe!io's %in'o%s of oppo!tunit"times 'u!in %hi$h info!mtion hs to be obtine' o! it %on*t be sto!e'.

/ oo' 'el of e+i'en$e e(ists fo! $!iti$l o! sensiti+e pe!io's. /s %e*+e seen& if kitten*s e"e is $lose'

'u!in n!!o% time spn in e!l" life& it %on*t 'e+elop p!ope! bino$ul! +ision be$use bino$ul! $ells in the $o!te(

'on*t mtu!e no!mll". The effe$t is !e+e!sible if the e"e is opene' %ithin the %in'o% of oppo!tunit"& but not fte!%!'.

This is %h" mislinment of $hil'*s e"es hs to be $o!!e$te' in e!l" life. On$e the $!iti$l pe!io' is o+e!tht is&

on$e s"npses in the $o!te( !e %i!e'the %in'o% $loses. /nothe! e(mple is bi!'son. )f bi!'s tht sin !en*t

e(pose' to thei! spe$ies-t"pi$l son 'u!in the sensiti+e pe!io' 2%hi$h beins in the %eeks fte! ht$hin n'

$ontinues until se(ul mtu!it"3& the" $n*t sin the son s 'ults. )f the" !e e(pose' onl" imme'itel" befo!e the

$!iti$l pe!io' 2%hen thei! s"npses !e not !e'"3 o! fte!%!' 2%hen the s"npses !e l!e'" %i!e'3& the" $nnot

le!n to sin. This is some%ht simil! to %ht hppens in lnue 'e+elopmentA lnue le!nin is mo!e fle(ible

in $hil'!en thn 'ults& s n"one %ho hs t!ie' to le!n se$on' lnue fte! pube!t" kno%s.

But not ll fo!ms of le!nin !e sub>e$t to $!iti$l pe!io's. /n' be$use 'iffe!ent s"stems of the b!in !e

in+ol+e' in le!nin 'iffe!ent thins& the!e*s no %" to ene!li,e f!om fe% instn$es to ll fo!ms of le!nin.

7hethe! mth o! musi$ le!nin hs $!iti$l pe!io' fo! s"npti$ 'e+elopment is not kno%n. Ho%e+e!& s f! s

e'u$tion is $on$e!ne'& these m" not be the most !ele+nt @uestions& t lest not t this point.

John B!ue!& le'in thinke! in e'u$tionl p!$ti$e& hs $utione' tht b!in-bse' e'u$tion is n i'e

%hose time hs not "et $ome& in spite of the f$t tht it is th!i+in pp!o$h. B!ue! !ues tht %e simpl" 'on*t

kno% enouh bout ho% $hnes in the b!in 2su$h s $hnes in s"npse numbe! o! 'ensit"& o! $hnes in b!in

ene!" metbolism3 !elte to le!nin& o! t lest not enouh on %hi$h to bse somethin s impo!tnt s e'u$tion

poli$".

)nste'& B!ue! !ues& e'u$to!s shoul' mke the most of ps"$holoi$l fin'ins in thei! effo!ts to imp!o+e

the e'u$tionl p!o$ess. On$e %e kno% mo!e bout ho% spe$ifi$ $p$ities !e use' n' %hen the" ppe!& %e

miht then in $lues bout %ht to look fo! n' %he!e to look fo! it in the b!in.

/n e($ellent e(mple of ho% ps"$holo" n' b!in s$ien$e $n inte!$t in %" !ele+nt to e'u$tion

$omes f!om the %o!k of Pul Tlll n' 0i$hel 0e!,eni$h. Tlll& $oniti+e ps"$holoist %ho stu'ies lnue&

'is$o+e!e' tht '"sle(i$ $hil'!en !e 'efi$ient t 'ete$tin n' 'is$!imintin !pi'l" $hnin soun's& n' tht the

bilit" of infnts to pe!$ei+e su$h stimuli p!e'i$ts lte! lnue skills. 7hen she pl"e' the sme soun's to '"sle(i$

$hil'!en t slo%e! !te& the" pe!$ei+e' the soun's mu$h mo!e $$u!tel". Tlll*s %o!k $uht the ttention of

0e!,eni$h& neu!os$ientist %ho h' been stu'"in the bilit" of the neo$o!te( to 'pt to en+i!onmentl stimultion&

sho%in& fo! e(mple& tht i+in monke"s e(tensi+e e(pe!ien$e %ith p!ti$ul! soun' in$!eses the !e of $o!te(

tht p!o$esses tht soun' 2this is 'es$!ibe' in 'etil in the ne(t $hpte!3. Tlll n' 0e!,eni$h $ollbo!te' to $!ete



spe$il +i'eo mes tht %oul' e(pose $hil'!en %ith '"sle(i to $e!tin $!efull" sele$te' stimuli in n effo!t to

imp!o+e thei! bilit" to p!o$ess spoken n' %!itten lnue. B" st!tin %ith slo% stimulus-p!esenttion !tes n'

buil'in up to%!' the !te t %hi$h spee$h n' !e'in no!mll" o$$u!& the" hope' to tke '+nte of the plsti$

ntu!e of the $o!te( to $ti+el" shpe its s"npti$ o!ni,tion b" t!inin it to p!o$ess stimuli mo!e effe$ti+el". )t is too

e!l" to tell ho% effe$ti+e thei! p!o!m is& but !e!'less of its ultimte out$ome& the" !e to be p!ise' fo! thei!

effo!ts to tke bsi$ !ese!$h f!om the lbo!to!" n' use it to help $hil'!en %ith !e'in 'iso!'e!s le!n to !e'.Pe!hps the!e !e lso lessons f!om thei! stu'ies tht miht suest ho% neu!os$ien$e !ese!$h $n lso be use' to

imp!o+e the %" $hil'!en %ithout le!nin p!oblems !e e'u$te'.

This %o!k is t the he!t of the 'ebte bet%een those %ho belie+e in spe$ili,e' le!nin mo'ules +s. mo!e

ene!l le!nin $p$ities& sin$e Tlll n' 0e!,eni$h !e usin nonlinuisti$ stimuli to t!" to influen$e lnue

le!nin. Those %ho belie+e tht lnue is n innte mo'ule %ith its o%n le!nin !ules !ue tht nonlnue

stimuli shoul' h+e no effe$t. So not onl" %ill the out$ome of this %o!k h+e p!$ti$l impli$tions& it m" lso be +e!"

!ele+nt to fun'mentl issues bout b!in o!ni,tion.

John B!ue!*s most !e$ent book tt$ks %ht he $lls the m"th of the fi!st th!ee "e!s. He !ues tht too

mu$h emphsis is i+en to the i'e tht spe$ifi$ kin's of le!nin h+e to tke pl$e +e!" e!l" in life& o! the b!in %ill

ne+e! in be ble to le!n tht kin' of info!mtion. Le!nin is in'ee' lifelon p!o$ess. /n' s /lison 9opnik n'

$olleues !ue' in nothe! !e$ent book& e+e!" time the infnt le!ns somethin& his o! he! b!in is $hne' in %"

tht helps it le!n somethin else. )n !e+ie% of this book& p!ominent 'e+elopmentl e(pe!t& 0!k Johnson& note'

tht the e!l" "e!s !e $!u$il not be$use the %in'o% of oppo!tunit" $loses but be$use %ht is le!ne' t this time

be$omes the foun'tion fo! subse@uent le!nin. )n'ee'& mu$h of the self is le!ne' b" mkin ne% memo!ies out of

ol' ones. Just s le!nin is the p!o$ess of $!etin memo!ies& the memo!ies $!ete' !e 'epen'ent on thins %e*+e

le!ne' befo!e.

0O6)19 O1

Le!nin n' 'e+elopment !e t%o si'es of the sme $oin. 7e $n*t le!n until %e h+e s"npses. /n' s

soon s s"npses st!t fo!min on the bsis of int!insi$ $ommn's& the" !e sub>e$t to bein influen$e' b" ou! %o!l'l"

e(pe!ien$es. 9enes& en+i!onment& sele$tion& inst!u$tion& le!ninthese ll $ont!ibute to the buil'in of the b!in n'

the shpin of the 'e+elopin self b" %i!in s"npses. /lthouh the e(tensi+e plsti$it" tht is p!esent in e!l" life

e+entull" stops& ou! s"npses 'o not stop $hnin& but !emin subtl" $hneble b" e(pe!ien$e. )t*s time to see

p!e$isel" ho% this hppens.

CHAPTER FIVE

/D6E1TU4ES )1 T)0E

YOU H/6E TO BE9)1 TO LOSE YOU4 0E0O4Y& )8 O1LY )1 B)TS /1D P)E:ES& TO 4E/L)E TH/T

0E0O4Y )S 7H/T 0/5ES OU4 L)6ES. L)8E



7)THOUT 0E0O4Y )S 1O L)8E /T /LL. . . OU4 0E0O4Y )S OU4 :OHE4E1:E& OU4 4E/SO1& OU4

8EEL)19& E6E1 OU4 /:T)O1. 7)THOUT )T& 7E /4E 1OTH)19.

Luis BuSue)

0emo!" is m!+elous 'e+i$e& mens of t!nspo!tin ou!sel+es to e!lie! times. 7e $n o b$k

moment& o! most of life. But s %e ll kno%& it*s not pe!fe$t& n' is $e!tinl" not lite!l. )t*s !e$onst!u$tion of f$ts

n' e(pe!ien$es on the bsis of the %" the" %e!e sto!e'& not s the" $tull" o$$u!!e'.* /n' it*s !e$onst!u$tion b"

b!in tht is 'iffe!ent f!om the one tht fo!me' the memo!". Sometimes& 'etils !e lost& but the ist is the!e. /t othe!

times& %e >ust $n*t $ome up %ith %ht %e*!e lookin fo!& thouh %e kno% %e on$e h' the info!mtion. O$$sionll"&%e !emembe! thins tht 'i'n*t $tull" hppen. 8llible s it is& ho%e+e!& memo!" usull" 'oes p!ett" oo' >ob fo!

us. /'elle D+is*s in'ispensble ui'e to si(ties 'iet!" hbits tol' us& “You !e %ht "ou et.# But Bunuel*s lment is

p!obbl" mo!e $$u!teA %e !e ou! memo!ies& n' %ithout them& %e !e nothin.

But %ht is memo!"= To most people& it is the bilit" to $ons$iousl" !e$olle$t& to !emembe! %ht hppene'

'"s& %eeks& o! "e!s o. This is %ht ps"$holoists $ll e(pli$it o! 'e$l!ti+e memo!"*. The info!mtion it summons

is e(pli$itl" +ilble fo! $ons$ious !e$olle$tion& n' $n be +e!bll" stte' o!'e'!e'. This kin' of memo!" is

e(t!emel" fle(ible& llo%in& fo! e(mple& the soun' of t%o $!s $!shin toethe! to t!ie! +ision in "ou! b!in of n

$$i'ent "ou on$e e(pe!ien$e'. Th!ouh e(pli$it memo!" "ou $n !e$ll phone numbe!& the %" someone looks&

%ht "ou h' fo! lun$h "este!'"& o! %ht "ou 'i' on "ou! lst bi!th'". )t is this memo!" tht is so s+el" t t$ke'

in /l,heime!*s 'isese. Thouh e(t!emel" impo!tnt in ou! li+es& it is& in f$t& onl" one kin' of memo!". 0" mothe!& n

/l,heime!*s +i$tim& $n*t $ons$iousl" !e$ll mu$h of n"thin tht hppens to he!& but she $n fl% lessl" e(e$ute the:>un tune “J*i Pss D*+nt T Po!t# on he! $$o!'ion. The kin' of memo!" tht llo%s he! to 'o this is $lle'

impli$it o! non'e$l!ti+e memo!". Su$h memo!ies !e !efle$te' in the %" %e $t mo!e thn in %ht %e $ons$iousl"

kno%. Un'e!l"in this ps"$holoi$l 'iffe!en$e is the f$t tht 'iffe!ent b!in s"stems !e in+ol+e' in impli$it fo!ms of

memo!"& on the one hn'& n' $ons$iousKe(pli$itK'e$l!ti+e memo!"& on the othe!. To stte this in the $onte(t of

te!ms use' in the lst $hpte!& impli$it memo!ies !e fo!me' b" s"stems tht ene in 'omin-spe$ifi$ le!nin&

%he!es 'omin-in'epen'ent s"stem fo!ms e(pli$it memo!ies.

)n $hpte! & ) p!esente' the outlines of theo!" of the self tht built on this +ie% of memo!". ) p!opose' tht

the self is in p!t m'e n' mintine' b" memo!"& n' tht both impli$it n' e(pli$it fo!ms !e in+ol+e'. )n this

$hpte!& %e*ll look t %ht is kno%n bout the neu!l $i!$uits un'e!l"in e(pli$it n' impli$it memo!" $p$ities. The

s"npti$ me$hnisms of memo!" !e the topi$ of the ne(t $hpte!.

IN SEARCH OF THE ENGRAM

)n FM& 4i$h!' Semon& 9e!mn s$ientist& $oine' the te!m en!ram to !efe! to the neu!l !ep!esenttion of

memo!". T%o 'e$'es lte!& 5!l Lshle"& n /me!i$n ps"$holoist& h' beun se!$h fo! the en!m& the lo$us

of memo!" in the b!in& @uest tht o$$upie' him fo! mu$h of his $!ee!.

Lshle" %s one of the pionee!s in the use of beh+io!l tsks& su$h s m,es& to in+estite the !eltion

bet%een b!in n' beh+io! in nimls. )n his no%-fmous stu'ies& he t!ine' !ts to “!un m,e.# On$e the hbit

%s le!ne'& he then e(mine' the effe$ts of !emo+l of 'iffe!ent p!ts of the neo$o!te(& %hi$h %s belie+e' e+en



monste!.# )n the e!l" p!t of the $entu!"& the hippo$mpus %s +ie%e' s p!t of the !hinen$ephlon 2%hi$h !efe!s to

smell o! olf$tion3. )t lte! eme!e' s one of the m>o! st!u$tu!es of the so-$lle' limbi$ s"stem& n' $me to be

thouht of s pl"in $!u$il !ole in emotionl fun$tions.#* Pul 0$Len& the o!iinto! of the limbi$ s"stem $on$ept&

$on$ei+e' of the hippo$mpus s the set of the 8!eu'in i'& pl$e in the b!in %he!e i'es $oul' be mi(e'

toethe! n' $onfuse'. 0$Len lo$te' the i' in the hippo$mpus be$use he thouht tht the p!imiti+e !$hite$tu!e

of this st!u$tu!e $oul' blen' thins in su!!el& '!emlike fshion& n' %oul' be ill-suite' to p!ti$ipte in $oniti+efun$tions. But& b" the en' of the Fs& stu'ies of H. 0. n' othe! ptients h' le' to the $on$lusion tht the

hippo$mpus %s $!u$ill" in+ol+e' in one of the most impo!tnt $oniti+e fun$tions of the b!inmemo!".

CANS AND CAN!TS

/t fi!st& it %s thouht tht H. 0. n' simil! ptients h' lobl mnesi& $omplete loss of memo!"& n'

tht the hippo$mpus %s in'ee' ene!l-pu!pose memo!" m$hine. Ho%e+e!& it %s soon noti$e' tht mnesi$s

$oul' le!n to pe!fo!m %ell on some tsks tht 'epen'e' on p!io! le!nin.* 8o! e(mple& B!en' 0ilne! ske' H. 0.

to $op" pi$tu!e of st! +ie%e' th!ouh mi!!o!. To 'o this& the mo+ements h' to be 'one in the 'i!e$tion opposite

f!om the %" the" seeme' the" shoul' be m'e. )t*s h!' t fi!st& but e+entull" most people $n 'o it. H. 0. %s no

e($eption. He le!ne' the tsk& n' he !etine' the le!nin. But if ske' bout the '!%in& he h' no $ons$ious

memo!" of h+in m'e it. Su,nne :o!kin of 0)T then foun' tht H. 0. lso imp!o+e' %ith p!$ti$e in nothe!

mnul skill le!nin tskone in %hi$h he %s !e@ui!e' to keep sti$k hel' in his hn' on 'ot spinnin on

tu!ntble. /s %ith the mi!!o! '!%in tsk& the mo!e times he 'i' it& the bette! he ot. His bilit" to fo!m memo!ies

bout ho% to mke p!e$ise mo+ements 2$lle' moto! skills3 seeme' int$t.

1el :ohen lte! e(mine' %hethe! the sp!e' skill-le!nin bilit" in mnesi %s !est!i$te' to moto! skills

o! miht e(ten' to %ht !e $lle' $oniti+e skills& the bilit" to et bette! t 'oin %ell-p!$ti$e' mentl tsks.# He

sho%e' tht mnesi$s $oul' le!n n' !etin the bilit" to !e' mi!!o! imes of %o!'s 6e!ral is the mi!!o! ime of

lar!e7 >ust s the" $oul' le!n to '!% mi!!o! imes. He lso sho%e' tht the ptients $oul' le!n some $ompli$te'

!ule-bse' st!teies !e@ui!e' to pl" $e!tin mes o! sol+e pu,,les. /s in othe! e(mples& lthouh the" $oul' le!n

to use !ules to pl" mes& the" lte! h' no !e$olle$tion of pl"in the mes themsel+es.

Stu'ies of phenomenon no% $lle' p!imin lso tu!ne' out to be +e!" influentil.# Eli,beth 7!!inton n'

L!!" 7eisk!nt, 'emonst!te' tht mnesi$ ptients %e!e ble to le!n to !e$oni,e stimuli 2pi$tu!es o! %o!'s3 on

the bsis of in$omplete 'epi$tions of the stimuli. E$h stimulus $me in fi+e +e!sions& f!om +e!" in$omplete to

$omplete. )nitill"& the" h' to see the mo!e $omplete stimuli to su$$essfull" fiu!e out %ht e$h %s. But %ith !e-

pete' t!ils& the" %e!e ble to !e$oni,e the stimuli on the bsis of the %eke! $ues. This kin' of le!nin& no% $lle'

p!imin& miht the!efo!e be in'epen'ent of the hippo$mpus. Lte! stu'ies b" L!!" S@ui!e sho%e' tht the

inst!u$tions i+en to sub>e$ts m'e bi 'iffe!en$e in %hethe! p!imin o$$u!s. 8o! e(mple& in one +e!sion of p!imin&

the sub>e$t is i+en list of %o!'s. Lte!& if ske' to !e$ll the items tht %e!e on the list& mnesi$ ptients pe!fo!m

poo!l". Ho%e+e!& if inste' of bein ske' to !e$ll the items& the" !e i+en f!ments of %o!'s 6mot7 n' ske' to

$omplete them& like no!ml sub>e$ts& the" !e mo!e likel" to $ome up %ith %o!'s tht %e!e in the o!iinl stu'" list

6motel7 thn %ith othe! %o!'s 6mother7 tht %e!e not in the list. /lthouh the mnesi$ ptients h' little $ons$ious

memo!" of the stu'" list items& p!io! e(posu!e to the list h' $le!l" been !etine' t some le+el& sin$e it ffe$te' thei!

pe!fo!mn$e.

7eisk!nt, n' 7!!inton lso sho%e' tht the $lssi$l $on'itionin of e"e blink !esponses is p!ese!+e' in

mnesi. )n this tsk& tone is pi!e' %ith n +e!si+e stimulus 2usull" n i! puff to the e"e3. /fte! hun'!e's of

t!ils& the tone eli$its e"eli' $losu!e imme'itel" befo!e the onset of the i! puff. This p!e$isel" time' !esponse

p!ote$ts the 'eli$te tissues of the e"e f!om the i! puff. /mnesi$ ptients sho% no!ml e"e blink $on'itionin& thouh

the" lte! h+e no memo!" of h+in seen the $on'itionin pp!tus.



)n the e!l" FGs& L!!" S@ui!e n' 1el :ohen int!o'u$e' the 'istin$tion bet%een 'e$l!ti+e +s.

p!o$e'u!l memo!" to $$ount fo! memo!" fun$tions of the hippo$mpus +s. othe! b!in s"stems. Thei! p!oposl %s

tht the hippo$mpus me'ites $ons$ious memo!" 2memo!" tht $n be +e!bll" 'e$l!e'3 n' tht othe! b!in

s"stems me'ite othe! fo!ms of memo!" tht !e not 'epen'ent on $ons$ious p!o$esses. The" initill" use' the te!m

procedural memory be$use t the time& mn" of the memo!" bilities tht su!+i+e' in mnesi$ ptients in+ol+e' the

e(e$ution of skills tht $oul' be le!ne' s !ules o! p!o$e'u!es. But s mo!e e(mples eme!e' of thins ththippo$mpl-'me' ptients $oul' le!n n' !etin& it %s $le! tht not ll of these in+ol+e' p!o$e'u!es.

P!o$e'u!l memo!" %s the!efo!e lte! !enme' %ith the mo!e neut!l 'esintionA nondeclarati+e memory) The

te!ms eplicit n' implicit memo!"& sueste' b" Dn S$h$te!& essentill" !efe! to the sme memo!" p!o$esses s

'e$l!ti+e n' non'e$l!ti+e memo!". Dme to m" mothe!*s hippo$mpus p!obbl" e(plins %h" she $n*t

$ons$iousl" !emembe! the thins tht hppen to he! 2he! 'e$l!ti+e o! e(pli$it memo!" s"stem is one3& n' l$k of

'me to the non'e$l!ti+e o! impli$it s"stem tht sto!es the skill of pl"in the $$o!'ion e(plins %h" she $n

!emembe! ho% to pl".

INS AND OUTS

The hippo$mpl $ont!ibutions to memo!"& like the $ont!ibutions of n" b!in !e to n" fun$tion& !e m'e

possible b" the s"npti$ pth%"s. These 'eli+e! info!mtion to the hippo$mpus& p!o$ess it %ithin the st!u$tu!e& n'

t!nsfe! the out$ome to t!et !es. 0u$h is kno%n bout hippo$mpl ntom"& but %e %ill onl" tou$h on some of

the ke" points he!e.

/s %e*+e seen in p!e+ious $hpte!s& info!mtion bout the e(te!nl %o!l' $omes into the b!in th!ouh

senso!" s"stems tht !el" sinls to the neo$o!te(& %he!e senso!" !ep!esenttions of ob>e$ts n' e+ents !e

$!ete'. Outputs of e$h of the neo$o!ti$l senso!" s"stems then $on+e!e in the !hinl $o!ti$l !es& lso kno%n s

the p!hippo$mpl !eion& %hi$h inte!tes info!mtion f!om the 'iffe!ent senso!" mo'lities befo!e shippin it to

the hippo$mpus p!ope!. . Stu'ies b" 7en'" Su,uki& D+i' /m!l& n' othe!s h+e elu$i'te' mn" of the 'etils of

$onne$ti+it".

The hippo$mpus n' p!hippo$mpl 2!hinl3 !es $onstitute %ht hs $ome to be $lle' the me'il

tempo!l lobe memo!" s"stem& the s"stem in+ol+e' in e(pli$it o! 'e$l!ti+e memo!". 2Ho%e+e!& the" !e not p!t of

the neo$o!ti$l tempo!l lobe n' !e not in+ol+e' in its senso!"-p!o$essin fun$tions. The" !e inste' e(mples of

the so-$lle' ol' $o!te( $hp. QC this is %h" the" !e sso$ite' %ith the limbi$ s"stem& %hi$h& s 'es$!ibe' e!lie!&

%s 'efine' b" the no%-nti@ute' 'istin$tion bet%een ol' n' ne% $o!te(.3

/lthouh %ithin the hippo$mpus mn" $omple( $i!$uits p!ti$ipte in the p!o$essin of in$omin sinls&

the!e is min-line $i!$uit !unnin th!ouh it $lle' the t!is"npti$ $i!$uit tht is espe$ill" impo!tnt. The tns"npti$

$i!$uit in+ol+es the !el" of sinls f!om the !hinl !es to n input !e of the hippo$mpus 2'entte "!us3 n' f!om

the!e to othe! !es 2the :/Q n' :/i !eions3 n' finll" to the output !eion 2the subi$ulum3& %hi$h p!o>e$ts b$k to

the !hinl $o!te(& $losin the loop.

The $onne$tions bet%een the hippo$mpus n' neo$o!te( !e ll mo!e o! less !e$ip!o$l. /s !esult& the

pth%"s tkin info!mtion f!om the neo$o!te( to the !hinl !es n' then into the hippo$mpus !e mi!!o!e' b"

pth%"s $omin out of the hippo$mpus to the !hinl !es n' en'in in the sme neo$o!ti$l !es tht o!iinte'

the inputs. )n this %"& $o!ti$l !es in+ol+e' in p!o$essin stimulus $n& s %e %ill soon see& lso p!ti$ipte in

the lon-te!m sto!e of memo!ies bout tht stimulus.

)t*s impo!tnt to !efle$t fo! moment on the ntu!e of these $onne$tions n' thei! impli$tions fo! %ht the

hippo$mpus n' !hinl !es 'o. The !hinl !es se!+e s $on+e!en$e ,ones& b!in !eions tht inte!te info!-

mtion $!oss senso!" mo'lities n' $!ete !ep!esenttions tht !e in'epen'ent of the o!iinl mo'lit" th!ouh

%hi$h the info!mtion %s p!o$esse'. /s !esult& sihts& soun's& n' smells $n be put toethe! in the fo!m of

lobl memo!" of sitution. 7ithout this $p$it"& memo!ies

%oul' be f!mente'. :on+e!en$e ,ones lso llo% mentl !ep!esenttions to o be"on' pe!$eptions n'



to be$ome $on$eptionsthe" mke possible bst!$t !ep!esenttions tht !e in'epen'ent of the $on$!ete stimuluS.

7hile the p!imte neo$o!te( hs se+e!l $o!ti$l $on+e!en$e ,ones& fe%e! su$h !es e(ist in the neo$o!te( of othe!

mmmls. This m" be n impo!tnt $lue to 'iffe!en$es bet%een the $oniti+e $p$ities of p!imtes n' othe!

nimls.

Be$use the hippo$mpus !e$ei+es inputs f!om se+e!l $on+e!en$e ,ones in the !hinl !eion& it $n be

thouht of s supe!$on+e!en$e ,one. This no 'oubt $$ounts fo! %h" the hippo$mpus pl"s n essentil !ole inou! 'omin-in'epen'ent memo!" $p$it". )t $n fo!m e(pli$it memo!ies bout the impli$it %o!kins of mn" 'omin-

spe$ifi$ s"stems& su$h s f$e- n' lnue-p!o$essin s"stems& llo%in us& fo! e(mple& to fo!m memo!" tht

in$lu'es both %ht someone s"s n' %ht he looks like.

NOMADIC MEMORIES

The!e !e bsi$ll" t%o kin's of mnesiA one is n inbilit" to !emembe! thins tht hppene' befo!e the

su!e!" o! b!in in>u!" 2$lle' !et!o!'e mnesi3& n' the othe! is n inbilit" to fo!m ne% memo!ies 2$lle'

nte!o!'e mnesi3. 7hile %e*+e fo$use' so f! on nte!o!'e mnesi& both fo!ms !e p!esent in ptients %ith

'me to the tempo!l lobe. )nte!estinl"& the 'e!ee of !et!o!'e mnesi is !'e' o+e! timememo!" is %o!se

fo! e+ents !iht befo!e the su!e!" thn fo! e!lie! ones. H. 0. !emembe!s his $hil'hoo'& but not his p!esent life.

The i'e tht mnesi ffe$ts !e$ent mo!e thn !emote memo!ies is kno%n s 4ibot*s l%& fte! the 8!en$h

ps"$holoist Tho'ule 4ibot& %ho p!opose' tht “the ne% pe!ishes befo!e the ol'. L!!" S@ui!e pe!fo!me' seminl

stu'" of 4ibot*s l% on ptients %ho !e$ei+e' ele$t!o$on+ulsi+e the!p" 2E:T3 fo! 'ep!ession& p!o$e'u!e tht often

p!o'u$es memo!" 'istu!bn$es s si'e effe$t.# S@ui!e teste' ptients befo!e n' fte! E:T t!etment in FNM on

thei! memo!" of tele+ision sho%s. Befo!e E:T& the ptients h' fi!l" !elible memo!" of sho%s f!om the e!l"

se+enties n' lte si(ties& %ith 'e$!esin memo!" fo! e!lie! pe!io's. This is @uite no!ml& sin$e %e ten' to

!emembe! !e$entl" le!ne' thins bette! thn ol'e! ones. /fte! E:T& thouh& thei! memo!" of sho%s f!om the e!l"

se+enties %s %o!se thn befo!e E:T& %hile memo!" fo! the e!lie! pe!io's %s unffe$te'.

The !'e' effe$t of !et!o!'e mnesi is no% belie+e' to o$$u! be$use the !ole of the hippo$mpus

$hnes o+e! timethe hippo$mpus is nee'e' fo! memo!" sto!e initill"& but its !ole 'e$!eses s time oes b".

7h" %oul' the b!in %o!k this %"= 7h" %oul' memo!ies be nom'i$=

J" 0$:lelln'& 4n'" O*4eill"& n' B!u$e 0$1uhton h+e p!opose' n ns%e!& one inspi!e' b" !esults

of kin' of $ompute! simultion $lle' $onne$tionist mo'elin. These simultions h+e been +e!" useful in ttempts

to un'e!stn' le!nin. 8o! e(mple& it is kno%n tht %hen $onne$tionist mo'el t!ies to le!n bout !eltions

bet%een stimuli& it 'oes bette! %hen ne% info!mtion is in$o!po!te' !'ull" into the memo!" sto!e !the! thn %hen

it is put in ll t on$e. So-$lle' inte!le+e' le!nin p!e+ents ne% info!mtion f!om inte!fe!in %ith ol' memo!ies. /s

!esult& if the mo'el is t!ine' to !e$oni,e $h!$te!isti$s of nimls like bi!'s 2“$n fl"#3 n' fish 2“$n s%im#3& n'

then en$ounte!s the f$t tht penuin is bi!' tht “$n s%im# but “$n*t fl"&# the !esult is +e!" 'iffe!ent %hen

inte!le+e' le!nin is use' thn if !pi' le!nin is use'. 7ith !pi' le!nin& the ne% info!mtion ten's to !esult in

shift of the kno%le'e bse su$h tht both fish n' bi!'s $ome to be t!ete' s s%immin nimls. But %ith

inte!le+e' le!nin& %he!e the !ep!esenttion is built up slo%l" o+e! mn" !epetitions& the net%o!k !'ull" !efines

the !ep!esenttion of penuin s bi!' tht s%ims but 'oesn*t fl". )n othe! %o!'s& the ne% info!mtion 'oesn*t

inte!fe!e %ith the kno%le'e bse n' is inste' !'ull" ''e' to it.

0n" !ese!$he!s belie+e tht e(pli$it memo!ies !e sto!e' in the $o!ti$l s"stems tht %e!e in+ol+e' in the

initil p!o$essin of the stimulus& n' tht the hippo$mpus is nee'e' to 'i!e$t the sto!e p!o$ess. 8o! e(mple& the

$!etion of memo!" fo! +isul s$ene in+ol+es the t!nsfe! of the pe!$eption f!om the +isul $o!te( to the

p!hippo$mpl $o!ti$l !es n' then into the hippo$mpl $i!$uits. The p!o$esse' sinl& the memo!"& is then fe'

b$k th!ouh the p!hippo$mpl !es b$k to the +isul $o!te(.

/$$o!'in to the inte!le+e' le!nin h"pothesis& then& the memo!" is initill" sto!e' +i s"npti$ $hnes

tht tke pl$e in the hippo$mpus. 7hen some spe$t of the stimulus sitution !e$u!s& the hippo$mpus p!ti$iptes



in the !einsttement of the ptte!n of $o!ti$l $ti+tion tht o$$u!!e' 'u!in the o!iinl e(pe!ien$e. E$h

!einsttement $hnes $o!ti$l s"npses little. Be$use the !einsttements 'epen' on the hippo$mpus& 'me to

the hippo$mpus ffe$ts !e$ent memo!ies& but not ol' ones tht h+e l!e'" been $onsoli'te' in the $o!te(. Ol'

memo!ies !e the !esult of $$umultions of s"npti$ $hnes in the $o!te( s !esult of multiple !einsttements of

the memo!". The slo% !te of $hne of the $o!te( p!e+ents the $@uisition of ne% kno%le'e f!om inte!fe!in %ith ol'

$o!ti$l memo!ies. E+entull"& the $o!ti$l !ep!esenttion $omes to be self-suffi$ient. /t tht time& the memo!"be$omes in'epen'ent of the hippo$mpus.

4ese!$he!s like Jonthn 7inson& 9"o!" Bu,ski& B!u$e 0$1uhton& n' 0tt 7ilson belie+e memo!"

$onsoli'tion o$$u!s 'u!in sleep&* n' spe$ifi$ll" tht it is 'u!in sleep tht the slo% inte!le+in of info!mtion into

$o!ti$l net%o!ks tkes pl$e. 4e$ent stu'ies suppo!t this notion. 8o! e(mple& 7ilson n' 0$1uhton !e$o!'e' the

$ti+it" of neu!ons in the !t hippo$mpus. Usin te$hni$ll" sophisti$te' p!o$e'u!es& the" %e!e ble to i'entif"

p!e$ise ptte!ns of $ell $ti+it" in the hippo$mpus s !ts e(plo!e' no+el en+i!onment. Subse@uentl"& %hen the !ts

%ent to sleep& the neu!l ptte!ns seeme' to be !epete' in the hippo$mpus& s if the !ts %e!e '!emin bout the

pl$es the" h' e(plo!e'. This is n imp!essi+e fin'in. /lthouh it hs not "et been 'emonst!te' tht the

hippo$mpl pl"b$k 'u!in sleep is $tull" !e' n' use' b" the $o!te(& the e(istin 't !e $onsistent %ith the

possibilit".

4e$entl"& the nom'i$ memo!" h"pothesis hs $ome un'e! fi!e. 0o!!is 0os$o+it$h n' L"nn 1'el h+e

!ue' tht the hippo$mpus l%"s !emins in+ol+e' in memo!" sto!e.N Ho%e+e!& %ith time& the memo!" t!$e

$omes to in+ol+e mo!e n' mo!e b!in !eions& espe$ill" $o!ti$l !eions& so tht 'me to n" one !e& like the

hippo$mpus& fils to p!o'u$e 'efi$it& sin$e the othe! !es $ompenste. 7hile this issue %ill no 'oubt $ontinue to

be 'ebte' in the $omin "e!s& !e$ent stu'" hs p!o+i'e' some impo!tnt ne% e+i'en$e. 0i$e %e!e t!ine' in

sptil tsk tht is usull" impi!e' b" hippo$mpl 'me. 1eu!l $ti+it" %s then mesu!e' in the hippo$mpus

t +!ious times fte! t!inin. )nitill"& neu!l $ti+it" %s hih in the hippo$mpus n' %s 'i!e$tl" !elte' to memo!"

pe!fo!mn$e. 20i$e %ith hihe! $ti+it" pe!fo!me' bette!.3 7ith time& hippo$mpl $ti+it" 'e$!ese' n' $me to be

un!elte' to memo!" pe!fo!mn$e& %hile $o!ti$l $ti+it" in$!ese' n' $me to be !elte' to memo!" pe!fo!mn$e.

:hlk one up fo! nom'i$ memo!".

FACT AND E"PERIENCES: ARE THEY DIFFERENT?

So f!& %e h+e t!ete' e(pli$it o! 'e$l!ti+e memo!" s sinle kin' of memo!" $p$it". Ho%e+e!& in the

e!l" FNs& the ps"$holoist En'el Tul+in p!opose' tht lon-te!m memo!ies $oul' be 'istinuishe' on the bsis of

%ht the" %e!e memo!ies a(out)8o He !ue' tht episo'i$ memo!ies !e bout pe!sonl e(pe!ien$es 2thins tht

hppene' to "ou t p!ti$ul! time n' pl$e3& %hile semnti$ memo!ies !e bout f$ts 2thins "ou $ome to kno%&

but h+e not ne$ess!il" e(pe!ien$e'3. 8o! e(mple& "ou $n kno% tht 'ese!ts !e hot n' '!" f!om pe!sonl

e(pe!ien$e& o! b" le!nin bout 'ese!ts in s$hool& %ithout e+e! h+in been to one. Tul+in sueste' tht episo'i$

memo!"& %hi$h !e@ui!es $ons$ious !e$olle$tion of the time n' pl$e of some pe!sonl e(pe!ien$e& is p!ti$ul!l"

$h!$te!isti$ of humns& %he!es semnti$ memo!"& bein the simple sto!e of f$t !the! thn pe!sonl e(pe!i-

en$e& is %ithin the $p$it" of mn" nimls.

4e$ent stu'ies b" 8!neh 6!h-5h'em& 0o!time! 0ishkin& n' $olleues suppo!t Tul+in*s 'istin$tion.

Thei! !ese!$h in+ol+e' $hil'!en in %hom the hippo$mpus %s 'me' e!l" in life. 4em!kbl"& these $hil'!en

mne' to tten' minst!em s$hools n' le!n the bsi$ f$ts tht s$hools imp!t& in spite of the f$t tht the" h'

poo! memo!" fo! thei! o%n e(pe!ien$es. Tken t f$e +lue& the !esults suest tht the hippo$mpus is in+ol+e' in

!emembe!in pe!sonl e(pe!ien$es& but not in !emembe!in f$ts. This %s une(pe$te' b" most !ese!$he!s& sin$e

both semnti$ n' episo'i$ memo!" !e lost in ptients %ith tempo!l lobe lesions. Ho%e+e!& most su$h ptients h+e

h' 'me to the hippo$mpus n' the su!!oun'in $o!ti$l !es 2p!hippo$mpl !eion3& %hile the $hil'!en

stu'ie' b" 6!h-5h'em !e belie+e' to h+e minl" sustine' hippo$mpl 'me.

1ot e+e!"one $$epts the $on$lusion tht the hippo$mpus is sele$ti+el" in+ol+e' in episo'i$ spe$ts of



'e$l!ti+e memo!". T%o p!ominent memo!"

!ese!$he!s& L!!" S@ui!e n' Stu!t ol& fo! e(mple& h+e lon p!omote' the +ie% tht the hippo$mpus

n' p!hippo$mpl $o!te( 2lon %ith $e!tin thlmi$ !es3 $onstitute sinle s"stem tht %o!ks s 'e$l!ti+e

memo!" unit& mkin both semnti$ n' episo'i$ memo!" possible. The" mention se+e!l p!oblems %ith 6!h-

5h'em*s $on$lusions. One is tht episo'i$ memo!"& %hile poo!& is still p!esent in the $hil'!en& n' tht e+en little

episo'i$ memo!" $p$it" m" be suffi$ient to suppo!t oo' 'el of semnti$ kno%le'e. /s !esult& the 'efi$itm" h+e in+ol+e' both episo'i$ n' semnti$ memo!"& but the episo'i$ 'efi$it m" be mo!e !e'il" 'ete$te'.

8u!the!& the" !ue tht 6!h-5h'em n' $olleues !e not >ustifie' in s"in& on the bsis of b!in imin& tht

the 'me in+ol+e' onl" the hippo$mpus. This $n be 'ete!mine' onl" f!om n utops" in %hi$h 'etile' nl"sis

of the b!in is $on'u$te'& n' not me!el" b" tkin b!in s$ns f!om li+in pe!sons. /$$o!'in to S@ui!e n' ol&

e+en if the!e %s mo!e of 'efi$it in episo'i$ thn semnti$ memo!"& the $on$lusion tht one in+ol+es the

hippo$mpus n' the othe! 'oesn*t %oul' still be suspe$t.

Ob+iousl"& it is +e!" 'iffi$ult to pu!sue the fine-!ine' nl"sis of @uestions bout the in+ol+ement of

p!ti$ul! b!in !eions situte' ne(t to e$h othe! in stu'ies of ptients %ith b!in lesions& fo! b!in 'me hs little

!espe$t fo! ntomi$l boun'!ies of inte!est to s$ientists. )n o!'e! to un'e!stn' the 'etile' ntom" of memo!"&

e+en of humn memo!"& it is ne$ess!" to tt$k the p!oblem th!ouh stu'ies of e(pe!imentl nimls& the topi$ to

%hi$h %e no% tu!n.

IN SEARCH OF H M

Soon fte! H. 0.*s mnesi %s 'is$o+e!e'& !ese!$he!s ben t!"in to $hie+e %ht Lshle" %s unble

to 'onmel"& to $!ete mnesi b" 'min the b!in in nimls. )f this $oul' be $$omplishe'& it %oul' !etl"

f$ilitte the stu'" of memo!" f!om bioloi$l point of +ie%. 7ith the hippo$mpus i'entifie' s the e(pe!imentl

t!et bse' on H. 0.*s misfo!tune& it seeme' tht su$$ess %oul' $ome @ui$kl". Ho%e+e!& effo!ts to p!o'u$e mnesi

in nimls b" 'min the hippo$mpus %e!e not !esoun'inl" su$$essful t fi!st. /s lte s FN& %ell o+e!

'e$'e fte! B!en' 0ilne! fi!st 'es$!ibe' H. 0.*s mnesi& Pete! 0ilne! 2B!en'*s e(-husbn' n' neu!os$ientist

t 0$9ill Uni+e!sit" in 0ont!el3 %!ote& “Unfo!tuntel" fo! the e(pe!imentl stu'" of the hippo$mpl mnesi effe$t&

effo!ts to !ep!o'u$e it in nimls h+e so f! p!o+e' unsu$$essful.#

/ bi p!t of the p!oblem %s tht it %s not un'e!stoo' initill" tht hippo-$mpl lesions in humns

ffe$te' onl" $e!tin kin' of memo!"& e(pli$it o! 'e$l!ti+e memo!". )n the niml stu'ies& %hi$h %e!e $on'u$te'

un'e! the influen$e of the beh+io!ist +ie% tht le!nin %s le!nin %s le!nin 2$hp. M3& n" tsk tht mesu!e'

the effe$ts of p!io! le!nin %s leitimte %" of ssessin the ene!l $p$it" fo! memo!". 7e no% kno% tht

onl" some kin's of memo!" 'epen' on the hippo$mpus& n' so onl" tsks tht mesu!e tht kin' of memo!" %ill be

ffe$te' %hen the hippo$mpus is 'me'.

)n humns& it tu!ne' out to be fi!l" $le! ho% to 'efine hippo$mpl'epen'ent memo!". )f $ons$ious

!et!ie+l %s !e@ui!e'& the hippo$mpus ten'e' to be in+ol+e'. But this $!ite!ion isn*t !ell" suitble fo! niml stu'ies.

7e h+e no %" of kno%in %hethe! nimls h+e the kin's of $ons$ious e(pe!ien$es %e h+e& so f!om s$ientifi$

point of +ie%& $ons$iousness is not +e!" oo' notion on %hi$h to bse $omp!ti+e pp!o$h to memo!".

So ho% $n %e stu'" hippo$mpl $ont!ibutions to memo!" in nimls= /s Pete! 0ilne!*s @uote bo+e

implie'& niml stu'ies !e impo!tnt fo! %o!kin out the 'etils n' me$hnisms. O+e! the "e!s& t%o pp!o$hes

eme!e'. One fo$use' on stu'ies of !e$onition memo!" in p!imtes un'e! the ssumption tht the best %" to fiu!e

out %h" H. 0. h' the p!ti$ul! memo!" 'iso!'e! he h' %s to fin' hippo$mpl-'epen'ent fo!m of memo!" in

spe$ies $lose to humns. The othe! %s the !esult of se!en'ipitous obse!+tion in !t.

MONKEY BUSINESS

The histo!" of p!imte stu'ies of !e$onition memo!" is lon n' $ompli$te'. ) !e+ie%e' it in some 'etil in



The Emotional Brain, n' %ill i+e onl" b!ief summ!" of the sto!" he!e. 0ost of the %o!k hs in+ol+e' test of

!e$onition memo!" $lle' 'el"e' nonmt$h to smple 'e+elope' b" D+i' 9ffn& n O(fo!' ps"$holoist. )n this

tsk& monke" sees one ob>e$t n' then& fte! 'el"& is i+en t%o ob>e$ts& one tht %s seen befo!e n' ne%

one. The $o!!e$t $hoi$e& !e%!'e' %ith penut o! 8!oot Loop& is the ne% ob>e$t 2the one tht 'oes not mt$h the

smple3. 0n" of the ke" fin'ins usin this tsk %e!e obtine' b" 0o!t 0ishkin n' Bets" 0u!!" t the 1tionl

)nstitute of 0entl Helth n' L!!" S@ui!e n' Stu!t ol in Sn Dieo& s %ell s 9ffn. )nitil stu'ies sho%e'tht 'me to the hippo$mpus p!o'u$e' sinifi$nt 'efi$it if the 'el" bet%een the fi!st n' the se$on'

p!esenttion of the ob>e$ts %s lon enouh. /n niml mo'el of H. 0. seeme' to e(ist. Then& it %s sho%n tht

'me to the m"'l n'

hippo$mpus toethe! p!o'u$e' e+en mo!e of 'efi$it. This mo'el seeme' e+en bette!& sin$e H. 0. h'

'me to both. )t tu!ne' out& thouh& tht the effe$ts of the lesions %e!e not 'ue to 'me to the m"'l o!

hippo$mpus& but to 'me of the su!!oun'in p!hippo$mpl !eion& %hi$h %s in$i'entll" in>u!e' 'u!in the

monke" b!in su!e!". This %s still stisf$to!" f!om the point of +ie% of mo'elin H. 0.& sin$e he lso h' 'me

in these !es& but it !ise' p!oblems fo! the +ie% tht the hippo$mpus is ke" p!t of the memo!" s"stem. Ho%e+e!&

stu'ies of othe! ptients %ho h' 'me !est!i$te' p!ett" mu$h to the hippo$mpus 2s 'ete!mine' b" postmo!tem

e(mintion of thei! b!ins3 sho%e' tht se+e!e e(pli$it memo!" 'efi$its $oul' !esult f!om hippo$mpl ptholo"

lone. This sueste' tht the hippo$mpus is in+ol+e' in humn e(pli$it memo!"& but tht 'el"e' nonmt$h to

smple is not oo' test of the hippo$mpl $ont!ibution. )t m" inste' be bette! mesu!e of the $ont!ibution of

the p!hippo$mpl $o!te( to !e$onition memo!".

)t is no% belie+e' b" some !ese!$he!s tht the hippo$mpus n' p!hippo$mpl !es !e sep!te

$omponents of tempo!l lobe memo!" s"stem3. /s %e*+e l!e'" seen& senso!" info!mtion $omes into the

hippo$mpus f!om the neo$o!te( b" %" of the p!hippo$mpl !es& n' memo!ies !e estblishe' in the

neo$o!te( b" %" of the !e+e!se $onne$tions. )n sum it seems tht the p!hippo$mpl !es n' hippo$mpus

mke uni@ue $ont!ibutions& n' the 'el"e' nonmt$h to smple tsk !efle$ts the p!hippo$mpl mo!e thn the

hippo$mpl $ont!ibution.

This %o!k is !ele+nt to the issue 'is$usse' e!lie! !e!'in the !ole of the tempo!l lobe in episo'i$ +s.

semnti$ memo!". Pe!hps 'el"e' nonmt$h to smple in the monke" is mo!e like humn semnti$ thn episo'i$

memo!". )f so& the 'istin$tion bet%een the p!hippo$mpl !es n' hippo$mpus p!opose' b" 6!h-5h'em

%oul' be suppo!te'. This %oul' still le+e open @uestions bout %ht !ole the hippo$mpus itself pl"s. 7hile mo!e

%o!k %ill be nee'e' to so!t out e($tl" %ht the hippo$mpus 'oes fo! memo!"& stu'ies in !ts h+e l!e'" beun to

suest some ns%e!s& s %e no% %ill see.

A PLACE FOR SPACE

The se$on' pp!o$h to niml stu'ies of e(pli$it memo!" ben mo!e o! less $$i'entll". )n the e!l"

FNS& John O*5eefe %s !ese!$he! t 0$9ill Uni+e!sit" in 0ont!el. B!en' 0ilne!& %ho 'i' mu$h of the initil

%o!k on H. 0.& %s >ust up the st!eet. So %s 7il'e! Pen'fiel'& neu!osu!eon %ho foun' tht $ons$ious memo!ies

%e!e eli$ite' in ptients %hen p!ti$ul! !es of the tempo!l lobe& like the hippo$mpus& %e!e ele$t!i$ll" stimulte'

in n effo!t to isolte the lo$us of epileps" p!io! to su!e!". 0emo!" n' the hippo$mpus %e!e bi topi$s in 0ont!el&

n' O*5eefe %nte' to kno% mo!e bout ho% the ltte! m'e the fo!me! possible.

He h' pl$e' ele$t!o'es in the hippo$mpus of !t in n effo!t to !e$o!' the ele$t!i$l $ti+it" in this

st!u$tu!e 'u!in the neu!l $o'in of e(pe!ien$e. 1o!mll"& p!o>e$tion $ells 2$hp. Q3 in the hippo$mpus fi!e fi!l"

slo%l"& bout on$e pe! se$on'. But O*5eefe noti$e' tht the fi!in !te in in'i+i'ul $ells !ose '!mti$ll"& up to

hun'!e's of times pe! se$on'& %hen the !t %s in $e!tin lo$tion. /s soon s the !t left tht spot& the $ell stoppe'

fi!in. 7hen it $me b$k to the sme spot& the $ell st!te' fi!in in. Be$use these $ells seeme' to be en$o'in

the sptil lo$tion of the !t& O*5eefe $lle' them pl$e $ells.

Sometimes& one fin'in $n help mke sense of othe!s. 4e$ll tht in FN Pete! 0ime! pointe' out tht



!ese!$he!s h' been unble to $!ete mnesi in nimls. He %ent on to note tht some tsks %e!e ffe$te' b"

'efi$its mo!e $onsistentl" thn othe!s. 7h" this o$$u!!e' %s not %ell un'e!stoo' t the time. Ho%e+e!& one of the

fe% tsks tht hippo$mpl lesions seeme' to impi! %ith n" $onsisten$" %s m,e le!nin& tsk tht is often

sol+e' b" sptil $ues. 0"be O*5eefe*s pl$e $ells %e!e !esponsible fo! memo!" pe!fo!mn$e in m,es. )n'ee'& in

the mi'-se+enties& D+i' Olton of Johns Hopkins Uni+e!sit" 'e+ise' m,e-le!nin tsk 2the eiht-!m !'il m,e3

tht $oul' onl" be sol+e' usin sptil info!mtion& n' 'me to the hippo$mpus inte!fe!e' %ith pe!fo!mn$e ofthis memo!" tsk.

)n the lte se+enties& O*5eefe& no% in Lon'on& toethe! %ith fo!me! $olleue f!om 0$9ill& L"nn 1'el&

%!ote fmous book& The #yppocampus as a Co!niti+e $ap, in %hi$h the" p!opose' tht the hippo$mpus is fun'-

mentll" sptil $onition m$hine& n' its $ont!ibution to othe! spe$ts of memo!" is se$on'!" to its !ole in sptil

p!o$essin. The book %s tou! 'e fo!$e tht estblishe' sptil $onition s m>o! !e of stu'" in neu!os$ien$e.

The stu'" of the hippo$mpus in sptil memo!" in p!ti$ul! be$me th!i+in !e of in+estition.

0n" 'iffe!ent !ese!$h !oups h+e stu'ie' the !ole of the hippo$mpus in sptil p!o$essin. )n FNQ& Jim

4n$k publishe' seminl stu'" of hippo$mpl $ell $ti+it" tht hs inspi!e' mu$h %o!k sin$e. 4n$k& n' espe-

$ill" his $olleues Bob 0ulle! n' John 5ubie& h+e !emine' ke" pl"e!s in the effo!t to un'e!stn' pl$e $ell

fun$tion. /lso note%o!th" is the !ese!$h of B!u$e 0$1uhton& :!ol B!nes& 0tt 7ilson& n' thei! $olleues.

The" h+e use' te$hni$l inenuit" to push stu'ies of pl$e $ells to the fo!ef!ont of inno+tion. )n one stu'"& the"

!e$o!'e' simultneousl" f!om mo!e thn one hun'!e' $ells& sho%in ho% hippo$mpl neu!ons !ep!esent sp$e n'

ho% the fi!in of these $ells p!e'i$ts %he!e the !t %ill o ne(t. /s %e s% bo+e& the" h+e 'emonst!te' tht the

!e$o!' of the !ts* t!+els is en$o'e' b" pl$e $ells n' pl"e' b$k 'u!in sleep& fin'in tht hs been use' to

suppo!t the notion tht the hippo$mpus slo%l" fee's ne% memo!ies to the $o!te( 'u!in sleep. /nothe! m>o!

$ont!ibuto! is 4i$h!' 0o!!is& %ho 'e+elope' no% %i'el" use' m,e& the 0o!!is %te! m,e& in %hi$h !ts use

e(te!nl $ues to s%im to%!' subme!e' pltfo!m. Dme to the hippo$mpus 'is!upts this fo!m of sptil

le!nin. Toethe!& the stu'ies of hippo$mpl fi!in n' the effe$ts of hippo$mpl lesions on m,e le!nin h+e

une@ui+o$ll" sho%n tht the hippo$mpus is in+ol+e' in sptil memo!". 0iht it be pl$e fo! sp$e=

RELATIONS

/lthouh most of the e+i'en$e f!om !ts fo! hippo$mpl !ole in memo!" hs in+ol+e' sptil le!nin&

mn" tsks tht monke"s n' humns %ith hippo$mpl 'me fil on h+e nothin ob+ious to 'o %ith sptil

p!o$essin. Does this men tht the !t hippo$mpus n' the p!imte hippo$mpus !e fun'mentll" 'iffe!ent= 1ot

ne$ess!il". Dme to the hippo$mpus in p!imtes 'oes p!o'u$e 'efi$its in sptil memo!"& lon %ith 'efi$its in

nonsptil memo!". Sptil p!o$essin miht be spe$ifi$ e(mple& one tht is espe$ill" impo!tnt to !ts& of mo!e

ene!l $p$it" of the hippo$mpus.

Ho%!' Ei$henbum hs lon p!omote' the i'e tht sptil memo!" is one spe$ifi$ e(mple of %ht the

hippo$mpus 'oes. )ts ene!l fun$tion& $$o!'in to Ei$henbum n' 1el :ohen& is 'e$l!ti+e memo!". But this

tkes us b$k to the p!oblem %e en$ounte!e' e!lie!. )f 'e$l!ti+e memo!" is $ons$ious memo!"& ho% $n %e

leitimtel" stu'" it in nimls= Ei$henbum n' :ohen p!opose' tht 'e$l!ti+e memo!" shoul' be 'efine' not b"

its $ons$ious spe$ts& but inste' b" the kin' of p!o$essin !e@ui!ements it mkes. Spe$ifi$ll"& 'e$l!ti+e memo!ies

!e !eltionl. Thus& $ti+tion of 'e$l!ti+e memo!" le's to the $ti+tion of othe! !elte' memo!ies. /s !esult&

'e$l!ti+e memo!ies $n be $ti+te' in'epen'ent of the $onte(t in %hi$h the" %e!e estblishe'& n' b" stimuli othe!

thn those tht %e!e initill" in+ol+e' in the le!nin. Ei$henbum n' :ohen p!opose tht the ntomi$l

!$hite$tu!e of the hippo$mpus llo%s it to ene in !eltionl p!o$essin& n' tht the +!ious kin's of tsks tht

impli$te the hippo$mpus in memo!" ll 'epen' on !eltionl p!o$essin.

)n Ei$henbum*s +ie%& the hippo$mpus is in+ol+e' in both the semnti$ n' episo'i$ spe$ts of 'e$l!ti+e

memo!". )n this sense& he si'es %ith S@ui!e n' ol in p!oposin tht the 'e$l!ti+e memo!" in ene!l is the



business of the hippo$mpus. Ho%e+e!& %hile S@ui!e n' ol p!opose tht the hippo$mpus n' p!hippo$mpl

$o!te( fo!m unifie' 'e$l!ti+e memo!" s"stem& Ei$henbum suests tht onl" the hippo$mpus is in+ol+e' in the

fle(ible n' !eltionl p!o$essin tht en$ompsses 'e$l!ti+e memo!"& n' tht the p!hippo$mpl !es !e

in+ol+e' in the less fle(ible& non!eltionl memo!" of in'i+i'ul $omponent !ep!esenttions tht o into 'e$l!ti+e

memo!".

CON#UNCTIONS

The !eltionl theo!" of hippo$mpl fun$tion is not uni+e!sll" $$epte'. The p!e'ominnt $hllene to it&

othe! thn the sptil theo!"& hs been the +ie% tht the hippo$mpus bin's stimuli toethe!& blen'in the +!ious ele-

ments of n e(pe!ien$e 2the %" it looks& soun's& n' feels3 into unifie' !ep!esenttion tht is 'i+o!$e' f!om

$omponent elements. )n this theo!"& the o!iinl elements& thouh& !e lost& h+in been fo!me' into $on>un$tions&

%hile in the !eltionl theo!"& the elements !emin 'is$!ete n' the hippo-$mpus links them toethe!. :onsi'e! n

e(mple. )n the !eltionl theo!"& "ou! memo!" of mel in !estu!nt %oul' in+ol+e the simultneous bin'in of

sep!te memo!ies of the people "ou %e!e %ith& the foo' "ou te& n' the ene!l mbien$e of the !estu!nt&

%he!es the $on>un$tion theo!" p!oposes tht ll of the elements !e blen'e' s sinle memo!" of the sitution.

/lthouh the notion of $on>un$tions hs been p!t of mn" theo!ies& !e$ent p!oposl b" 4n'" O*4eill"

n' Je!!" 4u'" seems p!ti$ul!l" p!omisin. The" built upon the e!lie! theo!" of 0$:lelln'& 0$1uhton& n'

O*4eill"& n' on 4u'"*s e!lie! $onfiu!l theo!"& %hi$h posite' tht in'i+i'ul ob>e$ts !e ;$onfiu!e'* in su$h %" to

$$ount fo! ll of the ob>e$ts in sinle !ep!esenttion. The theo!" file' to hol' up be$use su$h lobl

!ep!esenttions %e!e 'iffi$ult to substntite. O*4eill" n' 4u'" !ue tht the $onfiu!l theo!" %s in'ee' p!tl"

%!on be$use mu$h !ese!$h subse@uentl" sho%e' tht nimls %ith hippo$mpl lesions $oul' le!n $on>un$ti+e

!eltions. )n the ne% theo!"& thouh& O*4eill" n' 4u'" p!opose tht the 't $n be e(pline' b" ssumin tht the

sp!e' $on>un$ti+e le!nin %s pe!fo!me' b" the neo$o!te(& n' tht the neo$o!te( n' hippo$mpus le!n usin

fun'mentll" 'iffe!ent !ules. The hippo$mpus le!ns $on>un$tions ntu!ll" n' !pi'l". 7hen the hippo$mpus is

'me'& the neo$o!te( $n be fo!$e'& th!ouh e(tensi+e t!inin& to lso le!n $on>un$tions& but no!mll" it 'oes not

'o so. /s 0$:lelln'& 0$1uhton& n' O*4eill" h' p!opose'& the neo$o!te(& in $ont!st to the hippo$mpus& le!ns

b" slo%& inte!le+e' le!nin. Onoin !ese!$h is testin this ne% +e!sion of the $onfiu!l theo!" in !eltion to sptil

n' !eltionl theo!ies.

:le!l"& niml mo'els h+e ene!te' mn" inte!estin i'es bout e($tl" %ht e(pli$it o! 'e$l!ti+e

memo!" is n' ho% it is suppo!te' b" the ntom" of the tempo!l lobe. /lthouh %e still 'on*t h+e ll the ns%e!s&

imp!essi+e p!o!ess hs been m'e. 7e $n e(pe$t tht p!o!ess in un'e!stn'in the !ole of the hippo$mpus in

memo!" p!o$esses %ill $ontinue to be m'e in niml mo'els& n' tht this info!mtion %ill help& in tu!n& to un-

'e!stn' the ntu!e of e(pli$it memo!" in humns.

THE WAY YOU DO THE THINGS YOU DO

Thouh %e h+e fi!sthn' kno%le'e of ou! e(pli$it memo!ies 2%hi$h !e bout thins %e %e!e on$e %!e

of3& mn" spe$ts of ou! out%!' beh+io! n' inne! life !e $ont!olle' b" b!in s"stems tht sto!e n' use

info!mtion impli$itl"& tht is& %ithout ou! %!eness of thei! ope!tion. )mpli$it memoties !e !efle$te' mo!e in the

thins %e 'o& n' the %" %e 'o them& thn in the thins %e kno%.

7e*+e l!e'" en$ounte!e' some e(mples of impli$it memo!". /lmost b" 'efinition& these !e memo!ies

tht $n be fo!me' in H. 0. n' othe! ptients %ho h+e mnesi 'ue to 'me to the hippo$mpus n' !elte'

b!in !eions. 8o! e(mple& le!ne' moto!i$ n' $oniti+e skills& p!imin& n' $lssi$ll" $on'itione' !esponses $n

e$h be le!ne' n' pe!fo!me' in the bsen$e of the hippo$mpus. The" must be me'ite' b" b!in s"stems othe!



thn the one in+ol+e' in e(pli$it memo!".

7hile e(pli$it memo!" is me'ite' b" p!ti$ul! s"stem 2$ontine' %ithin $i!$uits of the me'il tempo!l

lobe3& mn" 'iffe!ent s"stems in the b!in ene in impli$it le!nin. 7hile these !e often 'es$!ibe' s “impli$it

memo!" s"stems&# this is somethin of misnome!. The s"stems tht ene in impli$it le!nin !e not st!i$tl"

spekin memo!" s"stems. The" %e!e 'esine' to pe!fo!m spe$ifi$ fun$tions& like pe!$ei+in stimuli& $ont!ollin p!e-

$ise mo+ements& mintinin bln$e& !eultin $i!$'in !h"thm& 'ete$tin f!ien' n' foe& fin'in foo'& n' so onCplsti$it" 2the bilit" to $hne s !esult of e(pe!ien$e3 is simpl" fetu!e of the neu!onl inf!st!u$tu!e of these

s"stems tht f$ilittes thei! ope!tion.

)t*s %o!th notin tht John O*5eefe suests the sme bsi$ s$en!io hol's fo! the tempo!l lobe memo!"

s"stem. /s %e s% bo+e& he belie+es tht the hippo$mpus %s built to p!o$ess sp$e& n' tht sp$e p!o$essin

'emn's $e!tin kin' of plsti$it" tht hs been $o-opte' in the se!+i$e of the mo!e ene!l $p$it" e(p!esse' s

e(pli$it memo!" in humns. )n this sense& e(pli$it memo!" is& in Stephen J" 9oul'*s te!ms& n e(pttion 2$hp. M3.

0n" of the neu!l s"stems tht ene in impli$it le!nin in humns h+e e(iste' th!ouhout mu$h of the

e+olution!" histo!" of mmmls& n' p!obbl" othe! +e!teb!tes. The" %o!k un$ons$iousl" not be$use of some

!n' 'esin to hi'e spe$ts of mentl life f!om ou! sentient self but simpl" be$use thei! ope!tion is not 'i!e$tl"

$$essible b" the $ons$ious b!in.

S"stems tht fun$tion impli$itl" $ont!ibute in impo!tnt %"s to ou! most $h!$te!isti$ t!its. E$h of us hs

his o! he! o%n st"le of %lkin& tlkin& n' thinkin. 7e hol' ou! bo'ies in $e!tin mnne! %hen %e !e stn'in o!

sittin. 7e noti$e thins tht some othe!s ino!e& n' ino!e thins tht some people noti$e. The %" %e smile n'

the kin's of +o$l infle$tions %e use lso help 'efine %ho %e !e. The e(tent to %hi$h %e !e $lm n' $olle$te'& o!

emotionll" !e$ti+e& %hen thins o %!" is lso !e+elin& s !e the loi$l pths n' illoi$l leps of thouht %e

h+e. These n' mn" othe! spe$ts of min' n' beh+io! !e e(p!esse' so utomti$ll"& so impli$itl"& tht the"

m" seem un$hneble& pe!hps innte. But %e shoul' not o+e!look the $!u$il !ole of e(pe!ien$e& %hi$h is to s" of

le!nin n' memo!"& in estblishin n' mintinin them.

)n !e$ent "e!s& $onsi'e!ble p!o!ess hs been m'e in elu$i'tin the neu!l $i!$uits un'e!l"in $e!tin

e(mples of impli$it le!nin n' memo!". 7hile obse!+tions on H. 0. n' othe! humns le' !ese!$he!s to the hip -

po$mpus n' its !ole in e(pli$it memo!"& it hs been stu'ies of nonhumn spe$ies tht h+e !e+ele' the neu!l

$i!$uits of impli$it memo!". Stu'ies in humns h+e& in mn" instn$es& +e!ifie' tht the sme $i!$uits !e t %o!k in

ou! b!ins& but the bsi$ fin'ins h+e fo! the most p!t been 'is$o+e!e' th!ouh stu'ies of othe! nimls.

THE RIGHT STUFF

/lthouh the fo!ms of impli$it le!nin n' memo!" tht !e no% un'e!stoo' in most bioloi$l 'etil in

mmmls !e e$h e(mples of $lssi$l $on'itionin& fe% stu'ies befo!e FN emplo"e' $lssi$l $on'itionin s

tool to e(plo!e the neu!l bsis of le!nin n' memo!" E!lie! !ese!$h %s inspi!e' b" the beh+io!ist t!'ition in

ps"$holo" %hi$h emphsi,e' ope!nt o! inst!umentl $on'itionin o+e! $lssi$l $on'itionin. )n $lssi$l

$on'itionin& the sub>e$t le!ns n sso$ition bet%een t%o stimuli bell n' foo'& fo! e(mple. The !esponses tht

!esult !e utomti$ 2e..& sli+tion o! he!t !te $hnes3. )n $ont!st& in inst!umentl $on'itionin& the sso$ition is

bet%een stimulus 2!e%!'3 n' !esponsefoo' o$$u!s %hen !t p!esses b! o! tu!ns the $o!net in m,e. The

foo' !einfo!$es the !esponse& n'& s !esult& the sub>e$t !epets the !esponse to et the foo'. The sub>e$t is

pssi+el" in+ol+e' in $lssi$l $on'itionin 2the foo' $omes %hen the stimulus o$$u!s& !e!'less of %ht the sub>e$t

is 'oin3 but in ope!nt $on'itionin& the sub>e$t is $ti+el" in+ol+e' sin$e the !e%!' 'oes not $ome unless the

sub>e$t !espon's in $e!tin %". )nst!umentl $on'itionin %s +ie%e' s mo!e suitble mens of $$ountin fo!

the full $omple(it" of humn beh+io!& %hi$h the beh+io!ists $le!l" hope' to 'o. 8!om Lshle" on%!'& !ese!$h on

the b!in me$hnisms of le!nin n' memo!" ten'e' to emphsi,e the use of inst!umentl tsks.

B" the FNs& thouh& $lssi$l $on'itionin p!o$e'u!es h' beun to tke on ne% life. Thei! !ebi!th ben



%ith the publi$tion of n !ti$le b" E!i$ 5n'el n' /l'en Spen$e! in FG. 1otin the p tht e(iste' bet%een

le!nin 2somethin tht in+ol+es beh+io!3 n' plsti$it" 2somethin tht in+ol+es neu!ons n' s"npses3& the"

p!opose' step-b"-step st!te" tht %oul' llo% the 'is$o+e!" of the neu!l bsis of le!nin t the le+el of $ells n'

thei! s"npti$ $onne$tions. This $ellul!-$onne$tion pp!o$h %s the !iht stuff. )t t!nsfo!me' the hel'& n' is still in

pl$e to'"

5n'el n' Spen$e! emphsi,e' tht the fi!st step %s to sele$t n o!nism tht e(p!esses n esil"mesu!e' n' @untifible beh+io! tht $hnes %ith e(pe!ien$e. Then& the neu!l $i!$uit un'e!l"in unle!ne' n'

le!ne' +e!sions of the beh+io! shoul' be i'entifie'. 1e(t& the $ells n' s"npses in the $i!$uit tht $hne %ith

le!nin shoul' be pinpointe'. 8inll" the me$hnisms tht me'ite the neu!l $hnes shoul' be 'ete!mine'.

5n'el n' Spen$e!*s mnifesto $hllene' !ese!$he!s to think in te!ms of

$i!$uits !the! thn l!e !es of the b!in. Lshle" h' se!$he' fo! the lo$us of memo!" b" mkin lesions

in %i'esp!e' !es& %ithout n" sense of %he!e to se!$hhe %s !ell" lookin fo! nee'le in h"st$k. The

$ellul!-$onne$tion pp!o$h tol' us ho% to pinpoint the p!t of the h"st$k %he!e the nee'le miht be hi'in.

5n'el n' Spen$e! belie+e' tht the $ellul!-$onne$tion pp!o$h $oul' best be implemente' in simple

ne!+ous s"stem $ontinin !elti+el" smll numbe! of %ell-'efine' neu!ons. 8o! this !eson& 5n'el $hose to stu'"

beh+io!l $on'itionin n' plsti$it" in snils. Sin$e the snil 'oesn*t h+e hippo$mpus& the l$k of in+ol+ement of

the hippo$mpus in $on'itionin %s not n impe'iment to the use of these p!o$e'u!es. The emphsis %s on

$on'itionin s tool fo! stu'"in beh+io!ll" !ele+nt neu!l $hnes !the! thn s 'i!e$t mo'el of humn

memo!" The p"off of this pp!o$h %s fst. B" the e!l" FNS& 5n'el n' $olleues h' impli$te' spe$ifi$

neu!ons n' s"npses in le!nin in snils. 7e*ll $onsi'e! some spe$ts of 5n'el*s elent n' !oun'b!ekin

!ese!$h in the ne(t $hpte!& %o!k tht le' to his bein 1obel P!i,e !e$ipient in .

The su$$ess $hie+e' b" 5n'el n' othe!s in in+e!teb!tes usin simple $on'itionin pp!o$hes to

le!nin tempte' !ese!$he!s to pu!sue this pp!o$h in mmmls n' othe! +e!teb!tes. The f$t tht the tools fo!

stu'"in neu!ontom" h' >ust un'e!one !e+olution !etl" f$ilitte' the effo!t to t!$e $onne$tions f!om st!t to

finish 2f!om senso!" input to moto! output s"stems3 in $omple( b!in. 1o%& se+e!l 'e$'es lte!& mu$h is kno%n

bout the neu!l $i!$uits un'e!l"in $e!tin fo!ms of $lssi$l $on'itionin. To the e(tent tht these $i!$uits 'o not

'epen' on the e(pli$it memo!" s"stem& the" !e e(mples of $i!$uits tht ene in impli$it le!nin.

But %hen this ne% %+e of !ese!$h on the neu!l bsis of $on'itionin st!te' in the FNs& the 'istin$tion

bet%een e(pli$it n' impli$it memo!" 'i' not e(ist. 4ese!$he!s pu!suin the $ellul!-$onne$tion pp!o$h in in-

+e!teb!tes n' +e!teb!tes like %e!e usin $on'itionin s tool fo! stu'"in the !eltion bet%een neu!l plsti$it"

n' beh+io!. Onl" lte! %s it !eli,e' tht these stu'ies %e!e !e+elin the neu!l bsis of %ht %e no% !e$oni,e

s impli$it memo!"

To'"& %e h+e 'etile' un'e!stn'in of $i!$uit!" in+ol+e' in onl" fe% of the mn" s"stems tht le!n

impli$itl" The e(mples 'is$usse' belo% !e the!efo!e not ne$ess!il" !ep!esentti+e of impli$it memo!" in ene!l&

but inste' !e !ep!esentti+e of the impli$it memo!" fun$tions tht h+e been $h!$te!i,e'& in the t!'ition of the

$ellul!-$onne$tion pp!o$h& f!om senso!" input to moto! output t the neu!l le+el.

BEING DEFENSIVE

One of the fi!st !ese!$he!s to tke up the $ellul!-$onne$tion pp!o$h n' ppl" it to the +e!teb!te b!in

%s D+i' :ohen. ;7hile !e$oni,in the impo!tn$e of stu'ies of simple $!etu!es& he felt tht it %s lso impo!tnt

to pu!sue this pp!o$h in +e!teb!te spe$ies. His niml of $hoi$e %s the pieon& n' his beh+io!l p!'im %s

P+lo+in $on'itionin.

P+lo+ h' been stu'"in 'iestion in 'os %hen he noti$e' tht the" sli+te' %hen the pe!son %ho fe'

them %lke' into the lb. He tu!ne' this into n e(pe!iment& n' 'emonst!te' tht if bell %s !un >ust s foo' %s

put in the 'o*s mouth& the 'o %oul' sli+te %hen it he!' the soun' of the bell& e+en if the foo' 'i' not follo%.#



:ohen*s !ese!$h in+ol+e' the sme ene!l p!o$e'u!e )*+e use' in m" %o!k& P+lo+in 'efense o! fe!

$on'itionin. )n :ohen*s $on'itionin p!o$e'u!e& the ppe!n$e of liht %s follo%e' b" sho$k. /s !esult& the

onset of the liht e+entull" le' to $hne in the !te t %hi$h the pieon*s he!t bet. The $hne in he!t !te& s

%e*+e seen& is but one of mn" !esponses tht o$$u! 'u!in 'efense $on'itionin. :ohen simpl" use' he!t !te s

$on+enient %" of ssessin tht 'efense $on'itionin h' tken pl$e. He m'e imp!essi+e p!o!ess in his $ellul!-

$onne$tion stu'ies& i'entif"in input $i!$uits th!ouh %hi$h the liht %s p!o$esse' n' output $i!$uits th!ouh %hi$hthe he!tbet %s $ont!olle'. Ho%e+e!& he 'i' not su$$ee' in $onne$tin the input s"stem %ith the output s"stem.

)t h' lon been kno%n tht the m"'l pl"s n impo!tnt !ole in fe! !esponses n' e+en in le!nin to

fe! ne% stimuli.# /n' one of the !eions impli$te' in he!t !te $on'itionin b" :ohen %s the bi!'-b!in e@ui+lent

of the m"'l. Ho%e+e!& :ohen*s %o!k fell sho!t of 'emonst!tin tht the m"'l is the inte!f$e bet%een inputs

n' outputs& n' likel" site of the ke" neu!l $hnes tht un'e!lie fe! le!nin.

Stu'ies in the FGs n' FFs pinte' fi!l" $omp!ehensi+e pi$tu!e of the fe!-le!nin $i!$uits in the

mmmlin b!in. 7o!k f!om m" o%n lb i'entifie' the %" tht inputs et to the m"'l& n' stu'ies b" B!u$e

5pp n' his $olleues t the Uni+e!sit" of 6e!mont p!o+i'e' e+i'en$e fo! the output pth%"s e(itin f!om the

m"'l. 0i$hel D+is& 0i$hel 8nselo%& n' 1o!mn 7einbe!e!& n' thei! stu'ents n' $olleues& lso m'e

impo!tnt $ont!ibutions to +!ious spe$ts of the fe!-$on'itionin $i!$uit!". 0n" of the 'etils of the fe!-$on'itionin

pth%"s %e!e 'es$!ibe' in The Emotional Brain, n' some spe$ts of fe!-$on'itionin $i!$uits h+e

l!e'" been 'is$usse' in e!lie! $hpte!s. He!e& )*ll i+e onl" b!ief summ!" of them.

The m"'l $ontins 'o,en o! so 'istin$t 'i+isions o! !es& but !elti+el" fe% !e impo!tnt fo! fe!

$on'itionin) The lte!l nu$leus of the m"'l 2lte!l m"'l3 se!+es s the input ,one. )t !e$ei+es info!mtion

f!om the +!ious senses& llo%in the outsi'e %o!l' to be monito!e' fo! th!etenin info!mtion. )n stu'ies pe!fo!me'

toethe! %ith /ls Pitknen& %e foun' tht the lte!l nu$leus hs $onne$tions %ith most of the othe! m"'l

!eions. 5!im 1'e!& P!in /mo!pnth& n' ) then 'ete!mine' tht onl" the $onne$tions %ith the $ent!l nu$leus

2$ent!l m"'l3 !e essentil fo! fe! $on'itionin. The $ent!l nu$leus& the output ,one& hs $onne$tions %ith

net%o!ks tht $ont!ol fe! beh+io! n' sso$ite' $hnes in bo'" ph"siolo" 7hen the lte!l nu$leus 'ete$ts

some th!etenin stimulus& the $ent!l nu$leus initites the e(p!ession of 'efensi+e beh+io!s 2like f!ee,in3 n' othe!

bo'il" !esponses sso$ite' %ith fe! !e$ti+it" 2$hnes in bloo' p!essu!e n' he!t !te& stom$h $ont!$tions&

s%et ln' $ti+it"& et$.3.

Stu'ies b" Li, 4omnski& :lu'i 8!b& 1eot Do!on n' me sho% tht the lte!l m"'l ets inputs

bout the stimuli f!om t%o sou!$es. )t !e$ei+es $!u'e but fst !ep!esenttion f!om sub$o!ti$l !e 2the senso!"

thlmus3 n' slo%e! but mo!e $omplete !ep!esenttion f!om $o!ti$l senso!" !es. The !ole of these t%o input

s"stems to the m"'l %s elu$i'te' in stu'ies pe!fo!me' in m" lb b" Li, 4omnski. The pth f!om the thlmus

th!ouh the $o!te( to the m"'l& the so-$lle' hih !o'& llo%s $omple( info!mtion bout ob>e$ts n'

e(pe!ien$es to initite fe! !e$tions. But the m"'l lso $n be $ti+te' 'i!e$tl" f!om the thlmus. Sin$e this

lo% !o' b"psses the neo$o!te(& it onl" p!o+i'es the m"'l %ith $!u'e !ep!esenttion of the e(te!nl stimulus.

But the !!i+l of $!u'e info!mtion $n h+e impo!tnt $onse@uen$es. 8o! e(mple& 8bio Bo!'i n' ) foun' tht $ells

in the m"'l !e ble to 'ete!mine the intensit" o! lou'ness of soun' th!ouh the thlmi$ pth%". Lou'ness

is oo' $lue to ho% $lose somethin is& n' 'istn$e is oo' $lue to ho% 'ne!ous tht thin is. )f "ou t!et lou'

thins s 'ne!ous& e+en if "ou 'on*t kno% the sou!$e of the noise& "ou !e p!obbl" oin to be bette! off in the lon

!un. So simpl" b" $omputin intensit" f!om the thlmus& the m"'l $n imme'itel" 'e'u$e sinifi$nt 'etils

bout stimulus. )ntensit" is not the onl" fetu!e ue' b" the lo% !o' f!om the thlmus& but it*s n impo!tnt one.

The $o!ti$l !oute in$lu'es se+e!l mo!e s"npti$ $onne$tions thn the thlmi$ pth to the lte!l m"'l.

E$h s"npti$ link ''s time to the t!nsmission p!o$ess& %hi$h is %h" $ells in the lte!l m"'l !espon' to in-

fo!mtion 'i!e$tl" f!om the thlmus fste! thn the" $n !espon' to info!mtion f!om the $o!te(. 0o!e p!o$essin

time b" the b!in mens slo%e! mentl n' beh+io!l !esponse f!om the o!nism. )n situtions %he!e !pi'

!esponses !e !e@ui!e'& spee' $n be mo!e impo!tnt thn $$u!$"



/lthouh inputs f!om the thlmi$ n' $o!ti$l pths !!i+e on 'iffe!ent s$he'ules& the inputs !e$h the sme

neu!ons. This mens tht in ''ition to >ump-st!tin the s"stem& llo%in fo! !pi' initil !esponses& the thlmi$ in-

fo!mtion $n lso p!ime lte!l m"'l $ells to !e$ei+e the mo!e e($tin info!mtion f!om the $o!te(. /s !esult&

the $ells !e then mo!e $pble of $h!in he' if the $o!ti$l info!mtion $onfi!ms the th!et& o! of puttin on the

b!kes if the $o!ti$l info!mtion estblishes tht no 'ne! is p!esent 2fo! e(mple& tht the lou' $!$klin soun' %s

f!om "ou steppin on b!n$h !the! thn f!om somethin 'ne!ous& like be! bout to poun$e on "ou& o! tht the$u!+e' shpe on the !oun' is sti$k& not snke3.

Just be$use the $o!ti$l !oute llo%s mo!e !efine' stimulus nl"sis to t!ie! the m"'l& it shoul' not

be ssume' tht the hih !o' is $ons$ious !oute to the m"'l. This %s often misun'e!stoo' b" !e'e!s of The

Emotional Brain) The m"'l enes in impli$it p!o$essin& in$lu'in impli$it le!nin& !e!'less of %hi$h

pth%" p!o+i'es it %ith senso!" info!mtion. /s %ith n" othe! stimulus& %e be$ome $ons$iousl" %!e of n

emotionl stimulus onl" %hen tht stimulus is p!o$esse' b" net%o!ks in+ol+e' in somethin $lle' %o!kin memo!"&

%hi$h %e*ll 'is$uss in 'etil in $hpte! N.

Usin the $ellul!-$onne$tion st!te"& likel" neu!l $i!$uit !e@ui!e' fo! fe! $on'itionin hs thus been

i'entifie' f!om senso!" inputs th!ouh moto! outputs. 7o!k is no% un'e! %" to%!' $hie+in the ol of 'ete!minin

%he!e the essentil plsti$it" is in this $i!$uit. 7hile this !ese!$h is still in p!o!ess& e(pe!iments h+e pointe' to the

lte!l nu$leus s ke" site of plsti$it" in situtions %he!e neut!l soun's !e pi!e' %ith sho$ks. 8i!st& stu'ies b"

Li, 4omnski foun' tht $ells in the lte!l nu$leus !e$ei+e $on+e!ent inputs f!om pth%"s tht p!o$ess both

soun's n' sho$ks.# Su$h $on+e!en$e is belie+e' to be essentil fo! $on'itionin to o$$u!. )n'ee'& 9!e ?ui!k&

:h!is 4ep& n' 0i$hel 4on foun' tht the $ti+it" of lte!l m"'l $ells in$!eses %hen the tone n' sho$k

o$$u! t the sme time but not %hen the" !e sep!te'. These $hnes in the neu!l !esponses p!e$e'e the

'e+elopment of $on'itione' fe! beh+io!& suestin tht the neu!l $hnes miht %ell be !esponsible fo! the

beh+io!l le!nin. Stu'ies b" Ste+e 0!en n' Denis P!e h+e no% lso sho%n plsti$it" in the lte!l m"'l.#

8u!the!& $on'itionin 'oes not o$$u! if the lte!l nu$leus is 'me'. :on'itionin is lso p!e+ente' if s"npti$

$ti+it" n'Ko! plsti$it" is 'is!upte' b" in>e$tin $e!tin '!us in the lte!l nu$leus& s sho%n b" Jeff 0ulle!& /nn

7ilensk"& n' 9lenn S$hfe in m" lb& s %ell s b" !ese!$h f!om othe! lbs.No Toethe!& these fin'ins in'i$te

tht the lte!l m"'l is ke" site of plsti$it" 'u!in fe! le!nin. /s %e %ill see in the ne(t $hpte!& p!o!ess

hs lso been m'e in un$o+e!in some of the p!e$ise $ellul! n' mole$ul! me$hnisms in the lte!l m"'l

tht un'e!lie fe! $on'itionin.

/s P+lo+ suspe$te'& 'efense $on'itionin pl"s n impo!tnt !ole in the e+e!"'" life of people n' othe!

nimls. )t o$$u!s @ui$kl" 2one pi!in of the neut!l n' +e!si+e stimulus is often suffi$ient3 n' en'u!es 2possibl"

fo! lifetime3. These fetu!es h+e no 'oubt be$ome p!t of the b!in*s $i!$uit!" 'ue to the f$t tht n niml

usull" 'oes not h+e the oppo!tunit" to le!n bout p!e'to!s o+e! the $ou!se of mn" e(pe!ien$es. )f n niml is

lu$k" enouh to su!+i+e one 'ne!ous en$ounte!& its b!in shoul' sto!e s mu$h bout the e(pe!ien$e s possible&

n' this le!nin shoul' not 'e$" o+e! time& sin$e p!e'to! %ill l%"s be p!e'to!. )n mo'e!n life& %e sometimes

suffe! f!om the e(@uisite ope!tion of this s"stem& sin$e it is 'iffi$ult to et !i' of this kin' of $on'itionin on$e it is no

lone! ppli$ble to ou! li+es& n' %e sometimes be$ome $on'itione' to fe! thins tht !e in f$t h!mless.

E+olution*s %is'om sometimes $omes t $ost. Thompson n' his stu'ents. Thompson h' %o!ke' %ith /l'en

Spen$e!& n' his stu'ies of plsti$it" in the spinl $o!' h' $ont!ibute' sinifi$ntl" to the enesis of the $ellul!-

$onne$tion pp!o$h subse@uentl" 'e+elope' b" 5n'el n' Spen$e!. )n the FNs& Thompson ben to stu'" b!in

me$hnisms un'e!l"in the P+lo+in $on'itionin of e"e blink !esponses in !bbits s simple mmmlin

p!ep!tion fo! pu!suin the lo$us of le!nin in the b!in. 7e en$ounte!e' this kin' of $on'itionin in ou! 'is$ussion

of H. 0.

E!lie! stu'ies b" )s'o!e 9o!me,no n' othe!s h' %o!ke' out in p!e$ise 'etil mn" of the bsi$

p!in$iples un'e!l"in e"e blink $on'itionin to soun' tht %s follo%e' b" n nno"in stimulus 2 sho$k o! puff of

i! to the e"e3. Befo!e $on'itionin& the sho$k o! puff $uses the e"e to blink but the soun' 'oes not. /fte!



$on'itionin& thouh& the soun' eli$its blink& n' the blink is p!e$isel" time' f!om the onset of the soun'the e"e

$loses !iht befo!e the time %hen the puff o! sho$k %oul' o$$u!. The blink the!efo!e ppe!s to be n 'pti+e

!esponse tht p!ote$ts the e"e f!om i!!ittion.

Buil'in on this beh+io!l %o!k& Thompson n' othe! !ese!$he!s pu!sue' the neu!l bsis of e"e blink

$on'itionin. )t %s 'is$o+e!e' tht !emo+l of the enti!e neo$o!te( h' no effe$t on the bilit" of !bbits to be

$on'itione'. )n f$t& e"e blink $on'itionin $oul' o$$u! follo%in !emo+l of most of the fo!eb!in& in$lu'in them"'l& hippo$mpus& n' othe! !es. This le' to the $on$lusion tht the essentil plsti$it" un'e!l"in this fo!m

of $on'itionin must be in the b!in stem !the! thn the fo!eb!in. )n'ee'& stu'ies b" John 0oo!e& fo!me! stu'ent of

9o!me,no*s& foun' tht 'me in the lo%e! b!in stem 'i' p!e+ent $on'itionin& %hile t the sme time le+in the

!esponse eli$ite' b" the un$on'itione' stimulus unffe$te'3. The !bbits $oul' the!efo!e blink thei! e"e in !esponse to

'i!e$t stimulus no!mll"& but $oul' not le!n to blink to the %!nin soun'.

Th!ouh se!ies of stu'ies in+ol+in the use of mn" 'iffe!ent te$hni@ues& Thompson n' othe!s 2in$lu'in

Joseph Steinmet,& 0ike 0u!& n' :h!is Yeo3 h+e elbo!te' the b!in stem me$hnisms of e"e blink $on'i-

tonn. The" h+e been le' to the $on$lusion tht the $!iti$l site in the b!in stem is the $e!ebellum& %!inkle'

mss of tissue tht sits on top of the b!in stem n' tht h' lon been belie+e' to be in+ol+e' in the $ont!ol of

postu!e n' mo+ement n' tht h' p!e+iousl" been h"pothesi,e' to be site of le!nin. The !ese!$he!s sho%e'

tht lesions of $e!tin !es of the $e!ebellum p!e+ente' $on'itionin& n' tht the $ti+it" of neu!ons in these !es

$hne' 'u!in the $ou!se of $on'itionin. Pth%"-t!$in stu'ies 'ete!mine' tht the $e!ebellum hs neu!l

$onne$tions tht llo% it to inte!te the soun' n' the i! puff& n' to $ont!ol the e"e blink !esponse. )n f$t& the e"e

blink $n be $on'itione' b" substitutin the tone n' the puff %ith 'i!e$t ele$t!i$l stimultion of the neu!l pth%"s

tht t!nsmit the tone n' the puff into the $e!ebellum. /lthouh not e+e!"one f+o!s the +ie% tht plsti$it" is n

impo!tnt fetu!e of $e!ebell! fun$tion&)o stu'ies b" Ste+e Lisbe!e! usin 'iffe!ent t!inin p!o$e'u!e h+e lso

impli$te' $e!ebell! $i!$uits in moto! le!nin.

7h" shoul' %e $!e bout ho% !bbits blink= /s %ith mn" pp!o$hes in neu!os$ien$e& it is impo!tnt to

>u'e this %o!k in b!o'e! $onte(t. The !ese!$h is not >ust sho%in ho% the !bbit b!in blinks the !bbit e"e& but

in-

ste' !ell" $on$e!ns ho% mo+ements $ome un'e! the $ont!ol of e(t!insi$ sinls. :ont!ol of p!e$ise

mo+ements t >ust the !iht time is fun'mentl spe$t of mn" kin's of $@ui!e' beh+io!l skill& f!om le!nin to

!i'e bike& to hittin n' $t$hin bseblls& to '!i+in $!s& n' mn" othe! thins tht %e 'o e+e!" '". The

$e!ebellum& s %e h+e seen& is lso in+ol+e' in postu!e n' bln$e& n' both of these fun$tions !e mo'ifie' b"

e(pe!ien$est!onuts& fo! e(mple& !e'il" 'pt to the $hne' bln$e n' postu!l !e@ui!ements impose' b"

lte!e' !+it". The %" %e hol' ou! bo'" t !est& the %" %e mo+e& n' the !$e 2o! l$k the!eof3 %ith %hi$h %e 'o

thins $ont!ibute sinifi$ntl" to the ph"si$l ime %e p!o>e$t. The" !e p!t of %ho %e !e. Stu'ies of the !ole of the

$e!ebellum in moto! le!nin !e thus !e+elin $lues bout n impo!tnt $lss of impli$it le!nin $p$ities.

THE TASTE OF THINGS TO COME

0ost people like s%eet n' 'islike bitte!-tstin foo's. This p!efe!en$e is p!esent +e!" e!l" in lifen infnt

%ill spit out bitte! foo's on the fi!st en$ounte!. )nfnts bo!n %ith mssi+e p!ts of the fo!eb!in missin n' !ts %ith

lesions of ll of the fo!eb!in n' mi'b!in still e(hibit tste p!efe!en$es& suestin tht tste is me'ite' b" the

hin'b!in. The e!l" ppe!n$e of tste p!efe!en$es suests tht the" !e built into the hin'b!in 'u!in p!entl

'e+elopment n' !e possibl" innte. 1e+e!theless& tste p!efe!en$es !e sub>e$t to mo'ifi$tion b" e(pe!ien$e.

0n" 'ults en>o" etin b!o$$oli n' spin$h& e+en if the" %e!e 'islike' in $hil'hoo'. /n' some foo's& on$e

en>o"e'& $n be$ome hihl" +e!si+e if the" mke "ou si$k.

Stu'ies of foo' poisonin in nimls& espe$ill" !ts& h+e helpe' us un'e!stn' fun'mentl kin' of

le!nin& so-$lle' $on'itione' tste +e!sion 2:T/3& spe$il fo!m of $lssi$l $on'itionin. 8!me!s h' lon kno%n



tht $ttle +oi' foo's tht mke them si$k& but this +oi'n$e %s not stu'ie' se!iousl" until the Fs& %hen John

9!$i n' his stu'ents foun' tht !ts m'e ill b" in>e$tion of mil' poison st!onl" +oi'e' the lst foo' eten be-

fo!e ettin si$k. 7ht %s p!ti$ul!l" st!ikin bout this e(pe!iment %s the f$t tht the +oi'n$e %oul' 'e+elop

e+en if si$kness %s in'u$e' hou!s fte! the foo' %s $onsume'. The fin'in +iolte' one of the $!'inl p!in$iples of

le!nintht sso$itions fo!m bet%een stimuli tht o$$u! t the sme time& n' not bet%een stimuli sep!te' b"

hou!s. The f$t tht :T/ +iolte' this l% %s one of the m>o! $hllenes to the uni+e!sl ntu!e of le!ninp!omote' b" the beh+io!ists 2$hp. M3. /n' be$use these 't %e!e +ie%e' b" st!i$t beh+io!ists s impossible&

9!$i h' !et 'el of t!ouble publishin his stu'ies. But he pe!siste' n' e+entull" su$$ee'e'.

:T/ hs be$ome m>o! !e of !ese!$h in beh+io!l neu!os$ien$e. /lthouh the $i!$uits in+ol+e' in it !e

not s %ell $h!$te!i,e' s those tht o+e!n fe! n' e"e blink $on'itionin& oo' 'el of p!o!ess hs been

m'e. 0ost of the %o!k hs use' s$$h!in& no+el s%eet tste& s the $on'itione' stimulus 2this is like the tone in

fe!-$on'itionin stu'"3. 4ts p!efe! '!inkin s$$h!in-fl+o!e' %te! o+e! plin %te!& but if the" et si$k fte!

'!inkin s$$h!in& the" %ill subse@uentl" +oi' it. Often the si$kness is in'u$e' b" n in>e$tion of lithium $hlo!i'e&

nuse-p!o'u$in substn$e tht se!+es s the un$on'itione' stimulus 2like the sho$k in fe! $on'itionin3.

Like othe! fo!ms of $lssi$l $on'itionin& :T/ !e@ui!es tht the neut!l tste n' the nuse-p!o'u$in

stimulus $ome toethe! s"npti$ll" t in'i+i'ul neu!ons. The tste pth%" f!om the tonue oes to !eion of the

hin'b!in $lle' the nu$leus of the solit!" t!$t& %hi$h is in+ol+e' in tste p!efe!en$es. The sme ene!l !eion of

the hin'b!in !e$ei+es fibe!s f!om the ut& tellin the b!in bout nuse n' othe! st!ointestinl $on'itions.

Ho%e+e!& be$use 'iffe!ent !eions of the hin'b!in !e$ei+e the nuse n' tste sinls& $on'itionin is not likel"

me'ite' b" s"npti$ inte!tion in this !e. The t%o p!ts of the nu$leus of the solit!" t!$t 'o p!o>e$t onto

$ommon !e in the mi'b!in $lle' the p!b!$hil nu$leus. Dme to this !eion& %he!e tste- n' nuse-

stimulus p!o$essin o+e!lp& p!e+ents :T/ f!om o$$u!!in. 8u!the!mo!e& in no!ml nimls& $ellul! $ti+it" eli$ite' in

this !eion b" tste stimuli in$!eses follo%in e(posu!e to the nuse-in'u$in stimulus& in'i$tin tht $ells in the

!eion !e in+ol+e' in the $on'itionin of tste b" nuse. The p!b!$hil nu$leus thus is likel" to be n impo!tnt

!e of plsti$it" un'e!l"in :T/.

But this is not the %hole sto!". 4emo+l of the fo!eb!in& %hi$h le+es onl" the b!in stem to !un the sho%&

'is!upts the $@uisition of :T/& in spite of the f$t tht the sme p!o$e'u!e le+es tste p!efe!en$es un'istu!be'.

The p!b!$hil nu$leus thus 'oes not %o!k lone in the me'ition of :T/ n' inste' 'epen's on the fo!eb!in

!es. /ntomi$l t!$in stu'ies i+e $lues s to %hi$h !es of the fo!eb!in !e impo!tnt he!e. The p!b!$hil

nu$leus sen's fibe!s to the tste !e of the thlmus& %hi$h in tu!n sen's fibe!s to the tste !e of the $o!te(.

8u!the!& the p!b!$hil nu$leus& tste !e of the thlmus& n' tste $o!te( ll sen' fibe!s to the $ent!l nu$leus of

the m"'l. Usin e(pe!imentl lesions& it hs been sho%n tht 'me to t%o of these !eions& the $o!ti$l tste

!e n' the $ent!l m"'l& inte!fe!es %ith :T/. The tste $o!te( is belie+e' to be in+ol+e' in 'ete$tin n' 'is

$!imintin no+el tstes& %hi$h is n impo!tnt spe$t of le!nin bout the $onse@uen$es of ne% tstes. The

!ole of the $ent!l m"'l is $ont!o+e!sil. Some belie+e it is not !e@ui!e' fo! le!nin& %he!es othe!s belie+e it is

essentil. Diffe!en$es in the %" :T/ is estblishe' o! teste' m" $$ount fo! the 'iffe!ent +ie%s. 7hile mo!e %o!k

is nee'e' to !esol+e these issues& :T/ hs p!o+en to be useful mo'el s"stem fo! stu'"in memo!" $i!$uits& n' hs

lso "iel'e' some impo!tnt fin'ins bout the mole$ul! bsis of memo!"& s %e %ill see in the ne(t $hpte!.

WHENCE SUCCESS?

E!l" !ese!$h on le!nin me$hnisms %s inspi!e' b" the beh+io!ist t!'ition in ps"$holo". B" the

FNs& thouh& !ese!$he!s $me to !eli,e tht less is mo!e %hen it $me to the $hoi$e of beh+io!l tsks use' to

stu'" le!nin& n' ben tkin thei! inspi!tion mo!e f!om neu!obiolo"& espe$ill" f!om the $ellul!-$onne$tionist

pe!spe$ti+e. The emphsis the!efo!e shifte' %" f!om $omple( inst!umentl le!nin p!o$e'u!es to simple!

$on'itionin tsks& sin$e& s 5n'el n' Spen$e! note'& it %oul' be esie! to 'is$o+e! the $i!$uits n' spe$ifi$



s"npti$ $hnes in+ol+e' in simple thn in mo!e $omple( fo!ms of le!nin.

The '+ntes of $lssi$l o+e! inst!umentl $on'itionin s st!tin point fo! neu!l nl"sis of

le!nin !e !e'il" illust!te' b" the histo!" of !ese!$h on fe! le!nin. E!l" %o!k in this !e emphsi,e'

+oi'n$e-$on'itionin p!o$e'u!es& inst!umentl tsks in %hi$h the sub>e$t le!ns to +oi' n +e!si+e e+ent& like foot

sho$k& on the bsis of %!nin sinl. )t tu!ns out& thouh& tht +oi'n$e $on'itionin beins s $lssi$l $on'ition-

inA the %!nin sinl p!o'u$es the +oi'n$e !esponse be$use it %s fi!st sso$ite' %ith sho$k. 8o! e(mple& !t $n be tuht tht if it !uns f!om one en' of m,e to the othe! %hen the tone $omes on& the sho$k %ill be p!e -

+ente'. But the fi!st step is tht the !t hs to le!n& th!ouh $lssi$l $on'itionin& tht the tone p!e'i$ts the sho$k.

Onl" then $n it use the tone-sho$k sso$ition to le!n the inst!umentl !esponse of +oi'in the sho$k b" !unnin

th!ouh the m,e in the p!esen$e of the tone. )t mkes oo' sense& in !et!ospe$t& tht the %" to fiu!e out ho% the

b!in me'ites +oi'n$e $on'itionin %oul' be to fi!st un'e!stn' ho% the tone-sho$k sso$ition is fo!me'& n'

then to sk ho% the tone-sho$k sso$ition is use' to estblish +oi'n$e. But this %s not !eli,e' in the e!l" '"s&

n' p!o!ess in un'e!stn'in fe! le!nin %s slo% until !ese!$he!s 'e$i'e' to simpl" fo$us on the $lssi$l

$on'itionin of fe!.

Ob+iousl"& memo!" !ese!$he!s %ill not be stisfie' %ith e(plinin onl" the simple fo!ms of le!nin. But

!me' %ith kno%le'e of ho% those simple fo!ms %o!k& %e m" %ell be ble to tke on mo!e $omple( ones. 8o!

e(mple& no% tht the $lssi$l $on'itionin of fe! is %ell un'e!stoo'& it miht be possible to fiu!e out the neu!l

bsis of +oi'n$e. This is n impo!tnt +enue of !ese!$h sin$e the hllm!k of n(iet" 'iso!'e!s is ptholoi$l

+oi'n$e of n(iet"-p!o'u$in situtions& %hi$h !etl" $onst!i$ts the li+es of n(ious people. /s %e %ill see in

$hpte! F& !e$ent stu'ies h+e m'e $onsi'e!ble p!o!ess in usin kno%le'e obtine' bout the neu!l bsis of

fe! $on'itionin s steppin-stone to un'e!stn'in +oi'n$e le!nin.

CONSCIOUS AND UNCONSCIOUS MEMORY RECONSIDERED

7ht e($tl" 'o %e men %hen %e s" tht the hippo$mpus is in+ol+e' in $ons$ious memo!" n' tht

othe! fo!ms of memo!"& %hi$h !e in'epen'ent of the hippo$mpus& !e not 'i!e$tl" $$essible to $ons$iousness=

Does it impl" tht the hippo$mpus mkes $ons$iousness possible= P!obbl" not& sin$e hippo$mpl 'me 'oes

not 'is!upt no!ml $ons$ious %!eness.

E(mples of memo!" 'efi$its p!o'u$e' b" hippo$mpl 'me in humns h+e in'ee' mostl" in+ol+e'

filu!es in the bilit" to $ons$iousl" !et!ie+e info!mtion bout pst e(pe!ien$es. 7hen teste' on le!nin tsks tht 'o

not !e@ui!e $ons$ious !et!ie+l& like p!imin o! $on'itionin& hippo$mpl'me' ptients bsi$ll" pe!fo!m

$$eptbl". But %hen !e@ui!e' to !et!ie+e info!mtion $ons$iousl"& often %ithin the sme tsk the" pe!fo!me' %ell on

impli$itl"& the" 'o poo!l". 8o! e(mple& s %e*+e seen& thouh hippo$mpl'me' ptients !espon' to tone

p!e+iousl" pi!e' %ith n i! puff to thei! e"e& the" h+e no $ons$ious memo!" of h+in been $on'itione'.

The impo!tn$e of $ons$ious !et!ie+l in 'efinin the hippo$mpl 'efi$it %s hihlihte' in stu'"

pe!fo!me' b" L!!" S@ui!e n' $olleues. The" h' no!ml sub>e$ts n' pe!sons %ith mnesi 'ue to hippo$mpl

'me %t$h silent mo+ie. The sub>e$ts %e!e ske' to p" ttention to the mo+ie %hile ino!in soun's n' i!

puffs tht %oul' o$$u! th!ouhout. This t"pe of inst!u$tion t"pi$ll" bises sub>e$ts to fo!m e(pli$it memo!ies bout the

tten'e' e+ent& n' %s ime' t keepin the tones n' puffs in the b$k!oun' of %!eness. The tones n' puffs

%e!e 'eli+e!e' in t%o 'iffe!ent %"s. Some of the sub>e$ts !e$ei+e' stn'!' p!o$e'u!e in %hi$h the puff o$$u!!e'

t the en' of the tone. /s e(pe$te' f!om p!io! %o!k& both the no!-

m $ont!ols n' the mnesi$ ptients $on'itione'the" le!ne' to blink in !esponse to the soun'in spite

of the f$t tht the" %e!e inst!u$te' to ino!e the tones n' puffs. 8o! othe! sub>e$ts& the puff $me some time fte!

the tone h' en'e'. This is $lle' t!$e $on'itionin n' is kno%n f!om stu'ies of !ts n' !bbits to be 'is!upte' b"

hippo$mpl 'me. )n'ee'& the ptients %ith hippo$mpl 'me 'i' not $on'ition in the t!$e tsk. 7ht is



p!ti$ul!l" sinifi$nt& thouh& is %ht hppene' to the no!ml $ont!ols. Some of them $on'itione' n' some 'i'n*t&

n' %hethe! the" $on'itione' %s $losel" !elte' to %hethe! the" !epo!te'& fte! the e(pe!iment& h+in noti$e'

!eltion bet%een the tone n' the puff. )n othe! %o!'s& if the" %e!e $ons$ious of the !eltion& the" un'e!%ent t!$e

$on'itioninC othe!%ise the" 'i' not. This sueste' tht t!$e $on'itionin !e@ui!es %!eness& n' tht the

hippo$mpus mkes this %!eness possible.

One p!oblem %ith this $on$lusion is tht it st!ins the inte!p!ettion of the !t n' !bbit 't& %hi$h !e+elthe sme effe$tA 'efi$its in t!$e $on'itionin follo%in hippo$mpl 'me. )f the humn hippo$mpus is in+ol+e' in

t!$e $on'itionin be$use of its !ole in %!eness& then the !t n' !bbit hippo$mpus must lso be in+ol+e' in

$ons$ious %!eness& sin$e the"& too& !e !e@ui!e' fo! t!$e $on'itionin. )f not& the hippo$mpus is not !ell" in-

+ol+e' in %!eness.

/ !e$ent stu'" b" 0!+in :hun n' Li, Phelps suests the ltte! is the $se. The" teste' no!ml sub>e$ts

n' mnesi$s on tsk tht !e@ui!e' the i'entifi$tion of sinle lette! Tin se of L9s) The L9s thus fo!me' the b$k-

!oun' o! $onte(t in %hi$h the t!et Tppe!e'. Unbekno%nst to the sub>e$ts& the $onte(t stimuli $me in t%o

+!ieties. Sometimes the T%s monst n !!nement of L9s tht h' $ome befo!e& n' sometimes the T%s in

no+el !!nement of L9s) Both no!ml $ont!ols n' mnesi$s ot bette! s the tsk %o!e on. Ho%e+e!& the no!mls

but not the mnesi$s benefite' f!om the !epetition of the b$k!oun' ptte!nA the" %e!e bette! t fin'in the Tin the !e-

pete' ptte!n thn in no+el ones. 1e+e!theless& the sub>e$ts %e!e not %!e& %hen ske' lte!& of the f$t tht the

b$k!oun' !epete'. The hippo$mpus& in othe! %o!'s& %s !e@ui!e' to p!o$ess n' le!n bout the untten'e'

b$k!oun' stimuli.

:hun n' Phelps %e!e moti+te' to pe!fo!m thei! stu'" b" the f$t tht stu'ies of !ts h' lon sueste'

tht the hippo$mpus %s in+ol+e' in $onte(tul p!o$essin. 8o! e(mple& s %e*ll see in $hpte! G& %hen "ou

$on'ition !t b" pi!in tone %ith sho$k& the !t be$omes f!i' not onl" of the tone but lso of the bo( in %hi$h

the $on'itionin tkes pl$e. The hippo$mpus& it tu!ns out& is ne$ess!" fo! this kin' of $on'itionin be$use it is

ble to put toethe! mn" thins t on$e& to !elte o! $onfiu!e them into $onte(t. This is not unlike the %" O*5eefe

o! Ei$henbum o! 4u'" +ie%s the !o'ent hippo$mpusA it hs $e!tin !!nement of neu!ons tht llo%s the

$!etion of memo!" in+ol+in $omple( set of stimuli. The!e is no nee' to $ll upon $ons$iousness in the

inte!p!ettion of the !o'ent %o!k.

The :hun n' Phelps fin'in st!onl" suests tht the humn n' !o'ent hippo$mpus %o!k the sme

%"& fo!min memo!ies bout the !eltions bet%een stimuli. 4e!'less of the ntu!e of the !eltions 2%hethe! the"

!e unifie' $onfiu!tionsK$on>un$tions of stimuli& !eltions mon 'iffe!ent memo!ies& o! memo!ies bout sptil

!!nements3& the ke" fun$tion of the hippo$mpus is p!obbl" p!o$essin !eltions. )f so& then the hippo$mpus

miht not be fun'mentll" 'iffe!ent f!om othe! s"stems tht sto!e info!mtion. Tht is& it p!obbl" oes bout its

business impli$itl". 7ht is 'iffe!ent bout the hippo$mpl n' othe! memo!" s"stems is inste' the f$t tht the

hippo$mpus is s"npti$ll" $onne$te' in su$h %" tht its $ti+it" is +ilble to the b!in s"stems tht me'ite

$ons$ious %!eness 2%hi$h %e*ll $onsi'e! lte! in $hpte! N3& %he!es impli$it s"stems !e not $onne$te' in this

fshion.

THE GOOD, THE BAD, AND THE UGLY

0emo!" is m,in. / simple thouht $n tke "ou to pst time in "ou! life. /n' often %ithout thinkin t ll

%e “!emembe!# to 'o %ht %e nee' to 'o e$h '". But %ith the oo' $ome the b'& n' e+en the ul"& spe$ts of

memo!"& its filu!es. 1o one kno%s mo!e bout this thn Dn S$h$te!& %ho put the te!ms e(pli$it n' impli$it

memo!" on the mp. His !e$ent book& The Se+en Sins of $emory, l"s out in !phi$ 'etil the %"s memo!" fils us.

S$h$te!*s sins !e t!nsien$e& bsent-min'e'ness& blo$kin& mistt!ibution& suestibilit"& bis& n' pe!sisten$e3

T!nsien$e is simpl" the inbilit" to hol' onto info!mtion. /bsent-min'e'ness is ou! nno"in $p$it" to fil



to p" ttention to %ht %e !e 'oin& s %hen "ou put "ou! ke"s 'o%n %hile 'oin somethin else& n' then $n*t

fin' them be$use %hen "ou put them 'o%n "ou %e!e mentll" in+ol+e' in some othe! $ti+it". Blo$kin is the filu!e

to pull out tht f$t o! nme tht is on the tip of "ou! tonue. Then the!e*s mistt!ibution& s t"pifie' b" the belief tht

memo!" fo!me' in one sitution %hen it $tull" o$$u!!e' in nothe!. This is p!ti$ul!l" impo!tnt in the $onte(t of

e"e%itness testimon".

Suestibilit" is lso !ele+nt to e"e%itness testimon" n' to the topi$ of flse memo!ies implnte' in thethe!peuti$ p!o$ess. Bis $!eeps into memo!" in se+e!l %"s& one of %hi$h is $onsisten$" bis& %hi$h le's us to

!e+ise ou! memo!" of sitution to mke it fit %ht %e feel o! think no%. 8inll"& the!e*s pe!sisten$e& %hi$h on the

su!f$e soun's oo'. Emotionl !ousl mkes n" memo!" st!one!& %hi$h $n be oo'& but %hen the memo!" is of

t!umti$ e(pe!ien$e& pe!sisten$e $n be 'ebilittin.

S$h$te! emphsi,es tht the sins !e less 'esin fl%s thn fetu!es. Tht is& he $lims tht the sins !e

b"-p!o'u$ts of +i!tuespe!sisten$e& s %e*+e seen& $n be oo'. 4e!'less of the 'pti+e +lue& if n"& of the sins&

t lest %ith kno%le'e of thei! e(isten$e %e $n t!" to p!ote$t ou!sel+es f!om thei! neti+e $onse@uen$es.

REMEMBERING WHO WE ARE

This $hpte! opene' %ith @uote f!om the Spnish su!!elist filmmke! Luis BuVuel& %ho si'& “Life %ithout

memo!" is no life t ll.. . . Ou! memo!" is ou! $ohe!en$e& ou! !eson& ou! feelin& e+en ou! $tion. 7ithout it& %e !e

nothin.# 0emo!" 'oes in'ee' mke us %ho %e !e. But it is impo!tnt to !emembe! tht memo!" is mo!e thn >ust

%ht %e $n $ons$iousl" !e$ll. )t the!efo!e follo%s tht loss of e(pli$it memo!"& 'ue to 'me to the hippo$mpus&

%hile 'e+sttin in mn" %"s& %oul' not eliminte pe!sonlit". )n /l,heime!*s 'isese& fo! e(mple& the

hippo$mpus n' !elte' !es !e the fi!st to be 'est!o"e'. E+en in the f$e of se+e!e memo!" p!oblems& its suffe!-

e!s initill" !emin mu$h the sme pe!son the" l%"s %e!ethe" %lk n' tlk the sme& n' h+e the sme bsi$

hbits n' t!its. /s the 'isese sp!e's %i'el" to othe! b!in !es& those tht fun$tion impli$itl"& pe!sonlit" beins

to b!ek 'o%n.

)n o!'e! to be "ou!self& "ou h+e to !emembe! %ho "ou !e. 5eep in min' thouh tht the memo!ies in+ol+e'

!e 'ist!ibute' $!oss mn" b!in s"stems& n' !e not l%"s o! e+en mostl" +ilble to "ou $ons$iousl".

CHAPTER SI"

S0/LL :H/19E

1OTH)19 E1DU4ES BUT :H/19E.

--He !$ ) tutS



/ L)6)19 TH)19 )S D)ST)19U)SHED 84O0 / DE/D TH)19 BY THE 0ULT)PL):)TY O8 THE :H/19ES

/T /1Y 0O0E1T T/5)19 PL/:E )1 )T.

He!ne!E Spen$e!

Life is $hne& n' the b!in is 'e+i$e fo! !e$o!'in $hnesfo! fo!min memo!ies th!ouh le!nin.

Le!nin n' memo!"& s %e*+e seen& fill in the 'etils of %ho %e !e s %e be$ome uni@ue pe!son. But %ht is the

ntu!e of the neu!l $hnes tht $onstitute le!nin n' memo!"= 0ost neu!os$ientists to'" belie+e tht lte!tions

in s"npti$ $onne$ti+it" un'e!lie le!nin& n' tht memo!" is the stbili,tion n' mintenn$e of these $hnes o+e!

time. Ho%& then& 'oes e(pe!ien$e $tull" $hne s"npses& n' %ht mkes the $hnes lst=

HEBB!S MAGIC

)n n GFM le$tu!e to the 4o"l So$iet" of Lon'on& Sntio 4mRn " :>l& %hom %e met in $onne$tion %ith

the neu!on 'o$t!ine& p!opose' tht “the bilit" of neu!ons to !o% in n 'ult n' thei! po%e! to $!ete ne% $onne$-

tions $n e(plin le!nin.#* 7hile this sttement is often $ite' s the o!iin of the s"npti$ theo!" of memo!"& it %s

nti$ipte' b" numbe! of othe! i'es. 8o! e(mple& in the mi'-Ns& the philosophe! D+i' H!tle" sueste' tht

mentl sso$itions 2memo!ies bout the !eltion bet%een stimuli3 !e the !esult of +ib!tions bet%een ne!+es., 0o!e

thn $entu!" lte!& 7illim Jmes& the fthe! of /me!i$n ps"$holo"& %!ote in his fmous GF te(tbookA “7hen

t%o element!" b!in p!o$esses h+e been $ti+e toethe! o! in imme'ite su$$ession& one of them& on !eo$$u!nn&

ten's to p!opte its e($itement into the othe!. /n' in his me'i$l !ese!$h '"s& Simun' 8!eu' !ue'& “0emo!"

is !ep!esente' b" the f$ilittions e(istin bet%een...

!ons. Still& these suestions& in$lu'in :>l*s& %e!e onl" p!till" fo!me' %hen $omp!e' to the +ie%

p!opose' b" the :n'in ps"$holoist Donl' Hebb& in his FMF book& The -r!ani:ation ofBeha+ior)

Hebb m'e mn" seminl $ont!ibutions to s$ientifi$ ps"$holo"s in$lu'in pionee!in stu'ies on pe!$eption&

instin$tul n' emotionl beh+io!& n' intellien$e. Ho%e+e!& he is best kno%n fo! his s"npti$ theo!" of memo!"& his

fi!e n' %i!e theo!"& %hi$h %e en$ounte!e' in $hpte! M in the $onte(t of b!in 'e+elopment. /n' lthouh this theo!"

is !e+e!e' b" b!in s$ientists to'"& Hebb pp!entl" 'i' not belie+e it to be p!ti$ul!l" impo!tnt& n' $e!tinl" 'i'n*t

$onsi'e! it to be his best i'e o! his most sinifi$nt $ont!ibution.

Hebb*s notion& s "ou*ll !e$ll& is tht “%hen n (on of $ell / is ne! enouh to e($ite $ell B o! !epete'l"

n' $onsistentl" tkes p!t in fi!in it& some !o%th p!o$ess o! metboli$ $hnes tke pl$e in one o! both $ells su$h

tht /*s effi$ien$"& s one of the $ells fi!in B& is in$!ese'.# Let*s e(pn' this i'e little so %e $n see ho% it miht

ppl" to memo!"& n' espe$ill" to memo!" of the f$t tht t%o stimuli on$e o$$u!!e' toethe!.

)n o!'e! fo! t%o stimuli to be boun' toethe! in the min'& to be$ome sso$ite'& the neu!l !ep!esenttions of

the t%o e+ents h+e to meet up in the b!in. This mens tht the!e hs to be some neu!on 2o! set of neu!ons3 tht

!e$ei+es info!mtion bout both stimuli. Then& n' onl" then& $n the stimuli be linke' toethe! n' n sso$ition be

fo!me' bet%een them.

7e*ll $onsi'e! simple e(mple to see ho% Hebb*s theo!" mkes sso$itions possible. )mine neu!on /

tht is posts"npti$ to t%o othe! neu!ons. One of these 23 is st!onl" $onne$te' n' the othe! 273 is %ekl"

$onne$te' to /. /s !esult& %hen S fi!es& / lso often fi!es& %he!es / is less likel" to fi!e in !esponse to $ti+it" in 7.



8u!the!& imine tht e$h of the t%o neu!ons $onne$te' to / is in+ol+e' in p!o$essin 'istin$t stimuli. Be$use the

$onne$tion f!om S to / is st!one! thn the $onne$tion f!om 7 to /& / is mo!e likel" to fi!e in !esponse to e(te!nl

stimuli tht $ti+te S thn those tht $ti+te 7. )f on some o$$sion stimuli p!o$esse' b" both of the $ells o$$u!

simultneousl"& the %ek input to / %ill likel" be o$$u!!in t the sme time tht / is bein fi!e' b" the st!on input.

/s !esult& $$o!'in to Hebb*s !ule& the %ek $onne$tion %ill be st!enthene'. / is no% pl$e in the b!in %he!e

the st!on n' %ek pth%"s !e !elte'& su$h tht $ti+tion of the %ek one no% hs the sme effe$t tht onl"$ti+tion of the st!on one h' befo!e. This so!t of thin hppens ll the time in 'il" life. )f "ou !e %lk in on the

si'e%lk in f!ont of "ou! neihbo!*s house 2%ek stimulus3 n' his 'o bites "ou 2st!on stimulus3& "ou %ill sso$ite

the si'e%lk %he!e "ou %e!e bitten %ith the 'o n' be less in$line' to %lk tht %".

To'"& neu!os$ientists use the te!m #e((ian learnin! to 'es$!ibe $hne in the $onne$tion st!enth bet%een

t%o neu!ons $use' b" the f$t tht th posts"npti$ $ell %s $ti+e %hen p!es"npti$ inputs !!i+e'3* Hebb !eli,ei

tht his i'e %s not $ompletel" no+el& notin tht othe!s h' p!opose s"npti$ theo!ies of memo!"& n' some

histo!ins h+e sueste' tht Heb3 be i+en less $!e'it in liht of pst +ie%s. The f$t !emins& ho%e+e!& th Hebb

'e+elope' theo!" of s"npti$ st!enthenin to $$ount fo! le!nin %he!es most of the othe!s simpl" p!opose' tht

su$h $hnes miht o$$u! /n'& s %e*ll see lte! in the $hpte!& Hebbin le!nin $tull" e(plins ho% $e!tin kin's

of s"npti$ $hnes tke pl$e in the b!in& n' m" in f$t be m>o! %" tht memo!ies !e m'e.

SEARCFHNG FOR SYNAPSES

/!oun' mi'-$entu!"& s"npti$ $hne %s topi$ tht %s in the i!. Hebb book h' been publishe'& s h'

one b" the !et Polish neu!os$ientist Je!, 5ono!ski. 5ono!ski use' the te!m plasticity to 'es$!ibe the bilit" of

neu!on to be lte!e' b" e(pe!ien$e n' h' p!opose' theo!" of s"npti$ plsti$it not too 'iffe!ent f!om Hebb*s. /n'

b" the e!l" Fs& numbe! of stu'ies h' su$$essfull" sho%n tht !epete' 'eli+e!" of b!ief ele$t!i$l stimulus t

ne!+e pth%" $oul' lte! s"npti$ t!nsmission in tht pth%"$oul'& i othe! %o!'s& p!o'u$e s"npti$ plsti$it"3*

8o! e(mple& Si! John E$$les& !e$ipient of the 1obel P!i,e fo! his %o!k o s"npti$ t!nsmission& n' one of

the leen's of mo'e!n neu!os$ien$e& foun tht !epetiti+e stimultion of ne!+es oin to the spinl $o!' le' to n

in$!es in the si,e of the ele$t!i$l !esponse eli$ite' in posts"nptl$ neu!ons in th spinl $o!'.u Ele$t!i$l stimultion of

pth%"s %s use' s simplifie' pp!o$h fo! $ti+tin s"npses in spe$ifi$ !e of the ne!+ous s"sten Thouh

!tifi$il& this metho' %s +ie%e' s !esonble pp!o(imtion 'i!e$t e(pe!ien$e be$use ou! e(pe!ien$es in the

%o!l' $n ffe$t the b!i onl" b" %" of ele$t!i$l $on'u$tion in ne!+e pth%"s 2$hp. Q3. /s !esul $hnes like

those foun' b" E$$les %e!e inte!p!ete' s step to%!' un'e!stn'in the neu!l bsis of le!nin. Ho%e+e!&

be$use the $hnes

mostl" sho!t-li+e'& the" %e!e not >u'e' to be suffi$ient to $$ount fo! t8 pe!sisten$e of memo!".

1e+e!theless& E$$les !emine' t!ue belie+e! in if theo!" tht memo!" in+ol+es s"npses.

)n F& 4i$h!' Thompson n' /l'en Spen$e! foun' in'i!e$t e+i'e!n tht s"npti$ $hnes miht $$ount

fo! !elti+el" simple e(mple of le!nin. The" stu'ie' hbitution of the limb-%ith'!%l !efle( in $ts. Hbitution

is fo!m of le!nin in %hi$h !epete' p!esenttion of stimulus le's to %ekenin of !esponse"ou >ump the

fi!st time "ou he! lou' noise& but if it is !epete' o+e! n' o+e!& "ou >ump ess. The limb-%ith'!%l !efle( h'

been kno%n sin$e Si! :h!les She!!inton*s time to be me'ite' b" s"npti$ pth%"s into n' out of the spinl $o!'

2$hp. Q3. Lte! stu'ies in'i$te' tht the $tul $i!$uit in+ol+e' the !el" of senso!" info!mtion f!om the skin to

!oup of inte!neu!ons in the spinl $o!' to the moto! 2o! output3 neu!ons tht $ont!ol mus$le mo+ement. Thompson

n' Spen$e! !ule' out $hnes in the bilit" of the input n' output ne!+es to t!nsmit sinls& n' $on$lu'e' tht the

plsti$ $hnes must h+e $!u$ill" in+ol+e' the inte!neu!ons. This impo!tnt se!ies of stu'ies helpe' boost the notion

tht le!nin in+ol+es $hnes in s"npti$ t!nsmission& but 'i' not $tull" pinpoint the e($t s"npti$ $onne$tions

tht %e!e mo'ifie'.

T%o "e!s lte!& Spen$e! n' E!i$ 5n'el* took n impo!tnt $on$eptul step& one tht helpe' $lose the p

left open b" Thompson n' Spen$e!the p bet%een beh+io!l le!nin n' s"npses. )n thei! $ellul!-$onne$tion



ppe! 2$hp. 3& the" p!opose' tht $hnes in s"npses in'u$e' b" le!nin $oul' be i'entifie' if simple beh+io!

%s stu'ie' in n niml %ith simple ne!+ous s"stem. :ts& !ts& o! othe! mmmls& %hose beh+io! %s mo!e

!ele+nt to humns& simpl" h' too mn" neu!ons n' too mn" s"npses to be stu'ie' effe$ti+el". Lo%e!

+e!teb!tes o!& bette! "et& in+e!teb!tes %e!e in thei! +ie% mo!e suitble sub>e$ts.

5n'el n' othe! !ese!$he!s follo%e' this pp!o$h n' %ent on to i'entif" the s"npti$ bsis of se+e!l

fo!ms of le!nin in the ne!+ous s"stem of in+e!teb!te spe$ies.

Espe$ill" notble %s thei! bilit" to pu!sue s"npti$plsti$it" ll the %" 'o%n to the le+el of spe$ifi$ mole$ules !e@ui!e' to mke memo!" lst. Thouh t!ul"

!oun'b!ekin f!om the point of +ie% of bioloi$l nl"sis of beh+io!ll" !ele+nt fo!m of neu!l plsti$it"& it %s

lon un$le! ho%& if t ll& this %o!k on lo%l" $!etu!es like snils miht ppl" to mmmls.

)n the mentime& thouh& mens of stu'"in s"npti$ plsti$it" in the mmmlin b!in eme!e'. /s this

pp!o$h mtu!e' o+e! the "e!s& its fin'ins ben to $on+e!e %ith those f!om the in+e!teb!te %o!k& le'in to the

$on$lusion tht& 'eep 'o%n& s"npti$ plsti$it" m" be $$omplishe' in simil! %"s in +stl" 'iffe!ent nimls n' in

+stl" 'iffe!ent kin's of le!nin situtions. /fte! %e tke look t the sto!" of ho% it finll" be$me possible to

in+estite s"npti$ plsti$it" in the mmmlin b!in& %e*ll !etu!n to the in+e!teb!te stu'ies to put the !ese!$h in

pe!spe$ti+e.

PRACTICAL MAGIC

)n the mi'-Fs& Te!>e Limo& %o!kin on his Ph.D. in Pe! /n'e!sen*s lb in Oslo& m'e $hn$e

obse!+tion. He noti$e' tht b!ief bu!st of ele$t!i$l stimuli 'eli+e!e' to fibe!s he'e' fo! the hippo$mpus in

!bbit le' to '!mti$ n' lon-lstin in$!ese in t!nsmission 2 bie! ele$t!i$l !esponse to test stimulus fte!&

s $omp!e' to befo!e& the bu!st3 t s"npses in the hippo$mpus& !eion belie+e' to be in+ol+e' in humn

memo!" 2$hp. 3. /lthouh this tu!ns out to h+e been one of the most sinifi$nt e(pe!imentl fin'ins in the histo!"

of memo!" !ese!$h& %hen Limo !epo!te' the !esult in le$tu!e t s$ientifi$ $onfe!en$e in F& the!e %s& s he

!e$lls& no !e$tion.

Lomo ne+e! ot !oun' to publishin his !esults n' mo+e' on to sub>e$ts of mo!e inte!est to him. But fe%

"e!s lte!& Tim Bliss& "oun !ese!$he! f!om Enln'& $me to Oslo to %o!k %ith /n'e!sen. Bliss h' been

stu'ent t 0$9ill Uni+e!sit"& %he!e he h' tten'e' Hebb*s semin!s& n' he %s @uite inte!este' in the ph"siolo"

of memo!". )n /n'e!sen*s lb& Bliss n' Lsmo pu!sue' the effe$ts of ele$t!i$l stimultion on hippo$mpl s"npti$

t!nsmission tht Lomo h' noti$e' e!lie!& n' in FNQ& the" publishe' ppe! 'es$!ibin the phenomenon of lon-

lstin potentition& %hi$h is no% $lle' lon-te!m potentition 2LTP3.

)n Bliss n' Limo*s e(pe!iment& stimultin ele$t!o'e %s put in the fibe! pth%" oin into the

hippo$mpus& n' !e$o!'in ele$t!o'e in the hippo$mpus itself The" then 'eli+e!e' sinle ele$t!i$l stimulus to

the pth%"& n' !e$o!'e' the ele$t!i$l !esponse of the posts"npti$ neu!ons. This se!+e' s the bseline& the

stn'!' inst %hi$h the !est of the e(pe!iment %s ue'. 1e(t the" +e the potentitin stimulus b!ief bu!st

of mn" !pi'l" !epete' pulses. Then the" st!te' testin in %ith sinle pulse& n' $ontinue' testin

pe!io'i$ll" fo! se+e!l hou!s.

The ke" fin'in %s tht& follo%in the potentitin pulses& the s"npti$ !esponse ot bie!& !elti+e to the

bseline !esponse& n' !emine' bie! fo! hou!s. /$$o!'in to Bliss& “7e kne% b" the en' of the fi!st niht tht %e

!ell" h' somethin p!ett" impo!tnt.

/lthouh Bliss n' Lomo h' p!o'u$e' the lon-lstin $hne in the posts"npti$ !esponse b" ele$t!i$ll"

stimultin neu!l pth%"s& !the! thn b" h+in the nimls $tull" le!n somethin& the" !eli,e' tht the" h'

i'entifie' me$hnism tht miht be ble to t!nslte neu!l $ti+it" ene!te' b" en+i!onmentl stimuli into $hnes

in s"npti$ effi$ien$"& me$hnism tht miht be use' to !e$o!' n' sto!e info!mtion bout life*s e(pe!ien$es. /n'

the f$t tht the" m'e this 'is$o+e!" in the hippo$mpus bolste!e' thei! $on$lu'in spe$ultion tht $hnes in the



effi$ien$" of s"npti$ t!nsmission miht $$ount fo! memo!".

)t*s inte!estin to note tht the pp!o$h use' b" Bliss n' Lomo to p!o'u$e lon-lstin $hnes in s"npti$

t!nsmission %s +e!" simil! to the pp!o$h tht h' file' in the hn's of E$$les n' othe!s in the spinl $o!' 7h"

%s it su$$essful %ith the hippo$mpus= One possibilit" is tht the hippo$mpus is espe$ill" plsti$. 7hile this is

t!ue to $e!tin e(tent& LTP hs sin$e been in'u$e' in mn" !es of the ne!+ous s"stem& in$lu'in the spinl $o!'.

0o!e likel"& LTP %s obse!+e' in the hippo$mpus be$use this p!t of the b!in is o!ni,e' into net l"e!stheinputs $ome into one l"e!& n' the outputs e(it f!om 'iffe!ent one. This ntu!l se!etion m'e it possible to

esil" isolte n' mesu!e the posts"npti$ !esponses eli$ite' b" ele$t!i$l stimultion of input fibe!s. On$e the

phenomenon of LTP %s %o!ke' out in the hippo$mpus& !ese!$he!s kne% %ht to look fo! n' ho% to look fo! it in

othe! neu!l $i!$uits.

)n the en'& it took lot of lu$k to $hie+e +ible mo'el of plsti$it" in the mmmlin b!in. )f the

hippo$mpus 'i'n*t h+e su$h simple o!ni,tion& Lomo miht not h+e been ble to $$i'entll" 'is$o+e! LTP.

/n' if Bliss h'n*t tten'e' Hebb*s semin!s& o! if he h'n*t one to 1o!%"& Lomo*s e!l" fin'in miht h+e

!emine' in '!%e!. But someho% the pie$es ll fell in pl$e& n' LTP be$me %" to p!$ti$e Hebb*s mi$.

A SLICE OF LIFE

Bliss n' Limo 'i' thei! stu'ies in li+in nimls. This %s te$hni$ll" $hllenin& %hi$h is %h" the stu'ies

lste' th!ouhout the niht. But soon it %s 'is$o+e!e' tht LTP $oul' be stu'ie' mo!e esil" in thin sli$es of the hip-

po$mpus !emo+e' f!om the b!in n' subme!e' in slt%te! bth& %ith ele$t!o'es pl$e' in the !ele+nt !eions.

Ho!'es of s$ientists flo$ke' to stu'ies of hippo$mpl LTP. )n the fi+e-"e! pe!io' beinnin in FN& the!e %e!e onl"

t%el+e publi$tions on LTP& %he!es in the ne(t fi+e "e!s& fte! the hippo$mpl sli$e te$hni@ue be$me +ilble&

the!e %e!e bout ninet"3 But this %s >ust the beinnin. Bet%een FF n' FFM& mo!e thn one thousn' LTP

ppe!s %e!e publishe'& n' the numbe! lmost 'ouble' in the ne(t fi+e "e!s. The hippo$mpl sli$e be$me one of

the p!efe!!e' %"s of stu'"in !eul! s"npti$ t!nsmission& s %ell s the p!emie! %" to stu'" s"npti$ plsti$it".

/s the p!ope!ties of LTP unfol'e' o+e! the "e!s& the possibilit" tht this

!tifi$il phenomenon miht h+e somethin to 'o %ith memo!" onl" in$!ese'. 8o! e(mple& in ''ition to

its !pi' in'u$tion n' pe!sisten$e o+e! time& LTP %s foun' to in+ol+e sso$iti+e inte!$tions bet%een posts"nptt$

neu!ons n' the spe$ifi$ p!es"npti$ inputs tht %e!e in+ol+e' in fo!min the sso$ition. 4pi' $@uisition&

pe!sisten$e& spe$ifi$it"& n' sso$iti+it" !e ll fetu!es one %oul' e(pe$t of memo!" me$hnism. Let*s $onsi'e!

the menin of spe$ifi$it" n' sso$iti+it" fu!the!.

Bliss n' Lomo sho%e' tht LTP %s specific to the stimulte' pth%". The" st!te' n e(pe!iment b"

stimultin t%o 'iffe!ent pth%"s tht eli$it $ti+it" f!om the sme popultion of posts"npti$ neu!ons. The" then

+e onl" one of the pth%"s the potentitin stimultion& n' subse@uentl" teste' posts"npti$ !esponse in both

the pth%"s. /lthouh stimultion of eithe! pth%" eli$ite' !esponse f!om the posts"npti$ $ell& onl" the poten-

tite' pth%" $hne'. 9i+in potentitin inputs to one pth%"& the!efo!e& 'oes not utomti$ll" $hne ll of the

s"npses on the posts"npti$ neu!onC it onl" $hnes those s"npses tht %e!e stimulte'. LTP is thus spe$ifi$ to the

s"npses in+ol+e' in the potentitin e(pe!ien$e n' 'oes not !ep!esent $hne th!ouhout the enti!e posts"npti$

neu!on. This mens tht i+en $ell $n p!ti$ipte in the sto!e of info!mtion bout mn" 'iffe!ent e(pe!ien$es so

lon s 'iffe!ent s"npses on the $ell !e in+ol+e' in !e$ei+in them.

/n impo!tnt p!elu'e to the 'emonst!tion of sso$iti+it" %s the fin'in tht LTP in+ol+e' $oope!ti+it"&

%hi$h %s sho%n b" B!u$e 0$1uhton n' $olleues. Like Bliss n' Lomo& the" use' t%o pth%"s. 7hen e$h

%s stimulte' in su$$ession %ith %ek stimuli& no LTP !esulte'. But if the

It%o pth%"s %e!e stimulte' simultneousl" %ith the %ek stimuli& the stimuli $oul' $ombine 2$oope!te3

to p!o'u$e LTP in both pth%"s. This sueste' tht LTP in+ol+es some kin' of inte!$tion t the $ellul! le+el be-

t%een s"npti$ inputs& n' miht the!efo!e be $pble of fo!min sso$itions bet%een 'iffe!ent inputs.

The bilit" to fo!m sso$itions bet%een stimuli is pe!hps the ben$hm!k test fo! s"npti$ me$hnism of



le!nin. Tht LTP miht be %" to fo!m sso$itions %s st!onl" sueste' b" the !esults of stu'" pe!fo!me' b"

:hip Le+" n' Os%l' Ste%!' in FNF The" pplie' %ek stimultion to one pth%" t the sme time tht st!on

stimultion %s 'eli+e!e' to nothe!. )n $ont!st to the 0$1uhton $oope!ti+it" e(pe!iment& in the Le+" n'

Ste%!' sso$iti+e e(pe!iment& the st!on stimulus lone %s suffi$ient to in'u$e LTP& n' the %ek stimulus ''e'

little. Ho%e+e!& if the %ek in-put !!i+e' %hile the st!on input %s $ti+tin the posts"npti$ $ells& LTP o$$u!!e' in

the %ek pth%" s %ell s the st!on one. Just s Hebb h' p!e'i$te'& if %ek inputs !!i+e %hile the posts"npti$$ell is $ti+e& the $onne$tion bet%een the %ek input pth%" n' the posts"npti$ $elis %ill be st!enthene'.

)n FG& se+e!l 'iffe!ent !ese!$h !oups !epo!te' tht the !esponse of sinle posts"npti$ $ell to %ek

input $oul' be potentite' if the post-s"npti$ $ell %s t!i$ke' into $tin s thouh it h' !e$ei+e' st!on input.

Usin sophisti$te' te$hni@ues& the !ese!$he!s %e!e ble to !tifi$ill" !e'u$e the ele$t!i$l neti+it" of the $ell >ust

befo!e %ek input !!i+e'. 24e$ll f!om $hpte! Q tht %hen $ell is st!onl" $ti+te' b" s"npti$ inputs& its inte!nl

ele$t!i$l stte be$omes less neti+e& %hi$h is ho% n $tion potentil is p!o'u$e'.3 7hen %ek p!es"npti$ input

!!i+e' 'u!in this in'u$e'

ti+it"& the s"npse o+e! %hi$h it %s t!nsmitte' to the posts"npti$ $ell %s st!enthene'. The $ombintion

of p!es"npti$ n' posts"npti$ $ti+it" is in'ee' the mi$ fo!mul fo! in$!esin s"npti$ st!enth.

ISN!T THAT A COINCIDENCE?

Ho% 'oes the b!in $tull" $hie+e Hebbin plsti$it"= Ho%& in othe! %o!'s& is the $o-$ti+it" of p!es"npti$

n' posts"npti$ $ells !eiste!e' n' sto!e'= T%o 'is$o+e!ies in the mi'-FGs ben to $l!if" this p!o$ess. The fi!st

%s b" 9!hm :ollin!i'e& %ho sho%e' tht blo$k'e of p!ti$ul! t"pe of lutmte !e$epto! 2$hp. Q3 p!e+ente'

the in'u$tion of LTP %ithout inte!fe!in %ith s"npti$ t!nsmission. Thus& %hen this !e$epto! %s blo$ke'& the s"npse

still %o!ke' >ust fine 2!elese of t!nsmitte! f!om the p!es"npti$ neu!on p!o'u$e' no!ml posts"npti$ !esponse3&

but it $oul' not be potentite' b" e(pe!ien$e. The se$on' 'is$o+e!" %s b" 9!" L"n$h n' 4oe! 1i$oll& %ho

sep!tel" 'emonst!te' tht LTP %oul' not o$$u! if $l$ium %s p!e+ente' f!om !isin in the posts"npti$ $ell 'u!in

$tion potentils. The t%o fin'ins $tull" $omplement e$h othe!& sin$e it is the spe$il lutmte !e$epto! tht

llo%s $l$ium to !ise in the posts"npti$ $ell %hen n $tion potentil o$$u!s.

You*ll !e$ll f!om $hpte! Q tht lutmte is the min e($itto!" t!nsmitte! in the b!in. 7hen it is !elese'

f!om p!es"npti$ te!minls n' bin's to posts"npti$ !e$epto!s& the likelihoo' of the posts"npti$ $ell*s fi!in is in-

$!ese'. /$tull"& the!e !e se+e!l 'iffe!ent kin's of lutmte !e$epto!s& n' e$h pl"s 'iffe!ent !ole. One 2the

/0P/ !e$epto!3 is in+ol+e' in !eul! s"npti$ t!nsmission& %hile nothe! 2the 10D/ !e$epto!3 is in+ol+e' in

s"npti$ plsti$it". The!e !e othe! lutmte !e$epto!s& but these t%o !e the ones most !ele+nt to this 'is$ussion.

P!es"npti$ll" !elese' lutmte fin's its %" to both /1MP/ n' 10D/ !e$epto!s. Bin'in of lutmte

to /0P/ !e$epto!s is one of the m>o! %"s tht posts"npti$ $ell $n be in'u$e' to fi!e n $tion potentil& n' is

the mens b" %hi$h $ells no!mll" et fi!e' up. )n $ont!st& %hen p!es"npti$ll" !elese' lutmte !e$hes 10D/

!e$epto! on the posts"npti$ $ell& it hs no effe$t initill" be$use p!t of the !e$epto! is blo$ke'3* Ho%e+e!& on$e

lutmte hs $ti+te' the posts"npti$ $ell 2$use' it to fi!e n $tion potentil3 b" bin'in to /0P/ !e$epto!s& the

blo$k on the 10D/ !e$epto!s is !emo+e'& n' lutmte $n open the !e$epto! $hnnel n' llo% $l$ium to ente!

the $ell. LTP is the !esult.

8o! 10D/ !e$epto!s to pss $l$ium& both p!es"npti$ n' posts"npti$ $ells must be $ti+e. This is the

bsi$ !e@ui!ement fo! Hebbin plsti$it". But ho% 'oes this set of e+ents fo!m n sso$ition bet%een t%o inputs to

$ell= )n the ne(t se$tion& %e*ll e(plo!e the $hemist!" of ho' $l$ium ent!" th!ouh 10D/ !e$epto!s p!o'u$es LTP 8o!

no%& thouh& %ht %e %nt to $onsi'e! is 'hy $l$ium ent!" th!ouh 10D/ !e$epto!s is mens of fo!min sso$i-

tions bet%een %ek n' st!on input.

/$ti+it" in the %ek input pth%" !esults in the !elese of lutmte n' the bin'in of lutmte to

posts"npti$ !e$epto!s. Be$use the $onne$tion is %ek& thouh& the input is not $pble on its o%n of mkin the

posts"npti$ $ell fi!e n $tion potentil. Ho%e+e!& %hen s"npti$ $ti+it" in the st!on pth%" $ti+tes the



posts"npti$ $ell& the blo$k on 10D/ !e$epto!s %ill be !emo+e'& e+en t the %ek s"npses. The!efo!e& if the %ek

pth%" is !elesin lutmte 'u!in this time& 10D/ !e$epto!s t both the st!on n' the %ek s"npses %ill be

ble to bin' the lutmte. :l$ium %ill flo% in th!ouh the 10D/ !e$epto!s& n' the %ek s"npses %ill be

st!enthene'.

)n sum& the !eson tht 10D/ !e$epto!s llo% LTP to o$$u! is tht the" !e $oin$i'en$e 'ete$to!sA the" !e

ble to !eiste! tht p!es"npti$ n' post-s"npti$ neu!ons %e!e $ti+e t the sme time. 0o!e spe$ifi$ll"& 10D/ !e-$epto!s llo% the $ell to !e$o!' e($tl" %hi$h p!es"npti$ inputs %e!e $ti+e %hen the posts"npti$ $ell %s fi!in.

This input spe$ifi$it" is ke" to sso$iti+it"& n' is e($tl" %ht Hebb 'es$!ibe' 'e$'es befo!e 10D/ !e$epto!s %e!e

'is$o+e!e'. )t is %ith this in min' tht Hole! Husi n' Seth 9!nt !e$entl" !efe!!e' to the 10D/ !e$epto! n'

sso$ite' mole$ules s Hebbosome& $omple( set of inte!$tin p!oteins fun$tionin s unit in the in'u$tion n'

mintenn$e of s"npti$ plsti$it".

MAKING CHANGE LAST

The bin'in of lutmte to its !e$epto!s is b!ief e+ent& lstin& t most& se$on's. But memo!ies $n lst

lifetime. )n o!'e! fo! s"npti$ $hnes en$o'e' b" 10D/ $ti+it" to pe!sist& $hemi$l p!o$esses tht outlst the

s"npti$ $tion itself !e !e@ui!e'. These p!o$esses h+e been stu'ie' usin t%o 'iffe!ent p!o$e'u!es& one tht

p!o'u$es fo!m of Hebbin LTP tht lsts onl" n hou! o! so& n' nothe! tht ene!tes mo!e pe!sistent fo!m of

Hebbin LTP. These !e $lle' e!l" n' lte LTP.QS 2The!e !e lso fo!ms of LTP in %hi$h 10D/ !e$epto!s pl" no

!ole& but %e %ill not h+e mu$h to s" bout these.3

E!l" n' lte LTP !e thouht of s nlos of sho!t- n' lon-te!m

o!". 8!om bioloi$l point of +ie%& sho!t- n' lon-te!m memo!" !e lso 'istinuishe' b" thei! $hemi$l

!e@ui!ements& in ''ition to thei! lone+it". )t hs been kno%n fo! se+e!l 'e$'es tht if nimls !e i+en '!us tht

p!e+ent the b!in f!om mkin ne% p!oteins& the" !e ble to le!n no!mll" but !e unble to fo!m lon-lstin

memo!ies. 2)f the" !e teste' %ithin n hou! o! so of le!nin some tsk& the" pe!fo!m %ell& but sho% no sins of

h+in le!ne' the tsk %hen teste' the ne(t '".3 This hs tu!ne' out to be t!ue of most if not ll kin's of memo!"

tsks tht h+e been stu'ie'& n' seems to ppl" to

most if not ll spe$ies& s %ell. )t is lso t!ue of e!l" n' lte LTPA blo$k'e of p!otein s"nthesis hs no

effe$t on e!l" LTP but p!e+ents lte LTP. These p!llels bet%een e!l" LTP n' sho!t-te!m memo!"C on the one

hn'& n' lte LTP n' lon-te!m memo!"& on the othe!& !e $onsistent %ith the +ie% tht LTP n' memo!" miht be

me'ite' b" the sme mole$ul! me$hnisms.

)n o!'e! to fu!the! un'e!stn' the $hemist!" of e!l" n' lte LTP& n' to pu!sue the @uestion of %hethe! LTP

n' memo!" h+e simil! mole$ul! un'e!pinnins& %e nee' to e(mine the $on$ept of se$on' messene!s. 1eu!o-

t!nsmitte!s like lutmte !e $onsi'e!e' fi!st messene!s. The" !e !esponsible fo! sinlin bet%een neu!ons.

Se$on' messene!s pi$k up %he!e fi!st messene!s le+e off. Thei! >ob is to initite $hemi$l !e$tions 'ithin the $ell

on the bsis of info!mtion p!o+i'e' f!om outside the $ell 'u!in neu!ot!nsmission b" fi!st messene!s.

:l$ium is one of the m>o! se$on' messene!s. /s %e*+e seen& %hen lutmte bin's to its 10D/

!e$epto!s& $l$ium flo%s into $ell 2fte! the blo$k hs been !emo+e'3. On$e this o$$u!s& $l$ium tkes o+e! n'

'i!e$ts the $hemi$l !e$tions tht st!enthen s"npti$ $onne$tions& both in the sho!t !un n' the lon !un.

5e" to the %hole p!o$ess !e en,"mes $lle' p!otein kinses tht $ti+te spe$ifi$ p!oteins. Thei! >ob is to

phospho!"lte $e!tin p!oteins. Te$hni$ll"& this mens tht the" '' phosphte !oup to the p!oteins. But ll "ou

!ell" nee' to kno% is tht phospho!"ltion tu!ns p!oteins on& t!nsfo!min them f!om n in$ti+e to n $ti+e stte.

)n e!l" LTP& kinses $t on p!ee(istin p!oteins tht !e p!esent in the $ell& %itin to be $lle' upon. /s

!esult of $l$ium influ( 'u!in e!l" LTP& se+e!l kinses !e $ti+te'.. One impo!tnt tsk pe!fo!me' b" these

kinses ppe!s to be the phospho!"ltion of /0P/ !e$epto! p!oteins. /s !esult& fte! the in'u$tion of LTP& the

sme mount of lutmte !elese' f!om the p!es"npti$ $ell b" n $tion potentil %ill h+e mo!e /1MP/ !e$epto!s



to bin' to& n' bie! posts"npti$ !esponse %ill o$$u!& llo%in e$h p!es"npti$ $tion potentil to mke !ete!

$ont!ibution to%!' the fi!in of the posts"npti$ $ell. 24e$ll f!om $hpte! Q tht it tkes mn" $losel" time' $tion

potentils t 'iffe!ent s"npses on posts"npti$ $ell to ene!te n $tion potentil in tht $ell& so e+e!" little bit

helps.3

/lthouh most s$ientists in this !e of !ese!$h !ee tht LTP is in'u$e' o! initite' b" $l$ium-t!ie!e'

$hemi$l !e$tions in the posts"npti$ $ell& some belie+e tht these posts"npti$ $hnes full" $$ount fo! LTP& %hileothe!s !ue tht the p!es"npti$ $ell $hnes s %ell. 8o! e(mple& popul! notion is tht fte! LTP hs been

in'u$e'& the p!es"npti$ $ell mo!e esil" !eleses lutmte %hen n $tion potentil o$$u!s in its te!minl& le'in to

bie! posts"npti$ !esponse. E+i'en$e fo! this theo!" hs been obtine' in sophisti$te' e(pe!iments& in+ol+in

the p!e$ise mesu!ement of lutmte !elese f!om p!es"npti$ neu!ons& pe!fo!me' b" :h!les Ste+ens of the Slk

)nstitute n' 4i$h!' Tsien of Stnfo!'& mon othe!s.# Ho%e+e!& be$use LTP is t!ie!e' onl" in the posts"npti$

$ell& in o!'e! fo! the p!es"npti$ h"pothesis to be +li'& somethin hs to be $ommuni$te' f!om the posts"npti$ to

the p!es"nptl$ neu!on fte! LTP is initite'. One possible %" this $oul' hppen is b" mens of !et!o!'e

messene!s& substn$es !elese' b" the posts"npti$ $ell fte! LTP is in'u$e' n' tken up b" the p!es"npti$

te!minl& %hi$h $use $hnes in the ese of lutmte !elese the!e. 4obe!t H%kins in 5n'el*s !oup n' othe!s

h+e foun' e+i'en$e tht !et!o!'e messene!s 'o mo'if" the p!es"npti$ te!minl in %"s sueste' b" the

p!es"npti$ h"pothesis& but s othe! le'in LTP !ese!$he!s& su$h s 4ob 0lenk n' 4oe! 1i$oll& point out& this

notion !emins $ont!o+e!sil.

;7hile e!l" LTP in+ol+es the $ti+tion of e(istin p!oteins b" kinses& the $!etion of lon-lstin o! lteLTP& like lon-te!m memo!"& in+ol+es the fo!mtion of ne% p!oteins. One of the ke" steps in this p!o$ess is the$ti+tion of kinses& espe$ill" p!otein kinse / 2P2/3& 0/P kinse 20/P53& n' $l$iumK$lmo'ulin p!otein kinse2:053& in spe$il %" tht llo%s them to mo+e insi'e the $ell nu$leus. On$e the!e& the" $ti+te p!otein $lle':4EB. The >ob of this ene t!ns$!iption f$to! is to $ti+te spe$ifi$ enes tht mke ne% p!oteins tht t!+el b$k tothe s"npses tht st!te' the %hole p!o$ess n' stbili,e the $onne$tions 2see “Tin /lon&# belo%3.

Ou! un'e!stn'in of the mole$ul! bsis of LTP hs $ome f!om t%o kin's of stu'ies. The t!'itionl

pp!o$h hs in+ol+e' the use of '!us tht blo$k $e!tin mole$ul! steps& like the flo% of $l$ium th!ouh 10D/ !e-

$epto!s& o! phospho!"ltion of kinses& o! s"nthesis of p!oteins. )n stu'ies of this t"pe& the '!us !e eithe! pl$e' in

the bth in %hi$h the sli$e of b!in is mintine' o! !e in>e$te' 'i!e$tl" into the posts"npti$ $ell. )f LTP is 'is!upte'&

the $hemi$l step inte!fe!e' %ith is impli$te' in the un'e!l"in plsti$it". 4e$entl"& thouh& ne% pp!o$h hs

eme!e'. 4the! thn ''in '!us to b!in sli$e& mi$e !e $!ete' tht eithe! l$k o! h+e n e($ess of spe$ifi$

mole$ules& like :4EB o! $e!tin kinses& s !esult of eneti$ lte!tions. LTP is then in'u$e' in b!in sli$es tken

f!om these mi$e. /s in the '!u stu'ies& if LTP is ffe$te'& then the missin o! e(e!te' mole$ule is impli$te'.

0ost %o!k to 'te usin eneti$ll" lte!e' mi$e hs in+ol+e' pe!mnent 'eletion of ene in line of

nimls& le'in to the bsen$e of the p!ti$ul! mole$ule in the enti!e bo'" th!ouhout life. The f$t tht the

mole$ule is missin th!ouhout life& ho%e+e!& !ises some @uestions bout ho% to inte!p!et the 't& sin$e n effe$t

on LTP $oul' be 'ue to the bsen$e of the mole$ule itself& o! $oul' be se$on'!" effe$t of the niml*s h+in one

th!ouh life %ithout the mole$ule. The +lue of this pp!o$h is bein !efine' b" the bilit" to sele$ti+el" lte!

mole$ules in spe$ifi$ b!in !eions& like the hippo$mpus& le+in othe! !es int$t& n' b" the bilit" to tu!n $e!tin

enes on o! off t $e!tin time. /s !esult& the mouse $n !o% up %ith ll its mole$ules int$t& n' then !iht

befo!e the LTP e(pe!iment $hemi$l s%it$h $n be th!o%n to eithe! 'e$!ese o! in$!ese the mole$ule bein stu'-

ie'. 7hile the ltte! pp!o$h is ob+iousl" mo!e po%e!ful& it is lso mo!e 'iffi$ult to implement. But !ese!$he!s !e

%o!kin 'ilientl" to imp!o+e these te$hni@ues& hopin to be ble to tu!n enes on o! off in spe$ifi$ b!in !es on

$ommn'. 9eneti$ll" lte!e' mi$e h+e l!e'" pl"e' ke" !oles in b!in !ese!$h& impli$tin 10D/ !e$epto!s&

p!otein kinses& n' :4EB in LTP& n' !e likel" to be$ome e+en mo!e +luble s the te$hni@ues fo! $!etin e-

neti$ll" lte!e' o!nisms imp!o+e in the $omin "e!s.

)*+e mentione' onl" b!iefl" some of the mn" mole$ules impli$te' in Hebbin LTPY Ou! kno%le'e of the

!ole of these substn$es is e(pn'in !pi'l". /n' %hile the!e !emin mn" un!esol+e' m"ste!ies bout the mole$-

ul! bsis of s"npti$ plsti$it"& t minimum it seems fi!l" $le! tht 10D/ !e$epto!s& $l$ium& $e!tin kinses&



:4EB-$ti+te' enes& n' p!otein s"nthesis !e in+ol+e'. The mssi+e mount of 't pou!in fo!th on the

mole$ul! bsis of LTP is bit o+e!%helmin& so mu$h so tht Josh Snes n' Jeff Li$htmn& t%o neu!os$ientists

%ho %o!k on b!in 'e+elopment& h+e $lle' fo! mo!to!ium on mole$ul! stu'ies of LTP. Othe!s& like D+i' S%ett

n' 0!" 5enne'"& see it s sin of the +itlit" of the fiel' tht so mu$h info!mtion is bein ene!te' bout ho%

LTP %o!ks. ) sh!e thei! optimism.

TAGGING ALONG

The s"npti$ $ti+it" tht t!ie!s LTP o$$u!s out on the 'en'!ites& %hile the enes tht mke the p!oteins

tht enble LTP to pe!sist !e lo$te' f! %" in the $ell nu$leus. 7e*+e l!e'" seen ho% the p f!om the s"npse

to the nu$leus is spnne'A $l$ium $omes in th!ouh the 10D/ !e$epto! n' t!ie!s mole$ul! $hnes tht

ultimtel" ffe$t enes in the nu$leus. 0o!e m"ste!ious hs been the %" this $i!$le is $lose'. Ho%& in othe! %o!'s& 'o

p!oteins m'e in the $ell bo'" kno% %hi$h of the mn" s"npses on the neu!on o!iinll" %e!e !esponsible fo! the

initition of the p!otein s"nthesis= )t*s these s"npses& n' these lone& tht h+e to be mo'ifie' in o!'e! fo! the

plsti$it" to be spe$ifi$ to the $ti+e s"npses.

4e$ent stu'ies h+e helpe' sol+e some of the m"ste!". )t ppe!s f!om %o!k b" t%o !ese!$h !oups 2E!i$

5n'el n' 5else" 0!tin in 1e% Yo!k& n' 4i$h!' 0o!!is n' U%e 8!e" in S$otln' n' 9e!mn"3 tht& follo%in

some sinifi$nt e(pe!ien$e& the $ti+e s"npses !e i+en mole$ul! t. 7hen the ne% p!oteins !e subse@uentl"

m'e in the $ell bo'"& the" !e then shippe' out to essentill" ll possible s"npses in the $ell& but onl" s"npses tht

%e!e te' 'u!in the initil stimultion !e ble to use the ne% p!oteins to stbili,e the $onne$tion %ith the

p!es"npti$ te!minl.

On$e the" fin' thei! %" b$k to the te' s"npses& the p!oteins stbili,e the $onne$tion bet%een the

p!es"npti$ n' posts"npti$ neu!on. The!e !e t%o p!ts to the e(plntion of ho% this o$$u!s. The fi!st hs to 'o

%ith the stbili,tion of e(istin s"npses. These !e kept in the ne%& imp!o+e'& f$ilitte' stte fte! LTP in se+e!l

'iffe!ent %"s. 8o! e(mple& b" mkin mo!e /0P/ !e$epto!s +ilble on p!olone' bsis& i+en mount of

lutmte !elese' b" the p!es"npti$ te!minl $ontinues to h+e bie! effe$t. 8u!-

the!& s %e s%& te!minls $onne$te' to the posts"npti$ $ell m" $ome to !elese t!nsmitte! mo!e

effi$ientl" s !esult of !et!o!'e messene! psse' b$k f!om the posts"npti$ $ell to the p!es"npti$ te!minl.

B" p!olonin tempo!!" $hnes& the effe$ts of LTP !e m'e to en'u!e.

The othe! p!t of the e(plntion is !elte' to the $tul !o%th of ne% s"npses. Se+e!l !ese!$he!s h+e

sho%n tht LTP 'oes in'ee' $!ete ne% $onne$tions. These ppe! to be foste!e' in p!t b" the !elese of !o%th-

in'u$in toni$s& neu!ot!ophins& f!om the posts"npti$ $ell. 7e 'is$usse' simil! !ole fo! neu!ot!ophins in the $onte(t

of 'e+elopment in $hpte! M. 1eu!ot!ophins !e !elese' f!om the posts"npti$ $ell %hen it is $ti+e. The" !e then

tken up b" the p!es"npti$ te!minls tht %e!e lso >ust $ti+e& n' en$ou!e the te!minl to sp!out ne% b!n$hes

n' fo!m ne% s"npti$ $onne$tions %ith the posts"npti$ neu!ons. The +ilbilit" of mo!e s"npti$ $onne$tions

mens tht i+en $tion potentil $omin 'o%n n (on %ill h+e bie! effe$t& sin$e it hs mo!e pl$es 2te!minl

b!n$hes3 to !elese t!nsmitte! f!om n' mo!e posts"npti$ sites to bin' to.

4e$ent stu'ies 'emonst!te tht p!oteins $n be s"nthesi,e' in 'en'!ites= )f 'en'!iti$ p!otein s"nthesis

o$$u!s 'u!in memo!" fo!mtion it %oul' simplif"& to some e(tent& the p!oblem of $hie+in s"npse spe$ifi$it" sin$e

p!oteins m'e lo$ll" %oul' not h+e to fin' thei! %" b$k f!om the $ell bo'" to the $ti+e 'en'!ites. This is n

e($itin ne% !e of !ese!$h.

FROM LTP TO MEMORY

)n the en'& %ht 'o LTP& 10D/ !e$epto!s& kinses& n' :4EB h+e to 'o %ith memo!"& s oppose' to b!in

$ells li+in in 'ish n' bein stimulte' ele$t!i$ll"= Let*s st!t %ith 10D/ !e$epto!s.

The fi!st bit of e+i'en$e suppo!tin !ole fo! 10D/ !e$epto!s in memo!" $me f!om stu'" pe!fo!me' b"



4i$h!' 0o!!is& %o!kin in $ollbo!tion %ith 9!" L"n$h in )!+ine& :lifo!ni. 0o!!is use' '!u tht spe$ifi$ll"

blo$ks 10D/ !e$epto!s& le+in /1MP/ !e$epto!s n' othe! spe$ts of b!in fun$tion unffe$te'. He put this '!u

into the b!in of !ts in %" tht bthe' the hippo$mpus& n' then teste' the !ts in his fmous %te! m,eone

of the bette! tsks fo! impli$tin the !t hippo$mpus in sptil memo!" 2$hp. 3. :ont!ol !ts %e!e ble to le!n

%he!e the subme!e' pltfo!m %s lo$te'. 4ts t!ete' %ith the '!u& thouh& h' !et 'iffi$ult" le!nin this tsk

in spite of the f$t tht the" %e!e ble to s%im to the pltfo!m if it %s bo+e %te!& sho%in tht the '!u 'i' notffe$t no!ml +ision o! s%immin bilit". Subse@uentl"& %hen the b!in %s !emo+e' f!om these !ts n' sli$es of the

hippo$mpus kept li+e in 'ish& LTP $oul' be !e'il" in'u$e' in the $ont!ols& but LTP in'u$tion %s impi!e' in the

'!u-t!ete' b!ins. Sin$e hippo$mpl LTP n' hippo$mpl memo!" %e!e both 'is!upte' b" the sme t!etment&

the $on$lusion %s tht hippo$mpl LTP miht h+e somethin to 'o %ith hippo$mpl memo!".

0n" subse@uent stu'ies h+e follo%e' up on these impo!tnt obse!+tions. The!e h+e been su$$esses

n' filu!es& s %ell s lte!nte inte!p!ettions& in the @uest to !elte 10D/ !e$epto!s in the hippo$mpus to sptil

memo!". P!ti$ul!l" 'iffi$ult to s$e!tin hs been the issue of %hethe! 10D/ blo$k'e p!o'u$es spe$ifi$ effe$t on

le!nin itself& o! inste' $hnes othe! less spe$ifi$ $p$ities& su$h s the bilit" to pe!$ei+e i+en stimulus o! the

bilit" o! 'esi!e to pe!fo!m the pp!op!ite !esponse. Ho%e+e!& the most !e$ent %o!k b" 0o!!is n' $olleues seems

to sho% fi!l" $on+in$inl" tht blo$k'e of 10D/ !e$epto!s in the hippo$mpus 'oes inte!fe!e %ith sptil le!nin.

Tht hippo$mpl 10D/ !e$epto!s !e in+ol+e' in sptil le!nin is lso sueste' b" the !esults of stu'ies

usin eneti$ll" lte!e' mi$e. Susumu Tone% n' $olleues t 0)T $!ete' mi$e l$kin impo!tnt $omponents

of 10D/ !e$epto!s. P!ti$ul!l" sinifi$nt %s the f$t tht the" %e!e ble to !est!i$t the loss to the hippo$mpus

in f$t& to spe$ifi$ p!t of the hippo$mpus. The mi$e pe!fo!me' poo!l" on sptil le!nin tsks& n' LTP in'u$tion

%s impi!e' s %ell. 0o!e !e$entl"& Joe Tsien& fo!me! $olleue of Tone%*s& took the opposite pp!o$h&

enhn$in the fun$tion of 10D/ !e$epto!s in spe$ifi$ !eion of the hippo$mpus. LTP in'u$tion %s f$ilitte'& n'

so& too& %e!e se+e!l memo!" fun$tions 'epen'ent on the hippo$mpus. These stu'ies p!o+i'e fi!l" 'i!e$t e+i'en$e

fo! the th!ee-%" !eltion bet%een hippo$mpl 10D/ !e$epto!s& hippo$mpl LTP& n' hippo$mpl-'epen'ent

memo!".

Simil! stu'ies $omp!in LTP n' sptil memo!" h+e lso been pe!fo!me' fo! some of the othe!

mole$ules tht h+e been impli$te' in LTP. The lite!tu!e is t this point fi!l" e(tensi+e but in$omplete& so )*ll

mention onl" fe% fin'ins. /l$ino Sil+ n' $olleues e(mine' the effe$ts of kno$kin out :4EB in mi$e& n'

'is$o+e!e' 'is!uption in both LTP n' hippo$mpl-'epen'ent memo!". 8u!the!& Te' /bel& 0!k 0"fo!'& E!i$

5n'el& n' $olleues h+e foun' tht eneti$ lte!tion of p!otein kinse / n' $l$iumK$lmo'ulin-'epen'ent

kinse& m>o! en,"me tht phospho!"ltes :4EB& 'is!upts lte LTP n' lon-te!m memo!" %ithout ffe$tin e!l"

LTP o! sho!t-te!m memo!".*

:onsi'e!ble !ese!$h thus suppo!ts the +ie% tht hippo$mpl LTP n' hippo$mpl-'epen'ent memo!"

ope!te b" simil! mole$ul! me$hnisms. The p!llels& in f$t& !e @uite imp!essi+e& but not pe!fe$t. 8o! e(mple& in

some stu'ies& hippo$mpl-'epen'ent le!nin is unffe$te' b" t!etments tht blo$k LTP. This t"pe of !esult&

thouh& hs been fi!l" !!e& n' $e!tinl" is not $ompellin enouh to un'e!mine the %hole fiel'. 8u!the!& %e no%

kno% tht the!e !e +!iet" of 'iffe!ent fo!ms of LTP& some in+ol+in 10D/ !e$epto!s n' some not& n' some

Hebbin 2!e@ui!in p!es"npti$ n' posts"npti$ $ti+it"3 n' some not 2possibl" !e@ui!in $hnes onl"

p!es"npti$ll"3&# n' the!e*s e+en lon-te!m 'ep!ession& %he!e s"npses !e %ekene' b" un$o!!elte' $ti+it"

bet%een p!es"npti$ n' posts"npti$ $ells. 7hile %e h+e lon %" to o befo!e %e full" un'e!stn' ho% the

s"npses mke memo!ies& t minimum& LTP hs been n e($ellent tool fo! pu!suin the topi$.

A MISSING LINK

Un'e!l"in mu$h of the %o!k on LTP is the ssumption tht LTP is not >ust %" to stu'" ho% e(pe!ien$e

$hnes s"npses& but is& in f$t& the %" tht s"npses !e $hne' %hen %e le!n. The +!ious fin'ins in'i$tin

tht the sme mole$ules !e in+ol+e' in LTP n' memo!" !e $onsistent %ith the +ie% tht LTP o$$u!s 'u!in



le!nin& but this e+i'en$e is& s $!iti$s h+e note'& $i!$umstntili* )n n effo!t to silen$e these $!iti$s& LTP

!ese!$he!s h+e ttempte' to 'emonst!te tht somethin like LTP 'oes tke pl$e in the hippo$mpus 'u!in

le!nin. Ho%e+e!& these stu'ies h+e& fo! +!ious !esons& $ome up sho!t. 8o! lon time& ) m"self %s

mbi+lent bout LTP. ) thouht it %s n inte!estin phenomenon but %s not $on+in$e' tht it %s the ns%e! to

ho% memo!ies !e $!ete'. ) be$me mo!e int!iue' %hen 0!ie-:h!istine :lunet n' ) foun' tht %e $oul' in'u$e

LTP in neu!l pth%" $!!"in u'ito!" info!mtion to the m"'l& pth%" m" lb h' been stu'"in be$useof its !ole in fe! $on'itionin. But %ht finll" m'e me $on+e!t %e!e stu'ies pe!fo!me' in m" lb b" 0i$hel 4on

%hile he %s %o!kin to%!' his PhD. 1o% ) m p!osel"ti,e!.

4on 'e$i'e' to tke on the $hllene of t!"in to sho% 'efiniti+el" tht LTP o$$u!s 'u!in le!nin. 7hile

most of the e!lie! %o!k in this !e h' in+ol+e' the hippo$mpus& the l$k of un'e!stn'in of the $tul $i!$uits in-

+ol+e' in hippo$mpl-'epen'ent memo!" 2sptil memo!"3 %s b!!ie!. 4on inste' st!te' %ith $i!$uit kno%n

to be in+ol+e' in fe! $on'itionin n' then ske' %hethe! LTP o$$u!!e' in tht $i!$uit. This !e+e!sl of the st!te"

2st!tin %ith le!nin $i!$uit n' lookin fo! plsti$it" in it& !the! thn st!tin %ith fo!m of plsti$it" n' skin

ho% it miht !elte to le!nin3 tu!ne' out to be +e!" '+nteous.

0" lb h' been stu'"in the ntom" of fe! $on'itionin in !ts n' h' sho%n tht in o!'e! fo! soun' to

$@ui!e +e!si+e p!ope!ties %hen sso$ite' %ith sho$k& the soun' h' to be !el"e' f!om the u'ito!" thlmus to

the lte!l nu$leus of the m"'l. /n'& s ) note' bo+e& %e h' lso foun' tht %e $oul' in'u$e LTP in this sme

pth%". 4on put these fin'ins toethe!& n' then took t%o ''itionl steps.

8i!st& i+en tht %e use' soun' stimuli in $on'itionin stu'ies& n' tht soun's et to the m"'l th!ouh

the thlmom"'l pth%"& 4on ske' %hethe! in'u$tion of LTP in this pth%" %oul' $hne the %" soun'

stimuli !e p!o$esse' in the m"'l. He in'u$e' LTP in the usul mnne! %ith !pi' ele$t!i$l stimuli& but m'e

ke" $hne in the %" LTP %s teste'usin ntu!l stimulus 2in this $se& soun'3 !the! thn ele$t!i$l

stimultion of ne!+e fibe!s. His fin'ins sho%e' tht in'u$tion of LTP in the pth%" tht $!!ies the soun' to the

m"'l enhn$e' the m"'l*s !esponse to tht soun'. 7hen this !ti$le %s publishe'& it %s $$ompnie' b"

$omment!ies f!om se+e!l le'e!s in the fiel' %ho note' tht this %s in'ee' n impo!tnt step fo!%!' in the lon

@uest to !elte LTP n' memo!"A

4on*s fi!st stu'" sho%e' tht !tifi$il lte!tion of s"npti$ t!nsmission in the pth%" $hnes the %"

tht pth%" p!o$esses e(te!nl stimuli. This %s n inte!estin 'is$o+e!"& but it left unns%e!e' the @uestion of

%hethe!& 'u!in ntu!l le!nin& somethin like LTP o$$u!s in the b!in. )n the se$on' stu'"& he the!efo!e substitute'

fe! $on'ititionin fo! LTP in'u$tion. / fe% "e!s e!lie!& Li, 4omnski h' sho%n tht sinle $ells in the lte!l

m"'l !e$ei+e both soun' n' sho$k info!mtion& thus 'emonst!tin tht the" miht be $oin$i'en$e 'ete$to!s. )t

thus seeme' !esonble tht fe! $on'itionin %ith sho$k miht $hne the !esponses eli$ite' f!om lte!l

m"'l $ells b" soun' stimuli. )n'ee'& 4on*s !esults sho%e' tht fe! $on'itionin n' LTP in'u$tion p!o'u$e'

+e!" simil! $hnes in the ele$t!i$l !esponses of m"'l $ells to soun' stimuli. 8e! $on'itionin& in othe! %o!'s&

seems to in'u$e LTP. This %o!k& %hi$h e!ne' 4on the p!estiious Lin'sle" P!i,e in FFF fo! the best 'isse!ttion

in beh+io!l neu!os$ien$e& p!ompte' $omment!" b" :h!les Ste+ens& one of the top !ese!$he!s in LTP& %ho

ske' %hethe! the “million-'oll! @uestion# bout

memo!" h' finll" been ns%e!e'. He $on$lu'e' tht thouh it h' not& %e h' tken ke" step to%!'

'oin so.

8e! $on'itionin hs thus been mo!e su$$essful in $losin the p bet%een LTP n' memo!" thn stu'ies

of sptil le!nin o! othe! hippo$mpl'epen'ent tsks. On the bsis of $!eful ntomi$l n' beh+io!l stu'ies&

%e h' 'e+elope' $le! i'e bout %hi$h s"npses miht be $hnin 'u!in fe! $on'itionin& n' %e $oul' esil"

stimulte them %ith both ntu!l n' ele$t!i$l stimuli. 7hile the $i!$uit!" of the hippo$mpus is %ell un'e!stoo'& the

!eltion of le!nin to spe$ifi$ $i!$uits in the hippo$mpus hs been 'iffi$ult to 'ete!mine be$use of the $omple(it" of

the le!nin tsks. )n sptil le!nin& !t is f!ee to le!n bout n" of the mn" stimuli p!esent in the en+i!onment&

mkin it 'iffi$ult to 'ete!mine& in Hebbin te!ms& p!e$isel" %ht*s bein sso$ite' %ith %ht. )n $ont!st& fe!



$on'itionin is st!ihtfo!%!' fo!m of sso$iti+e le!nin tht is es" to 'efine in te!ms of Hebbin plsti$it"&

%he!e st!on 2foot sho$k3 n' %ek 2soun'3 stimuli inte!$t t s"npses on the sme $ells.

/n impo!tnt @uestion is %hethe! the hue mount of %o!k tht hs been 'one on the mole$ul! bsis of

hippo$mpl LTP pplies e@ull" to m"'l LTP n' fe! $on'itionin. 8o!tuntel"& mu$h of this !ese!$h 'oes

seem !ele+nt. 8o! e(mple& stu'ies b" se+e!l !ese!$he!s& in$lu'in S!in 4o'!iues in m" lb& n' 0ike D+is

n' $olleues n' 0ike 8nselo% n' $olleues 2espe$ill" Jensok 5im n' Ste+e 0!en3 h+e sho%n thtblo$k'e of 10D/ !e$epto!s in the lte!l m"'l p!e+ents the $@uisition of fe! $on'itionin. 8u!the!& 9lenn

S$hfe in m" lb hs sho%n tht 'is!uption in the lte!l m"'l of p!otein s"nthesis o! of some of the sme

kinses tht p!e+ent the in'u$tion of lte LTP in the hippo$mpus inte!fe!es %ith the fo!mtion of lon-te!m memo!"

fo! fe! $on'itionin %ithout ffe$tin sho!t-te!m memo!". Some of the min kinses in+ol+e' !e P5/ n' 0/P

kinse. P5/ hs lso been impli$te' in $onte(t $on'itionin b" S$hfe n' b" 4usiko Bou!t$houl',e in 5n'el*s

lb& but the e($t site of $tion in the b!in is not kno%n. /lso& %hen :4EB le+els !e in$!ese' in the !eion of the

lte!l m"'l& %ek t!inin p!o'u$es st!on le!nin. :4EB& P5/& n' othe! mole$ules h+e lso been

impli$te' in spe$ts of fe! $on'itionin th!ouh stu'ies of eneti$ll" lte!e' mi$e b" E!i$ 5n'el& /l$ion Sil+& 0!k

0"fo!'& Tsunmo Tone%& Joe Ts>en& n' othe!s. )mpo!tntl"& Y. Y Hun n' 5n'el h+e sho%n tht lte-phse

LTP in the lte!l m"'l lso 'epen's in p!t on 10D/ !e$epto!s& P5/& 0/P kinse& n' p!otein s"nthesis&

fu!the! $losin the p bet%een memo!" fo!mtion n' LTP in the lte!l m"'l. 8e! $on'itionin n' lte!l

m"'l LTP thus seem to !e@ui!e the sme mi( of mole$ules tht hs been impli$te' in s"npti$ plsti$it" n'

memo!" in the hippo$mpusA Hebbin $hnes in s"npti$ st!enth& %hi$h !e t!ie!e' b" $l$ium ent!" th!ouh

10D/ !e$epto!s& %hi$h !e stbili,e' b" p!otein kinses tht in'u$e :4EB-!elte' enes to mke ne% p!oteins.

10D/ !e$epto!s& 0/P kinse& :4EB& n' p!otein s"nthesis lso h+e been impli$te' in $on$lssi$l $on'itionin&

b" Y'in Du'i n' $olleues t the 7ei,mnn )nstitute in )s!el 2espe$ill" 4ffl Lmp!e$ht& 5obi 4osenblum& n'

Dieo Be!mn3.

7ht is the sinifi$n$e of the f$t tht fe! $on'itionin n' tste-+e!sion le!nin b" the

m"'l n' !eltionl 2sptil3 le!nin b" the hippo$mpus ll in+ol+e simil! mole$ul! $hnes= Ob+iousl"& the

$i!$uits !e +e!" 'iffe!ent t se+e!l le+els. 8o! e(mple& the fe!-$on'itionin $i!$uits of the m"'l !e one

s"npse !emo+e' f!om senso!" s"stems& %hile the hippo$mpus is se+e!l s"npti$ steps !emo+e' f!om them. )n

''ition& the $onse@uen$es of $ti+tin these $i!$uits !e @uite 'istin$t. /$ti+tion of fe!-$on'itionin $i!$uits in the

m"'l le's to the e(p!ession of h!'-%i!e' bo'il" !esponses b" %" of $onne$tions %ith the b!in stem& %he!es

$ti+tion of hippo$mpl $i!$uits le's to !ep!esenttions tht llo% fo! multitu'e of !esponses th!ouh %i'esp!e'

$onne$tions %ith $o!ti$l !es. Diffe!ent fo!ms of memo!" !e thus 'istinuishe' not b" the mole$ules tht mke

them but b" the $i!$uits in %hi$h those mole$ules $t.

The!e is still @uite lot of %o!k to be 'one on the mole$ul! bsis of fe! $on'itionin to pin 'o%n some of

the p!ti$ul!s. 8o! e(mple& !e$ent stu'ies in b!in sli$es of the m"'l b" 0!$ 7eisskopf n' Li, Bue! in m"

lb h+e sueste' tht t lest some of the plsti$it" m" be me'ite' b" $l$ium ent!" th!ouh spe$il $l$ium

$hnnels. 8ollo%in up on this %o!k& Bue! n' 9lenn S$hfe sho%e' tht fe! $on'itionin $oul' be p!e+ente' b"

blo$kin these $l$ium $hnnels& suestin tht $l$ium ent!" th!ouh both 10D/ !e$epto!s n' $l$ium $hnnels

m" $ont!ibute to fe! le!nin. The theo!" is bein e+lute' in onoin stu'ies. )n hippo$mpl LTP& this $ombine'

in+ol+ement of 10D/ !e$epto!s n' $l$ium $hnnels hs been seen. Othe! !ese!$h in'i$tes tht p!es"npti$

plsti$it" m" o$$u! t some s"npses in the m"'l 'u!in LTP in'u$tion n' 'u!in fe! $on'itionin* )f so&

$lssi$l fe! $on'itionin in the !t miht tu!n out to be simil! to $lssi$l $on'itionin in in+e!teb!tes& in tht both

p!es"npti$ n' posts"npti$ $hnes tke pl$e. 7e*ll !e+isit this issue belo% %hen %e $onsi'e! in+e!teb!te

le!nin. /lso un!esol+e' is the lo$us of memo!" sto!e plsti$it" in the lte!l m"'l is $le!l" in+ol+e'& but

%hethe! this is the onl" site of $hne tht is mintine' o+e! time !emins to be 'ete!mine'.

Stu'ies of fe! $on'itionin h+e lso !e+i+e' inte!est in st!ne but possibl" +e!" sinifi$nt phenomenon

in memo!" !ese!$h!e$onsoli'tion. The !e$ent 'is$o+e!"& m'e b" 5!im 1'e! n' 9lenn S$hfe in m" lb& is



tht p!otein s"nthesis in the m"'l seems ne$ess!" fo! !e$entl" $ti+te' memo!" to be kept s memo!".

Tht is& if "ou tke memo!" out of sto!e "ou h+e to mke ne% p!oteins 2"ou h+e to !esto!e& o! !e$onsoli'te it3

in o!'e! fo! the memo!" to !emin memo!". One %" of thinkin bout this is tht the b!in tht 'oes the

!emembe!in is not the b!in tht fo!me' the initil memo!". )n o!'e! fo! the ol' memo!" to mke sense in the $u!!ent

b!in& the memo!" hs to be up'te'. This %o!k hs stimulte' lot of inte!est f!om both s$ientists n' l" pe!sons.

One mn $lle' n' ske' %hethe! it miht be possible fo! him to eliminte the memo!" of his e(-%ife b" blo$kinp!otein s"nthesis in his b!in %hile thinkin of he!. The p!$ti$l si'e of this is tht it miht be possible some '" to

h+e t!um +i$tims !e$ll'itione' tste-+e!sion le!nin& nothe! fo!m of +e!si+e thei! t!um in the p!esen$e of

some '!u o! othe! b!in lte!tion tht !e'u$es the st!nlehol' of the memo!" on the pe!son*s ps"$he. /fte! %e p!o-

pose' this& thouh& the!pist m'e +e!" oo' point. 7ht %oul' it men to Holo$ust su!+i+o!& fo! e(mple& to

lose su$h memo!ies fte! h+in li+e' fo! mn" "e!s n' h+in 'e+elope' n i'entit" bse' in p!t on them= This is

+e!" impo!tnt $on$e!n& n' tou$hes on the 'eep ethi$l issues tht s$ientifi$ 'is$o+e!ies $n !ise.

8e!-$on'itionin !ese!$h hs $pitli,e' on b!ekth!ouhs in mo'e!n neu!os$ien$e to mo+e us fo!%!' in

ou! un'e!stn'in of ho% s"npti$ $hnes un'e!lie memo!". :onsistent %ith the $ellul!-$onne$tion st!te"

outline' b" 5n'el n' Spen$e! in FG& simple beh+io! %s $hosen n' the $i!$uit %s mppe'. The plsti$it" of

$ells in the $i!$uit %s stu'ie'. The $ellul! $hnes h+e been !elte' to spe$ifi$ s"npses& n' the s"npti$

$hnes h+e been !elte' to spe$ifi$ mole$ul! e+ents. )t %s in$on$ei+ble in FG tht this $oul' be 'one in

mmmlin b!in& n' it is testimon" to ho% fst the fiel' of neu!os$ien$e hs '+n$e' tht so mu$h hs been

$hie+e' in !e$ent "e!s.

S1/)L T/LES

The mole$ules of memo!" !e $onse!+e' not >ust $!oss 'iffe!ent kin's of memo!" %ithin spe$ies but lso

$!oss +stl" 'iffe!ent kin's of o!nisms. )n f$t& mn" of the bsi$ f$ts bout the mole$ul! bsis of plsti$it" %e!e

fi!st !e+ele' in stu'ies of in+e!teb!te o!nisms& n' onl" lte! %e!e the" foun' to be ppli$ble to plsti$it" in the

mmmlin b!in th!ouh stu'ies of LTP n' beh+io!l le!nin. )t is time to put the mmmlin b!in si'e n' tke

look t some of the !ese!$h on in+e!teb!tes tht le' to ou! $u!!ent mole$ul! un'e!stn'in of memo!".

The neu!l bsis of le!nin n' memo!" hs been in+estite' in mn" 'iffe!ent in+e!teb!tes 2bees&

!sshoppe!s& $!"fish& slus& flies& n' +!ious mollusks3& but stu'ies of the mollusk Aplysia californica h+e been

p!ti$ul!l" tho!ouh n' info!mti+e. 0u$h of the %o!k on this m!ine snil hs been $on'u$te' b" E!i$ 5n'el n'

his stu'ents n' $olleues t :olumbi Uni+e!sit" n' else%he!e. This pionee!in !ese!$h %s m>o! f$to! in

5n'el*s !e$eipt of the 1obel P!i,e in .

BEH/6)O4/L STUD)ES

Ap;ysia b!ethe th!ouh ills tht !e $o+e!e' b" pie$e of skin $lle' the mntle. )f the mntle is lihtl"

tou$he'& the ill !et!$ts. This 'efensi+e !efle(

p!ote$ts the ill f!om in>u!"& n' hs been the sub>e$t of e(tensi+e in+estition s beh+io!l mo'el of

le!nin n' memo!". The plsti$it" of othe! !efle(es in Ap;ysia hs lso been stu'ie'& but the ill-%ith'!%l !efle(%ill be use' to illust!te the bsi$ fin'ins.

The $ent!l ne!+ous s"stem of n Aplysia hs onl" bout t%ent" thousn' neu!ons. )t hs been estimte'

tht fe%e! thn one thousn' neu!ons 2n' possibl" s fe% s fou! hun'!e'3 !e $ti+e 'u!in the ill-%ith'!%l

!efle(& n' mn" of these !e not belie+e' to be essentil. Essentil ones in$lu'e senso!" neu!ons tht p!o$ess the

tou$h of the mntle skin& n' moto! o! output neu!ons tht $ont!ol the ill %ith'!%l. The senso!" neu!ons mke

s"npti$ $onne$tions %ith the moto! neu!ons. /lso impo!tnt !e sets of e($itto!" n' inhibito!" inte!neu!ons tht

mke s"npses %ith the senso!" o! moto! neu!ons n' !eulte the !efle(. 7hen "ou $omp!e this %ith the billions of



neu!ons in the mmmlin b!in& it is $le! %h" it miht be esie! to in+estite the neu!l bsis of beh+io!l

fun$tions in the Aplysia)

The ill-%ith'!%l !efle( e(hibits se+e!l fo!ms of le!nin& in$lu'in hbitutionA the ill !et!$ts less if the

the mntle is tou$he' !epete'l". Hbitution is fo!m of nonsso$iti+e le!ninA sinle stimulus is in+ol+e'& n' it

is not sso$ite' %ith n"thin else. Hbitution $n be !e+e!se' !pi'l" b" i+in st!on stimulus& su$h s n

ele$t!i$ sho$k& to some othe! p!t of the mollusk*s bo'"& like the til. Tou$h of the mntle fte! sho$k !esults in bi!esponse. This is n in'epen'ent fo!m of nonsso$iti+e le!nin $lle' sensiti,tion n' is not simpl" !e$o+e!"

f!om hbitution& sin$e the !esponse to the tou$h of se$on' !e of skin& one tht %s not hbitute'& is lso mpli-

fie' b" the sho$k. Sensiti,tion is $onsi'e!e' nonsso$iti+e be$use the tou$h-test stimulus n' the sho$k %e!e

ne+e! !elte'& n' the le!nin is not spe$ifi$ to the test stimulusmn" stimuli i+en fte! the sho$k p!o'u$e bie!

effe$ts. The effe$ts of sensiti,tion $n be sho!t-li+e' o! lon-lstin& 'epen'in on the st!enth of t!inin. / %ek

sho$k i+en onl" on$e %ill p!o'u$e sho!t-lstin $hnes in the !efle( tht 'isppe! %ithin mtte! of hou!s&

%he!es !epete' p!esenttion of the sho$k le's to $hnes tht $n lst fo! '"s. Like hbitution& sensiti,tion is

lso !e!'e' s fo!m of nonsso$iti+e le!nin be$use sinle stimulus 2the sho$k3 $uses the beh+io!l

$hne.

/sso$iti+e le!ninnmel"& $lssi$l 'efense o! fe! $on'itioninlso o$$u!s in the ill-%ith'!%l

!efle(. This is essentill" the sme kin' of $on'itionin tsk tht %e*+e l!e'" en$ounte!e' se+e!l times in

mmmls. See& fo! e(mple& the 'is$ussion of impli$it le!nin in $hpte!. )f sho$k is 'eli+e!e' to the til %hile the

mntle is tou$he'& subse@uentl" the tou$h lone %ill le' to st!one! %ith'!%l of the ill thn it 'i' befo!e

$on'itionin. Tht this is sso$iti+e le!nin 2n' not >ust sensiti,tion 'ue to the sho$k3 is 'emonst!te' b" the f$t

tht the $on'itione' !esponse is smlle! if the tou$h n' sho$k 'o not o$$u! t the sme time. The !eltion bet%een

the t%o stimuli is thus ke". The sso$iti+e ntu!e of the le!nin is fu!the! in'i$te' b" the f$t tht if t%o tou$h

stimuli !e use' 2tht is& if 'iffe!ent p!ts of the mntle !e tou$he'3& n' onl" one is pi!e' %ith the sho$k& the pi!e'

tou$h eli$its bie! !esponse thn the unpi!e' one.

:on'itionin n' sensiti,tion !e simil! in tht st!on stimulus $hnes the !esponse to %ek one. But

the" 'iffe! in spe$ifi$it"A in sso$iti+e $on'itionin& the mplifie' !esponse onl" o$$u!s in !e$tion to stimulus tht

%s pi!e' %ith the sho$k& %he!es in sensiti,tion the !esponse to stimuli tht h+e no !eltion to the sho$k is lso

bie!. Sensiti,tion bsi$ll" mkes the snil >ump"& so tht n" stimulus to %hi$h it is e(pose' fte! st!on

stimulus %ill le' it to !e$t& %he!es it is $on'itione' if it !e$ts to stimulus tht o$$u!!e' t the sme time s

st!on stimulus but not to othe! no+el stimuli tht o$$u! fte!%!'. Stu'ies of $lssi$l $on'itionin often use unpi!e'

t!inin 2sensiti,tion3 s $ont!ol to ensu!e tht the $on'itione' !esponse is 'ue to the sso$iti+e !eltion bet%een

the st!on n' %ek stimulus& s oppose' to the nonsso$iti+e effe$ts of the st!on stimulus lone.

The bi '+nte of stu'ies of nimls like the Aplysia is& of $ou!se& tht the smll numbe! of neu!ons

in+ol+e' in the $ont!ol of beh+io!l !esponse like the ill-%ith'!%l !efle( mkes it !elti+el" es" to pu!sue

@uestions bout e($tl" %hi$h neu!ons n' s"npses !e $hne' b" e(pe!ien$e& n' %ht so!ts of mole$ul! e+ents

miht un'e!lie the s"npti$ lte!tions tht $onstitute the memo!". But e+en in simple ne!+ous s"stem like tht of the

Ap;ysia, it hs p!o+en useful to n!!o% the fo$us 'o%n e+en fu!the!. Be$use the $tul beh+io!l !esponse is

$ont!olle' b" numbe! of 'iffe!ent neu!ons& some stu'ies si'esteppe' beh+io! $ompletel" n' inste' e(mine' the

ele$t!i$l $ti+it" of sinle moto! neu!on s n in'i$to! of %hethe! le!nin o$$u!!e'. )n this e(pe!imentl setup& the

ele$t!i$l $ti+it" of moto! neu!ons in !esponse to ntu!l stimuli 2tou$hes n' sho$ks3 o! to ele$t!i$l stimultion of

the senso!" pth%"s tht t!nsmit ntu!l stimuli $n be ssesse'. The senso!" o! moto! neu!ons lso $n be

'i!e$tl" t!ete' %ith $hemi$ls& like '!us tht mimi$ o! blo$k the effe$ts of neu!ot!nsmission o! othe! spe$ts of $ell

fun$tion. / fu!the! !e'u$ti+e step hs in+ol+e' $omplete elimintion of the Ap;ysia, e($ept fo! sinle senso!" n'

sinle moto! neu!on tht !o% s"npses bet%een e$h othe! in 'ish. The !esponse of the moto! neu!on to ele$t!i$l

stimultion of the senso!" neu!on o! to 'i!e$t ppli$tion of '!us to the neu!on $n then be teste'. 7ith these

pp!o$hes& Aplysia !ese!$he!s h+e le!ne' mu$h bout ho% s"npti$ $hnes su$h s those o$$u!!in 'u!in



le!nin !e estblishe' n' mintine'.

0E0O4Y 0E:H/1)S0S

/ll fo!ms of ill-!efle( le!nin in+ol+e $hnes in s"npses bet%een senso!" neu!ons tht !e$ei+e inputs

f!om the mntle skin n' moto! neu!ons tht $ont!ol the ill !esponse. )n hbitution& fo! e(mple& the !esponse of theposts"npti$ neu!on to p!es"npti$ input %ekens& n' the ill !esponse ets smlle!& be$use the p!es"npti$

te!minl $omes to !elese less lutmte. )t simpl" ets 'eplete'.

)n $ont!st& in sensiti,tion& the ill !e$ts mo!e to the sme stimulus fte! the til is sho$ke' thn befo!e

be$use the senso!" neu!on $omes to !elese mo!e lutmte. To un'e!stn' %h" mo!e lutmte $omes out fte!

the til is sho$ke' !e@ui!es tht %e $onsi'e! the %" the sho$k pth%" inte!$ts %ith the s"npses tht $onne$t the

senso!" n' moto! neu!ons.

The sho$k pth%" fo!ms s"npses on the te!minls of the senso!" neu!ons. These !e $lle' (o(oni$

s"npses& sin$e the (on te!minls of the sho$k pth%" mke s"npses %ith othe! (on te!minls& in this $se&

te!minls of the senso!" pth%". This $ont!sts %ith the sitution %e*+e $onsi'e!e' most so f!& in %hi$h (on

te!minls $ont$t 'en'!ites. The til sho$k pth%" thus en's on the p!es"npti$ te!minl of the senso!" neu!on n'

$uses mo!e t!nsmitte! to be !elese'. Be$use the in$!ese in the effi$ien$" of t!nsmission bet%een the senso!"

n' moto! neu!on is 'ue enti!el" to lte!tions in the senso!" neu!on te!minl& it is !efe!!e' to s p!es"npti$ f$il-

ittion. Be$use the stte of $ti+it" of the posts"npti$ neu!on is i!!ele+nt& sensiti,tion b" 'efinition is fo!m of

non-Hebbin plsti$it" 2!e$ll tht Hebbin plsti$it" !e@ui!es p!es"npti$ n' posts"npti$ $ti+it"3.

Ho% 'oes the til sho$k $use p!es"npti$ f$ilittion= The til sho$k pth%" !eleses the mo'ulto!

se!otonin t the senso!" te!minl. 7hen se!otonin bin's to its !e$epto!s on the te!minl& it $ti+tes se$on'

messene!s the!e tht ultimtel" le' to the $ti+tion of p!otein kinse& nmel" P5/& %hi$h is lso in+ol+e' in LTP.

P5/ in tu!n le's to othe! $hnes tht $use $tion potentils to lst little lone! thn usul. /s !esult& mo!e

lutmte is !elese' f!om the te!minl fte! the sho$k thn befo!e. This $uses bie! !esponse in the moto!

neu!on& n' the!efo!e beh+io!s $ont!olle' b" moto! neu!ons& like ill %ith'!%l& !e mo!e st!onl" e(p!esse'.

The sensiti,in effe$ts of sho$k !e sho!t-li+e' unless the sho$k is i+en !epete'l". 7hen !epete' sho$k

is 'ministe!e'& ''itionl p!o$esses !e $ti+te'& n' the effe$ts of sensiti,tion $n lst fo! '"s. )n p!ti$ul!&

P5/ is $ti+te' in spe$il %" tht llo%s it to ente! the $ell nu$leus. )n ''ition& se$on' p!otein kinse& 0/P

kinse 2%hi$h is in+ol+e' in hippo$mpl n' m"'l plsti$it"3& is lso $ti+te' b" !epete' sho$ks n' mo+es

insi'e the nu$leus. P5/ n' 0/P kinse then phospho!"lte the ene t!ns$!iption f$to!& :4EB& %hi$h %e lso

en$ounte!e' e!lie! in ou! su!+e" of LTP.

:4EB-$ti+te' enes mke ne% p!oteins tht en' up f$ilittin t!nsmission bet%een the senso!" n'

moto! neu!on in +!ious %"s. One effe$t of these p!oteins is tht P5/ be$omes pe!sistentl" $ti+te'& %hi$h mens

tht the sho!t-te!m sensiti,in effe$ts of P5/ !e lenthene'& $ontinuin the effe$ts on t!nsmitte! !elese 'es$!ibe'

bo+e. P!es"npti$ f$ilittion simpl" $ontinues. But the!e is t lest one othe! effe$t tht is lso impo!tntA some of

the p!oteins stimulte the senso!" te!minl to !o% ne% (onl b!n$hes tht mke ne% s"npses %ith the moto!

neu!on. 7ith mo!e s"npti$ $onne$tions bet%een t%o $ells& i+en $tion potentil in the p!es"npti$ (on hs mo!e

%"s to influen$e the posts"npti$ $ell& le'in to st!one! !esponse. The t%o effe$ts 2pe!sistent $ti+tion of P5/

n' fo!mtion of ne% $onne$tions3 $ombine to p!o'u$e lon-lstin in$!eses in t!nsmission bet%een the senso!"

n' moto! neu!ons& n' st!one! !efle( !esponses.

:lssi$l $on'itionin& thouh ob+iousl" sso$iti+e in ntu!e& %s lon belie+e' to be me'ite' b" non-

Hebbin s"npti$ me$hnism& nmel"& n mplifi$tion of p!es"npti$ f$ilittion. Tht is& %hen s"npti$ $ti+it" o$-

$u!!e' in the p!es"npti$ te!minl %hile the t!nsmitte! !elese %s bein f$ilitte' 2sensiti,e'3 b" the sho$k& the

'e!ee of f$ilittion in$!ese' n' $me to be $ouple' to the stimulus tht eli$ite' the $ti+it". This %s $onsi'e!e'

sso$iti+e& sin$e it in+ol+e' $hnes !est!i$te' to the stimulus tht %s $ti+tin the te!minl& but it %s non-

Hebbin be$use the posts"npti$ $ell %s not belie+e' to be in+ol+e'. Ho%e+e!& !e$ent %o!k hs sho%n tht the



initil stu'ies on %hi$h this +ie% %s bse' %e!e in$omplete. )t is no% kno%n tht the posts"npti$ $ell 'oes

p!ti$ipte in sso$iti+e $lssi$l $on'itionin. 4ese!$he!s like D+i' 9ln,mn n' J$k B"!ne !ue tht

$lssi$l $on'itionin in the Aplysia 'oes in'ee' in+ol+e Hebbin s"npti$ $hnes& n' p!obbl" lso in+ol+es

10D/ !e$epto!s& in ''ition to n $ti+it"-'epen'ent enhn$ement of p!es"npti$ f$ilittion. One %" of

un'e!stn'in this is tht nonsso$iti+e 2non-Hebbin3 p!es"npti$ f$ilittion fun$tions s the p!es"npti$

$omponent of sso$iti+e 2Hebbin3 plsti$it".:onsi'e!ble %o!k hs lso been $on'u$te' on the mole$ul! bsis of $lssi$l $on'itionin in the Aplysia)

7hile some of the e!l" steps !e 'iffe!ent f!om those in+ol+e' in sensiti,tion& the lon-te!m $hnes in+ol+e phos-

pho!"ltion of :4EB b" p!otein kinses n' s"nthesis of ne% p!oteins b" :4EB-$ti+te' enes. The estblishment

of lon-te!m plsti$it" seems to follo% $ommon ptte!n e+en %hen it is t!ie!e' b" 'iffe!ent kin's of sho!t-te!m

$hnes.

The most ob+ious 'iffe!en$es bet%een sso$iti+e $on'itionin in the Aplysia n' plsti$it" in the

mmmlin b!in is thus the impo!tn$e of p!es"npti$ plsti$it" in the Aplysia) The !e$ent fin'in tht 10D/-

me'ite' plsti$it" in the posts"npti$ $ell is lso sinifi$nt in Aplysia plsti$it" helps $lose the p. /n' the

possibilit" tht fe! $on'itionin& m"'l LTP& n' se+e!l fo!ms of hippo$mpl plsti$it" miht& like plsti$it"

inAplysia, in+ol+e p!es"npti$ s %ell s posts"npti$ $hnes fu!the! st!enthens the notion tht simil! me$hnisms

!e use' to mke memo!ies in 'i+e!se spe$ies& suestin tht memo!" me$hnisms !e $onse!+e' $!oss mn"

le+els of e+olution.

8LY 9E1ES

4ese!$h on the f!uit fl"& /rosophila melano!aster, hs lso been inst!umentl in the $$umultion of ou!

kno%le'e of memo!" n' its mole$ules. But in $ont!st to the hihl" fo$use' $ellul!-$onne$tion pp!o$h use' to

stu'" the mole$ul! bsis of plsti$it" in Aplysia, the fl" %o!k hs fo$use' on beh+io!l stu'ies of mutnt st!ins of

flies tht l$k spe$ifi$ mole$ules& n' hs fo! the most p!t not !elte' the mole$ul! effe$ts on le!nin n' memo!"

to spe$ifi$ $ells n' s"npses.

The stu'ies of eneti$ll" lte!e' mi$e %e 'is$usse' e!lie! !e 'es$en'nts of fl" muttion stu'ies st!te'

se+e!l 'e$'es e!lie! b" Se"mou! Ben,e! n' his $olleues. /lthouh Ben,e! st!te' in+estitin fl" beh+io! in

the

Fs& the use of flies in !ese!$h on le!nin ben in the follo%in 'e$'e& %hen :hip ?uinn n' Y'in

Du'i in Ben,e!*s lb sho%e' tht no!ml flies $oul' !emembe! smell sso$ite' %ith ele$t!i$ sho$k. 7hen i+en

the $hoi$e bet%een oin into $hmbe! tht $ontine' n o'o! sso$ite' %ith the sho$k n' $hmbe! tht hel'

'iffe!ent o'o!& the flies often +oi'e' the fo!me! $hmbe!.

0ost %o!k on mutnt flies hs in+ol+e' this kin' of le!nin tsk& %hi$h is simpl" +!ition of $lssi$l

'efense o! fe! $on'itionin. These flies !e $lle' le!nin mutnts& sin$e the" !e lte!e' eneti$ll" in %" tht

$uses them to fil to le!n o! !emembe!. Le!nin mutnts !e $!ete' b" t!etin no!ml flies %ith $hemi$l tht

p!o'u$es mo!e o! less !n'om muttions in thei! D1/. The flies !e then teste' fo! 'efi$its in le!nin n' memo!".

Those tht !e 'efi$ient !e b!e' follo%in p!e$ise mtin s$hemes tht $!ete lines of eneti$ll" i'enti$l flies tht

h+e le!nin n' memo!" impi!ments.

9eneti$ muttions $n 'is!upt le!nin fo! +!iet" of 'iffe!ent !esons tht h+e nothin to 'o 'i!e$tl" %ith

le!nin n' memo!"& n' it is ne$ess!" to !ule these out %hen '!%in $on$lusions bout %hethe! mutnt hs

spe$ifi$ 'efi$it in these !es. 8o! e(mple& fl" tht $nnot smell o! tht is 'efe$ti+e in pe!$ei+in sho$k& o! one

tht is $h!oni$ll" ill& %ill not le!n. These !e $on$e!ns tht ppl" to the stu'ies of eneti$ll" lte!e' mi$e 'es$!ibe'

e!lie!& s %ell. )n ''ition& s in the mouse stu'ies& it is impo!tnt to keep in min' tht mutnt niml oes th!ouh

its enti!e life %ith the eneti$ lte!tion& sometimes mkin it 'iffi$ult to 'istinuish effe$ts on le!nin n' memo!"

f!om othe! mo!e ene!l $onse@uen$es of h+in !o%n up %ithout $e!tin p!oteins n' thei! p!o'u$ts. Beh+io!l

$hnes in mutnt $oul'& in othe! %o!'s& be 'ue eithe! to the muttion itself o! to the $onse@uen$es of su!+i+in %ith



the muttion.

The fi!st fl" le!nin mutnt to be i'entifie' %s $lle' 'un$e. Then $me mnesi$& $bbe& !utb&

tu!nip. /ll of these +!ints pe!fo!me' poo!l" on the fe!-$on'itionin tsk. )n e$h of these mutnts& le!nin $tull"

'i' tke pl$e to some e(tent& but then 'e$"e' !pi'l" fte! t!inin. 0emo!" tht !emins fte! the initil 'e$"&

ho%e+e!& is fi!l" stble. This suests tht the muttions ffe$t the e!l" mo!e thn the lte phse of memo!".

0ost of the initil %o!k on le!nin mutnts fo$use' on !elti+el" sho!tlstin memo!ies. Ho%e+e!& !e$entstu'ies b" Tim Tull"& Je!!" Yin& n' :hip ?uinn sho%e' tht lon-lstin memo!" tht pe!sists fo! '"s $n be $!ete'

b" i+in no!ml /rosophila multiple t!inin t!ils tht !e sp!e' out o+e!-time 2this is $lle' sp$e' t!inin3.

Dis!uption of p!otein s"nthesis p!e+ents this lon-te!m memo!" f!om fo!min but hs no effe$t on sho!te!-lstin

kin' of memo!" in'u$e' b" fe% t!inin t!ils i+en ll t on$e 2$lle' msse' t!inin3. Like $ollee stu'ent& the

fl" 'oes bette! if it tkes in info!mtion t !eul! p$e o+e! time thn if it $!ms.

Yin n' Tull" m'e use of this 'iffe!en$e in msse' +s. sp$e' t!inin to e(mine %hethe! $/0P-me'ite'

ene in'u$tion n' p!otein s"nthesis un'e!lies lon-lstin memo!". The" emplo"e' eneti$ te$hni@ues 2see bo+e3

to in$!ese the le+el of the ene t!ns$!iption f$to! :4EB +ilble in flies t the time >ust befo!e t!inin. This step

o+e!$omes mn" $on$e!ns bout %hethe! the 'efi$it is 'ue to filu!e to fo!m memo!" o! to some i!!ele+nt

$onse@uen$e of !o%in up %ithout the ene. The !ese!$he!s foun' tht in the nimls %ith e(t! :4EB& sinle

t!inin t!il $oul' $$omplish %ht !e@ui!e' multiple sp$e' t!ils in no!ml flies$!ete memo!" tht lsts fo!

'"s. This suests tht t!inin-in'u$e' :4EB $ti+tion 2n' the $onse@uent in'u$tion of :4EB-!elte' enes3 is

n essentil step in the p!o'u$tion of p!oteins essentil fo! lon-te!m memo!". The mole$ules le'in to in'u$tion of

:4EB-!elte' enes n' thei! p!oteins !e thus the st!s of memo!" $!oss spe$ies n' t!inin p!o$e'u!es.

8lies !e i'el in mn" %"s fo! pe!fo!min eneti$ stu'ies of le!nin n' memo!". The" e(hibit !obust

fo!m of le!nin& n' be$use of thei! b!ief life spn& mn" ene!tions $n be stu'ie' in sho!t time. But the" !e

not espe$ill" %ell-suite' spe$imens fo! pu!suin the in'i+i'ul $ells n' s"npses in+ol+e' in le!nin n' memo!".

/lthouh !e$ent %o!k hs m'e some p!o!ess in pinpointin the lo$us of plsti$it"& $i!$uit nl"sis in the fl" %ill

p!obbl" !emin 'iffi$ult 'ue to the smll si,e of the ne!+ous s"stem in this tin" $!etu!e.

) H/6E TO /D0)T )T*S 9ETT)19 BETTE4

/ ke" @uestion "ou m" no% be skin "ou!self is %hethe! ll this h!'-$o!e neu!os$ien$e hs& in f$t& n"

p!$ti$l ppli$tion. )n othe! %o!'s& miht it be possible to use this kin' of %o!k to help imp!o+e no!ml memo!" n'&

e+en mo!e impo!tnt& to !es$ue o! p!e+ent e-!elte' memo!" loss=

One of the pionee!s in LTP !ese!$h& 9!" L"n$h of the Uni+e!sit" of :lifo!ni& hs been lookin into %"s

of lte!in the mole$ul! bsis of s"npti$ plsti$it" in the hope of fin'in mens of imp!o+in memo!". Se+e!l

"e!s o& he n' his $olleues 'is$o+e!e' $lss of mole$ules the" $lle' m-

pkines. These '!us in$!ese the effi$ien$" of lutmte t!nsmission t /0P/ !e$epto!s& the!eb" llo%in

%eke! stimuli to $ti+te 10D/ !e$epto!s. 7hen hippo$mpl sli$es %e!e t!ete' %ith these '!us& LTP in'u$tion

%s f$ilitte'. /n' %hen !ts %e!e i+en the '!u& hippo$mpl-'epen'ent le!nin spee'e' up. 0i$hel 4on n'

) teme' up %ith U!sul Stubli to test the effe$t of these substn$es in fe! $on'itionin in !ts. 7e foun' tht in the

p!esen$e of mpkine t!etment& the !ts le!ne' fste!. )t thus ppe!s tht enhn$in lutmte t!nsmission in

both the m"'l n' hippo$mpus f$ilittes le!nin. L"n$h is $u!!entl" %o!kin on %"s to ppl" these potentill"

po%e!ful ents to humn memo!" in the hope of 'e+elopin memo!"-enhn$in '!us.

4e$entl"& Joe Tsien of P!in$eton eneti$ll" eninee!e' mi$e so tht thei! 10D/ !e$epto!s %o!ke' mo!e

effi$ientl". These mi$e sho%e' fste! le!nin of both sptil tsk n' fe! $on'itionin. Tsien ni$knme' the st!in

“Dooie# 2fte! the p!e$o$ious 'o$to! of p!ime-time fme3. This fin'in p!o+i'es po%e!ful suppo!t fo! the !ole of 10D/

!e$epto!s in le!nin& n' lso hihlihts the possibilit" tht the eneti$ mnipultions miht some'" mke possible

the !es$ue of the loss of memo!" fun$tion in in humns.

The essen$e of %ho "ou !e is sto!e' s s"npti$ inte!$tions in n' bet%een the +!ious s"stems of "ou!



b!in. /s %e le!n mo!e bout the s"npti$ me$hnisms of memo!"& %e le!n mo!e bout the neu!l bsis of the self.

:H/PTE4 SE6E1

THE 0E1T/L T4)LO9Y

BET7EE1 51O7LED9E /1D DES)4E ST/1DS . .. 8EEL)19.

)mmnuel 5nt

Th!ouhout mu$h of histo!"& the min' hs been +ie%e' s t!ilo"C t!ip!tite mlm tht in$lu'es

$onition& emotion& n' moti+tion3 8o! some& the t!ilo" %s 'es$!iption of 'iffe!ent spe$ts of sinle mentl

f$ult"C %he!es fo! othe!s& it !ep!esente' th!ee 'istin$t& sep!te $p$ities. Du!in most of the t%entieth $entu!"&

both +e!sions of the mentl t!ilo" %e!e out of f+o!J 7hen the beh+io!ists !eine'& ps"$holo" ino!e' the min'

ltoethe!& mkin the mentl t!ilo" moot. Lte!& the $oniti+e !e+olution b!ouht the min' b$k to ps"$holo"& but

thinkin n' !elte' $oniti+e p!o$esses %e!e 2n' fo! the most p!t still !e3 emphsi,e' t the e(pense of emotion

n' moti+tion. :le!l"& ho%e+e!& it is impo!tnt to un'e!stn' not >ust ho' %e tten' to& !emembe!& o! !eson& but

lso 'hy %e tten' to& !emembe!& o! !eson bout some thins !the! thn othe!s. Thinkin $nnot be full"

$omp!ehen'e' if emotions n' moti+tions !e ino!e'.

)n p!e+ious $hpte!s& %e*+e seen ho% neu!onl $i!$uits !e ssemble' 'u!in 'e+elopment& n' ho% these

$i!$uits !e mo'ifie' %hen %e le!n n' !emembe!. 1o% %e %ill bein to use this bsi$ info!mtion bout $i!$uits n'

thei! plsti$ p!ope!ties to e(plo!e b!o'e! spe$ts of mentl fun$tion& tht is& to bein to ssemble neu!obioloi$l

+ie% of the self. )n 'oin this& %e %ill $onsi'e! e$h $omponent of the mentl t!ilo"& s %ell s inte!$tions mon

them. Thinkin is the sub>e$t of this $hpte!& n' emotion n' moti+tion the follo%in t%o.

0E1T/L JU99L)19

/n i'e& n ime& senstion& feelinA e$h is n e(mple of %ht ps"$holoists $ll mentl $ontent

stuff tht is in the min'. 0entl $ontent %s the sub>e$t mtte! of e(pe!imentl ps"$holo" %hen it fi!st eme!e' s

'is$ipline inthe lte nineteenth $entu!". But John 7tson n' fello% beh+io!ists !epl$e' this fo$us on sub>e$ti+e

sttes %ith min'-less ps"$holo" of ob>e$ti+el" mesu!ble e+ents 2stimuli n' !esponses3. 7hen the $oniti+e

!e+olution lte! m'e the min' fi! me in& it 'i' not 'o so b" !e+i+in sub>e$ti+e ps"$holo". The thinkin

p!o$ess itself& !the! thn the $ons$ious $ontent tht !esults f!om thinkin& be$me& n' l!el" !emins& the sub>e$t



mtte! of $oniti+e s$ien$e.

“)n o!'e! fo! min' to think& it hs to >ule f!ments of its mentl sttes.# This simple sttement b" 0!+in

0insk"& one of the !$hite$ts of the b!n$h of $oniti+e s$ien$e kno%n s !tifi$il intellien$e& ets !iht to the he!t

of the mtte!. )mine& s 0insk" suests& !e!!nin the fu!nitu!e in !oom fmili! to "ou. You shift "ou! ttention

b$k n' fo!th bet%een lo$tions. Diffe!ent i'es n' imes $ome into fo$us& n' some inte!!upt othe!s. You

$omp!e n' $ont!st lte!nte !!nements. You m" $on$ent!te "ou! enti!e min' on smll 'etil one moment&n' on the %hole !oom the ne(t. Ho% 'oes the min' 'o this >ulin& n' ho% 'oes it keep t!$k of the imin!"

$hnes= The ns%e! is tht the min' uses somethin $lle' %o!kin memo!".

Ho% mn" times h+e "ou looke' up phone numbe! n' then fo!otten it fte! bein moment!il"

'ist!$te'= The !eson fo! this is tht "ou put the numbe! into %o!kin memo!"& mentl %o!kshop tht

$$ommo'tes one tsk t time. /s soon s ne% tsk enes %o!kin memo!"& the $ontent of the ol' tsk is

bumpe' out. 8o! tht !eson& unless "ou keep !ehe!sin the phone numbe! n' mne to ino!e othe! thins tht

$ompete fo! "ou! ttention& it %ill not !emin in "ou! min'.

7o!kin memo!" is one of the b!in*s most sophisti$te' $p$ities n' is in+ol+e' in ll spe$ts of thinkin

n' p!oblem-sol+in. )t llo%s "ou to !e' menu n' keep its +!ious options in min' %hile lso $onsi'e!in the spe-

$ils nnoun$e' b" the %ite! n' then !etu!n to the thouht "ou %e!e h+in befo!e the %ite! ppe!e'. )t un'e!lies

"ou! bilit" to hol' $on+e!stion& pl" bo!' mes like $hess& o! 'i!e$t "ou!self to n unfmili! 'estintion on the

bsis of h+in >ust looke' t mp. )n ''ition to bein use' in su$h !outine 'il" $ti+ities& %o!kin memo!" lso

$ont!ibutes to spe$il humn en'e+o!s& like $omposin musi$ o! sol+in $omple( mthemti$l p!oblems& o! n"

othe! sitution in %hi$h info!mtion hs to be hel' in min' in o!'e! to $omplete tsk.

Ou! un'e!stn'in of %o!kin memo!" o%es mu$h to the pionee!in %o!k of /ln B''ele" in the e!l"

)FNs. On the bsis of his stu'ies of sho!t-te!m memo!"& he $me to +ie% the min' in te!ms of t%o kin's of $oniti+e

s"stemsA set of spe$ili,e' s"stems 'e'i$te' to spe$ifi$ mentl tsks& n' ene!l-pu!pose s"stem utili,e' in ll

$ti+e thinkin p!o$esses.

Spe$ili,e' s"stems $ome in t%o fl+o!s. 6e!bl s"stems& like s"stems in+ol+e' in spee$h $omp!ehension&

!e minl" p!esent in the humn b!in& %he!es non+e!bl s"stems !e p!esent in ll b!ins. 1on+e!bl spe$ili,e'

s"stems !e epitomi,e' b" senso!" s"stems. E$h is in+ol+e' in p!o$essin uni@ue kin's of stimuli 2sihts& soun's&

smells& n' so on3. /s p!t of thei! ope!tion& the +e!bl n' non+e!bl spe$ili,e' s"stems !e ble to !etin %ht

the"*+e >ust p!o$esse' fo! b!ief mounts of time 2se$on's3. This $p$it" i's in pe!$eption& llo%in the s"stem to

$omp!e %ht it is seein o! he!in no% to %ht it s% o! he!' moment o. 8o! e(mple& %hen listenin to

le$tu!e& "ou h+e to hol' the sub>e$t of e$h senten$e in "ou! min' until the +e!b ppe!s& n' sometimes "ou h+e

to !efe! b$k to "ou! memo!" of e!lie! senten$es to fiu!e out the !efe!ent of p!onoun.

The ene!l-pu!pose s"stem $onsists of %o!ksp$e n' set of mentl op e!tions $lle' e(e$uti+e

fun$tions tht !e $!!ie' out on info!mtion hel' in the %o!ksp$e. /lthouh onl" limite' mount of info!mtion $n

be !etine' t n" one time& the %o!ksp$e $n hol' on to n' inte!!elte info!mtion of 'iffe!ent t"pes f!om 'iffe!ent

spe$ili,e' s"stems 2the %" somethin looks& soun's& n' smells $n be sso$ite' %ith its lo$tion in e(te!nl

sp$e n' %ith its nme3. This bilit" to inte!te info!mtion $!oss s"stems llo%s fo! bst!$t !ep!esenttion of

ob>e$ts n' e+ents. )t is espe$ill" %ell-'e+elope' in humns& n' is likel" to $ont!ibute to the uni@ueness of humn

$onition.

The info!mtion in "ou! %o!kin memo!" is %ht "ou !e $u!!entl" thinkin bout o! p"in ttention to. /n'

be$use %o!kin memo!" is tempo!!"& its $ontents h+e to be $onstntl" up'te'. But %o!kin memo!" is not pu!e

p!o'u$t of the he!e n' no%. )t lso 'epen's on %ht %e kno% n' %ht kin's of e(pe!ien$es %e*+e h' in the pst.

)n othe! %o!'s& it 'epen's on lon-te!m memo!".

The impo!tn$e of lon-te!m memo!" to thouht $nnot be o+e!emphsi,e'. One of the e!liest e(mples of

its sinifi$n$e is still one of the best. )n the FQs& Si! 8!e'e!i$ B!tlett h' people listen to folktles f!om fo!ein

$ount!ies n' lte! ske' them to !e$ount the sto!ies. 1ot su!p!isinl"& he foun' tht these unfmili! sto!ies %e!e not



!emembe!e' +e!" $$u!tel". 7ht %s su!p!isin %s tht the e!!o!s of !e$ll %e!e not !n'om but %e!e @uite

s"stemti$. The sub>e$ts often !e%!ote the sto!ies in thei! o%n min's& espe$ill" p!ts tht %e!e p!ti$ul!l" fo!ein to

them& !e+isin the plot to the point %he!e it !esemble' mo!e fmili! 7este!n n!!ti+e. To e(plin his fin'ins&

B!tlett p!opose' tht “4emembe!in is ... n iminti+e !e$onst!u$tion& o! $onst!u$tion& built out of the !eltion of ou!

ttitu'e to%!'s %hole $ti+e mss of pst e(pe!ien$es.# He $on$lu'e' tht %hen %e f$e p!oblem& %e '!% upon

mentl s$hemt& o!ni,e' bun'les of sto!e' kno%le'e. 8o! e(mple& if "ou !e ske' @uestion bout ho%bsebll is pl"e'& "ou %oul' '!% upon bsebll s$hem& "ou! $olle$ti+e kno%le'e of bsebll obtine' f!om

spe$ifi$ 'i!e$t e(pe!ien$es "ou*+e h' %ith the me s spe$tto! o! pl"e!& s %ell s thins "ou*+e he!' o! !e'

bout bsebll. B!tlett*s fin'ins 'o not >ust $on$e!n the pe!sonl& i'ios"n$!ti$& n' fllible ntu!e of memo!"& but

lso emphsi,e ho% lon-te!m memo!ies& %hen !et!ie+e' into the tempo!!" %o!ksp$e of %o!kin memo!"& $n

ui'e ou! thouhts n' $tions& s %ell.

)t hs been kno%n fo! $entu!ies tht %e $n onl" keep fe% thins $ti+e in ou! min's 2in %o!kin memo!"3

t on$e.# 9eo!e 0ille!& one of the pionee!s in $oniti+e ps"$holo"& fiu!e' out& th!ouh ps"$holoi$l e(pe!iments&

tht the mi$ numbe! is bout se+en pie$es of info!mtion. Some people $n hn on to eiht o! nine& %he!es

othe!s mne onl" fi+e& but& on +e!e& tempo!!" sto!e $n hol' bout se+en items. 2)t*s p!obbl" no $o-

in$i'en$e tht telephone numbe!s %ithin n !e $o'e %e!e 'esine' to h+e se+en 'iits.3 But& s 0ille! note'& %e

$n effe$ti+el" e(pn' tht $p$it" b" $hunkin o! !oupin info!mtionitWs bout s es" to !emembe! se+en let-

te!s s se+en %o!'s o! i'es. 1o 'oubt one of the !esons humn $onition is so po%e!ful is be$use %e h+e

lnue in ou! b!ins& %hi$h e(ponentill" in$!eses the bilit" to $teo!i,e info!mtion& to $hunk. / %hole $ultu!e&

fo! instn$e& $n be implie' b" nme.

The $on$ept of %o!kin memo!" subsumes %ht use' to be $lle' sho!tte!m memo!". But s the te!m

'or1space implies& %o!kin memo!" is mo!e thn >ust n !e fo! tempo!!" sto!e. )t un'e!lies mentl %o!k. /s

0insk" note'& thinkin in+ol+es >ulin of mentl items$omp!in& $ont!stin& >u'in& p!e'i$tin. )t is the >ob of

the e(e$uti+e fun$tions of %o!kin o!" to 'o the >ulin.

)n the spi!it of +ie%in the min' in te!ms of $ompute!-like ope!tions& some $oniti+e s$ientists like Tim

Shlli$e n' Phillip Johnson-Li!' h+e !efe!!e' to e(e$uti+e fun$tions s supe!+iso!" o! ope!tin s"stem fun$tions.

/ $ompute! ope!tin s"stem is !esponsible fo! $ont!ollin the flo% of info!mtion p!o$essin& mo+in info!mtion f!om

pe!mnent memo!" 24O03 to $ent!l p!o$essin unit %ith $ti+e memo!" 24/i1M3& s$he'ulin tsks to be pe!fo!me'

usin the $ti+e memo!"& n' so on. Simil!l"& e(e$uti+e fun$tions !e in+ol+e' in the $onstnt up'tin of tempo!!"

memo!"& sele$tin %hi$h spe$ili,e' s"stems to %o!k %ith 2p" ttention to3 t the moment& n' then mo+in !ele+nt

info!mtion into the %o!ksp$e f!om lon-te!m sto!e b" !et!ie+in spe$ifi$ memo!ies o! $ti+tin s$hemt

pe!tinent to the imme'ite sitution. Th!ouh e(e$uti+e fun$tions& spe$ili,e' s"stems !e lso 'i!e$te' to tten' to

$e!tin spe$ifi$ stimuli n' to ino!e othe!s& 'epen'in on %ht %o!kin memo!" is %o!kin on. )n $omple( tsks

in+ol+in multiple kin's of mentl $ti+ities& e(e$uti+e fun$tions pln the se@uen$e of mentl steps n' s$he'ule the

p!ti$iption of the 'iffe!ent $ti+ities& s%it$hin the fo$us of ttention bet%een $ti+ities s nee'e'. E(e$uti+e

fun$tions !e $!u$ill" in+ol+e' in 'e$ision-mkin& llo%in "ou to $hoose bet%een 'iffe!ent $ou!ses of $tion i+en

%ht is hppenin in the p!esent& %ht "ou kno% bout su$h situtions& n' %ht "ou $n e(pe$t to hppen if "ou 'o

'iffe!ent thins in this p!ti$ul! sitution. E(e$uti+e fun$tions& in sho!t& mke p!$ti$l thinkin n' !esonin

possible.

The e(e$uti+e !ep!esents po%e!ful mentl $p$it"& but is not ll-po%e!ful. Like the %o!ksp$e& it hs its

limits. )t bsi$ll" $n 'o one o! t most fe% thins t time. This is %h" "ou fo!et phone numbe! if "ou !e

'ist!$te' %hile 'ilin. 7ith p!$ti$e n' t!inin& %e $n le!n to 'i+i'e ou! ttention bet%een t%o mentl tsks

simultneousl"& but onl" %ith 'iffi$ult". )n this sense& the e(e$uti+e is mo!e like n ol'-fshione' DOS ope!tin

s"stem tht $n onl" !un one p!o!m t time thn like multitskin 7in'o%s ope!tin s"stem tht $n

$on$u!!entl" !un %o!' p!o$essin& sp!e'sheet& e-mil& $len'!& n' othe! p!o!ms.

But the!e*s lso so!t of $hunkin tht tkes pl$e in e(e$uti+e fun$tions. /s %e*+e seen& the e(e$uti+e is



in+ol+e' in s$he'ulin the se@uen$e of steps in $omple( tsk. He!e& the e(e$uti+e is 'oin mo!e thn one thin t

time& but the thins !e ll !elte' to the o+e!ll ol. )f the e(e$uti+e hs to %o!k on multiple un!elte' ols t the

sme time& ho%e+e!& the s"stem beins to

fll p!t& espe$ill" if the ols $onfli$t %ith one nothe!. /n es" %" to st!ess people is to mke them 'o

too mu$h t on$e. Plnnin& 'e$ision-mkin& n' othe! spe$ts of mentl life suffe! %hen the e(e$uti+e is

o+e!lo'e'.

HE/D?U/4TE4S

/leksn'! 4omno+i$h Lu!i& the !et 4ussin ps"$holoist& 'e+elope' b!o'-!nin n' influentil

theo!ies of b!in fun$tion on the bsis of his stu'ies of 7o!l' 7! )) sol'ie!s %ho h' sustine' unshot %oun's to

the he'. One of his m>o! $on$lusions %s tht 'me to the f!ontl lobe inte!fe!es %ith the bilit" to pln n'

e(e$ute ol-'i!e$te' beh+io!. Othe! stu'ies of neu!oloi$l ptients %ith f!ontl lobe 'me& s %ell s of ps"-

$hit!i$ ptients %ho un'e!%ent f!ontl lobotom"& suppo!te' the $on$lusion tht the f!ontl lobes !e in+ol+e' in

e(e$uti+e fun$tions 2plnnin& p!oblem-sol+in& n' beh+io!l $ont!ol3& s %ell s in sho!t-te!m o! tempo!!"

o!". 0o!e !e$entl"& it hs been sho%n tht neu!l $ti+it"& s mesu!e' %ith 'e+i$es su$h s PET n' 04)

s$ns& in$!eses in the f!ontl $o!te( %hen humns pe!fo!m tsks tht !e@ui!e tempo!!" sto!e n' e(e$uti+e

fun$tions.# 7o!kin memo!" thus hs $ome to be thouht of s fun$tion of neu!l $i!$uits in the f!ontl lobes.

The f!ontl lobes 2one sits on e$h si'e of the b!in3 !e hue& n' $$ount fo! bout one-thi!' of the mss

of the humn b!in.# /ll mmmls h+e f!ontl $o!te(& but& fo! most $!etu!es& its min >ob is mo+ement $ont!ol. The

p!ef!ontl $o!te(& %hi$h is lo$te' in f!ont of the mo+ement-$ont!ol !eions& is espe$ill" %ell 'e+elope' in p!imtes

2some s" this !eion 'oesn*t e+en e(ist in nonp!imte mmmls3. This is the !eion $lssi$ll" impli$te' in %o!kin

memo!".

/s in most !es of neu!os$ien$e& niml !ese!$h is $!u$il fo! 'ete!minin e($tl" ho% neu!l s"stems

p!ti$ipte in ps"$holoi$l fun$tions& n' mu$h of ou! $u!!ent un'e!stn'in of the !ole of the p!ef!ontl $o!te( in

%o!kin memo!" hs $ome f!om stu'ies of monke"s. The fi!st $lues eme!e' in the FQs& %hen it %s foun' tht

'me to the monke" p!ef!ontl $o!te( inte!fe!e' %ith the bilit" to !emembe! un'e! %hi$h of t%o ob>e$ts !e%!'

2fo! e(mple& !isin3 %s hi''en 'u!in 'el" pe!io' in %hi$h the ob>e$ts %e!e out of siht.Q This tempo!!"

sto!e 'efi$it in the so-$lle' 'el"e' !esponse tsk in nimls %ith p!ef!ontl 'me hs been e(tensi+el" stu'ie'

n' hs been !epete'l" $onfi!me' in +!ious %"s usin 'iffe!ent kin's of stimuli.

The !ole of the monke" p!ef!ontl $o!te( in %o!kin memo!" hs been elbo!te' in %o!k b" the lbo!to!ies

of Jo@uin 8uste! t U:L/ n' Pt 9ol'mn4ki$ t Yle. Both !ese!$he!s h+e !e$o!'e' the ele$t!i$l $ti+it" of

p!ef!ontl neu!ons %hile monke"s pe!fo!m 'el"e' !esponse tsks n' othe! tests !e@ui!in tempo!!" sto!e n'

h+e sho%n tht $ells in this !eion be$ome p!ti$ul!l" $ti+e 'u!in the 'el" pe!io's. )t is likel" tht these $ells !e

'i!e$tl" in+ol+e' in !etinin info!mtion 'u!in the 'el".

The s"npti$ $onne$tions of the p!ef!ontl $o!te(& lso elu$i'te' th!ouh stu'ies of monke"s& e(plin its

bilit" to p!ti$ipte in %o!kin memo!" tsks in+ol+in mn" 'iffe!ent kin's of stimuli3 The p!ef!ontl $o!te( is

$on+e!en$e ,one. )t !e$ei+es $onne$tions f!om +!ious spe$ili,e' s"stems 2like the +isul n' u'ito!" senso!"

s"stems3& enblin it to be %!e of %ht*s oin on in the outsi'e %o!l' n' to inte!te the info!mtion it the!s. )t

lso !e$ei+es $onne$tions f!om the hippo$mpus n' othe! $o!ti$l !es in+ol+e' in lon-te!m e(pli$it memo!"&

llo%in it to !et!ie+e sto!e' info!mtion 2f$ts& pe!sonl e(pe!ien$es& s$hemt3 !ele+nt to the tsk t hn'. )n

''ition& it sen's $onne$tions to !es in+ol+e' in mo+ement $ont!ol 2in$lu'in mo+ement-$ont!ol !es in the f!ontl

$o!te( s %ell s in sub$o!ti$l !eions3& llo%in e(e$uti+e 'e$isions to be tu!ne' into +olunt!" $tions.

/ 6)S)O1 O8 7O45)19 0E0O4Y



The +isul s"stem is one of the most tho!ouhl" stu'ie' s"stems in the b!in. 8o! this !eson& !ese!$h on

%o!kin memo!" n' othe! $oniti+e p!o$esses often uses +isul stimuli. Stu'ies of +isul p!o$essin& $ombine' %ith

the +st mount of kno%le'e bout the ntomi$l $onne$tions n' fun$tion of the +isul s"stem& h+e thus helpe'

$onst!u$t fi!l" 'etile' un'e!stn'in of the s"npti$ $onne$tions un'e!l"in %o!kin memo!".

:o!ti$l +isul p!o$essin beins in the p!im!" +isul !e lo$te' in the o$$ipitl lobe 2the !e!most p!t of

the $o!te(3. This !e !e$ei+es +isul info!mtion f!om the +isul thlmus& p!o$esses it& n' then 'ist!ibutes its out-puts to +!iet" of othe! $o!ti$l !eions. The %o!k of Leslie Une!lei'e!& Semi! eki& n' D+i' 6n Essen& mon

othe!s& hs been !esponsible fo! elu$i'tin the pth%"s of +isul p!o$essin in the $o!te(3 /lthouh these $i!$uits

!e eno!mousl" $omple(&* the pth%"s !esponsible fo! t%o b!o' spe$ts of +isul p!o$essin !e fi!l" %ell

un'e!stoo'. Thnks to Une!lei'e! n' 0o!t 0ishkin& these h+e $ome to be kno%n s the “%ht# n' “%he!e# +isul

pth%"s. The “%ht# pth%" is in+ol+e' in ob>e$t !e$onition& n' the “%he!e# pth%" in fiu!in out the sptil

lo$tion of tht ob>e$t !elti+e to othe! stimuli in the outsi'e %o!l'. The “%ht# pth%" in+ol+es p!o$essin st!em

tht t!+els f!om the p!im!" +isul $o!te( to the tempo!l $o!te(& n' the “%he!e# pth%" oes f!om the p!im!"

$o!te( to the p!ietl $o!te(.

The en' ste of the “%he!e# pth%" in the p!ietl $o!te( is 'i!e$tl" $onne$te' %ith the p!ef!ontl $o!te(.

/s 9ol'mn-4ki$& 8uste!& n' othe!s h+e sho%n& $ells in the p!ef!ontl !eion !e $ti+e 'u!in 'el" pe!io's in

sptil tsks 2%hi$h in+ol+e “%he!e# p!o$essin3& in'i$tin tht these $ells m" be in+ol+e' in the tempo!!" sto!e

of the stimulus info!mtion 'u!in the time %hen the stimulus is bsent. 0o!eo+e!& $ells in the “%he!e# p!o $essin

!e in the p!ietl $o!te( !e lso $ti+e 'u!in the 'el". S"npti$ inte!$tions bet%een the p!ietl “%he!e# !e

n' p!ef!ontl $o!te( m" the!efo!e llo% the nimls to keep in min' the sptil lo$tion of the !e%!'.

The “%ht# !e in the tempo!l $o!te( is lso $onne$te' %ith the p!ef!ontl $o!te(. E!l 0ille! n' Bob

Desimone the!efo!e ske' %hethe! $ells in the “%ht +isul pth%" n' the p!ef!ontl $o!te( miht both be $ti+e

'u!in 'el" pe!io' in %hi$h monke"s h' to !emembe! %hi$h of t%o simil! stimuli %s sso$ite' %ith !e%!'. )n

this e(pe!iment& the !e%!' %s pi!e' %ith p!ti$ul! stimulus& %hi$h is %h" the “%ht# st!em of p!o$essin %s

in+ol+e'. The" foun' tht $ells in both the p!ef!ontl $o!te( n' the tempo!l $o!te( “%ht# p!o$essin !e %e!e

$ti+e 'u!in the 'el".

The mintenn$e of +isul info!mtion in %o!kin memo!" thus ppe!s to 'epen' $!u$ill" on info!mtion

t!nsfe! o+e! s"npti$ pth%"s bet%een spe$ili,e' !es of the +isul $o!te( n' the p!ef!ontl !eion. The

pth%"s f!om the spe$ili,e' +isul !es tell the p!ef!ontl $o!te( “%ht# is out the!e n' “%he!e# it is lo$te'.

0o!eo+e!& these !e t%o-%" st!eetsA the p!ef!ontl $o!te(& b" %" of s"npti$ pth%"s b$k to the +isul !es&

inst!u$ts the +isul !es to tten' to n' st" fo$use' on those ob>e$ts n' sptil lo$tions tht !e bein

p!o$esse' in %o!kin memo!". 4e$ent stu'ies b" 9ol'mn4ki$ n' Li, 4omnski h+e foun' tht u'ito!" %o!kin

memo!" in+ol+es simil! !eltions bet%een u'ito!" p!o$essin st!ems n' p!ef!ontl !es& suestin tht this

s$heme in+ol+in linkes bet%een spe$ili,e' senso!" p!o$essin s"stems n' p!ef!ontl $o!te( m" be ene!ll"

ppli$ble $!oss mn" s"stems.

O4DE4S 84O0 THE TOP

The flo% of info!mtion f!om lo%e!- to hihe!-le+el p!o$essin sttions is %ht $oniti+e ps"$holoists $ll

bottom-up p!o$essin& n' the flo% f!om hihe! to lo%e! sttions is $lle' top-'o%n p!o$essin3 Thus& the pth%"

f!om the “%ht# !e to the p!ef!ontl $o!te( t!nsmits bottom-up info!mtion 2pl$in ob>e$t-i'entif"in

info!mtion in the %o!ksp$e3& n' the pth%" f!om p!ef!ontl $o!te( b$k to the “%ht# !e t!nsmits top-'o%n

info!mtion 2e(e$uti+e $ont!ol sinls tht help keep ttention fo$use' on the

ob>e$t tht is !ep!esente' in the %o!ksp$e3. Top-'o%n $ti+ities !e >ust nothe! nme fo! e(e$uti+e

fun$tions.

Jonthn :ohen n' D+i' Se!+n-S$h!eibe! use' the so-$lle' St!oop tsk to stu'" top-'o%n e(e$uti+e



influen$es on lo%e!-o!'e! p!o$essin3. )n this p!o$e'u!e people !e i+en b!ief +isul p!esenttions of simple %o!'s

2$olo! nmes3 n' !e ske' to eithe! nme the %o!' o! stte the $olo! of ink the %o!' is p!inte' in. On some t!ils&

the %o!' nme n' $olo! !e in $onfli$t 2the %o!' !reen is p!esente' in !e' lette!s3 n' on othe!s the" !e $on!uent

2the %o!' !reen is p!esente' in !een lette!s3. )t tkes mu$h lone! to stte the ink $olo! in the $onfli$t thn in the

$on!uent sitution& but sub>e$ts ten' to et it !iht. Unlike no!ml sub>e$ts& ptients %ith 'me to the p!ef!ontl

$o!te( fil this tsk3. The" !e unble to use the inst!u$tion i+en b" the e(pe!imente! to supp!ess the mo!e$ommonl" i+en !esponse of %o!'nmin. S$hi,oph!eni$s& %ho !e belie+e' to h+e f!ontl '"sfun$tion& lso 'o

poo!l". 8un$tionl imin stu'ies b" se+e!l !oups h+e sho%n tht the p!ef!ontl $o!te( is $ti+te' 'u!in the

$onfli$t $on'ition in no!ml sub>e$ts but not in s$hi,oph!eni$s. These fin'ins suest tht e(e$uti+e fun$tions& b"

%" of $onne$tions f!om the p!ef!ontl $o!te( b$k to lo%e!-o!'e! p!o$esso!s 2$olo! n' %o!' p!o$esso!s3& use the

inst!u$tions i+en b" the e(pe!imente! 2n' kept $ti+e in %o!kin memo!"3 to inhibit the mo!e ntu!l %o!'-nmin

!esponse n' f$ilitte the less $ommon !esponse of sttin the ink-$olo! nme. :oniti+e s$ientists often fin' it

useful to p!o!m $ompute! simultions to help them un'e!stn' ho% ps"$holoi$l n' sometimes neu!l p!o$esses

%o!k. :ohen n' Se!+n-S$h!eibe! 'i' this in n effo!t to $$ount fo! the !ole of the p!ef!ontl $o!te( in the St!oop

tsk.

/lthouh it ene!ll" hs been ssume' tht tempo!!" sto!e n' e(e$uti+e fun$tions !e $!!ie' out b"

the sme net%o!ks in the p!ef!ontl $o!te(& most stu'ies h+e fo$use' on the fo!me! !the! thn the ltte!. Ho%e+e!&

0!k D*Esposito n' $olleues 'esine' n e(pe!iment to e(plo!e e(pli$itl" the !ole of p!ef!ontl !es in e(e$uti+e

fun$tions. The" h' humn sub>e$ts pe!fo!m +e!bl i'entifi$tion tsk 2e..& !espon' if "ou he! +eetble nme3

n' +isul tsk 2!espon' if $e!tin sptil !!nement of stimuli o$$u!s3 .

The tsks %e!e pe!fo!me' eithe! sep!tel" 2%hi$h %s es" n' 'i' not !e@ui!e e(e$uti+e fun$tions3 o!

simultneousl" 2%hi$h %s 'iffi$ult n' 'i' !e@ui!e e(e$uti+e fun$tions& sin$e the sub>e$ts h' to keep t!$k of t%o

'iffe!ent kin's of stimuli t on$e3. The !esults sho%e' tht the p!ef!ontl $o!te( %s $ti+te' %hen the t%o tsks

%e!e pe!fo!me' simultneousl"& but not %hen the tsks %e!e pe!fo!me' in'i+i'ull". Sin$e the!e %s no tempo!!"

sto!e !e@ui!ement in the tsk 2no 'el" bet%een stimulus n' !esponse3& the !esults spe$ifi$ll" impli$te the

p!ef!ontl !eion in e(e$uti+e fun$tions. / numbe! of othe! stu'ies h+e lso no% $le!l" 'emonst!te' tht the

humn p!ef!ontl $o!te( is in'ee' $ti+te' %hen e(e$uti+e ope!tions !e pe!fo!me'& s %ell s %hen info!mtion is

sto!e' tempo!!il".

8o! ob+iousl" !esons& it is mo!e 'iffi$ult to stu'" e(e$uti+e fun$tions in nonhumn p!imtes. You

$n*t >ust i+e +e!bl inst!u$tions to monke"& %hi$h hs to be t!ine' non+e!bll" on e$h step of i+en tsk. But it

hs lon been thouht tht 'efi$it in 'el"e' !esponse pe!fo!mn$e b" monke"s %ith f!ontl lesions %s not simpl"

'ue to loss of tempo!!" sto!e& sin$e the 'efi$it %s %o!se %hen the!e %e!e 'ist!$tin $ues. )t %s s if the mon-

ke"s $oul'n*t ino!e i!!ele+nt& 'ist!$tin info!mtion.

4e$entl"& stu'ies h+e beun to p!o+i'e e+i'en$e fo! the ope!tion of e(e$uti+e-like fun$tions in the monke"

b!in. 8o! e(mple& John 4e"nol's n' Bob Desimone t!ine' the monke"s to fo$us thei! ttention on the lo$tion on

s$!een %he!e 'ot ppe!s. This is& in essen$e& the t!inin of n e(e$uti+e fun$tion& ttention. Then the"

p!esente' pi$tu!e in tht sme !e 2tht is& %ithin the fiel' of ttention3. :ells in the e!l" stes of the +isul $o!te(

!espon'e' to the pi$tu!e. 7hen se$on' stimulus %s p!esente' on the s$!een %ith the fi!st& thouh& the $ells 'i' not

!espon'. E(e$uti+e fun$tions $ontinue' to fo$us $ellul! $ti+it" on the fi!st pi$tu!e& n' the ne% info!mtion bout the

se$on' pi$tu!e %s ino!e'. This %o!k& like the stu'ies 'es$!ibe' bo+e& suests tht ttentionl sinls !e

in+ol+e' in 'i!e$tin t!ffi$ in the “%ht# pth%"& $ont!ollin %hi$h stimuli !e p!o$esse'. )n !elte' %o!k& Leslie

Une!lei'e! n' $olleues h' humn sub>e$ts pe!fo!m simil! tsks %hile fun$tionl b!in $ti+it" %s mesu!e'.

The" !e$he' +e!" simil! $on$lusionA tht top-'o%n $ti+it" !eultes lo%e! +isul !es.

Stu'ies b" E!l 0ille!*s lb suest tht the p!ef!ontl $o!te( in the monke" b!in& s in the humn b!in& is

the sou!$e of top-'o%n sinls. 0onke"s %e!e fi!st sho%n t!et stimulus. Tht stimulus then ppe!e' in n !!"

%ith t%o i!!ele+nt stimuli. /fte! 'el"& the th!ee-stimulus !!" ppe!e' in. )f the t!et stimulus %s in the

sme lo$tion& the monke" h' to mke !esponse on le+e!. The !esults sho%e' tht p!ef!ontl $ells %e!e



p!ti$ul!l" !esponsi+e to the sele$tion of the t!et stimulus f!om the !!".

8u!the!& lthouh $ells in the +isul $o!te( !e lso sensiti+e to t!et sele$tion& thei! $ti+it" o$$u!!e' fte!

p!ef!ontl $ti+it"& suestin tht the ttentionl sinl o!iintes in the p!ef!ontl !eion n' is t!nsmitte' in top-

'o%n fshion to the +isul $o!te(.

But is the $ti+it" o$$u!!in in the p!ef!ontl $o!te( ne$ess!" in $onition& o! >ust lon fo! the !i'e= )n othe!

%o!'s& is the f!ontl $o!te( $ti+it" the !esult o! the $use of top-'o%n $onition= 4esults obtine' b" 4obe!t 5nihtsuest tht it is ne$ess!"& tht it is $usl. 5niht !e$o!'e' ele$t!i$l $ti+it" in the +isul $o!te( of humns usin

ele$t!o'es pl$e' on the s$lp. /lthouh this te$hni@ue 'oes not p!o+i'e 'etile' info!mtion bout spe$ifi$ neu!l

$i!$uits& it is suffi$ient to 'ete$t $ti+it" in !es like the +isul $o!te(. 1o!mll"& if sub>e$ts !e inst!u$te' to e(pe$t

$e!tin stimulus& the ele$t!i$l !esponse to tht stimulus in the +isul $o!te( %ill be enhn$e'. Ho%e+e!& this

ttentionl mo'ultion of lo%e!-le+el senso!" p!o$essin 'i' not o$$u! in ptients %ith 'me in the p!ef!ontl !eion.

The p!ef!ontl $o!te( ppe!s to be ne$ess!" fo! top-'o%n $onition to %o!k.

The impo!tn$e of top-'o%n sinls f!om the p!ef!ontl $o!te( in sele$tin neu!l $ti+it" in lo%e! p!o$esso!s

%s lso 'emonst!te' in n elent stu'" b" Ysushi 0i"shit*s tem in Jpn. The" m'e lesions in the b!ins of

monke"s in su$h %" tht llo%e' them to p!esent +isul stimuli so tht the “%he!e# !e in the tempo!l $o!te(

!e$ei+e' info!mtion eithe! bottom-up 2f!om the lo%e! !es of the +isul s"stem3 o! top-'o%n 2f!om the p!ef!ontl

$o!te(3& but not both. The" foun' tht top-'o%n info!mtion f!om the p!ef!ontl !e %s suffi$ient to sele$ti+el"

$ti+te $ells in the “%he!e# pth%".

/ $ent!l spe$t of e(e$uti+e fun$tions is 'e$ision-mkin. Stu'ies b" se+e!l !ese!$h !oups h+e beun

to !e+el ho% this %o!ks in the b!in. 0ost of the in+estition hs fo$use' on simple beh+io!& e"e mo+ement&

%hi$h is one tht offe!s mn" '+ntes to the e(pe!imente!. / monke" is fi!st inst!u$te'& th!ouh beh+io!l

t!inin& to !espon' to $e!tin stimulus $on'itions b" mo+in its e"es to $e!tin lo$tion. This !esponse is then use'

to ssess ho% the monke" mkes 'e$isions bout %ht to !espon' to on the bsis of %ht it sees. 8o! e(mple&

0i$hel Sh'len n' Jon-1m 5im sho%e' monke"s +isul stimuli mo+in in one 'i!e$tion o! nothe!. The mo+in

stimuli %e!e embe''e' in bus" b$k!oun'& mkin it impossible to !espon' $o!!e$tl" e+e!" time. The monke"& in

othe! %o!'s& h' to use the impe!fe$t info!mtion +ilble to mke 'e$ision bout the stimulus. 8u!the!& 'el"

%s impose' bet%een the stimulus n' the !esponse. E!lie! %o!k h' sho%n tht the motion stimulus is p!o$esse'

in spe$il !e of the +isul $o!te( $lle' 0T& %hi$h hs $onne$tions %ith the p!ef!ontl $o!te(. )n the ne%

e(pe!iment& 5im n' Sh'len !e$o!'e' neu!l !esponses in the p!ef!ontl $o!te( n' foun' tht neu!l $ti+it" in this

!eion p!e'i$te'& 'u!in the 'el"& %hi$h 'i!e$tion the e"es %e!e bout to mo+e in. The" $on$lu'e' tht these

p!ef!ontl $ells !e in+ol+e' in the $on+e!sion of stimulus info!mtion into !esponse plns. These $ells !e& in thei!

+ie%& p!t of the 'e$ision-mkin p!o$ess.

Some in+estito!s !ue tht $i!$uits in the so-$lle' “%he!e# !e of the p!ietl $o!te(& like p!ef!ontl $ells&

!e in+ol+e' in plnnin n' 'e$ision-mkin bout mo+ements. )n mn" %"s& these $ells pp!entl" fun$tion

simil!l" to p!ef!ontl $o!te( $ells. Ho%e+e!& one 'iffe!en$e seems to be tht the p!ietl $i!$uits !e in+ol+e' in

plnnin the ne(t mo+ement& %he!es p!ef!ontl $i!$uits p!ti$ipte in plnnin se+e!l steps he'. Lte!& %hen %e

$onsi'e! emotion n' moti+tion& %e %ill h+e the oppo!tunit" to e(plo!e othe! spe$ts of 'e$ision-mkin.

O1E SYSTE0 O4 0/1Y=

Stu'ies b" Jo@uin 8uste! fi!st sueste' tht the p!ef!ontl $o!te( miht inte!te sptil 2“%he!e#3 n'

ob>e$t 2“%ht#3 info!mtion& sin$e $ells !espon'in to these t%o kin's of info!mtion %e!e inte!mi(e' in the p!ef!ontl

$o!te(i This !esult %s $onsistent %ith the +ie% tht the p!ef!ontl $o!te( enes in ene!l-pu!pose tempo!!"

sto!e $!oss mn" p!o$essin 'omins. 0o!e !e$entl"& thouh& Pt 9ol'mn-4ki$ hs @uestione' the ssumption

tht the p!ef!ontl $o!te( is ene!l-pu!pose %o!kin memo!" p!o$esso!. She n' 8!se! 7ilson foun' e+i'en$e

tht $ells in+ol+e' in ob>e$t n' sptil p!o$essin !e $luste!e' in 'iffe!ent !es of the p!ef!ontl $o!te(. 4e$entl"&

Li, 4omnski n' 9ol'mn-4ki$ foun' ''itionl !es tht the" belie+e !e in+ol+e' in u'ito!" %o!kin memo!".



These fin'ins suest tht tempo!!" sto!e is $!!ie' out b" 'omin-spe$ifi$ !eions in the p!ef!ontl $o!te( n'

@uestion the notion of uni+e!sl %o!ksp$e. E' Smith n' John Joni'es !e$he' simil! $on$lusion& on the bsis

of su!+e" of fun$tionl imin stu'ies of %o!kin memo!" in humns. Ho%e+e!& E!l 0ille! hs pointe' out tht

the!e !e numbe! of $ells in e$h f!ontl !e tht 'o not !espon' e($lusi+el" to one kin' of stimulus. 8u!the!& the

'iffe!ent !es !e inte!$onne$te' e(tensi+el" %ith one nothe!. )t is @uite possible tht the +!ious !es %o!k

toethe! to inte!te info!mtion $!oss 'omins& n' $oul'& in f$t& $onstitute sinle 'ist!ibute' s"stem 2 s"stemtht is sp!e' o+e! se+e!l b!in !eions3 tht me'ites tempo!!" sto!e& !the! thn $olle$tion of in'epen'ent

s"stems. /''itionl %o!k is nee'e' to !esol+e this issue.

4e!'less of ho% tempo!!" sto!e fun$tions !e li' out& it ppe!s tht e(e$uti+e fun$tions !e not

p!titione' in the p!ef!ontl $o!te( on the bsis of the stimulus 'omin. This 'oes not men& ho%e+e!& tht the!e is

sinle e(e$uti+e !e tht tkes $!e of ll e(e$uti+e fun$tions. E(e$uti+e fun$tions& in f$t& seem to be sp!e' $!oss

multiple !eions of the f!ontl $o!te(. 8o! e(mple& the $lssi$ !e of the p!ef!ontl $o!te( impli$te' in %o!kin

memo!" hs been the lte!l p!ef!ontl $o!te(& lo$te' on the outsi'e su!f$e of the f!ontl $o!te(. Ho%e+e!& nothe!

!e& lo$te' on the me'il o! insi'e su!f$e of the f!ontl $o!te(& hs lso been $onsistentl" $ti+te' in fun$tionl

imin stu'ies of %o!kin memo!"& n' is one of the min !eions impli$te' in e(e$uti+e fun$tions. This !eion& the

nte!io! $inulte $o!te(& like the $lssi$ %o!kin memo!" !e in the lte!l p!ef!ontl !eion& !e$ei+es inputs f!om

+!ious spe$ili,e' senso!" s"stems& n' is ntomi$ll" inte!$onne$te' %ith the $lssi$ lte!l !e. 0o!eo+e!& both

!eions !e p!t of %ht $oniti+e ps"$holoist 0i$hel Posne! hs $lle' the f!ontl lobe ttentionl net%o!k&

$oniti+e s"stem in+ol+e' in sele$ti+e ttention& mentl !esou!$e llo$tion& 'e$ision-mkin p!o$esses& +olunt!"

mo+ement $ont!ol& n'Ko! !esol+in $onfli$t bet%een $ompetin stimuli. )t is temptin to think of the e(e$uti+e spe$ts

of %o!kin memo!" s in+ol+in s"npti$ inte!$tions bet%een neu!ons in the lte!l p!ef!ontl n' nte!io! $inulte

!eions& n' pe!hps othe! !es. 1e+e!theless& the +!ious spe$ts of e(e$uti+e fun$tions m" not be e@ull"

'ist!ibute' $!oss the +!ious !es. The!e is& in f$t& some e+i'en$e fo! lo$li,tion of p!ti$ul! e(e$uti+e fun$tions

tht is& in some tsks 'iffe!ent spe$ts of e(e$uti+e fun$tions 2fo! e(mple& stimulus o! !esponse sele$tion +s.

$onfli$t !esolution +s. 'e$ision-mkin3 h+e been foun' to ene 'iffe!ent !es of the p!ef!ontl $o!te( to 'iffe!ent

'e!ees. This in no %" implies the e(isten$e of multiple e(e$uti+es& e$h %ith thei! o%n plnnin n' 'e$ision-

mkin $p$ities. )nste'& it suests tht the +!ious $omponent e(e$uti+e fun$tions !e $hie+e' b" set of

inte!$onne$te' $i!$uits tht !e sp!e' o+e! se+e!l b!in !eions in the f!ontl $o!te(& n' e+en othe! !eions& s

'is$usse' mo!e in $hpte! F.

THE 1UTS /1D BOLTS O8 THOU9HT

Ho% 'oes %o!kin memo!" fun$tion t the le+el of $ells n' s"npses= 7hile this p!o$ess is still not full"

un'e!stoo'& %e $n t lest bein to pie$e toethe! n e(plntion.

The p!ef!ontl $o!te(& like othe! !es of the neo$o!te(& hs si( l"e!s. /n'& s in othe! !es& the mi''le

l"e!s ten' to !e$ei+e inputs f!om othe! !eions& %hile the 'eep l"e!s ten' to sen' outputs to othe! !eions. So (ons

f!om othe! $o!ti$l !es& su$h s !es in+ol+e' in “%ht# n' “%he!e# p!o$essin& fo!m s"npses on $ells in the

mi''le l"e!s of p!ef!ontl $o!te(. These input $ells then sen' (ons to $ells in the 'eep l"e!s& %hi$h i+e !ise to $on-

ne$tions tht o b$k to the mi''le-l"e! $ells& o! to othe! $o!ti$l o! sub$o!ti$l !es& espe$ill" !es in+ol+e' in the

$ont!ol of mo+ement& n' thus of beh+io!l !esponses. )n this mnne!& the 'eep n' mi''le l"e!s $n influen$e

e$h othe!. )n ''ition& thouh& input $ells in the mi''le l"e!s n' output $ells in the 'eep l"e!s e$h i+e !ise to

lo$l $onne$tions to othe! $ells in the sme l"e!. This !!nement llo%s the input $ells to influen$e othe! input

$ells& n' output $ells to influen$e othe! output $ells.

T!nsmission of inputs to n' outputs f!om the p!ef!ontl $o!te(& n' bet%een $ells %ithin n' bet%een

l"e!s %ithin the p!ef!ontl $o!te(& is me'ite' b" the bin'in of p!es"npti$ll" !elese' lutmte to posts"npti$

!e$epto!s. )nte!estinl"& e(t!insi$ inputs to these $i!$uits $$ount fo! onl" smll p!t of the e($itto!" s"npti$

$onne$ti+it" of the p!ef!ontl $o!te(. The $onne$tions %ithin the p!ef!ontl $o!te(& both %ithin n' bet%een l"e!s& !e



f! mo!e nume!ous thn the $onne$tions $omin in f!om othe! !es& su$h s senso!" p!o$essin !eions. The mutul

e($ittions me'ite' b" the inte!nl $onne$tions enble input sinls f!om the outsi'e to be mplifie' n' kept $ti+e&

n' m" %ell $ont!ibute to the sustine' $ti+it" tht hs been obse!+e' 'u!in 'el" pe!io'sA

Of $ou!se& the!e is lso inhibition in these $i!$uits. 0ost of the inhibito!" $onne$tions !e on the 'eep-l"e!

output $ells. Ho%e+e!& be$use these $ells lso h+e e($itto!" p!o>e$tions b$k to uppe! l"e!s n' to othe! $ells in

the sme l"e!& lo$l inhibition in the lo%e! l"e!s $n !eulte mu$h of the e($itto!" flo% th!ouh the net%o!k.0u$h of %ht %e kno% bout the $ont!ibution of e($itto!" n' inhibito!" $i!$uits in the p!ef!ontl $o!te( to

%o!kin-memo!" $ente!s !oun' the neu!omo'ulto! 'opmine. The p!ef!ontl $o!te( !e$ei+es !i$h suppl" of (ons

$ontinin 'opmine& n' 'epletion of the substn$e in the p!ef!ontl $o!te( 2b" in>e$tin 'opmine-'est!o"in '!us3

is s effe$ti+e s $omplete !emo+l of the p!ef!ontl $o!te( in 'is!uptin 'el"e'-!esponse pe!fo!mn$e in monke"s.

)n 'opmine-'eplete' nimls& pe!fo!mn$e !e$o+e!s if '!u tht $ti+tes $e!tin $lss of 'opmine !e$epto!s is

infuse' into the p!ef!ontl $o!te(& thus t!i$kin the !e$epto!s n' the posts"npti$ $ells into $tin s if 'opmine

fibe!s %e!e still the!e !elesin thei! t!nsmitte!s. )nfusion of 'opmine into the p!ef!ontl $o!te( of "oun monke"s

enhn$es %o!kin memo!" $p$it"& n' in ol'e! ones& it !e+e!ses the e-!elte' 'e$!ement in %o!kin memo!".

Dopmine $ell bo'ies !e lo$te' in the b!in stem& in !eion $lle' the +ent!l tementl !e. The (ons

of these $ells then b!n$h e(tensi+el" n' !e$h mn" !es of the fo!eb!in& in$lu'in the p!ef!ontl $o!te(& %he!e

thei! te!minls !elese 'opmine. )n p!imtes& the 'opmine te!minls !e fi!l" e+enl" 'ist!ibute' th!ouhout the

l"e!s& llo%in 'opmine to bin' to !e$epto!s n' then mo'ulte e($itto!" n' inhibito!" t!nsmission in both the

input n' output l"e!s. /lthouh the!e !e mn" sub$lsses of 'opmine !e$epto!s& the Di fmil" 2%hi$h in$lu'es Di

n' Ds !e$epto!s3 hs been most $le!l" impli$te' in %o!kin memo!". These !e$epto!s !e lo$te' on the spines

n' shfts of 'en'!ites of e($itto!" $ells n' seem to !e'u$e the t!nsfe! of e($ittion f!om the 'en'!ites to the $ell

bo'ies& llo%in onl" espe$ill" st!on e($itto!" inputs to et th!ouh to the $ell bo'" n' eli$it e($ittion. Dopmine

!elese in the p!ef!ontl $o!te( lso seems to f$ilitte 9/B/ inhibition& possibl" b" %" of p!es"npti$ f$ilittion of

t!nsmitte! !elese& le'in to fu!the! !e'u$tion of e($ittion th!ouh p!ef!ontl $i!$uits. Some of these effe$ts

ppe! to in+ol+e the t!ie!in of p!otein kinse / in $ells $ontinin 'opmine !e$epto!s. )nte!tin these fin'ins&

/m" /!nsten hs p!opose' tht 'opmine p!ti$iptes in %o!kin memo!" b" bisin $ells to minl" !espon' to st!on

inputs n' the!eb" fo$usin ttention on $ti+e $u!!ent ols n' %" f!om 'ist!$tin stimuli.

THE 7)/4D O8 O

0ost of us h+e n intuiti+e sense tht thinkin 2$onition3 n' $ons$iousness !e $losel" !elte'. This

intuition is $o!!e$t but in$omplete. 6i!ini 7oolf %s p!obbl" !efe!!in to this %hen she pointe' out& “7e ll in'ule

in the st!ne& plesnt p!o$ess $lle' thinkin& but %hen it $omes to s"in..& %ht %e think& then ho% little %e !e

ble to $on+e" )mine tht "ou !e mentll" ene' in some $ti+it"& like !e'in the ne%sppe!. You ino!e the

othe! thins oin on !oun' "ou. But if somethin meninful o$$u!s in the b$k!oun'& like the soun' of "ou! nme&

"ou stop !e'in n' tu!n to the pe!son %ho $lle' "ou. /lthouh "ou! $ons$ious min' %s ino!in e+e!"thin p!t

f!om the +isul sinls f!om the ppe!& "ou! b!in %s not. )nputs f!om othe! senso!" s"stems $ontinue' to be $ ti+el"

p!o$esse'& othe!%ise the mention of "ou! nme $oul' not h+e inte!!upte' "ou. :onition n' $ons$iousness&

the!efo!e& !e not the sme. 7ht& then& is $ons$iousness& n' %ht 'ete!mines %ht %e !e $ons$ious of=

:ons$iousness $n be thouht of s the p!o'u$t of un'e!l"in $oniti+e p!o$esses. 7e*+e $tull" l!e'"

seen ho% the ke" p!o$esses %o!k. The stuff %e!e !e $ons$ious of is the stuff tht %o!kin memo!" is %o!kin on.

Thouh $oniti+e s$ien$e p!o+i'e' %" of stu'"in the min' %ithout et tin entnle' on the $ont!o+e!sil @uestion

of $ons$iousness& it hs& in the p!o$ess of $$ountin fo! %o!kin memo!"& lso p!o+i'e' p!$ti$l pp!o$h fo!

un'e!stn'in ho% $ons$iousness %o!ks.

Let*s t!nslte the e(mple bo+e into $oniti+e lnue. Du!in fo$use' ttention& mentl !esou!$es !e



llo$te' to the tsk t hn'. The e(e$uti+e& in othe! %o!'s& keeps lo%e!-le+el p!o$esso!s ene' in $ti+ities tht

suppo!t the tsk bein %o!ke' on. Ho%e+e!& if lo%e!-le+el p!o$esso!s tht !e not bein %o!ke' %ith t the moment

'ete$t some e+ent tht is un!elte' to the $u!!ent tsk but is mo!e impo!tnt thn the $u!!ent tsk& !esou!$es !e llo-

$te' to p!o$essin the ne% e+ent. The tsk mnement& s$he'ulin& n' $onfli$t !esolution fun$tions of the

e(e$uti+e shift ttention to the ne% e+ent n' mo+e info!mtion !ele+nt to it into %o!kin memo!". This fo!$es out the

e(istin info!mtion. Beh+io!s !ele+nt to the ne% tsk !e initite'A "ou tu!n to%!' the sou!$e of the soun'. )f& fte!s"in "ou! nme& the pe!son ske'& “7ht*s tht smell=# "ou %oul' p!obbl" st!t sniffin in n effo!t to ns%e! the

@uestion. Du!in these ope!tions& memo!ies !e !et!ie+e' into %o!kin memo!"& enblin "ou to !e$oni,e tht the

soun' spoken %s "ou! nme n' tht it %s "ou! f!ien' %ho spoke it. 2Ho% else %oul' "ou kno% "ou! nme e($ept

b" +i!tue of the f$t tht "ou !emembe! itC n' ho% else 'o "ou kno% tht it %s "ou! f!ien' %ho si' "ou! nme

e($ept tht "ou !emembe! he! +oi$e n' ppe!n$e=3 4et!ie+e' episo'i$ n' semnti$ memo!ies& s %ell s

s$hemt& then i' in e(e$uti+e 'e$ision-mkin.

/lthouh the en' !esult of e(e$uti+e p!o$esses 2monito!in& !esou!$e llo$tion& tsk mnement& $onfli$t

!esolution& memo!" !et!ie+l& et$.3 %s the !ep!esenttion of "ou! nme s $ons$ious $ontent in %o!kin memo!"& it*s

impo!tnt to !e$oni,e tht the e(e$uti+e p!o$esses tht m'e this possible fun$tione' un$ons$iousl". /s

neu!os$ien$e pionee! 5!l Lshle" pointe' out in the e!l" Fs& %e !e ne+e! %!e of p!o$essin& but onl" of the

$onse@uen$es of p!o$essin. Like the 7i,!' of O,& e(e$uti+e p!o$esses %o!k behin' the s$enes.

The %o!kin-memo!" mo'el of $ons$iousness suests tht the p!ef!ontl $o!te( shoul' pl" some !ole in

$ons$iousness. This is not no+el i'e. 8o! e(mple& the 4ussin ps"$holoist Lu!i& %hom %e en$ounte!e' e!lie!&

pointe' out t%o $h!$te!isti$ 'efi$its of ptients %ith 'me to the f!ontl lobesA the" l$k spontneous& pu!poseful

beh+io! n' the" l$k n un'e!stn'in of thei! 'efi$its. /n' /!thu! Benton& n /me!i$n neu!oloist %ho lon

stu'ie' the effe$ts of f!ontl lobe 'me& 'es$!ibe' t"pi$l ptient in the follo%in %"A “He hs ne+e! been seen

to sit self-bso!be'& to '"'!em o! to in'ule in int!ospe$tion. These ptients !e not& st!i$tl" spekin&

;;un$ons$ious&** but !the! seem to h+e f!$tu!e' un'e!stn'in of %ht the". /t the sme time& the" 'o not

t"pi$ll" suffe! totl 'est!u$tion of the p!ef!ontl $o!te(& n' the !emnnts of thei! $ons$ious sttes m" be 'ue to the

un'me' p!ts of this l!e n' $omple( b!in !eions %e*+e seen& %o!kin-memo!" fun$tions !e not lo$te'

in sinle !eion of the p!ef!ontl $o!te( but !e 'ist!ibute' $!oss %i'esp!e' !eions.

On the othe! hn'& the!e m" e(ist p!imiti+e le+els of $ons$iousness& espe$ill" in+ol+in the pssi+e

%!eness of e+ents s oppose' to the $ti+e use of on-line info!mtion to ui'e 'e$ision-mkin n' beh+io!& tht

'o not 'epen' on the p!ef!ontl $o!te(. These kin's of mentl sttes m" t"pif" $ons$iousness& to the e(tent tht it

'oes e(ist& in o!nisms tht h+e less o! no p!ef!ontl $o!te(& s 'is$usse' belo%.

)f the p!ef!ontl $o!te( pl"s n essentil !ole in humn $ons$iousness& it shoul' be in+ol+e' in e(pli$it

memo!"& memo!" to %hi$h %e h+e $ons$ious $$ess. )n'ee'& 'me to the humn p!ef!ontl $o!te( 'is!upts the

$ons$ious !et!ie+l of lon-te!m memo!ies& espe$ill" episo'i$ memo!ies. The p!ef!ontl $o!te( is $ti+te' 'u!in

episo'i$ memo!" !et!ie+l& n' the!e is lso e+i'en$e tht the p!ef!ontl $o!te( is in+ol+e' in the en$o'in 2fo!mtion3

of episo'i$ memo!". These fin'ins suest tht& in o!'e! to h+e n e(pli$it& $ons$ious memo!"& in ''ition to the

in+ol+ement of the me'il tempo!l lobe 2$hp. 3& t%o $on'itions nee' to be stisfie'A "ou h+e to be $ons$ious of

the info!mtion $onstitutin it t the time of the o!iinl e(pe!ien$e 2tht is& the e(pe!ien$e h' to be !ep!esente' in

%o!kin memo!" t the time it o$$u!!e'3& n' 'u!in !et!ie+l& "ou h+e to t!nsfe! the info!mtion f!om $o!ti$l

sto!e $i!$uits 2$hp. 3 into %o!kin memo!".

Just s !ese!$he!s stu'"in %o!kin memo!" often use +isul stimuli& theo!ists inte!este' in the b!in n'

$ons$iousness ten' to fo$us on +isul %!eness s %in'o% on $ons$ious e(pe!ien$e. 8o! e(mple& 1obel lu!ete

8!n$is :!i$k n' his $olleue :h!istof 5o$h h+e p!opose' n e(plntion of +isul %!eness tht buil's upon

kno%le'e of the !ole of the +isul s"stem in %o!kin memo!"Y The" !ue tht %e h+e $$ess to info!mtion p!o-

$essin o$$u!!in in +isul-p!o$essin !es $onne$te' %ith the %o!kin memo!" !es of the p!ef!ontl $o!te( but 'o

not h+e $$ess to info!mtion p!o$esse' b" !es not $onne$te' to these !es. )n'ee'& the p!im!" !e of the



+isul $o!te( is not $onne$te' %ith the p!ef!ontl $o!te(& n' %e 'o not e(pe!ien$e the $ontou!s n' sh'ins of

stimuli tht it p!o$esses. Ho%e+e!& the lte! p!o$essin !es !e $onne$te' %ith the p!ef!ontl $o!te( n' %e e(-

pe!ien$e the p!o'u$ts of these !eslobl fetu!es of ob>e$ts& like thei! shpe& $olo!& motion& n' lo$tion.

Se+e!l stu'ies p!o+i'e suppo!t fo! the :!i$kK5o$h theo!". 8o! e(mple& 4oe! Tootell n' $olleues

e(mine' %hethe! the b!in net%o!ks in+ol+e' in the p!o$essin of +isul motion %oul' be $ti+e %hen sub>e$ts %e!e

t!i$ke' into seein motion %he!e none e(ists. The" use' the %te!fll illusion& %hi$h is p!o'u$e' b" the p!esenttionof sttion!" stimuli t slihtl" 'iffe!ent times. The !esult %s in'ee' tht the motion-p!o$essin !e& %hi$h is n

'+n$e' +isul !e tht is $onne$te' %ith the p!ef!ontl $o!te(& %s p!ti$ul!l" $ti+e 'u!in the illusion of

mo+ement.

9i+en tht 'iffe!ent fetu!es of +isul stimulus 2shpe& $olo!& lo$tion& motion3 !e p!o$esse' in 'iffe!ent

$o!ti$l !es& in o!'e! to h+e $ons$ious pe!$eption of the stimulus s %hole ob>e$t& !the! thn s $olle$tion of

fetu!es& the elements h+e to be boun' toethe!. /lthouh %e $n sep!tel" i'entif" these fetu!es& %e usull"

e(pe!ien$e them toethe! s the $ohe!ent ob>e$t !the! thn s $omponent p!ts. Un'e!stn'in ho% the inte!tion

o$$u!s is $lle' the bin'in p!oblem3.

Bin'in is tken $!e of& t lest in p!t& b" the t!nsfe! of info!mtion f!om the in'i+i'ul p!o$essin !eions

to !es tht inte!te the info!mtion. /s %e*+e seen& this kin' of $on+e!en$e o$$u!s %ithin e$h senso!" s"stem.

8o! e(mple& the e!liest stes of the +isul $o!te( p!o$ess p!imiti+e fetu!es of ob>e$ts 2$ontou!s n' b!ihtness& fo!

e(mple3 n' the lte! stes p!o$ess mo!e $omple( fetu!es 2“%ht&# “%he!e&# n' mo+ement& fo! e(mple3. 8u!the!&

'iffe!ent $omple( fetu!es !e p!o$esse' in 'iffe!ent $i!$uits& !e@ui!in inte!tion o! bin'in $!oss $i!$uits s %ell s

%ithin them. /n' +isul stimuli 'o not o$$u! in isoltion but in the $onte(t of othe! kin's of stimuli 2soun's n' smells&

fo! e(mple3& !e@ui!in bin'in $!oss senso!" mo'lities. 8u!the!& the $ons$ious e(pe!ien$e of senso!" stimulus is

not >ust senso!" e(pe!ien$e. 7e usull" e(pe!ien$e stimuli s meninful ob>e$ts !the! thn s !% senstions.

Thus& the %" the stimulus looks& soun's& n' smells hs to be inte!te' %ith !ele+nt info!mtion sto!e' in memo!"&

in$lu'in f$ts n' pst e(pe!ien$es& s %ell s sto!e' info!mtion bout the emotionl n' moti+tionl sinifi$n$e

of the stimulus. Be$use p!ef!ontl !eions !e$ei+e $on+e!ent inputs f!om senso!"& memo!"& emotionl& n'

moti+tionl $i!$uits& the" !e belie+e' to be $pble of pe!fo!min the $omple( kin' of info!mtion inte!tion

2bin'in3 tht must o$$u! in the b!in 'u!in $ons$ious e(pe!ien$e.

But some !ese!$he!s feel tht info!mtion $on+e!en$e in %o!kin memo!" is not suffi$ient to $$ount fo!

the $ons$ious e(pe!ien$e of stimulus& o! fo! ou! bilit" to mke 'e$isions n' tke $tion !ele+nt to tht stimulus.

The" !ue tht the ''itionl in!e'ient nee'e' is neu!onl s"n$h!on". This te!m !efe!s to the simultneous fi!in of

popultions of neu!ons. S"n$h!on" is p!opose' to $hie+e t%o impo!tnt olsenhn$e' $ti+tion of posts"npti$

$ells n' $oo!'intion %ithin lo$l !es $!oss %i'esp!e' !eions. )t is %ell-estblishe' tht !oup of posts"npti$

$ells !e mo!e st!onl" $ti+te' %hen the" !e$ei+e s"n$h!onous inputs f!om p!es"npti$ $ells. Thus& if the b!in is

p!o$essin slient +isul stimulus& $ells in the +isul !es %ill fi!e s"n$h!onousl". /s !esult& the info!mtion

p!o$esse' in these !es %ill $ti+te p!ef!ontl !es mo!e st!onl"& n' the +isul stimulus %ill mke it into %o!kin

memo!" mo!e esil". The othe! p!opose' !ole of s"n$h!on" is $oo!'intion. Tht is& s"n$h!on" is belie+e' b" some to

help sol+e those spe$ts of the bin'in p!oblem tht info!mtion $on+e!en$e $nnot. /$$o!'in to this +ie%& neu!ons

tht fi!e toethe! in %i'esp!e' b!in !eions !e tempo!!il" boun' toethe!& n' this $ohe!en$e of fi!in& %hen

$ombine' in >ust the !iht %" $!oss the b!in& f$ilittes the !ep!esenttion in %o!kin memo!" of moment!il"

!ele+nt info!mtion f!om 'i+e!se !eions. 7hile $onsi'e!ble e+i'en$e e(ists sho%in tht s"n$h!on" o$$u!s n'

enhn$es posts"npti$ fi!in& the se$on' !ole of s"n$h!on"& $oo!'intion $!oss %i'esp!e' !eions& is $ont!o+e!sil&

espe$ill" s n e(plntion of $ons$ious pe!$eption. 27e*ll en$ounte! less $ont!o+e!sil !ole of s"n$h!on" in

$hpte! ii, nmel" in the $oo!'intion of s"npti$ plsti$it" $!oss b!in !eions.3

The %o!kin memo!" theo!" of $ons$iousness& e+en %ithout the ssistn$e of s"n$h!onous info!mtion

$oo!'intion $!oss b!in !eions& i+es us neu!l hn'le on $ons$iousness. But ho% f! $n %e o %ith this pu!suit

of $on-



s$iousness n' the b!in %ithout buttin he's %ith the min'-bo'" p!oblem 2$hp. 3= /fte! ll& it*s one thin

to s" tht the info!mtion in %o!kin memo!" is %ht %e $ons$iousl" e(pe!ien$e& n' nothe! to e(plin ho% those

e(pe!ien$es eme!e f!om %o!kin memo!". Simil!l"& it*s one thin to s" tht +olunt!" beh+io! !esults %hen

$ons$ious $ontent in %o!kin memo!" initites e(e$uti+e fun$tions tht then le' to mus$le mo+ements& n' @uite n-

othe! to e(plin ho% $ons$ious $ontent is t!nslte' into e(e$uti+e $ont!ol. To 'ulist& one %ho belie+es in

sep!te min' substn$e tht hs to someho% be me!e' %ith ph"si$l mtte!& these !e in'ee' 'iffe!entphenomen. But if& inste'& "ou& like me& belie+e tht the thins %e 'es$!ibe in mentl te!ms !e& in f$t& p!o$esses

oin on in the b!in& %o!kin memo!" point of +ie% is n e($ellent %" of tt$kin the p!oblem. 7hile it m" not t

this point full" $$ount fo! ll the subtleties of ho% $ons$iousness n' othe! spe$ts of the min' !ise f!om the b!in&

%o!kin memo!" is $le!l" $on$ept %e $n %o!k %ith %ell.

THE 4E6OLUT)O1 O8 THE TH)15)19 B4/)1

/s ) 'is$usse' in $hpte! Q& the p!ef!ontl $o!te( is espe$ill" %ell-'e+elope' in humns& is p!esent in othe!

p!imtes& !u'iment!" in nonp!imte mmmls& n' 'oesn*t e+en e(ist in othe! $!etu!es. 7ht !e the impli$tions o)

this fo! un'e!stn'in %o!kin memo!" n' $ons$iousness=

Let*s fo$us fi!st on the 'iffe!en$e bet%een nonhumn p!imtes n' othet mmmls. To 'o so& %e h+e to

$onsi'e! the o!ni,tion of the p!ef!ontl $o!te( in mo!e 'etilspe$ifi$ll"& the 'istin$tion bet%een 'iffe!ent p!e-

f!ontl !es. 7e*+e l!e'" 'is$usse' the lte!l p!ef!ontl $o!te(& %hi$h ls$ hs 'i+isions&oo bo+e. The me'il

p!ef!ontl $o!te( is lo$te' on the insi'$ %ll of the hemisphe!e. )mine the b!in*s hemisphe!es s the t%o p!ts oi

hot 'o bun. The b!o%n p!t on the outsi'e is like the lte!l $o!te( n' the %hite p!t on the insi'e is like the me'il

$o!te(. One !eion of the me'il p!ef!ontl $o!te( is the nte!io! $inulte& %hi$h& s %e*+e seen& is ls$ in+ol+e' in

e(e$uti+e fun$tions. )n ''ition& the +ent!l p!ef!ontl $o!te(& espe$ill" the o!bitl $o!te(& ppe!s to pl" !ole in

%o!kin memo!"& p!ti$ul!l" fo! emotionl info!mtion& s %e*ll 'is$uss in $hpte!s G n' F. 7hile othe! mmmls

h+e me'il n' +ent!l p!ef!ontl $o!ti$es& p!imtes lone ppe! to h+e lte!l p!ef!ontl $o!te(. Thus& one of the

m>o! !eions in+ol+e' in %o!kin memo!" in p!imtes $le!l" 'oes not e(ist in othei nimls. The f$t tht the

$oniti+e $p$ities of these $!etu!es 'o not $omp!e %ith those of p!imtes suests tht the uni@ue fetu!es of

p!imte $onition $me %ith the 'e+elopment of the lte!l p!ef!ontl !eion n' its inte!tion %ith e(istin net%o!ks

in+ol+in the me'il n' +ent!l !es. 8o! e(mple& !ts $n ene in tempo!!" sto!e& espe$ill" bout

emotionll" !ele+nt info!mtion& n' $n fo$us ttention on spe$ifi$ stimuli n' so fo!th& but !e f! mo!e limite' thn

p!imtes in thei! $p$it" to $teo!i,e the %o!l'& to 'is$!iminte mon 'iffe!ent stimuli n' e+ents& to !elte o!

sso$ite thins %ith one nothe! on-line& n' to use the !esults of these $oniti+e nl"ses to ui'e p!oblem-sol+in

n' 'e$ision-mkin.

)t*s impo!tnt to point out tht tempo!!" sto!e $n be $!!ie' out in 'omin-spe$ifi$ s"stems& like senso!"

o! emotionl s"stems& %hi$h $$ounts fo! sho!t-te!m memo!" in su$h nimls s bi!'s n' !eptiles. )t lso $$ounts

fo! 'omin-spe$ifi$ sho!t-te!m memo!" in mmmls. These 'omin-spe$ifi$ kin's of sho!t-te!m memo!" p!o$esses

m" un'e!lie p!imiti+e $ons$ious !ep!esenttions in nimls tht l$k elbo!te %o!kin memo!" fun$tions. Domin-

spe$ifi$ tempo!!" sto!e m" llo%& fo! e(mple& n %!eness of sinifi$nt stimuli& like the siht of p!e'to!& the

pin of bein in>u!e'& the tste of foo'& o! the >o" of se(. 7hen the !ousl eli$ite' b" the tempo!!il" sto!e'

info!mtion is suffi$ientl" intense& the $ti+it" of othe! s"stems m" be inhibite'& llo%in the $ti+e s"stem to

'ominte b!in fun$tion until the !ousin sitution subsi'es. )t is kno%n& fo! e(mple& tht se(ul impulses !e

inhibite' in th!etenin situtions. This kin' of !ousl $oul' be $hie+e' b" %" of inte!$tions bet%een& fo!

e(mple& p!e'to! 'ete$tion s"stem n' b!in stem !ousl $i!$uits 2s 'es$!ibe' in the ne(t $hpte!3. )n'ee'& 9!"

/ston-Jones of the Uni+e!sit" of Penns"l+ni n' othe!s h+e sho%n tht b!in stem !ousl s"stems un'e!lie

+iiln$e& sustine' beh+io!l enement in tsk. Su$h $onne$tions $oul' mke possible fo$use' ttention e+en

in $!etu!es l$kin p!ef!ontl $o!te( n' its multimo'l inte!ti+e $p$it" n' e(e$uti+e fun$tions.

)t is& of $ou!se& 'iffi$ult to kno% if othe! nimls e(pe!ien$e n"thin& sin$e %e $n*t sk them out!iht& but if



the" 'o& it m" be somethin kin to 'omin-spe$ifi$ senso!" $ons$iousness. The ke" element tht 'istinuishes

%o!kin memo!" f!om senso!" $ons$iousness is tht the fo!me! llo%s fo! the simultneous inte!!eltion of tempo!!il"

sto!e' info!mtion $!oss 'omins n' the fle(ible use of su$h info!mtion in 'e$ision-mkin& $p$ities tht

p!ef!ontl $i!$uits seem to mke possible. B" this nl"sis& somethin kin to humn $ons$iousness %oul' be p!esent

in othe! nimls %ith %ell-'e+elope' %o!kin memo!" s"stems 2nonhumn p!imtes3 but not in othe! $!etu!es.

But e+en nonhumn p!imtes l$k the uni@ue fetu!es of humn $ons$iousness. /s the no+elist n'ntu!list /nnie Dill!' s"s& “)t is i!oni$ tht the one thin tht ll !eliions !e$oni,e s sep!tin us f!om ou!

$!eto!ou! +e!" self-$ons$iousnessis lso the one thin tht 'i+i'es us f!om ou! fello% $!etu!es. )t %s bitte!

bi!th'" p!esent f!om e+olution.

Othe! thn si,e& %hi$h in this $se is sinifi$nt& the humn p!ef!ontl $o!te( hs nothe! impo!tnt

'+nte o+e! the p!ef!ontl $o!te( of nonhumn p!imtesA it hs $$ess to p!o$essin mo'ule spe$ili,e' fo!

lnue use. )n$!ese' si,e ''s po%e!& but the p!esen$e of lnue 'oes mo!e thn >ust soup up the $o!te(. 2)*m

!efe!!in he!e to the kin' of !mmti$l ntu!l lnue tht $h!$te!i,es essentill" e+e!" humn b!in& !the!

thn the othe! $ommuni$ti+e $p$ities tht $n o$$u! in othe! kin's of nimls& like $himps n' e+en p!!ots.3

Lnue !'i$ll" lte!s the b!in*s bilit" to $omp!e& $ont!st& 'is$!iminte& n' sso$ite on-line& in !el time& n'

to use su$h info!mtion to ui'e thinkin n' p!oblem-sol+in. The 'iffe!en$e bet%een h+in onl" non+e!bl %o!kin

memo!" n' h+in both +e!bl n' non+e!bl %o!kin memo!" is eno!mous fo! ho% the $oniti+e s"stem %o!ks.

)t is& in m" opinion& the st!u$tu!in of $onition !oun' lnue tht $onfe!s on the humn b!in its uni@ue

@ulities. Othe! nimls m" be $ons$iousl" %!e& in some sense& of e+ents oin on in thei! %o!l'. The" m" h+e

'omin-spe$ifi$ $ons$iousness& o! in the $se of nonhumn p!imtes& 'omin-in'epen'ent non+e!bl $ons$iousness&

but l$kin lnue n' its $oniti+e mnifesttions& the" !e unlikel" to be ble to !ep!esent $omple(& bst!$t

$on$epts 2like “me# o! mine o! “ou!s#3& to !elte e(te!nl e+ents to these bst!$tions& n' to use these

!ep!esenttions to ui'e 'e$ision-mkin n' $ont!ol beh+io!. Some '+n$e' p!imtes 'o h+e the bilit" to

+isull" !e$oni,e themsel+es in mi!!o! %hi$h suests sense of self-!e$onition in the bsen$e of ntu!l

lnue. )nte!estinl"& !e$ent stu'ies in 'olphins n' %hles sho% somethin simil!& suestin p!llel e+olution of

this $p$it"but @uestions h+e lso been !ise' bout the inte!p!ettion of these fin'ins. )n n" e+ent& self-

!e$onition 'oes not ne$ess!il" impl" self%!eness. 7e kno% f!om mn" kin's of e(pe!iments tht stimulus !e$o-

nition is not the sme s bein $ons$iousl" %!e of the stimulus. Stimulus !e$onition !e@ui!es onl" tht n

imme'itel" p!esent stimulus mt$h some !ep!esenttion of simil! stimulus in memo!". The!e is no nee' to h+e

$ons$ious %!eness to h+e !e$onition.

7hen ) use the te!m consciousness, ) usull" m !efe!!in to the spe$il @ulities of humn $ons$iousness&

espe$ill" those m'e possible b" lnue. 2The!e m" be othe! %"s tht the humn b!in 'iffe!s s %ell& but

lnue is p!ti$ul!l" impo!tnt 'iffe!en$e.3 This 'oes not impl" tht %e !e $ons$ious in Enlish o! :hinese o!

S%hili& no! 'oes it suest tht pe!sons %ho !e 'ef n' mute shoul' be $onsi'e!e' $oniti+el" impi!e'. 0" point&

!the!& is bout the %" the humn b!in is %i!e'. Tht is& the eme!en$e of the $oniti+e $p$ities un'e!l"in

lnue $hne' the %" the b!in %o!ks& mkin it possible fo! humn b!ins to think n' e(pe!ien$e e+ents in

%"s tht othe! b!ins $nnot. The ''ition of lnue into the humn b!in in+ol+e' !e+olution !the! thn n

e+olution of fun$tion.

P.S.

0" i'e tht lnue embellishes %o!kin memo!"& n' in so 'oin mkes humn $ons$iousness uni@ue&

be!s some !eltion to 0ike 9,,ni*s notion of n inte!p!eti+e s"stem in the left hemisphe!e tht i+es !ise to the

uni@ue p!ope!ties of humn $ons$iousness. )n nutshell& the essen$e of the inte! p!ete! theo!" is tht ou! $ons$ious



%!eness of %ho %e !e 'epen's on ou! linuisti$ inte!p!ettion 2lbelin& $teo!i,in& e(plinin3 of ou! e(pe!i-

en$es s %e o th!ouh life 2this is !elte' to the notion of n!!ti+e o! $onst!u$te' $ons$ious self 'is$usse' in

$hpte! 3. The simil!it" of m" i'es bout $ons$iousness to 9,,ni*s is pe!hps not su!p!isin& sin$e he %s m"

Ph.D. mento! in the FNs. 0ike h' been pu!suin $ons$iousness in the b!in sin$e his o%n '"s in !'ute s$hool

in the Fs. /s p!t of m" Ph.D. !ese!$h& %e 'i' stu'ies of split-b!in ptient& kno%n s P. S.& tht !etl" in -

fluen$e' us both.flo 0ike eme!e' %ith the theo!" of the inte!p!ete!& n' ) %ith "e!nin to un'e!stn' the emotionlb!in. But %e*+e $ome full $i!$le. Emotions no% pl" n impo!tnt !ole in his theo!ies of $ons$iousness& n'& s %e

see in the ne(t $hpte!& $ons$iousness& in the fo!m of %o!kin memo!"& hs $ome to be n impo!tnt p!t of the %" )

think bout emotions& espe$ill" feelins.

:H/PTE4 E)9HT

THE E0OT)O1/L B4/)1

4E6)S)TEDTHE /D6/1T/9E O8 THE E0OTPO1S PS TH/T THEY LE/D US /ST4/Y

Os$! 7ple

Emotions $n& s 7il'e s"s& le' us st!". But thei! in$lusion in the mentl t!ilo" b" !et thinke!s

th!ouh the es $omes less f!om thei! 'ist!$tin @ulities thn f!om thei! $ont!ibution to 'efinin %ho %e !e. /

pu!el" $oniti+e +ie% of the min'& one tht o+e!looks the !ole of emotions& simpl" %on*t 'o. /s %e bein to ssemble

the self in te!ms of s"npses& emotions must pl" m>o! !ole.

THE E0OT)O1/L B4/)1 /1D )TS 6):)SS)TUDES

/s soon s pionee!in b!in !ese!$he!s of the lte nineteenth $entu!" i'entifie' !eions of the neo$o!te(



in+ol+e' in senso!" pe!$eption n' mo+ement $ont!ol 2$hp. Q3& 7illim Jmes ske' %hethe! emotions miht lso be

e(pline' in te!ms of these p!ti$ul! fun$tions& o! %hethe! the" %e!e !the! the business of sep!te& "et

un'is$o+e!e'& b!in s"stem.* Bein p!mtist& he p!opose' theo!" of emotion bse' solel" on fun$tions of

senso!" n' moto! me$hnisms. Spe$ifi$ll"& he !ue' tht emotionll" !ousin stimuli !e pe!$ei+e' b" senso!"

$o!te(& %hi$h $ti+tes moto! $o!te( to p!o'u$e pp!op!ite bo'il" !esponses. Emotionl feelins then !esult %hen ou!

senso!" $o!te( pe!$ei+es the senstions tht $$ompn" bo'il" !esponses. Sin$e 'iffe!ent emotions in+ol+e spe$ifi$bo'il" !esponses& the" h+e 'istin$t senso!" sintu!es n' thus feel 'iffe!ent. The essen$e of Jmes*s !ument is

$ptu!e' b" his $on$lusion tht %e 'o not !un f!om be! be$use %e feel f!i'& but inste' %e feel f!i' be$use

%e !un.

Jmes*s theo!" %s @ui$kl" !efute' b" !ese!$h sho%in tht $omplete !emo+l of the neo$o!te( file' to

'is!upt the e(p!ession of emotionl !esponses eli$ite' b" senso!" stimuli& thus suestin tht senso!" n' moto!

$o!te( $oul' not be the ke"3* Subse@uent stu'ies then impli$te' spe$ifi$ b!in !es& mn" in+ol+in sub$o!ti$l o!

ol' $o!ti$l !eions& s oppose' to neo$o!te(& t!en' tht le' to the +ie% tht the b!in 'oes in'ee' h+e spe$il

emotion s"stem. This t!en' ultimtel" $ulminte' !oun' mi'-$entu!" in the fmous n' still popul! limbi$ s"stem

theo!" of emotion& %hi$h inspi!e' mn" subse@uent stu'ies 2%e*ll $onsi'e! this theo!" in 'etil belo%3. B" the mi'-

Fs& thouh& !ese!$h on the neu!l bsis of emotion h' ll but $ome to hlt& o! t lest slo% $!%lfte!

'e$'es of $on$ent!te' ttention& neu!os$ientists fo!sook the topi$.*

Like ps"$holoists& b!in !ese!$he!s %e!e st!onl" influen$e' b" the eme!en$e of $oniti+e s$ien$e& n'

emotions %e!e not p!t of the $oniti+e me pln. Emotions seeme' mo!e mtte! of mentl $ontent thn of mentl

p!o$essin& n' %e!e not pu!sue' b" those inte!este' in the thinkin p!o$ess. /lthouh $oniti+e s$ientists 'i'n*t

'en" tht emotions %e!e impo!tnt& the" belie+e' the sub>e$t %s not !ele+nt to thei! flel'. /s inte!est in $onition

!ose& !ese!$h on emotion 'e$line' in neu!os$ien$e.

)n !e$ent "e!s& ho%e+e!& emotion& p!t t%o of the mentl t!ilo"& hs in be$ome popul! topi$ fo!

in+estition in neu!os$ien$e. /n' enthusism b" b!in !ese!$he!s hs in tu!n helpe' !e+itli,e inte!est in emotions

b" ps"$holoists. /lthouh ) 'is$usse' some spe$ts of this ne% %+e of !ese!$h in The Emotional Brain, mu$h hs

hppene' sin$e& espe$ill" in te!ms of ho% niml stu'ies of emotion !elte to the humn b!in. Befo!e %e tu!n to !e -

se!$h on the neu!l bsis of emotion& ) the!efo!e %nt to spen' some time 'is$ussin the !eltion of niml n'

humn stu'ies of emotion.

THE :4ED)B)L)TY P4OBLE0

Emotion !ese!$he!s& %hethe! in ps"$holo" o! b!in s$ien$e& h+e t"pi$ll" souht to $$ount fo! %ht most

people think of s the essen$e of n emotion& the sub>e$ti+e e(pe!ien$e tht o$$u!s 'u!in n emotionl sttethe

feelin of fe! %hen in 'ne!& of ne! %hen m'& o! of >o" %hen somethin oo' hppens. This %s $le!l" the ol

of emotionl b!in theo!ies f!om Jmes th!ouh the limbi$ s"stem $on$ept. Ho%e+e!& most of %ht %e kno% bout

the 'etile' b!in me$hnisms of emotion $omes f!om stu'ies of emotionl beh+io! !the! thn f!om stu'ies of

feelins themsel+es. The e(plntion fo! this sitution is simple. 8eelins $n be stu'ie' in humns& but& fo! !esons

tht %ill be 'is$usse' belo%& the"*!e mo!e 'iffi$ult to e(mine in nimls. Sin$e& fo! both p!$ti$l n' ethi$l !esons&

most b!in !ese!$h is $on'u$te' in nimls& %e en' up %ith p bet%een %ht emotion theo!ies !e bout

2feelins3 n' %ht b!in !ese!$he!s $tull" mesu!e 2beh+io!3. This p& in tu!n& $!etes $!e'ibilit" p!oblem fo!

b!in !ese!$h on emotions.

The $!e'ibilit" issue $oul' be o+e!$ome if the!e %e!e some %" to in+estite feelins in nimls. )n

humns& the min metho' b" %hi$h feelins !e stu'ie' is tht of self-e+lution& often in the fo!m of +e!bl self-

!epo!ti Ho%e+e!& e+en self-e+lution is p!oblemti$ s s$ientifi$ tool fo! stu'"in emotionsA /s Donl' Hebb& fthe!

of the Hebb s"npse 2$hp. 3& pointe' out& outsi'e obse!+e!s !e often mo!e $$u!te in $h!$te!i,in emotionl

feelins thn the e(pe!ien$in sub>e$t. Jelous"& $$o!'in to Hebb& is often !e'il" 'ete$te' b" imp!til obse!+e!s

but 'enie' b" the >elous pe!son& %ho m" inste' $h!$te!i,e his stte s in'intion o! nno"n$e. Hebb note'



tht %hen obse!+e!s !ee n' the sub>e$t 'is!ees bout n emotionl stte& the $on$lusion of the obse!+e!s is

often mo!e !elible p!e'i$to! of futu!e beh+io!.

The t!'itionl %" of usin self-!epo!t to stu'" feelins is to sk people to !efle$t b$k on some p!e+ious

emotionl e(pe!ien$e. But ssessments f!om memo!" !e p!ti$ul!l" p!oblemti$. Dniel 5hnemn n' $olleues

h+e sho%n& in +!iet" of %"s& tht %ht %e !emembe! bout n emotionl e(pe!ien$e is n impe!fe$t !efle$tion of

%ht %s $tull" e(pe!ien$e'.# 8o! one thin& people ten' to !emembe! ho% the" felt t the en' of n emotionlepiso'e !the! thn ho% the" felt bout the %hole episo'e. )n one stu'"& ptients un'e!oin pinful me'i$l

p!o$e'u!e& $olonos$op"& %e!e ske' to !te thei! pin e+e!" si(t" se$on's. 8o! some sub>e$ts& the p!o$e'u!e %s

p!olone' fo! one minute& but un'e! mo!e $omfo!tble $on'itions 2the s$ope %s sttion!" 'u!in this time3. Lte!&

fte! it %s $omplete'& the" %e!e ske' to e+lute the enti!e e(pe!ien$e. 8o! sub>e$ts %ho h' the sttion!" s$ope

fo! the e(t! minute& n' thus e(pe!ien$e' less pin t the en'& the !emembe!e' e(pe!ien$e %s less +e!si+e& e+en

thouh the p!o$e'u!e $tull" lste' lone!. On the bsis of this n' mn" othe! stu'ies& 5hnemn $on$lu'e' tht

the !emembe!e' emotionl sinifi$n$e 2%ht he $lls the !e

membe!e' utilit"3 of n e(pe!ien$e 'oesn*t ne$ess!il" !efle$t the o+e!ll e(pe!ien$e 2its totl utilit"3.

Disto!tions in memo!" lso e(ten' be"on' the intensit" of e(pe!ien$e n' in$lu'e the $ontent of %ht is

!emembe!e'. 8o! e(mple& stu'ies b" Eli,beth Loftus n' othe!s h+e sho%n tht memo!ies of emotionl

e(pe!ien$es !e often sinifi$ntl" 'iffe!ent f!om %ht $tull" hppene' 'u!in them. She !epo!ts mn" instn$es in

%hi$h +i+i' memo!ies of $!ime s$enes tu!n out to be in$$u!te& if unintentionll" soC sometimes& in

unintentionll"& the" !e $ompletel" fb!i$te'.u /s B!tlett 'emonst!te' lon o& memo!ies !e $onst!u$tions

ssemble' t the time of !et!ie+l& n' the info!mtion sto!e' 'u!in the initil e(pe!ien$e is onl" one of the items

use' in the $onst!u$tionC othe! $ont!ibuto!s in$lu'e info!mtion l!e'" sto!e' in the b!in& s %ell s thins the

pe!son he!s o! sees n' then sto!es fte! the e(pe!ien$e.

Be$use !emembe!e' e(pe!ien$e is 'isto!tion of $tul e(pe!ien$e& n' be$use it*s 'iffi$ult to eli$it !el

emotionl e(pe!ien$e in lbo!to!" stu'ies& some $ontempo!!" !ese!$he!s emphsi,e the impo!tn$e of obtinin

imme'ite o! on-line e+lutions 'u!in !el emotionl episo'es 2mesu!es of instnt utilit"3& espe$ill" in ntu!l

settins. Thouh su$h stu'ies $i!$um+ent the e!!o!s of !emembe!e' utilit" n' the !tifi$ilit" of lbo!to!" !ese!$h&

the" !e e(t!emel" h!' to implement& s %ell s bein time-$onsumin& n' in the en' !e still sub>e$t to the bises

n' mesu!ement p!oblems inhe!ent in n" metho' tht !elies on one*s int!ospe$ti+e e+lution of his o! he! o%n

mentl sttes. The fllibilit" n' sub>e$ti+it" of int!ospe$tion !e& fte! ll& %ht t!ie!e' the beh+io!ist !e+olution in

ps"$holo" in the e!l" t%entieth $entu!". /n' !e$ll tht the $oniti+e !e+olution onl" su$$ee'e' in b!inin the min'

b$k to ps"$holo" be$use it fiu!e' out ho% to stu'" the min' %ithout !el"in on int!ospe$tionb" fo$usin on

mentl p!o$esses !the! thn mentl $ontent.

But if "ou %nt to ssess the int!ospe$ti+e $ontent of sub>e$ti+e e(pe!ien$e& the!e >ust !en*t mn"

lte!nti+es to self-e+lution n' +e!bl !epo!t. / sub>e$ti+e e(pe!ien$e is b" 'efinition one tht is kno%n 'i!e$tl" onl"

b" the e(pe!ien$in pe!son& n' +e!bl 'es$!iptions of sub>e$ti+e sttes !e the most 'i!e$t %" of ssessin them.

7hile the use of $he$klists o! s$les& %hi$h llo% sub>e$ts to in'i$te thei! feelins b" sele$tin f!om $hoi$es&

si'esteps the nee' fo! +e!bl beh+io! s the finl !esponse& in the en' the"& too& 'epen' on int!ospe$ti+e e+lution

of mentl sttes& n' ines$pbl" in+ol+e the use of %o!'s to $lssif" n' $teo!i,e mentl $ontent. 8o! e(mple&

the esiest %" to i'entif" %hi$h emotion "ou !e feelin is to lbel it +e!bll" s fe!& ne!& lo+e& o! 'isust. Some

e+en insist tht "ou 'on*t !ell" kno% %ht "ou !e feelin until "ou h+e lbele' it.

8EEL)19S )1 /1)0/LS

Some h+e !ue' tht n niml*s beh+io! $n be use' s kin' of non+e!bl self-!epo!t to ssess its

feelins. The neu!os$ientist Jk Pnksepp tkes this pp!o$h in Affecti+e Neuroscience, s 'oes& mo!e

$ont!o+e!sill"& the ps"$honl"st Jeff!e" 0sson in "hen Elephants "eep)9 Thei! loi$ is s follo%sA



Sin$e nimls n' humns beh+e simil!l" %hen emotionll" !ouse' 2fo! e(mple& simil! fe! !esponses

!e e(p!esse' b" !ts n' people in the p!esen$e of 'ne!3& the" must e(pe!ien$e the sme sub>e$ti+e sttes s

%ell. )f so& it %oul' be possible to use beh+io!l !esponses in nimls s in'i$to!s of feelins.

The fl% in this pp!o$h& %hi$h tkes us !iht b$k to the $!e'ibilit" p!oblem& is !e+ele' b" the !esults of

stu'" of humn he!oin ''i$ts. The sub>e$ts %e!e llo%e' to p!ess button to 'ministe! eithe! sline o! hih o!

lo% 'ose of mo!phine th!ouh n int!+enous tube. The sub>e$ts 'i' not kno% %ht %s in the tube t n" i+en point.Pe!io'i$ll"& the" %e!e ske' to !te ho% the" felt. 7hen hih 'ose of mo!phine %s in the tube& the" p!esse'

+io!ousl" n' lso !epo!te' feelin hih. 7hen sline %s in the tube& the sub>e$ts p!esse' little n' !epo!te' feelin

nothin. But %hen the 'ose of mo!phine %s %ek& the sub>e$ts +io!ousl" p!esse' the button in spite of the f$t tht

the" !epo!te' feelin nothin. :le!l"& one %oul' be misle' b" usin beh+io! s mesu!e of %ht %s felt in this

$se& sin$e the sub>e$ts beh+e' but 'i'n*t feel. Emotionl !esponses !e not l%"s e(te!nl mi!!o!s of inte!nl

feelins& but !e !the! $ont!olle' b" mo!e fun'mentl p!o$esses.

The p!oblem is onl" $ompoun'e' %hen %e e(mine the !eltion of beh+io! to feelins in 'iffe!ent spe$ies.

Just be$use t%o $!etu!es $t the sme 'oes not men the" h+e the sme e(pe!ien$es %hen the" pe!fo!m those

$tions. / beetle tht fin's itself un'e! the pp!o$hin footstep of humn 'oes %ht humn %oul' 'oit t!ies to

es$pe befo!e the foot ln's. / !obot $n be p!o!mme' to 'o %ht humn %oul' 'o if n ob>e$t is sent fl"in

to%!' his o! he! he'!ise n !m to 'efle$t the ob>e$t. Do the beetle n' !obot feel fe!& o! 'o the" simpl"

e(p!ess 'efensi+e !esponse= The f$t tht %e h+e feelins %hen %e $t emotionl 'oes not men tht e+e!" $t

tht looks emotionl is $$ompnie' b" feelins. The !eno%ne' etholoist

1iko Tinbe!en !e$he' simil! $on$lusionA “/lthouh. . . the etholoist 'oes not %nt to 'en" the possible

e(isten$e of sub>e$ti+e phenomen in nimls& he $lims tht it is futile to p!esent them s $uses& sin$e the" $nnot

be obse!+e' b" s$ientifi$ metho's. . . . Hune!& like ne!& fe!& n' so fo!th& is phenomenon tht $n be kno%n

onl" b" int!ospe$tion. 7hen pplie' to nothe! sub>e$t& espe$ill" one belonin to nothe! spe$ies& it is me!el"

uess bout the possible ntu!e of the niml*s sub>e$ti+e sttes.

9i+en tht %e !e left %ith non+e!bl beh+io! s ou! min tool fo! ssessin emotionl sttes in nimls&

n' tht niml stu'ies !e the best %" to stu'" the b!in& ho% $n %e es$pe the $!e'ibilit" p!oblem n' in

!i$he! ps"$holoi$l un'e!stn'in of the b!in*s emotionl $i!$uits= Ho% $n %e& in othe! %o!'s& stu'" emotions

usin non+e!bl emotionl beh+io! s mesu!e %ithout usin it s mesu!e of feelins= )!oni$ll"& n impo!tnt

$lue bout ho% to 'o this $omes f!om $oniti+e s$ien$e. /s %e s% in the lst $hpte!& $oniti+e s$ien$e %s

su$$essful be$use it fiu!e' out ho% to stu'" the min' %ithout ettin boe' 'o%n in @uestions bout sub>e$ti+e

e(pe!ien$e. The t!i$k %s to t!et the min' s n info!mtion-p!o$essin 'e+i$e !the! thn s pl$e %he!e

e(pe!ien$es o$$u!. /lthouh e!l" $oniti+e s$ientists $onsi'e!e' emotions to be mo!e mtte! of mentl $ontent

thn of info!mtion p!o$essin& n' thus not sub>e$t to $oniti+e nl"sis& thei! p!o$essin pp!o$h is& in f$t& 'i!e$tl"

ppli$ble to the stu'" of emotion. Just s it is possible to stu'" ho% the b!in p!o$esses the $olo! o! shpe of

stimulus %ithout fi!st fiu!in out ho% the $ons$ious e(pe!ien$e of $olo! o! shpe $omes bout& it is lso possible to

e(mine ho% the b!in p!o$esses the emotionl sinifi$n$e of stimulus %ithout ne$ess!il" fi!st fiu!in out ho%

tht stimulus $omes to eli$it $ons$ious feelins. Sin$e emotions s p!o$esses $n be stu'ie' in nimls n' humns

like& n' sin$e& s %e*ll see& emotionl p!o$essin un'e!lies both emotionl beh+io! n' emotionl feelins& p!o-

$essin pp!o$h is %" out of the $!e'ibilit" p!oblem.

E+en if this metho' llo%s us to $$ount fo! impo!tnt spe$ts of emotion in nimls %ithout h+in to !eso!t

to sub>e$ti+e sttes& it shoul' not be tken to men tht sub>e$ti+e sttes e(ist onl" in humns. )n the lst $hpte!& )

'is$usse' ho% othe! nimls miht h+e 'omin-spe$ifi$ fo!ms of $ons$iousness& n' in the $se of nonhumn

p!imtes& 'omin-in'epen'ent fo!ms of non+e!bl $ons$iousness& but ho% onl" humns h+e +e!bl %o!kin mem-

o!"& n' thus lnue-bse' $ons$iousness n' the mentl f!ills tht lnue mkes possible. The p!oblem is tht

s soon s %e !el" on sub>e$ti+e sttes to e(plin beh+io!& %e $onf!ont ou! inbilit" to kno% %hethe! su$h sttes

!ell" 'o e(ist in $!etu!es othe! thn humns. So m" pp!o$h hs been to 'is$uss $ons$ious emotions 2feelins3



onl" %ith !espe$t to humns& n' to !est!i$t m"self to the notion of emotionl p!o$essin %hen ) tlk bout $!etu!es

othe! thn humns. )n this %"& ) +oi' the $onst!u$tion of theo!" tht $n ne+e! be p!o+en& but t the e(pense of

h+in one tht m" be in$omplete. )*m $omfo!tble %ith this pp!o$h& thouh othe!s p!efe! the lte!nti+e.

E0OT)O1/L P4O:ESS)19

)n o!'e! to st" li+e& !emin helth"& n' p!opte thei! spe$ies& nimls h+e to be ble to 'ete$t f!ien'

n' foe& i'entif" sfe n' nut!itious foo's& sele$t mtes& n' !espon' pp!op!itel" to these n' othe! stimuli n'

situtions. /ttemptin to h+e se( %ith !the! thn 'efen' inst p!e'to! %oul' be $ostl". The!e must the!efo!e be

some me$hnism& some $i!$uit& lo$te' bet%een input n' output s"stems tht t!nsltes en+i!onmentl info!mtion

into spe$ifi$ !esponses %hen $e!tin kin's of stimuli o$$u!. )n f$t& the!e must be numbe! of su$h $i!$uits in the

b!in& sin$e 'iffe!ent s"stems !e in+ol+e' in 'efensi+e& fee'in& n' se(ul beh+io!s& to nme >ust fe% $teo!ies

of $ti+ities !elte' to su!+i+l n' %ell-bein. 7hen ) use the te!m emotional processin!, ) h+e the fun$tions of

$i!$uits like these in min'.

Spe$ifi$ll"& f!om this point of +ie%& emotion $n be 'efine' s the p!o$ess b" %hi$h the b!in 'ete!mines o!

$omputes the +lue of stimulus. Othe! spe$ts of emotion then follo% f!om this $omputtion. 8i!st& emotionl !e$-

tions o$$u!. These o+e!t bo'il" !esponses n' sso$ite' $hnes in inte!nl bo'" ph"siolo" !e the '+n$e u!'

of emotionl !esponsi+it". Subse@uentl" 2t lest in humns3& feelin eme!es s %e be$ome %!e tht ou! b!in

hs 'ete!mine' tht somethin impo!tnt is p!esent n' %e !e !e$tin to it. )n ''ition& i+en tht %e !e in n

emotionll" !ousin sitution& %e often tke $tion. Tht is& %e 'o thins to $ope %ith o! $pitli,e on the e+ent tht

is $usin us to be emotionll" !ouse'. Emotionl $tions& in othe! %o!'s& o$$u! %hen emotions moti+te us to 'o

thins. )*m oin to fo$us on emotionl !e$tions n' feelins he!e& n' s+e $tion fo! the ne(t $hpte!& %hi$h is

bout moti+tion.

)t*s !elti+el" es" to $$ount in neu!l te!ms fo! ho% emotionl !e$tions follo% f!om emotionl p!o$essinA

info!mtion !e$ei+e' b" senso!" s"stems $ti+tes emotionl-p!o$essin $i!$uits& %hi$h e+lute the menin of the

stimulus input n' initite spe$ifi$ emotionl !esponses b" t!ie!in output

$i!$uits. Defense& foo'-seekin& n' se( $i!$uits !e$ei+e inputs f!om the sme senso!" s"stems& n' thus

!e$ei+e simil! info!mtion& but i+en $i!$uit is onl" $ti+te' %hen the senso!" influ( $ontins stimulus info!mtion

!ele+nt to its ope!tion. These 'ete$tion n' !e$tion p!o$esses tke pl$e utomti$ll"& in'epen'ent of $ons$ious

%!eness of the stimulus n' feelins bout it. This is %h" $!e'ibilit" is not p!oblem f!om the point of +ie% of

emotionl p!o$essin.

The simplest %" to illust!te the in'epen'en$e of emotionl p!o$essin f!om $ons$iousness in the $ont!ol of

emotionl beh+io! is to 'es$!ibe n e(mple in %hi$h $ons$iousness is not f$to!. /t some point in "ou! life& "ou*+e

p!obbl" >umpe' out of the %" of somethin !pi'l" pp!o$hin n' onl" fte!%!' noti$e' %ht it %s bll

th!o%n t "ou o! bus fl"in b"& fo! e(mplen' lso onl" fte!%!' noti$e' "ou! he!t pumpin st!onl". The

feelin of fe! $me fte! "ou >umpe' n' fte! "ou! he!t %s l!e'" pumpinthe feelin itself 'i' not $use the

>umpin o! the pumpin. 7hile n ne$'ote like this 'oesn*t p!o+e n"thin& the!e is lso @uite lot of s$ientifi$

e+i'en$e fo! this kin' of !e$tion. The he!oin ''i$t stu'" 'es$!ibe' bo+e is one e(mple. Let*s $onsi'e! nothe!.

)t*s possible to p!esent stimuli to the b!in subliminll" 2un$ons$iousl"3. This $n be 'one in numbe! of

'iffe!ent %"s& but one $ommonl" use' is b$k%!'s mskin.Q )n this p!o$e'u!e& n emotionll" !ousin +isul

stimulus is flshe' on s$!een +e!" b!iefl" 2fo! fe% millise$on's3 n' is then follo%e' imme'itel" b" some neut!l

stimulus tht st"s on the s$!een fo! se+e!l se$on's. The se$on' stimulus blnks out the fi!st& p!e+entin it f!om

ente!in $ons$ious %!eness 2b" p!e+entin it f!om ente!in %o!kin memo!"3& but it 'oes not p!e+ent the fi!st f!om

eli$itin n emotionl !e$tion 2the stimulus still $hnes the betin of the he!t o! mkes the plms s%et3. Sin$e

the stimulus ne+e! !e$hes %!eness 2be$use it is blo$ke' f!om %o!kin memo!"3& the !esponses must be bse'

on the un$ons$ious p!o$essin of the menin of the stimulus !the! thn on the $ons$ious e(pe!ien$e of it. B" sho!t-

$i!$uitin the stes ne$ess!" fo! the stimulus to !e$h $ons$iousness& the mskin p!o$e'u!e !e+els p!o$esses

tht o on outsi'e of $ons$iousness in the humn b!in.



)n $!etu!es tht l$k the kin's of %o!kin memo!" p!o$esses tht enble info!mtion to be hel' in min'

$ons$iousl" 2see the 'is$ussion of the e+olution of thinkin in the lst $hpte!3& non$ons$ious p!o$essin is the !ule

!the! thn the e($eption. The bsi$ beh+io!l !epe!toi!e of these $!etu!es is !eulte' non$ons$iousl" be$use

the" l$k the kin' of b!in tht $n h+e $ons$ious e(pe!ien$e. The humn b!in hs these non$ons$ious

$pbilities s %ell. B" usin beh+io!l !e$tions 2n' sso$ite' $hnes in bo'" ph"siolo"C su$h s !esponses of

inte!nl o!ns3 tht o$$u! in emotionl situtions to in'e( o! mesu!e emotionl p!o$essin in e(pe!imentl nimls&the b!in me$hnisms tht un'e!lie this p!o$essin $n be un$o+e!e'. Stu'ies of people %ith b!in 'me& n'

fun$tionl imin stu'ies of un'me' people& $n be use' to +e!if" %hethe! the sme s"stems !e in+ol+e' in

emotionl p!o$essin in the humn b!in 2it*s mu$h esie! to +e!if" tht the sme s"stem is in+ol+e' thn to mke the

initil 'is$o+e!" in humns& %hi$h is %h" the niml stu'ies !e essentil to le' the %"3. /s lon s %e 'on*t pu!sue

spe$ts of emotion tht !e uni@ue to the humn b!in& n' s lon s %e $hoose n-

imls tht h+e emotionl p!o$esses tht !e !ele+nt to the humn emotion %e !e inte!este' in stu'"in&

%e $n pu!sue the b!in me$hnisms of humn emotionl p!o$essin in niml b!ins.

)t*s impo!tnt to 'istinuish p!o$essin pp!o$h to emotion f!om t%o othe! pp!o$hes. On the one hn'&

sin$e p!o$essin pp!o$h !elies on o+e!t !esponses& n' si'esteps sub>e$ti+e e(pe!ien$e& it m" soun' fun'men-

tll" beh+io!isti$. / fe% "e!s o& fte! i+in le$tu!e in %hi$h ) !ue' fo! this pp!o$h& ) %s& in f$t& $$use' of

bein !'i$l beh+io!ist 2one %ho 'enies tht the min' e(ists3 'isuise' s neu!os$ientist. But tht 'es$!iption

'oes not suit me fo! t%o !esons. 8i!st& )*m inte!este' in %ht oes on in the bl$k bo(& n' espe$ill" in ho% $i!$uits

in the b!in !ep!esent n' e+lute the menin of emotionl stimuli. ) 'on*t stu'" beh+io! to un'e!stn' beh+io! so

mu$h s to un'e!stn' ho% p!o$esses in the b!in %o!k. This inte!est in inte!nl p!o$esses lone 'is@ulifies me f!om

bein $onsi'e!e' !'i$l beh+io!ist. But& lso& )*m +e!" inte!este' in feelins n' $ons$iousness& topi$s tht

beh+io!ists shunne'. 7hile beh+io!ists tu!ne' %" f!om the nl"sis of the $ontent of sub>e$ti+e sttes& )& in

$ont!st& %nt to un'e!stn' sub>e$ti+e phenomen in te!ms of un'e!l"in p!o$esses !the! thn s $ons$ious

$ontent. Lte!& in f$t& ) %ill $onsi'e! ho% feelins eme!e f!om neu!l p!o$esses.

/ p!o$essin pp!o$h m" lso be $onfuse' %ith the so-$lle' $oniti+e pp!o$h to emotions& %hi$h

t!ets emotions s pp!islstht is& s thouhts bout i+en sitution. 7hile some pp!isl theo!ists llo% fo!

un$ons$ious pp!isls 2%hi$h is $onsistent %ith p!o$essin pp!o$h3& most emphsi,e pp!isls s $ons$ious

thouhts n' use +e!bl self-!epo!t to un'e!stn' the ntu!e of the pp!isl p!o$ess. This pp!o$h& ob+iousl"& tkes

us !iht b$k to the $!e'ibilit" p!oblem. :ons$ious pp!isls m" in'ee' o$$u! 'u!in n emotionl stte& but the!e

!e othe!& mo!e fun'mentl p!o$esses t %o!k s %ell. /n un'e!stn'in of these mo!e fun'mentl p!o$esses is

the ol of the p!o$essin pp!o$h.

)n si'esteppin the $!e'ibilit" p!oblem& p!o$essin pp!o$h thus llo%s us to stu'" un$ons$ious emotionl

fun$tions simil!l" in humns n' nimls& n' t the sme time offe!s metho' of un'e!stn'in emotionl $on-

s$iousness 2feelins3 s %ell 2sin$e feelins themsel+es !esult f!om p!o$esses tht o$$u! un$ons$iousl"3. )n ''ition&

p!o$essin pp!o$h p!esents nothe! '+nte. )t llo%s emotion n' $onition to be t!ete' the sme 2s

un$ons$ious p!o$esses tht $n but 'o not ne$ess!il" le' to $ons$ious e(pe!ien$es3& n' it opens the 'oo! fo! the

mu$h nee'e' inte!tion of $onition n' emotion 2n'& s %e*ll 'is$uss lte!& moti+tion3in sho!t& the !essembl"

of the mentl t!ilo".

/ ?U):5 8)X=

One %" to bein to !essemble the mentl t!ilo" miht be to put ll the ne%l" $@ui!e' info!mtion bout

the thinkin b!in tht $me f!om the $oniti+e !e+olution toethe! %ith the $ompellin +ie% of the emotionl b!in

p!o+i'e' lon o b" the limbi$ s"stem $on$ept. Pe!hps the notion of the limbi$ s"stem simpl" nee's to be

mo'e!ni,e' b" t!etin it s n emotionl-p!o$essin net%o!k !the! thn s the set of $ons$ious feelins. Ho%e+e!&

%hile the limbi$ s"stem !emins the p!e'ominnt e(plntion 2both in neu!os$ien$e n' popul! $ultu!e3 of ho% the

b!in mkes emotions& it is fl%e' n' in'e@ute theo!" of the emotionl b!in. ) m'e this point +e!" fo!$efull" in



The Emotional Brain, but those $!iti$isms be! !epetin.

The limbi$ s"stem $on$ept& b!in$hil' of the pionee!in neu!os$ientist Pul 0$Len& %s put fo!th in the

$onte(t of n e+olution!" e(plntion of min' n' beh+io!. )t built upon the +ie%& p!omote' b" $omp!ti+e

ntomists e!lie! in the t%entieth $entu!"& tht the neo$o!te( is mmmlin spe$ili,tionothe! +e!teb!tes h+e

p!imo!'il $o!te(& but onl" mmmls %e!e belie+e' to h+e neo$o!te( 2$hp. Q3. /n' sin$e thinkin& !esonin&

memo!"& n' p!oblem-sol+in !e espe$ill" %ell 'e+elope' in mmmls& n' p!ti$ul!l" in humns n' othe!p!imtes tht h+e !elti+el" mo!e neo$o!ti$l tissue& these $oniti+e p!o$esses %e!e belie+e' to be me'ite' b" the

neo$o!te( n' not b" the ol' $o!te( o! othe! b!in !es. )n $ont!st& the ol' $o!te( n' !elte' sub$o!ti$l !eions

fo!m the limbi$ s"stem& %hi$h %s si' to me'ite the e+olution!il" ol'e! spe$ts of mentl life n' beh+io!& ou!

emotions. )n this %"& $onition $me to be thouht of s the business of the neo$o!te(& n' emotions of the limbi$

s"stem.

The limbi$ s"stem theo!" ben to !un into t!ouble lmost imme'itel" %hen it %s 'is$o+e!e'& in the mi'-

Fs& tht 'me to the hippo$mpus& n ol' $o!ti$l !e n' the $ente!pie$e of the limbi$ s"stem& le' to se+e!e

'efi$its in 'istin$tl" $oniti+e fun$tion& lon-te!m memo!". This fin'in %s in$omptible %ith the o!iinl i'e tht

the p!imiti+e !$hite$tu!e of the limbi$ s"stem& n' espe$ill" of the hippo$mpus& %s poo!l" suite' to p!ti$ipte in

$oniti+e fun$tions. Subse@uentl"& in the lte Fs& it %s 'is$o+e!e' tht the e@ui+lent of mmmlin neo$o!te(

%s p!esent& thouh in !u'iment!" fo!m& in nonmmmlin +e!teb!tes 2$hp. Q3. /s !esult& the ol'Kne% $o!te(

'istin$tion b!oke 'o%n& $hllenin the e+olution!" bsis of

the ssinment of emotion to the ol' $o!te( 2limbi$ s"stem3 n' $onition to the neo$o!te(.

The limbi$ s"stem itself hs been mo+in t!et. 7ithin fe% "e!s fte! its in$eption& the 'efinition

e(pn'e' f!om the o!iinl notion of the ol' $o!te( n' !elte' sub$o!ti$l fo!eb!in nu$lei to in$lu'e some !es of

the mi'b!in& n' e+en some !eions of the neo$o!te(Y Se+e!l ttempts h+e been m'e to sl+e the limbi$

s"stem b" 'efinin it mo!e p!e$isel". 1e+e!theless& fte! hlf $entu!" of 'ebte n' 'is$ussion& the!e !e still no

ene!ll" $$epte' $!ite!i fo! stipultin %hi$h !es of the b!in belon to the limbi$ s"stem. Some s$ientists h+e

sueste' tht the limbi$ s"stem be bn'one'.

)n spite of these 'iffi$ulties& the limbi$ s"stem $ontinues to su!+i+e& both s n ntomi$l $on$ept n' s n

e(plntion of emotions& in te(tbooks& !ese!$h !ti$les& n' s$ientifi$ le$tu!es. This is in p!t tt!ibutble to the f$t

tht both the ntomi$l foun'tion n' the emotionl fun$tion it %s suppose' to me'ite %e!e 'efine' so +uel"

s to be i!!efutble. 8o! e(mple& in most 'is$ussions of ho% the limbi$ s"stem me'ites emotion& the menin of the

te!m emotion is not 'efine'. 4e'in bet%een the lines& it seems tht the utho!s !e often !efe!!in to somethin

kin to the $ommon Enlish-lnue use of the te!m& %hi$h is to s" feelins. Ho%e+e!& s %e*+e seen& $on$eption

of emotion in te!ms of feelins is p!oblemti$.

8u!the!& the ntomi$l $!ite!i fo! in$lusion of b!in !es in the limbi$ s"stem !emin un'efine'& n'

e+i'en$e tht n" limbi$ !e& in %hte+e! 'efinition& $ont!ibutes to n" spe$t of n" emotion hs ten'e' to be use'

s +li'tion fo! the %hole $on$ept. 8o! e(mple& be$use the m"'l %s in$lu'e' s one of the limbi$ !es&

stu'ies sho%in tht the m"'l p!ti$iptes in fe! %e!e +ie%e' s e+i'en$e tht the limbi$ s"stem theo!" %s

$o!!e$t& in spite of the f$t tht mn" othe! limbi$ !es pl"e' little o! no ob+ious !ole in fe! o! othe! emotions. )n

spite of mn" hun'!e's of e(pe!iments ime' t elu$i'tin the !ole of limbi$ !es in emotion& the!e is still +e!" little

un'e!stn'in of ho% ou! emotions miht be the p!o'u$t of the limbi$ fo!eb!in. P!ti$ul!l" t!oublin is the f$t tht

one $nnot p!e'i$t& on the bsis of the o!iinl limbi$ theo!" of emotion o! n" of its 'es$en'nts& ho% spe$ifi$

spe$ts of emotion %o!k in the b!in. The e(plntions !e ll post hoc, $on$o$te' fte! i+en e(pe!iment to e(plin

the 'ts$ientists t"pi$ll" put mo!e sto$k in p!e'i$tions thn e(plntions. This p!oblem is p!ti$ul!l" pp!ent in

!e$ent %o!k usin fun$tionl imin to stu'" the humn b!in. 7hene+e! so-$lle' emotionl tsk is p!esente'&

n' limbi$ !e is $ti+te'& the $ti+tion is e(pline' b" !efe!en$e to the f$t tht limbi$ !es me'ite emotion.

/n' %hen limbi$ !e is $ti+te' in pu!el" $oniti+e tsk& it is often ssume' tht the!e must h+e& in fact, been

some emotionl $omponent to the tsk. 7e !e& in othe! %o!'s& t point %he!e the limbi$ theo!" hs be$ome n off-



the-shelf e(plntion of ho% the b!in %o!ks& one !oun'e' in t!'ition !the! thn in f$ts. Defe!en$e to the $on$ept

is inhibitin $!eti+e thouht bout ho% mentl life is me'ite' b" the b!in.

/lthouh the limbi$ s"stem theo!" is in'e@ute s n e(plntion of the spe$ifi$ b!in $i!$uits of emotion&

0$Len*s o!iinl i'es !e insihtful n' @uite inte!estin in the $onte(t of ene!l e+olution!" e(plntion of

emotion n' the b!in. )n p!ti$ul!& the notion tht emotions in+ol+e !elti+el" p!imiti+e $i!$uits tht !e $onse!+e'

th!ouhout mmmlin e+olution seems !iht on t!et. 8u!the!& the !ument tht $oniti+e p!o$esses miht in+ol+eothe! $i!$uits& n' miht fun$tion !elti+el" in'epen'ent of emotionl $i!$uits& t lest in some $i!$umstn$es& lso

seems $o!!e$t. These fun$tionl i'es !e %o!th p!ese!+in& e+en if %e ultimtel" bn'on the limbi$ s"stem s n

ntomi$l theo!" of the emotionl b!in.

LESS )S 0O4E

The limbi$ s"stem theo!" file' in p!t be$use it ttempte' to $$ount fo! ll emotions simultneousl"& n'

in so 'oin 'i' not 'e@utel" $$ount fo! n" one emotion. 7hen ) ot in+ol+e' in emotion !ese!$h in the lte

FNs& ) 'e$i'e' to tke the opposite pp!o$h n' stu'" one emotionfe!-in 'etil. Belo%& )*m oin to fo$us

spe$ifi$ll" on %ht %e*+e le!ne' bout fe!& be$use it is the emotion bout %hi$h %e kno% most. But the bsi$

p!in$iples tht h+e been un$o+e!e' bout the fe! s"stem !e likel" to be ppli$ble to othe! s"stems s %ell.

/lthouh 'iffe!ent b!in $i!$uits m" be in+ol+e' in 'iffe!ent emotion fun$tions& the !eltion of spe$ifi$ emotionl-

p!o$essin $i!$uits to senso!"& $oniti+e& moto!& n' othe! s"stems is likel" to be simil! $!oss emotion $teo!ies.

0u$h of %ht %e*+e 'is$o+e!e' bout the neu!l bsis of fe! hs $ome f!om stu'ies of fe! $on'itionin

o+e! the pst t%o 'e$'es. This p!o$e'u!e& lon stn'!' tool in beh+io!l ps"$holo" h' not been use' mu$h to

stu'" the b!in until ) n' se+e!l othe! !ese!$he!s 'opte' it s %" of stu'"in emotionl le!nin $i!$uits. 2/s

mentione' in $hpte! 4, mu$h of the ke" %o!k on the neu!l bsis of fe! $on'itionin %s 'one b" the lbs of 4obe!t

n' :!oline Bln$h!'& B!u$e 5pp& 0i$hel D+is& n' 0i$hel 8nselo%& s %ell s mineC lso impo!tnt %e!e

e!lie! stu'ies b" D+i' :o

hen in pieons.3 7hile some limbi$ !es 'i' tu!n out to be in+ol+e' in fe! $on'itionin& the e($t lo$tions

n' the ntu!e of thei! in+ol+ement %oul' ne+e! h+e been p!e'i$te' b" the limbi$ s"stem theo!" lone.

)n the en'& fe! $on'itionin m" not tell us e+e!"thin %e %oul' like to kno% bout fe!& espe$ill" humn

fe!. 8o! e(mple& the neu!l $i!$uits in+ol+e' in !espon'in to $on'itione' fe! stimuli m" p!ti$ipte in& but !e

p!obbl" not suffi$ient to $$ount fo!& mo!e $omple( spe$ts of fe!-!elte' beh+io!& espe$ill" !esponses tht

'epen' not on spe$ifi$ stimuli but on bst!$t $on$epts n' thouhts& su$h s the fe! of filin& fe! of bein f!i'&

o! of fllin in lo+e. 1e+e!theless& fe! $on'itionin hs been n e($ellent %" to st!t un'e!stn'in some bsi$

f$ts bout fe!& espe$ill" ho% fe! !esponses !e $ouple' to spe$ifi$ stimuli tht people n' othe! nimls en-

$ounte! in thei! 'il" li+es.

7ht mkes fe! $on'itionin so useful f!om $i!$uit-t!$in point of +ie%= 8o! one thin& it*s simple

p!o$e'u!e. /ll it !e@ui!es to tu!n meninless stimulus& like tone pip& into fe!-!ousin e+ent is fe% o$$u!-

!en$es of the pip 2often onl" one3 t the sme time s n +e!si+e e+ent& like mil' sho$k to the skin. /lso& it*s

+e!stile>ust bout n" stimulus tht p!e'i$ts sho$k o! mn" othe! kin's of 'ne!ous stimuli $n se!+e s $on'i-

tione' fe! stimulus. )n ''ition& the le!nin is lon-lstin& n' m"be e+en pe!mnent. /n' it $n be 'ministe!e'

simil!l" in humns n' !ts& mkin it possible to stu'" the !t b!in fo! the pu!pose of un'e!stn'in humn fe!.

8u!the!& the !esponses !e h!'%i!e' n' utomti$. 7e 'on*t h+e to le!n to f!ee,e o! !ise bloo' p!essu!e in the

p!esen$e of 'ne!ous stimuli& fo! the b!in is p!o!mme' b" e+olution to 'o these thins. 7e h+e to le!n %ht to

be f!i' of& but not ho% to $t f!i'.

)mpli$it in ll this& of $ou!se& is st!te" fo! mppin out the fe!-p!o$essin $i!$uit. /ll %e h+e to 'o is

t!$e the pth%" fo!%!' f!om the input s"stem 2the senso!" s"stem tht p!o$esses the $on'itione' stimulus& s" the

tone pip3 to the output s"stem 2the s"stem tht $ont!ols f!ee,in o! othe! h!'%i!e' !esponses3. The fe!-p!o$essin

$i!$uits& b" this loi$& shoul' be lo$te' t the inte!se$tion of the input n' output s"stems.



1UTS )1 YOU4 B4/)1

Stu'ies of fe! $on'itionin h+e sho%n be"on' 'oubt tht the b!in !eion tht sits t the inte!se$tion of

input n' output s"stems of fe!& n' the ke" to un'e!stn'in ho% 'ne! is p!o$esse' b" the b!in& is the

m"'l. /$tull"& the!e !e t%o of them& one on e$h si'e of the b!in& but& fo! $on+enten$e& %e*ll tlk bout the

m"'l in the sinul!& sin$e the t%o 'o p!ett" mu$h the sme thin.

On$e n obs$u!e !eion of the b!in& the m"'l is p!$ti$ll" househol' %o!' these '"s. The Btmn

$omi$ se!ies Shado' of the Bat fetu!e' monste! $lle' “/m"'l# %ho %s nme' fte! the “lmon'-shpe'

mss of ne!+es in the b!in tht $ont!ols feelins of !e# 2“lmon'# is in'ee' the Enlish t!nsltion of amy!dala, the

9!eek-'e!i+e' %o!' use' to nme this st!u$tu!e be$use of its ppe!n$e3. 4e$entl"& ne%sppe! $olumn $lle'

“5i's* :it"# 'is$usse' the !ole of the m"'l in $hil'hoo' fe!s. / 7ebsite e(ists %he!e "ou $n “$li$k "ou!

m"'l&# tht is& $li$k on $e!tin buttons to e(pose "ou!self to stimuli tht %ill suppose'l" tu!n on "ou! m"'l.

One niht& %hile $hnnel su!fin& ) $me $!oss S$i-8i :hnnel sho% in %hi$h n lien %s ble to $ont!ol people*s

fe!s b" influen$in thei! m"'le 2tht*s the plu!l3. ) h+e e+en been $ont$te' b" l%"e!s hopin to mount n

“m"'l 'efense&# n !ument tht the +iolent $!ime pe!fo!me' b" thei! $lient %s the fult of the $lient*s m"'l

!the! thn his f!ee %ill. 8o! bette! o! %o!se& the m"'l is no lone! obs$u!e. But let*s put these issues !elte' to

the m"'l*s popul!it" si'e fo! no% n' o bit 'eepe! into its s"npti$ o!ni,tion n' fun$tion.

/s 'es$!ibe' in $hpte! & the m"'l $ontins 'o,en o! so 'istin$t 'i+isions o! !es& of %hi$h onl" t%o

!e ne$ess!" fo! fe! $on'itionin. )nfo!mtion bout the outsi'e %o!l' is t!nsmitte' to the lte!l nu$leus f!om

senso!"-p!o$essin !eions in the thlmus n' $o!te(& llo%in the m"'l to monito! the outsi'e %o!l' fo! sins

of 'ne!. )f the lte!l nu$leus 'ete$ts 'ne!& it $ti+tes the $ent!l nu$leus& %hi$h initites the e(p!ession of be-

h+io!l !esponses n' $hnes in bo'" ph"siolo" tht $h!$te!i,e sttes of fe!.

But %ht mkes $on'itionin o$$u!= 7e*+e l!e'" $onsi'e!e' this in $hpte!s n' & n' %ill >ust

summ!i,e he!e. 7hen soun' is p!esente' to ni+e niml& it !e$hes the lte!l nu$leus n' mil'l" $ti+tes

neu!ons the!e. 9/B/ inhibition p!e+ents mu$h f!om hppenin in !esponse& n' if the soun' is !epete' %ithout

$onse@uen$e& the $ells @ui$kl" stop !espon'in. But if the soun' is follo%e' b" sho$k& the %ek p!ee(istin

!esponse is !etl" mplifie' follo%in the !ules of Hebbin plsti$it"A the sho$k $ti+tes the posts"npti$ $ell %hile

the soun' is $usin the p!es"npti$ te!minls to !elese lutmte. Du!in the $ti+tion& $l$ium ente!s the

posts"npti$ $ell& n' then host of int!$ellul! $hemi$l !e$tions& in+ol+in kinses n'

t!ns$!iption f$to!s& $ti+te enes& in'u$in them to mke p!oteins tht then stbili,e the !eltion bet%een

the p!es"npti$ n' posts"npti$ neu!on. /s !esult of $on'itionin& the soun' $@ui!es the bilit" to eli$it st!on e(-

$ittion in the m"'l& mkin it mo!e potent stimulus fo! $ti+tin m"'l $i!$uits fte! $on'itionin thn it

%s befo!e. / stimulus tht %oul' no!mll" not et pst the 9/B/ u!' in the lte!l nu$leus the!eb" $omes to t!+el

%ith ese to the $ent!l nu$leus& %he!e the floo'tes of emotionl !e$ti+it" !e opene'.

PUTT)19 8E/4 )1 )TS PL/:E

:le!l"& mu$h hs been le!ne' bout the !ole of m"'l $i!$uits in fe! $on'itionin. 7ith this info!mtion

in hn'& %e $n no% bein to sk ho% p!o$essin in the m"'l !eltes to p!o$essin in $o!ti$l $i!$uits in+ol+e' in

$oniti+e p!o$essin. 7e st!t %ith $onsi'e!tion of the $onne$tions bet%een the hippo$mpus n' the m"'l&

n' thei! $ont!ibution to the $onte(tuli,tion of fe!tht is& the !eultion of fe! on the bsis of ou! ssessment of

the sitution %e !e in.

)n n emotionll" $h!e' sitution& the!e is often some stimulus tht stn's out& n' othe!s tht !e less

p!ominent& thouh ne+e!theless impo!tnt. 8o! e(mple& if "ou !e bein !obbe' t unpoint %hile +isitin fo!ein

$it"& the most slient f$to! is the u" %ith the pistol pointe' t "ou. But the $onte(t in %hi$h the !obbe!" o$$u!s is lso

sinifi$nt"ou m" %ell feel unes" if "ou o b$k to the st!eet $o!ne! %he!e it hppene'& o! e+en b$k to tht $it"



o! $ount!". 20" son n' his f!ien's %e!e on thei! %" to bsketbll me t nothe! s$hool %hen one of the bo"s

tu!ne' !oun' n' %ent home so tht he %oul' not h+e to $!oss n inte!se$tion %he!e he t!ippe' n' b!oke t%o

teeth se+e!l "e!s e!lie!.3 )n the lbo!to!"& %hen !t is $on'itione' to tone-sho$k $ombintion in $e!tin

$hmbe!& it %ill f!ee,e n' othe!%ise $t f!i' if it simpl" fin's itself b$k in tht $hmbe! t some lte! point. The

tone %s the most slient $ue& but othe! $ues in the $hmbe! %e!e $on'itione' s %ell.

The neu!l bsis of so-$lle' $onte(tul $on'itionin hs been stu'ie' e(tensi+el" in !e$ent "e!s& espe$ill"b" 4uss Phillips in m" lb n' b" 0ike 8nselo% n' $olleues. Like tone $on'itionin& $onte(tul $on'itionin is

'epen'ent on the m"'l& but unlike tone $on'itionin& it is lso 'epen'ent on the hippo$mpus. Just s the

u'ito!" s"stem p!o+i'es the m"'l %ith info!mtion bout tone& the hippo$mpus& b" +i!tue of its !ole in

!eltionlK$onflu!lKsptil p!o$essin 2$hp. 47, p!o+i'es the m"'l %ith info!mtion bout $onte(t in %hi$h the

emotionl le!nin is tkin pl$e. The $onte(t is& in othe! %o!'s& ps"$holoi$l $onst!u$tion& kin' of memo!"

$!ete' on the spot& bout the +!ious f$to!s tht $onstitute n emotionl sitution. /n' >ust s tone-sho$k inte!tion

o$$u!s in the m"'l 'u!in $on'itionin& $onte(t-sho$k inte!tion o$$u!s the!e s %ell. Ho%e+e!& %hile the lte!l

nu$leus is in+ol+e' in tone-sho$k inte!tion& it is not ne$ess!" fo! $onte(t-sho$k inte!tion. The bsl nu$leus

2bsl m"'l3& %hi$h !e$ei+es the $onne$tions f!om the hippo$mpus& is $!iti$l inste'. The bsl nu$leus

$ommuni$tes %ith the $ent!l nu$leus in the $ont!ol of fe! !e$tions to the $onte(t. /n' b" %" of these

hippo$mplm"'l $i!$uits& fe! !esponses $n be '>uste' 'epen'in on the spe$ifi$s of the situtionA best in

the %il' eli$its fe!& but one in the ,oo >ust fs$intes. Beneth it ll& thouh& is !e$ti+e s"stem tht is still p!ep!e'

to !espon'& s :h!les D!%in foun' out %hen he t!ie'& %ithout su$$ess& to %ithhol' !esponse to the st!ike of

poisonous snke behin' p!ote$ti+e lss $e in ,oo.

The i'e tht the hippo$mpus is in+ol+e' in $onte(t $on'itionin hs been $hllene' se+e!l times.

Ho%e+e!& these $hllenes h+e so f! been met& le+in int$t the $on$lusion tht $onne$tions bet%een the

hippo$mpus n' the m"'l $$ount fo! $onte(tul p!o$essin in fe!.

:HE:5S /1D B/L/1:ES

The m"'l lso inte!$ts %ith the me'il p!ef!ontl $o!te(. This !eion in$lu'es the nte!io! $inulte n'

o!bitl !eions& s %ell s !es in t!nsition bet%een them 2inf!limbi$Kp!elimbi$ $o!te(3. These !es sen'

$onne$tions to se+e!l m"'l !eions& in$lu'in the $ent!l nu$leus& s %ell s to b!in stem outputs of the $ent!l

nu$leus& llo%in $oniti+e fun$tions o!ni,e' in p!ef!ontl !eions to !eulte the m"'l n' its fe! !e$tions.

Se+e!l "e!s o& 0!i 0o!n of m" lb pu!sue' the !ole of the me'il p!ef!ontl $o!te( in fe! !eultion.

She foun' tht the $onse@uen$es of 'me to this !eion +!ie'& 'epen'in on %he!e the lesion %s lo$te'. Some

lesions le' to m!ke' e(e!tion of fe! !e$tions!ts %ith su$h 'me f!o,e mu$h mo!e thn $ont!ols e$h

time the $on'itione' fe! stimulus 2the soun' tht h' been pi!e' %ith sho$k3 ppe!e'. )n $ont!st& %ith othe! le-

sions& no su$h e(e!tion of fe! intensit" o$$u!!e'. Ho%e+e!& %hen the soun' %s p!esente' %ithout the sho$k

!epete'l" until fe! !e$tions no lone! o$$u!!e'& nimls %ith the lesion !e@ui!e' mn" mo!e e(posu!es to the

soun' thn unlesione' nimls to e(tinuishto stop $tin fe!ful. The !ole of the me'il p!ef!ontl $o!te( in fe!!eultion !e$entl" hs been $onfi!me' in stu'ies b" 9!e ?ui!k& m" fo!me! $olleue no% in Pue!to 4i$o& n' b"

4ene 9!$i in 8!n$e.

:olle$ti+el"& this %o!k suests tht the p!ef!ontl $o!te( n' m"'l !e !e$ip!o$ll" !elte'. Tht is& in

o!'e! fo! the m"'l to !espon' to fe! !e$tions& the p!ef!ontl !eion hs to be shut 'o%n. B" the sme loi$&

%hen the p!ef!ontl !eion is $ti+e& the m"'l %oul' be inhibite'& mkin it h!'e! to e(p!ess fe!. Ptholoi$l

fe!& then& m" o$$u! %hen the m"'l is un$he$ke' b" the p!ef!ontl $o!te(& n' t!etment of ptholoi$ fe! m"

!e@ui!e tht the ptient le!n to in$!ese $ti+it" in the p!ef!ontl !eion so tht the m"'l is less f!ee to e(p!ess



fe!. :le!l"& 'e$ision-mkin bilit" in emotionl situtions is impi!e' in humns %ith 'me to the me'il n'

+ent!l p!ef!ontl $o!te(& n' bno!mlities the!e lso m" p!e'ispose people to 'e+elop fe! n' n(iet" 'iso!'e!s.

These bno!mlities $oul' be 'ue to eneti$ o! epieneti$ o!ni,tion of p!ef!ontl s"npses o! to e(pe!ien$es tht

subtl" lte! p!ef!ontl s"npti$ $onne$tions. )n'ee'& the beh+io! of nimls %ith bno!mlities of the me'il p!ef!ontl

$o!te( is !eminis$ent of humns %ith n(iet" 'iso!'e!sA the" 'e+elop fe! !e$tions tht !e 'iffi$ult to !eulte.

/lthouh ob>e$ti+e info!mtion bout the %o!l' m" in'i$te tht sitution is not 'ne!ous& be$use the" $nnotp!ope!l" !eulte fe! $i!$uits& the" e(pe!ien$e fe! n' n(iet" in these sfe situtions.

The me'il p!ef!ontl $o!te( m" thus se!+e s n inte!f$e bet%een $oniti+e n' emotionl s"stems&

llo%in $oniti+e info!mtion p!o$essin in the p!ef!ontl $o!te( to !eulte emotionl p!o$essin b" the m"'l. )n

''ition& emotionl p!o$essin b" the m"'l m" influen$e 'e$ision-mkin n' othe! $oniti+e fun$tions of the

p!ef!ontl $o!te(. 7e*ll h+e mo!e to s" bout p!ef!ontl-m"'l inte!$tions %hen %e $onsi'e! the !eltion be-

t%een fe! $i!$uits n' $ons$ious feelins of fe! lte! in this $hpte!.

O8 4/TS /1D 0E1

Bus& slus& shellfish& n' othe! in+e!teb!tes l$k n m"'l. 8e! $on'itionin is tken $!e of in othe!

%"s in these $!etu!es. But fo! +e!teb!tes 2t lest !eptiles& bi!'s& n' ll +!ieties of mmmls& in$lu'in humns3&

the m"'l is !esponsible fo! fe! $on'itionin.

)t*s mu$h mo!e 'iffi$ult to stu'" humn thn !t o! othe! niml b!ins. Ho%e+e!& in the lst fe% "e!s&

stu'ies of b!in-'me' ptients n' stu'ies usin ne% b!in-imin te$hni@ues h+e e(mine' the !ole of the

humn m"'l in fe! n' othe! emotionl p!o$esses. These in+estitions still $nnot pinpoint the $ont!ibution of

spe$ifi$ $i!$uits %ithin the m"'l& but h+e nonetheless been +e!" su$$essful in sho%in tht mn" of the bsi$

fe!-$on'itionin obse!+tions in nimls ppl" e@ull" to the humn b!in.

The ln'm!k "e! %s FF& %hen t%o stu'ies on the effe$ts of b!in 'me on humn fe! $on'itionin

%e!e publishe'. :ollbo!to!s of mine 25e+in LB!& Li, Phelps& Dennis Spen$e!3 %o!kin t Yle e(mine' se!ies

of bout t%ent" ptients %ho h' un'e!one unilte!l tempo!l lobe$tom"& p!o$e'u!e in %hi$h l!e !es of the

tempo!l lobe 2in$lu'in the m"'l3 !e !emo+e' on one si'e of the b!in in n effo!t to $ont!ol se+e!e epileps".

4e!'less of the si'e of the !emo+l& the ptients e(hibite' impi!e' fe! $on'itionin. /!oun' the sme time&

/ntonio Dmsio n' $olleues !epo!te' tht fe! $on'itionin %s 'is!upte' in ptient %ho h' !!e $on'ition

tht !esulte' in he! sustinin 'me !est!i$te' to the m"'l on both si'es of he! b!in. )n the ptients in both

ou! stu'" n' thei!s& e(pli$it o! 'e$l!ti+e memo!" fo! the $on'itionin e(pe!ien$e %s int$t& in'i$tin tht fe!

$on'itionin n' 'e$l!ti+e memo!" !e sep!ble in the humn b!in& s in the !t b!in. /lso& 'me to the

hippo$mpus in humns& s it 'oes in !ts& 'is!upts fe! $on'itionin to $onte(tul $ues.

These fin'ins on the effe$ts of b!in 'me on fe! in humns h+e !e$entl" been $omplemente' b"

fun$tionl-imin stu'ies. One stu'" %s pe!fo!me' b" LB!& Phelps& n' me& n' se$on' %s b" John 0o!!is&

/!ne Ohmn& n' 4" Doln. Both use' fun$tionl 04) n' both foun' tht the m"'l of humns %s $ti+te'

'u!in fe! le!nin. The 0o!!is stu'" h' n ''itionl inte!estin t%istthe +isul $on'itione' stimuli %e!e mske'&

n' thus ne+e! !e$he' $ons$iousness& sho%in tht the humn m"'l $n un'e!o emotionl le!nin to stimuli

tht !e ne+e! e(pe!len$e'.

Some !ese!$he!s& espe$ill" those %ho %o!k on the neo$o!te(& h+e !ue' tht the 'i!e$t pth%" f!om

the thlmus to the m"'l& the so$lle' lo% !o'& is unlikel" to be +e!" sinifi$nt in the b!ins of humns n'

othe! p!imtes.s Thei! loi$ is tht the $o!te( is so impo!tnt in p!imtes tht n" effe$t of lo%-le+el sub$o!ti$l

p!o$essin %oul' be o+e!sh'o%e'. Ho%e+e!& subse@uent stu'" b" Doln*s !oup helps put this $!iti$ism to !est.

T"pi$ll"& most imin stu'ies look fo! !es %he!e neu!l $ti+it" in$!eses o! 'e$!eses.ss Suppose $ti+it" on the

+e!e in$!eses in e$h of t%o !es& / n' B& 'u!in th!ee p!esenttions of stimulus. Suppose fu!the! tht in

!e / the $ti+it" %s hih on the fi!st t!il& me'ium on the se$on'& n' lo% on the thi!'. The +e!e $hne %oul'

be me'ium in$!ese. The sme +e!e in$!ese $oul' o$$u! in !e B if the $ti+it" %s lo% on the fi!st& me'ium



on the se$on'& n' hih on the thi!'. This ptte!n& thouh& %oul' not suppo!t the $on$lusion tht the t%o !es !e

fun$tionll" $onne$te'& sin$e $ti+it" 'i' not $hne the sme %" in the t%o !es on e$h t!il. But if the t%o !es

'i' $hne in the sme %" on e$h t!il& then fun$tionl $onne$ti+it" %oul' be implie'. Doln n' $olleues 'i' this

kin' of nl"sis on the 't the" obtine' in the mske' $on'itionin stu'". Spe$ifi$ll"& the" ske' %hi$h b!in

!es $hne' in %" tht %oul' in'i$te $onne$ti+it" %ith the m"'l. The" foun' tht $!oss the %hole b!in

m"'l $ti+it" 'u!in $on'itionin %s most 'i!e$tl" !elte' to $ti+it" in sub$o!ti$l +isul-p!o$essin !es&in$lu'in n !e of the +isul thlmus. P!ti$ul!l" sinifi$nt %s the f$t tht m"'l $ti+it" %s not t ll

!elte' to $ti+it" in !es of the +isul $o!te(. This fin'in thus in'i$tes tht un$ons$ious emotionl le!nin o$$u!s

th!ouh the pth f!om +isul senso!" !es of the thlmus to the m"'l. The lo% !o' is in'ee' use' in both the

!t n' humn b!in.

9i+en ll the p!llels %e*+e seen bet%een the !t n' the humn& fin'ins f!om !ts shoul' be ssume' to

ppl" to humns until the" !e p!o+en not to& t lest in the !e of fe! !e$tions. This 'oesn*t men tht the humn

b!in shoul'& like the !t b!in& be f!i' of $ts& but !the! tht the ene!l %i!in pln of the humn n' !t fe!

s"stem is the sme. /s !esult& the s"npti$ $i!$uits tht tu!n on the !t m"'l in the p!esen$e of $ts %ill simil!l"

tu!n on the humn m"'l in the p!esen$e of stimuli tht !e 'ne!ous to us.

)n ''ition to stu'ies on the !ole of the m"'l in $on'itionin& the!e h+e been numbe! of othe! imin

stu'ies of humns tht !e !ele+nt to the topi$ of fe!. 8o! e(mple& it is %ell kno%n tht the e(p!ession of emotion

on humn f$e is potent emotionl stimulus. Stu'ies b" Doln*s !oup in Lon'on& s %ell s b" Hns B!eite!& Pul

;7hlen& n' S$ott 4us$h& foun' tht e(posu!e of humn sub>e$ts to fe!ful o! n!" f$es potentl" $ti+tes the

m"'l. ;7hlen n' $olleues foun' tht e+en mske' p!esenttions of su$h f$es $use su$h $ti+tion. /lon

simil! lines& 'me to the humn m"'l inte!fe!es %ith the bilit" to >u'e the emotions e(p!esse' in f$es n'

+oi$es. People %ith m"'l 'me& in f$t& seem to h+e t!ouble in thei! 'il" li+es 'e$i'in %hom to t!ust.

These ltte! fin'ins in humns !e !eminis$ent of n obse!+tion fi!st m'e in the e!l" Fs n' then

popul!i,e' in FQN !epo!t b" 5lu+e! n'

Bu$"A monke"s %ith tempo!l lobe lesions tht in$lu'e' the m"'l lost thei! fe! of thins the" %e!e

no!mll" @uite f!i' of& su$h s humns n' snkes. Some%ht lte!& E'mun' 4olls& Tketoshi Ono& n' othe!

in+estito!s !e$o!'e' f!om neu!ons in the monke" m"'l in n effo!t to she' some liht on the so-$lle' 5lu+e!-

Bu$" s"n'!ome. The" foun' $ells tht !espon'e' spe$ifi$ll" to f$es n' othe! kin's of bioloi$ll" sinifi$nt stim-

uli& like foo' items n' th!etenin ob>e$ts.

4e$ent %o!k in humns b" Li, Phelps n' Pul 7hlen hs fu!the! impli$te' the m"'l in so$il

inte!$tions. )n sep!te stu'ies& the" foun' tht e(posu!e of %hite sub>e$ts to the f$es of unfmili! /f!i$n

/me!i$ns le' to m"'l $ti+tion& n' the 'e!ee of $ti+tion %s 'i!e$tl" !elte' to the sub>e$ts* s$o!e on test

tht mesu!es !$il bises. P!ti$ul!l" sinifi$nt is the f$t tht the bis test %s n impli$it mesu!e of !$il bis.

This suests tht impli$it 2un$ons$ious3 ten'en$ies to%!' !$ism !e !efle$te' in the 'e!ee to %hi$h the m"'l

is $ti+te' b" stimuli !ep!esentin the !oup bise' inst. This %o!k is tkin us into ne% n' p!o+o$ti+e !es&

but is lso !isin se!ious ethi$l issues fo! !ese!$he!s. 9i+en tht neti+e ttitu'es n' bises h+e thei! st!onest

effe$ts on beh+io! %hen the" !e un$ons$ious& n' thus $nnot be u!'e' inst n' $ompenste' fo!& shoul'

!ese!$he!s info!m sub>e$ts of these bises= Su$h stu'ies lso fo!$e us to $onf!ont ethi$l 'e$isions s so$iet".

Ho% f! shoul' %e o in usin b!in imin to !e' min's& n' ho% shoul' %e use the info!mtion %e 'is$o+e!= )t is

testimon" to the p!o!ess bein m'e tht these @uestions nee' to be ske'.

4EL)6)19 THE E0OT)O1/L P/ST

8e! $on'itionin b" the m"'l& s )*+e si' mn" times& is n impli$it fo!m of le!nin& one tht 'oes not

!e@ui!e $ons$ious p!ti$iption. Du!in n" e(pe!ien$e in %hi$h %e !e %ke n' le!t& ho%e+e!& %o!kin memo!"

%ill be %!e of %ht is oin on& n' if %ht is oin on is sinifi$nt& the e(e$uti+e %ill 'i!e$t the sto!e of

info!mtion bout the sitution in the e(pli$it memo!" s"stem. 7e !e thus lte! ble to $ons$iousl" !e$ll 2!et!ie+e into



%o!kin memo!"3 those spe$ts of the e(pe!ien$e tht %e!e sto!e' e(pli$itl". 7hile this is t!ue of n" kin' of e(pli$it

memo!"& e(pli$it memo!ies bout emotion !e uni@ue.

E(pli$it memo!ies estblishe' 'u!in emotionl situtions !e often espe$ill" +i+i' n' en'u!in& n' fo! this

!eson !e $lle' flshbulb memo!ies. The $lssi$ e(mple is tht most bb"-boome!s kno% %he!e the" %e!e n'

%ht the" %e!e 'oin %hen the" he!' the ne%s tht J85 h' been shot. But %e !e ll %!e f!om ou! o%n 'il"

e(pe!ien$es tht %e !emembe! p!ti$ul!l" %ell those thins tht !e most impo!tnt to us& those thins tht !ouseou! emotions. Emotions& in sho!t& mplif" memo!ies.

Stu'ies b" Jim 0$9uh n' $olleues spnnin se+e!l 'e$'es h+e impli$te' the m"'l in the

emotionl mplifi$tion of e(pli$it memo!". Du!in emotionl !ousl& outputs of the $ent!l m"'l t!ie! the

!elese of ho!mones f!om the '!enl ln' tht !etu!n to the b!in. The m"'l& it tu!ns out& is n impo!tnt t!et

of su$h fee'b$k. The fee'b$k $onsists of the 'i!e$t $tion of bo'" ho!mones 2like $o!tisol !elese' f!om the '!enl

$o!te(3 on m"'l neu!ons& s %ell s in'i!e$t $tions %he!eb" ho!mones 2like epineph!ine n' no!epineph!ine

!elese' f!om the '!enl me'ull3 inte!$t %ith ne!+es tht t!+el f!om the bo'" into the b!in n' ultimtel" !e$h

n' influen$e neu!l $ti+it" in the m"'l. B" %" of its $onne$tions %ith the hippo$mpus n' othe! !eions of

the e(pli$it memo!" s"stem& the m"'l then mo'ultes 2st!enthens3 the $onsoli'tion of e(pli$it memo!ies bein

fo!me' 'u!in emotionl !ousl. Lte!& the memo!ies !e mo!e esil" !et!ie+e'& n' the 'etils of the o!iinl

e(pe!ien$e !e mo!e +i+i'. Thus& in ''ition to storin! impli$it memo!ies bout 'ne!ous situtions in its o%n $i!$uits&

the m"'l modulates the fo!mtion of e(pli$it memo!ies in $i!$uits of the hippo$mpus n' !elte' !es. Stu'ies

in !e$ent "e!s le' b" L!!" :hill n' Benno 4oo,en'l in 0$9uh*s lb h+e helpe' to !efine the ltte!

$on$lusion.

/$$o!'in to the moo' $on!uit" h"pothesis& memo!ies !e mo!e esil" !et!ie+e' %hen the emotionl stte t

the time of memo!" fo!mtion mt$hes the stte t the time of !et!ie+l.# 8o! e(mple& %e !e mo!e likel" to !emembe!

s' thn hpp" e+ents %hen 'ep!esse'. Pe!hps m"'l $ti+tion 'u!in !et!ie+l f$ilittes !ememb!n$e b" !e-

$!etin& t lest in p!t& the emotionl stte 2the stte of the b!in !esultin f!om m"'l $ti+tion& n' ll its

$onse@uen$es& s 'is$usse' bo+e3 tht o$$u!!e' 'u!in the o!iinl e(pe!ien$ethe mo!e simil! the ptte!n of

$ti+tion is 'u!in le!nin n' !et!ie+l& the mo!e effi$ient !et!ie+l is likel" to be. The un!elibilit" of !emembe!e'

emotion 25hnemn*s !emembe!e' utilit"3 n' the fllibilit" of e"e%itness testimon" m" be !elte' to the f$t tht the

emotionl stte t the time of the !et!ie+l %ill b" ne$essit" be some%ht 'iffe!ent f!om the stte t the time of the

o!iinl e(pe!ien$e.

/s lon s the 'e!ee of emotionl !ousl is mo'e!te 'u!in memo!" fo!mtion& memo!" is st!enthene'.

But if the !ousl is st!on& espe$ill" if it is hihl" st!essful& memo!" is often impi!e'. Stu'ies b" 4obe!t Spolsk"&

B!u$e 0$E%en& 9us P+li'es& D+i' Dimon'& T!$" Sho!s& n' Jensok 5im suest tht st!ess impi!s e(pli$it

memo!" b" lte!in the fun$tionin of the hippo$mpus. Thus& 'u!in hihl" st!essful $on'itions& the $on$ent!tion of

ste!oi' ho!mone 2$o!tisol3 !elese' f!om the '!enl $o!te( !ises in the bloo'st!em. 8o! e(mple& %hen the st!ess is

in'u$e' b" th!etenin stimuli& the m"'l is $ti+te' n' $o!tisol is !elese'. The ho!mone then t!+els to the

b!in n' bin's to !e$epto!s in the hippo$mpus& the net effe$t of %hi$h is to 'is!upt hippo$mpl $ti+it"& %ekenin

the bilit" of the tempo!l lobe memo!" s"stem to fo!m e(pli$it memo!ies. St!esse' !ts& s !esult& 'o poo!l" in tsks

tht !e@ui!e the hippo$mpus& su$h s sptil le!nin. )n ''ition& it is mo!e 'iffi$ult to in'u$e hippo$mpl LTP in

st!esse' !ts.# )f the st!ess $ontinues& hippo$mpl $ells bein to 'eene!te n' ultimtel" 'ie. These $hnes

ppe! to $$ount in p!t fo! the memo!" 'istu!bn$es t"pi$l of st!ess-!elte' ps"$hit!i$ $on'itions su$h s

postt!umti$ st!ess 'iso!'e!& o! PTSD& n' 'ep!ession. St!ess ho!mones lso h+e n '+e!se imp$t on the

p!ef!ontl $o!te(& n' m" $ont!ibute to the f$t tht people often mke b' 'e$isions un'e! st!ess. )n $ont!st to its

effe$ts on the hippo$mpus n' p!ef!ontl $o!te(& intense st!ess seems to enhn$e the m"'l*s $ont!ibution to

fe!. Tht st!ess ho!mones !e in+ol+e' in this mplifi$tion of fe! b" st!ess is sueste' b" stu'ies in %hi$h the

le+el of st!ess ho!mones in the bloo' is !tifi$ill" ele+te'& %hi$h hs the sme effe$t s st!ess itself on fe!

!esponses.



)n sho!t& the e($t $on'itions tht le' to %ekene' bilit" to fo!m e(pli$it memo!ies& n' to !eulte fe!

b" thinkin n' !esonin& $n lso mplif" fe! !e$tions n' enhn$e ou! bilit" to impli$itl" sto!e info!mtion bout

st!essful o! t!umti$ situtions. The!e*s oo' n' b' ne%s he!e. The oo' ne%s is tht e+en %hen the bilit" to

fo!m e(pli$it memo!" is impi!e'& %e $n sto!e useful info!mtion bout h!mful situtions. The b' ne%s is tht if %e

'on*t kno% %ht it is %e !e le!nin bout& those stimuli miht on lte! o$$sions t!ie! fe! !esponses tht %ill be

'iffi$ult to un'e!stn' n' $ont!ol& n' $n le' to ptholoi$l !the! thn 'pti+e $onse@uen$es. 7e*ll !etu!n to thispoint %hen %e 'is$uss s"npti$ si$kness in lte! $hpte!.

8E/4 )TSEL8

Emotionl !ousl hs po%e!ful influen$es o+e! $oniti+e p!o$essin. /ttention& pe!$eption& memo!"&

'e$ision-mkin& n' the $ons$ious $on$omitnts of e$h !e ll s%"e' in emotionl sttes. The !eson fo! this is

simpleA emotionl !ousl o!ni,es n' $oo!'intes b!in $ti+it". He!e ) %nt to fo$us on ho% the emotionl

$oo!'intion of b!in $ti+it" $on+e!ts $ons$ious e(pe!ien$es into emotionl e(pe!ien$es.

)n the lst $hpte!& ) !ue' tht ou! imme'ite $ons$ious $ontent& the thin %e !e $ons$ious of t n" one

moment& is %ht o$$upies %o!kin memo!". )f this is $o!!e$t& then it le's to the $on$lusion tht feelin 2the

$ons$ious e(pe!ien$e of n emotion3 is the !ep!esenttion in %o!kin memo!" of the +!ious elements of n

imme'ite emotionl stte. )n this +ie%& the feelin of bein f!i' %oul' be stte of $ons$iousness in %hi$h %o!kin

memo!" inte!tes the follo%in 'isp!te kin's of info!mtionA 23 n imme'itel" p!esent stimulus 2s"& snke on

the pth in f!ont of "ou3C 23 lon-te!m memo!ies bout tht stimulus 2f$ts "ou kno% bout snkes n' e(pe!ien$es

"ou*+e h' %ith them3C n' emotionl !ousl b" the m"'l. The fi!st t%o !e $omponents of n" kin' of $ons$ious

pe!$eptul e(pe!ien$e& s the onl" %" to i'entif" n imme'itel" p!esent stimulus is b" $omp!in its ph"si$l

fetu!es 2the %" it looks o! soun's3 %ith memo!ies bout the sme o! simil! stimuli. But the thi!' kin' of info!mtion

o$$u!s onl" 'u!in n emotionl e(pe!ien$e. /m"'l $ti+tion& in othe! %o!'s& tu!ns plin pe!$eptul e(pe!ien$e

into fe!ful one. Usin 5hnemn*s te!m& the m"'l is the sou!$e of instnt utilit" in th!etenin Sitution.

The ke" @uestion& then& isA Ho% 'oes the m"'l $hie+e this lte!tion of $ons$iousness& this

t!nsfo!mtion of $onition into emotion& o!& bette! "et& this hostile tkeo+e! of $ons$iousness b" emotion= The

ns%e!& ) belie+e& is tht emotion $omes to monopoli,e $ons$iousness& t lest in the 'omin of fe!& %hen the

m"'l $omes to 'ominte %o!kin memo!".

The m"'l $n influen$e %o!kin memo!" in +!iet" of %"s& some of %hi$h %ill be 'es$!ibe'. The fi!st

is b" lte!in senso!" p!o$essin in $o!ti$l !es. 7o!kin memo!" fin's out bout the outsi'e %o!l' f!om senso!"-

p!o$essin !es& so n"thin tht lte!s ho% these !es p!o$ess senso!" stimuli %ill ffe$t the mte!il tht

is +ilble to %o!kin memo!". B" %" of $onne$tions %ith senso!"-p!o$essin !es in the $o!te(& m"'l !ousl

$n mo'if senso!" p!o$essin. D+i' /m!l hs pointe' out tht %hile onl" the ltest stes of senso!" p!o$essin in

the $o!te( sen' $onne$tions to the m"'l& the m"'l sen's $onne$tions to ll stes& llo%in the m"'l to

influen$e e+en +e!" e!l" p!o$essin in the neo$o!te(. Tht senso!" $o!te( !es !e influen$e' b" $ti+it" o$$u!!in

in the m"'l is sueste' b" 1o!mn 7einbe!e!*s stu'ies sho%in tht the !te t %hi$h $ells in the u'ito!"

$o!te( fi!e to tone is in$!ese' %hen tht tone is pi!e' %ith sho$k in fe!-$on'itionin sitution toethe! %ith

stu'ies pe!fo!me' b" Jo!e /!mon" n' 9!e ?ui!k in m" lb 'emonst!tin tht 'me to the m"'l p!e+ents

some of the $o!ti$l $hnes f!om tkin pl$e. Be$use the senso!" $o!te( p!o+i'es impo!tnt inputs to %o!kin

memo!"& the m"'l $n influen$e %o!kin memo!" b" lte!in p!o$essin in the senso!" $o!te(.

The senso!" $o!te( is $!u$ill" in+ol+e' in the $ti+tion of the me'il tempo!l lobe memo!" s"stem 2$hp.

47) B" influen$in the senso!" $o!te(& the m"'l $n h+e n imp$t on the lon-te!m memo!ies tht !e $ti+e

n' +ilble to %o!kin memo!". But the m"'l lso hs st!on $onne$tions %ith the !hinl $o!te(& llo%in it to

'i!e$tl" influen$e the me'il tempo!l lobe memo!" s"stem n' thus the memo!ies +ilble to %o!kin memo!".

The m"'l $n lso $t 'i!e$tl" on %o!kin memo!" $i!$uits. /lthouh the m"'l 'oes not h+e 'i!e$t

$onne$tions %ith the lte!l p!ef!ontl $o!te(& it 'oes h+e $onne$tions %ith othe! !es of the p!ef!ontl $o!te( in-



+ol+e' in %o!kin memo!"& in$lu'in the me'il 2nte!io! $inulte3 n' +ent!l 2o!bitl3 p!ef!ontl $o!te(A /s

'es$!ibe' in the lst $hpte!& $onne$tions %ithin n' bet%een these !eions $onstitute 'ist!ibute' $i!$uits tht un'e!lie

the inte!ti+e fun$tions of %o!kin memo!". Dme to the me'il p!ef!ontl $o!te( in !ts& s l!e'" 'is$usse'&

le's to loss of fe! !eultion. /n' stu'ies of monke"s n' humns h+e impli$te' the o!bitl !eion in

p!o$essin emotionl $ues 2!e%!'s n' punishments3 n' in the tempo!!" sto!e of info!mtion bout su$h $ues.

The o!bitl !eion is $onne$te' %ith the nte!io! $inulte& n' like the nte!io! $inulte& it lso !e$ei+es info!mtionf!om the m"'l n' hippo$mpus. Humns %ith o!bitl $o!te( 'me be$ome obli+ious to so$il n' emotionl

$ues& h+e poo! 'e$isionmkin bilities& n' some e(hibit so$iopthi$ beh+io!. )n ''ition to bein $onne$te' %ith

the m"'l& the nte!io! $inulte n' o!bitl !es !e

intimtel" $onne$te' %ith one nothe!& s %ell s %ith the lte!l p!ef!ontl $o!te(& n' e$h of the p!ef!ontl

!es !e$ei+es info!mtion f!om senso!"-p!o$essin !eions n' f!om !es in+ol+e' in +!ious spe$ts of impli$it n'

e(pli$it memo!" p!o$essin. The nte!io! $inulte n' o!bitl !es thus p!o+i'e mens th!ouh %hi$h emotionl

p!o$essin b" the m"'l miht be !elte' in %o!kin memo!" to imme'ite senso!" info!mtion n' lon-te!m

memo!ies p!o$esse' in othe! !es of the $o!te(.

/ttention n' %o!kin memo!" !e $losel" !elte' 2$hp. N3& n' !e$ent stu'ies b" Li, Phelps h+e sho%n

tht m"'l 'me inte!fe!es %ith n impo!tnt spe$t of ttention. 1o!mll"& if %e !e tten'in to one stimulus&

%e ino!e othe!s. This is sele$ti+e ttention& n' it llo%s us to fo$us ou! thouhts on the tsk t hn'. But if se$on'

stimulus is emotionll" sinifi$nt& it $n o+e!!i'e the sele$tion p!o$ess n' slip into %o!kin memo!". Dme to the

m"'l& thouh& p!e+ents this f!om o$$u!!in. The m"'l& in othe! %o!'s& mkes it possible fo! impli$itl"

p!o$esse' 2untten'e'3 emotionl stimuli to mke thei! %" into %o!kin memo!" n' $ons$iousness.

)n ''ition& the m"'l $n influen$e %o!kin memo!" in'i!e$tl" b" %" of p!o>e$tions to the +!ious mine

$ell !oups in the b!in stem n' fo!eb!in tht p!ti$ipte in $o!ti$l !ousl& in$lu'in $holine!i$& 'opmine!i$&

no!'!ene!i$& n' se!otone!i$ s"stems. )n the lst $hpte!& %e 'is$usse' the impo!tn$e of 'opmine n'

no!epineph!ine in the !eultion of %o!kin memo!". /n' s %e s% bo+e& no!epineph!ine pl"s $!iti$l !ole in the

mplifi$tion of e(pli$it memo!" 'u!in emotionl sttes. These !ousl pth%"s !e !elti+el" nonspe$ifi$ sin$e the"

influen$e mn" $o!ti$l !es simultneousl". Spe$ifi$it" $omes f!om the f$t tht the effe$ts of !ousl !e most

sinifi$nt on $i!$uits tht !e $ti+e. /s !esult& if the $o!te( is fo$use' on some th!etenin stimulus& the $i!$uits

in+ol+e' %ill be f$ilitte' b" the !ousl s"stems. This %ill help keep ttention fo$use' on the th!etenin sitution.

8inll"& on$e the outputs of the m"'l eli$it l!m-!elte' beh+io!s n' $$ompn"in $hnes in bo'"

ph"siolo" 2fihtKfliht kin's of !esponses3& the b!in beins to !e$ei+e fee'b$k f!om the bo'il" !esponses. 8ee'b$k

$n be in the fo!m of senso!" messes f!om inte!nl o!ns 2+is$e!l senstions3 o! f!om the mus$les

2p!op!io$epti+e senstions3 o! $n be in the fo!m of ho!mones o! pepti'es !elese' b" bo'il" o!ns tht ente! the

b!in f!om the bloo'st!em n' influen$e neu!l $ti+it". /lthouh the e($t mnne! in %hi$h bo'il" fee'b$k

influen$es %o!kin memo!" is not $le!& it is likel" tht %o!kin memo!" hs $$ess to this info!mtion in one fo!m o!

nothe!. But the fee'b$k f!om these !esponses is !elti+el" slo%& on the o!'e! of se$on's& %hen $omp!e'

to the fee'b$k tht o$$u!s b" %" of s"npti$ t!nsmission %ithin the b!in& %hi$h t!nspi!es %ithin mtte! of

millise$on's. Bo'" fee'b$k ''s t lest intensit" n' 'u!tion& but m" lso help !efine ou! inte!p!ettion of the

emotion %e !e e(pe!ien$in& on$e the episo'e hs been t!ie!e'. /s %e s% bo+e& bo'il" fee'b$k in the fo!m of

st!ess ho!mones $n eithe! enhn$e o! impi! lon-te!m memo!" fun$tions of the tempo!l lobe memo!" s"stem&

%hi$h %ill in tu!n influen$e the $ontent of %o!kin memo!".

)n the p!esen$e of fe!-!ousin stimuli& $ti+tion of the m"'l %ill le' %o!kin memo!" to !e$ei+e

!ete! numbe! of inputs& n' inputs of !ete! +!iet"& thn in the p!esen$e of emotionll" neut!l stimuli. ) p!opose

tht these e(t! inputs '' ffe$ti+e $h!e to %o!kin memo!" !ep!esenttions& n' !e %ht mke p!ti$ul!

sub>e$ti+e e(pe!ien$e fe!ful emotionl e(pe!ien$e.

But %ht bout nimls %ithout %ell-'e+elope' p!ef!ontl $o!te(= Do the" h+e n" kin's of emotionl

e(pe!ien$es= ) !ue' in the lst $hpte! tht it miht be possible to h+e $e!tin kin's of mo'lit"-spe$ifi$ $ons$ious



sttes %hen the $ti+it" of one s"stem 'omintes the b!in. This miht hppen %ith st!on senso!" stimultion 2lou'

noise o! pinful stimulus3& o! in !esponse to emotionll" $h!e' stimuli 2siht of p!e'to!3. 0o'lit"-spe$ifi$ feel-

ins $n be thouht of in te!ms of pssi+e sttes of %!eness& s oppose' to the mo!e fle(ible kin' of $ons$ious

%!eness& $omplete %ith on-line 'e$ision-mkin $p$ities& m'e possible b" %o!kin memo!".

/lthouh m" theo!" of emotionl e(pe!ien$e is bse' on stu'ies of fe!& it is ment s ene!l-pu!pose

theo!" tht is ppli$ble to ll kin's of emotionl e(pe!ien$es. The p!ti$ul!s %ill be 'iffe!ent& but the o+e!ll s$heme2%he!eb" %o!kin memo!" inte!tes senso!" info!mtion bout the imme'itel" p!esent ph"si$l stimulus %ith

memo!ies f!om pst e(pe!ien$es %ith su$h stimuli n' %ith the $u!!ent emotionl $onse@uen$es of those stimuli3 %ill

ppl" to ll +!ieties of emotionl e(pe!ien$e in humns& f!om fe! to ne! to >o" n' '!e'& n' e+en lo+e.

BEYO1D 8E/4A THE B4/)1 )1 LO6E

7hene+e! ) i+e le$tu!e on emotions n' the b!in& the @uestion ) m most often ske' t the en' isA “)s

the m"'l in+ol+e' in emotions besi'es fe!& espe$ill" positi+e emotions=# This is not @uestion tht m" %o!k

hs ''!esse' 'i!e$tl". )*+e been t!"in to un'e!stn' spe$ifi$ll" the me$hnism of fe! !the! thn ho% the

m"'l %o!ks in ene!l. But othe! !ese!$he!s h+e stu'ie' the !ole of the m"'l in p!o$essin stimuli tht

p!e'i$t 'esi!ble thins 2like tst" foo's n' se(ull" !e$epti+e p!tne!s3. )n$lu'e' is the %o!k of B!!" E+e!itt n'

T!e+o! 4obbins t :mb!i'e Uni+e!sit"& D+i' 9ffn n' E'mun' 4olls t O(fo!'& 1o!mn 7hite t 0$9ill& 0i$hel

9llhe! t Johns Hopkins& n' Tketoshi Ono t To"om Uni+e!sit" in Jpn. Ho%e+e!& the impli$tions of this

%o!k in nimls fo! un'e!stn'in spe$ifi$ humn emotions !e less $le! thn the !eltion of fin'ins on fe!-

p!o$essin in nimls to humn fe!. 1e+e!theless& this !ese!$h is e(t!emel" impo!tnt n' %ill be m>o! p!t of

n" tho!ouh un'e!stn'in of ho% the b!in $!etes emotions. 7e*ll $onsi'e! some of this %o!k in the ne(t $hpte!

%hen %e e(plo!e ho% beh+io! is moti+te' b" emotionl p!o$essin.

)n the !est of this $hpte!& thouh& ) %nt to tu!n to +e!" inte!estin set of stu'ies tht h+e beun to

pp!o$h the neu!l bsis of n emotion tht is ne! n' 'e! to humnsnmel"& lo+e.

The ke" to un'e!stn'in ho% n" mentl o! beh+io!l fun$tion %o!ks in the b!in& s )*+e si' often in this

book& is to be ble to stu'" it in e(pe!imentl nimls. Lo+e miht the!efo!e seem to be n unlikel" topi$ fo! b!in

!ese!$he!s& one p!ti$ul!l" +ulne!ble to the $!e'ibilit" p!oblem. The ke" issue is %hethe! the!e is some %" to

stu'" the fun$tion in nimls tht mkes sense in te!ms of humn beh+io!. 8o! fe!& %e %e!e ble to use

$on'itionin be$use $on'itione' fe! !esponses !e simil! in humns n' othe! mmmls. )n the $se of lo+e&

thouh& the sitution is mo!e $ompli$te' fo! se+e!l !esons& not the lest of %hi$h is the f$t tht most nimls 'on*t

pi! up %ith one nothe! e($lusi+el". 1ot onl" 'i' !ese!$he!s h+e to fin' %"s to stu'" lo+e beh+io!ll"& the" lso

h' to fin' spe$ies tht %e!e monomous.

Onl" bout Q pe!$ent of mmmls !e monomous& n' e+en %ithin nonhumn p!imtes& monom" is

fi!l" !!e. One spe$ies %hose membe!s 'o !emin toethe! s pi! fte! mtin to !ise thei! offsp!in s fmil"&

e+en $!oss ene!tions& is the p!i!ie +ole& smll !o'ent li+in in the mi'%este!n plins in the Unite' Sttes. 9i+en

tht pi!-bon'in is so !!e& the monomous p!i!ie +ole offe!s possible %in'o% into the biolo" of tt$hment.

/tt$hment 2pi!-bon' fo!mtion3 is ke" element of lo+e. Pe!hps the s"npti$ me$hnisms tht un'e!lie

tt$hment in +oles !e lso t %o!k in othe! spe$ies tht !e fi!l" monomous& nmel"& us.

6ole !ese!$he!s use' $ompletel" 'iffe!ent st!te" thn the one $ommonl" use' to stu'" fe!. 4the!

thn st!tin %ith the $i!$uits n' then t!"-

in to fiu!e out the $hemist!"& the" st!te' %ith $hemi$l fin'ins n' h+e ttempte' to !elte them to

$i!$uits. 0u$h of the %o!k hs been $on'u$te' b" Tom )nsel& Sue :!te!& n' thei! $olleues n' stu'ents. )t*s lso

%o!th notin tht )nsel $!e'its his mento!& Pul 0$Len& fo! intelle$tul inspi!tion. 0$Len*s i'es thus $ontinue to

moti+te !ese!$h on the emotionl b!in mo!e thn hlf $entu!" fte! his int!o'u$tion of the limbi$ s"stem $on$ept.

)n !e$ent !ti$le& )nsel pointe' out t%o fetu!es of p!i!ie +oles tht m'e them tt!$ti+e fo! stu'"in pi!-

bon'in. The fi!st is tht monom" e+en o$$u!s in +oles li+in in lbo!to!" settins. )f bon'in onl" o$$u!!e' in the



%il'& it %oul' be +e!" 'iffi$ult to stu'" its neu!l bsis. )n the lbo!to!"& bon'in $n be mesu!e' b" puttin +ole in

the mi''le $hmbe! of bo( %ith th!ee $omp!tments. The +ole is f!ee to t!+el to the $omp!tment on eithe! si'e. )n

one of these& it en$ounte!s its mte& n' in the othe!& st!ne! is p!esent. 6oles tht h+e mte' $hoose to be %ith

thei! p!tne!& %he!es unbon'e' ones h+e no p!ti$ul! p!efe!en$e. /fte! bon'in& if nothe! +ole $omes into the

!e& the mle enes in mte p!ote$tion& tt$kin the int!u'e!.

The se$on' fetu!e of +oles tht hs helpe' mo+e this %o!k fo!%!' is the f$t tht pi!-bon'in is p!esentonl" in p!i!ie +oles n' not in $losel" !elte' $!etu!e& montne +oles& %hi$h !e foun' in the 4o$kies n' li+e in'i-

+i'ull" !the! thn in fmil" !oups. These nimls 'on*t fo!m mte p!efe!en$es fte! se(ul inte!$ou!se& so tht

%hen pl$e' in the th!ee-$hmbe! bo(& the" 'on*t spen' mo!e time %ith +ole the" mte' %ith thn no+el one& n'

the mles 'on*t tt$k int!u'e!s fte! se(. Diffe!en$es in the b!ins of these t%o kin's of +oles miht the!efo!e p!o+i'e

impo!tnt $lues bout the biolo" of pi!-bon'in& fmil" o!ni,tion& n' pe!hps lo+e itself

One of the min 'is$o+e!ies %s tht !e$epto!s fo! t%o ho!mones belie+e' to pl" n impo!tnt !ole in

!ep!o'u$ti+e beh+io! %e!e lo$te' in 'iffe!ent $i!$uits in p!i!ie n' montne +oles. These ho!mones& $lle'

+sop!essin n' o("to$in& !e foun' onl" in mmmls& n' !e !elte' to n$est!l ho!mones tht pl" ke" !ole in

beh+io!s like nest-buil'in in nonmmmlin spe$ies. )n mmmls& the" $ontinue to be sinifi$nt in !ep!o'u$ti+e

beh+io!. 8o! e(mple& o("to$in is in+ol+e' in ute!ine $ont!$tions 'u!in lbo! n' in milk !elese 'u!in nu!sin. )n

the b!in& thouh& these $hemi$ls fun$tion not >ust s ho!mones& but lso s neu!ot!nsmitte!s n'Ko! mo'ulto!s&

bein !elese' f!om ne!+e te!minls n' bin'in to posts"npti$ !e$epto!s.

8o! no%& %e*ll skip o+e! the e($t lo$tion of the $i!$uits in %hi$h the $hemi$ls !e p!esent& s the !eltion of

the $hemi$ls& $i!$uits& n' beh+io! is still not pe!fe$tl" $le!. ;7ht is $le!& thouh& !e the fun$tions of these

$hemi$ls in the beh+io!l 'iffe!en$es bet%een the +oles. This hs been 'ete!mine' b" in>e$tin '!us into the b!in

tht eithe! stimulte o! inhibit the $tion of +sop!essin o! o("to$in. The '!us h+e not been in>e$te' into spe$ifi$

b!in !es but into the +ent!i$les& $+ities tht $ontin :S8 2$e!eb!ospinl flui'3& %hi$h flo%s f!om the +ent!i$les into

the sp$es su!!oun'in neu!ons. 7ith su$h in>e$tions& the '!u %ill !e$h %i'esp!e' !es of the b!in n' $n then

influen$e neu!l fun$tion in those !es tht $ontin $ells %ith pp!op!ite !e$epto!s. 7hen '!u tht blo$ks the

$tion of ntu!ll" !elese' o("to$in is pl$e' in the +ent!i$les of femle p!i!ie +ole >ust befo!e mtin& she mtes

but 'oes not bon' %ith the se( p!tne!. The '!u 'is!upts tt$hment& not se(& suestin tht o("to$in !elese'

'u!in mtin un'e!lies bon' fo!mtion in femles. )n $ont!st& if '!u tht blo$ks +sop!essin is pl$e' in the

+ent!i$les of mle p!i!ie +ole befo!e mtin& the mle like%ise mtes but 'oesn*t bon'& n' lso 'oesn*t ene in

mte-u!'in !ession. But if the sme '!u is in>e$te' fte! mtin& int!u'e! !ession 'oes o$$u!. This ptte!n

of !esults in mles 'emonst!tes tht the '!u blo$ks tt$hment n' not se(ul o! !essi+e !esponses. Thus&

blo$kin o("to$in in femle n' +sop!essin in mle p!i!ie +oles $uses them to beh+e like montne +oles.

O("to$in onl" ffe$ts bon'in in femle b!ins& n' +sop!essin onl" ffe$ts bon'in in mle b!insC the femle se(

ho!mone est!oen is ke" to o("to$in*s $tion& >ust s testoste!one is essentil fo! the no!ml fun$tion of +sop!essin.

7hile o("to$in n' +sop!essin !e lso p!esent in the b!ins of humns n' !e !elese' 'u!in se(ul

beh+io!& the" h+e not "et been p!o+en to un'e!lie tt$hment. 4e!'less of %hethe! the +ole fin'ins on o("to$in

n' +sop!essin en' up bein $ompletel" ppli$ble to the humn b!in& this %o!k illust!tes impo!tnt p!in$iples tht

%ill su!el" ui'e !ese!$h fo! some time.

/n impo!tnt !e fo! futu!e %o!k is to pinpoint the e($t $i!$uits in %hi$h +sop!essin n' o("to$in !e

$tin 'u!in se(-!elte' pi!-bon' fo!mtion. 0n" stu'ies h+e been pe!fo!me' on the neu!l bsis of se(ul be-

h+io!& espe$ill" in !o'ents. )mpli$te' !e !es %ithin the m"'l 2me'il n' poste!io! nu$lei3& the so-$lle'

e(ten'e' m"'l 2n e(tension of the m"'l into the be' nu$leus of the st!i te!minlis3& the st!itum 2es-

pe$ill" the nu$leus $$umbens3& n' the h"pothlmus 2in$lu'in +ent!o

me'il& me'il p!eopti$& p!+ent!i$ul!& n' sup!opti$ !es3. 9i+en tht these !eions !e intimtel"

$onne$te' n' tht !e$epto!s fo! o("to$in n' +sop!essin !e p!esent on neu!ons in se+e!l of them& it is temptin to

think of them s fo!min s"npti$ $i!$uits $!u$il not >ust fo! se(ul beh+io!& but lso fo! pi!-bon'in& but this



!emins unp!o+en.

/!es of the m"'l !e in$lu'e' in both the fe! n' se( $i!$uits. Ho%e+e!& the $i!$uits !e othe!%ise

@uite 'istin$t. E+en %ithin the m"'l& 'iffe!ent !es !e in+ol+e' in se( 2me'il n' poste!io! nu$lei3 n' fe!

2lte!l n' $ent!l nu$lei3. This fin'in emphsi,es the impo!tn$e of mppin the $i!$uit fo! 'iffe!ent kin's of

emotionl s"stems !the! thn ssumin tht the!e is uni+e!sl $i!$uit!" fo! ll emotions. /t the sme time& 'iffe!ent

emotion $i!$uits& like the fe! n' se( $i!$uits& sometimes inte!$t %ith one nothe!. 8o! e(mple& the me'il nu$leussen's $onne$tions to the $ent!l nu$leus& %he!e o("to$in !e$epto!s !e p!esent. This m" be !elte' to the bilit" of

both o("to$in n' positi+e so$il inte!$tions to !e'u$e fe! n' st!ess.

Pi!-bon'in in nimls hs p!o+i'e' !ese!$he!s %" of stu'"in somethin kin to lo+e %ithout h+in to

$onf!ont the $!e'ibilit" p!oblem tht ine+itbl" !ises %hen n" emotion is $onsi'e!e'. But in the en' %e %nt to kno%

not >ust bout tt$hment beh+io! but lso bout the p!ti$ul! feelins of lo+e. /lthouh %e h+e little !ese!$h to

'!% upon t this point& %e $n use ou! mo!e 'etile' un'e!stn'in of $oniti+e-emotionl inte!$tions in fe! to

spe$ulte bout ho% the b!in 'oes feel lo+e.

Suppose "ou une(pe$te'l" see pe!son "ou $!e bout. Su''enl"& "ou feel the lo+e "ou h+e fo! tht

pe!son. Let*s follo% the flo% of info!mtion f!om the +isul s"stem th!ouh the b!in to the point of the e(pe!ien$e of

lo+e s best %e $n. 8i!st of ll& the stimulus %ill flo% f!om the +isul s"stem to the p!ef!ontl $o!te( 2puttin n ime

of the lo+e' one in %o!kin memo!"3. The stimulus lso !e$hes the e(pli$it memo!" s"stem of the tempo!l lobe n'

$ti+tes memo!ies bout tht pe!son. 7o!kin memo!" then !et!ie+es !ele+nt memo!ies n' inte!tes them %ith

the ime of the pe!son. Simultneousl" %ith these p!o$esses& the sub$o!ti$l !es p!esume' to be in+ol+e' in

tt$hment %ill be $ti+te' 2the e($t pths b" %hi$h the stimulus !e$hes these !es is not kno%n& ho%e+e!3.

/$ti+tion of tt$hment $i!$uits then imp$ts on %o!kin memo!" in se+e!l %"s. One in+ol+es 'i!e$t $onne$tions

f!om the tt$hment !es to the p!ef!ontl $o!te( 2s %ith fe!& it is the me'il p!ef!ontl !eion tht is $onne$te' %ith

sub$o!ti$l tt$hment !es3. /$ti+tion of tt$hment $i!$uits lso le's to $ti+tion of b!in stem !ousl

net%o!ks& %hi$h then p!ti$ipte in the fo$usin of ttention on the lo+e' one b" %o!kin memo!". Bo'il" !esponses

%ill lso be initite' s outputs of tt$hment $i!$uits& n' $ont!st %ith the l!m !esponses initite' b" fe! n'

st!ess $i!$uits. 7e pp!o$h !the! thn t!" to es$pe f!om o! +oi' the pe!son& n' these beh+io!l 'iffe!en$es !e

$$ompnie' b" 'iffe!ent ph"sioloi$l $on'itions %ithin the bo'". This ptte!n of inputs to %o!kin memo!" f!om

%ithin the b!in n' f!om the bo'" bises us mo!e to%!' n open n' $$eptin mo'e of p!o$essin thn to%!'

tension n' +iiln$e. The net !esult in %o!kin memo!" is the feelin of lo+e.

This h"pothesis is p!obbl" in$omplete& but it is p!obbl" not $ompletel" %!on. )t sho%s ho% %e $n buil'

upon !ese!$h on one emotion to ene!te h"potheses bout othe!s. 9i+en tht so mu$h of %ho %e !e is 'efine' b"

ou! emotions& it is impo!tnt tht %e un$o+e! s mu$h s %e $n bout the b!in me$hnisms of mn" emotions. This

tsk is >ust beinnin& but the futu!e is b!iht.

:H/PTE4 1)1E

THE LOST 7O4LD

E6E4Y 7HY H/TH / 7HE4E8O4E.



Shkespe!e& The Comedy of Errors, $! & s$ene

7h" 'o %e 'o the thins %e 'o& think the thins %e think& n' mke the 'e$isions %e mke= "hy @uestions

@uestions bout ou! moti+tions!e fun'mentl to un'e!stn'in %ht mkes e$h of us uni@ue. 8ollo%in the

$oniti+e !e+olution& thouh& moti+tions& like emotions& %e!e o+e!looke' b" mn" ps"$holoists n' b!in s$ientists.

The !ehbilittion of moti+tion in both these fiel's hs been slo%e! thn tht of emotion& but it is lso un'e! %".

/n'& s %ith emotion& the p!essu!e to !e+i+e !ese!$h on n' theo!" bout moti+tion is $omin s mu$h if not mo!e

f!om b!in s$ien$e s ps"$holo". So let*s !e'is$o+e! the lost %o!l' of moti+tion& p!t th!ee of the mentl t!ilo"& f!om

the pe!spe$ti+e of ho% it %o!ks in the b!in.

/:T)19 OUT

On %!m summe! e+enin in FF& $!o%' %s en>o"in $on$e!t in Ol"mpi$ P!k in /tlnt. Su''enl"&

bomb e(plo'e'. The s$ene& $ptu!e' on +i'eo& %s sho%n !epete'l" on :11. /s soon s the e(plosion o$$u!!e'&

ne!l" e+e!"one in the $!o%' !e$te' b" f!ee,in. /fte! !eminin motionless fo! se+e!l se$on's& some people

st!tin !unnin %"& n' soon e+e!"one %s in motion.

This sho!t sement of +i'eo is oo' 'emonst!tion of the %" n emotionl episo'e unfol's o+e! time. )n

situtions of su''en 'ne!& %e initill" !e$t b" usin e+olution!il" p!o!mme' !esponses& like f!ee,in& tht h+e

lon been su$$essful in keepin o!nisms like us li+e. These !e$tions !e eli$ite'& not emitte' %illfull"& n' o$$u!

utomti$ll"& befo!e %e h+e time to think. But %e $n*t f!ee,e fo!e+e!C soone! o! lte!& %e h+e to tke $tion. )n the

lst $hpte!& %e $onsi'e!e' ho% emotionl !e$tions !e utomti$ll" t!ie!e' b" e(te!nl stimuli. )n this $hpte!&

%e fo$us on ho% emotions& on$e $ti+te'& moti+te us to 'o thins& to tke $tions.

$oti+ation hs mn" 'efinitions. ) use the te!m he!e to !efe! to neu!l $ti+it" tht ui'es us to%!' ols&

out$omes tht %e 'esi!e n' fo! %hi$h %e %ill e(e!t effo!t& o! ones tht %e '!e' n' %ill e(e!t effo!t to p!e+ent&

es$pe f!om& o! +oi'. 9ols 'i!e$t $tion& n' $n be s $on$!ete s spe$ifi$ stimulus 2fo! e(mple& p!ti$ul!

$onsume! p!o'u$t3 o! s bst!$t s belief o! i'e 2fo! e(mple& the belief tht h!' %o!k %ill le' to su$$ess& o! the

i'e tht f!ee'om is %o!th '"in fo!3.

9ol ob>e$ts !e lso $lle' in$enti+es. Some !e int!insi$ll" moti+tin 2s in the $se of foo'& %te!& n'

pinful stimultion3& %hile othe!s $@ui!e moti+tin p!ope!ties th!ouh ou! e(pe!ien$es %ith them. )n the ltte! $se&

the" !e $lle' se$on'!" in$enti+es. These $n !ise b" sso$ition 2%hen stimulus %ith lo% +lue o$$u!s in

$onne$tion %ith one of hihe! +lue& s in $lssi$l $on'itionin3& b" obse!+tionl le!nin 2seein the %" stimulus

ffe$ts othe! people3& b" %o!' of mouth 2he!in bout %hethe! somethin is oo' o! b'3& o! b" shee! fo!$e of

imintion.

The +ie% of moti+tion tht )*m oin to pu!sue he!e is tht in$enti+es 'o thei! moti+tin b" $ti+tin



emotion s"stems. 8!ee,in in !e$tion to bomb !efle$ts the $ti+tion of n emotionl s"stem& %he!es !unnin

%" fte! se+e!l se$on's of f!ee,in !efle$ts the moti+tionl $onse@uen$es of tht $ti+tion ) /$tions moti+te' b"

emotionl !ousl h+e pu!pose to 'el %ith the emotion bein !ouse'. 7hethe! ll moti+te' $tions !e

ne$ess!il" bse' on emotionl $ti+it" is 'ebtble. But tht emotions !e po%e!ful moti+to!s seems in'isputble.

9ol-'i!e$te' beh+io! is best thouht of in fun$tionl te!ms. 7hile %e no!mll" t!" to es$pe f!om o! +oi'

h!mful stimuli& in some $ses& %e h+e to $ti+el" ene 'ne!ous ob>e$t in o!'e! to $hie+e p!ote$tion. 7ithmoti+te' beh+io!& espe$ill" in humns& it often is the !eltion of the $t to the ol& not the $t itself& tht is ke". )n

f$t& fo! humns& most moti+te' $ts !e onl" !bit!!il" !elte' to p!ti$ul! ols. 7hen hun!"& %e $n obtin foo'

in mn" 'iffe!ent %"s%lkin o! '!i+in to !estu!nt o! sto!e& $llin fo! 'eli+e!"& skin f!ien' to pi$k up

somethin. E$h t"pe of $ti+it" is pp!op!ite un'e! $e!tin $i!$umstn$es& but none hs p!e'e te!mine'& ine+itble

!eltion to foo' $@uisition n' $onsumption. The sme ene!l kin's of $ti+ities 2%lkin& '!i+in& $llin& skin3

$n be use' to $hie+e mn" +!ie' kin's of ols. 8iu!in out %ht to 'o un'e! 'iffe!ent sets of $i!$umstn$es in

o!'e! to $hie+e "ou! ols is %ht life is ll bout. Le!nin n' moti+tion !e thus $losel" inte!t%ine' topi$s.

PUSH /1D PULL

0" inte!est in the topi$ of moti+tion %s sp!ke' b" seein the f!ee,in $!o%' tke fliht in the +i'eo of the

Ol"mpi$ bombin. This beh+io! !emin'e' me of %ht hppene' in $lssi$ e(pe!iment pe!fo!me' b" 1el 0ille! in

the FMs.*

0ille! pl$e' !ts in n pp!tus tht $onsiste' of t%o $omp!tments& one pinte' %hite n' the othe! bl$k&

sep!te' b" n open 'oo!%". The !ts st!te' out in the %hite !e& %he!e the" !e$ei+e' sho$k fte! 'el". /t

fi!st& the" simpl" f!o,e. But then the" fiu!e' out tht the" $oul' es$pe f!om the sho$k b" oin into the bl$k !e.

E+entull"& the" le!ne' tht the" $oul' +oi' the sho$k ltoethe! b" !unnin out of the %hite $omp!tment s soon

s the" %e!e pl$e' in it. The !t $me to !outinel"in f$t& hbitull" pe!fo!m the !esponse& e+en if the sho$k %s

tu!ne' off. Then& in lte! phse of the stu'"& the 'oo! bet%een the t%o !es %s $lose'& !en'e!in the ol' hbit no

lone! useful. But th!ouh t!il-n'-e!!o! beh+io!& the !ts le!ne' tht if the" tu!ne' smll %heel& the 'oo! opene'.

The" thus le!ne' ne% hbit.

0ille! inte!p!ete' his !esults in te!ms of the p!e'ominnt theo!" of moti+tion t the time& :l!k Hull*s '!i+e

theo!". )n Hull*s +ie%& ll le!nin in+ol+es the !e'u$tion of bsi$ '!i+es 2like hune!& thi!st& se(& o! pin3& n' $u!!ent

beh+io! is the!efo!e p!o'u$t of '!i+e !e'u$tion in the pst. Tht is& %ht %e 'o to'" in $e!tin sitution is

fun$tion of %ht %e 'i' in the pst tht %s su$$essful in !e'u$in '!i+es in simil! situtions. This is essentill"

ps"$holoi$l +e!sion of the philosophi$l position kno%n s he'onism& the i'e tht %e li+e ou! li+es in su$h %"

s to seek plesu!e n' +oi' pin.

)n the lte nineteenth $entu!"& the pionee! e(pe!imentl ps"$holoist E'%!' Tho!n'ike use' he'onism s

the bsis fo! ps"$holoi$l metho'olo". Tho!n'ike sho%e' tht hun!" $ts %oul' le!n $omple( beh+io!l !e-

sponses tht h' no ntu!l !eltion to fee'in but tht llo%e' them to open 'oo! n' obtin bite of foo' tht %s

+isible outsi'e the $e. The $ts bsi$ll" %ent th!ouh p!o$ess of t!il n' e!!o!& n' those !esponses tht

opene' the 'oo! %e!e then lte! !epete'. Tho!n'ike $lle' this the l% of effe$tA beh+io!s tht !e effe$ti+e in

obtinin 'esi!ble ols n' +oi'in un'esi!ble ones !e !e%!'e' o! !einfo!$e' n' then !epete'& %hile those

tht fil to obtin 'esi!ble ols o! tht le' to un'esi!ble ones !e punishe' n' !e not !epete'.

The kin' of le!nin tsk use' b" Tho!n'ike $me to be $lle' inst!umentl $on'itionin!efe!!in to the

f$t tht the beh+io! is inst!umentl in $hie+in the !e%!' o! punishment. Be$use the !e%!'in o! punishin

stimulus is sso$ite' %ith the beh+io!l !esponse& inst!umentl $on'ition-

in is $lle' stimulus-!esponse le!nin. )nst!umentl $on'itionin $ont!sts %ith P+lo+in o! $lssi$l

$on'itionin& %he!e the !e%!'in o! punishin stimulus o$$u!s !e!'less of %ht the niml 'oes. The sso$ition

fo!me' is thus not bet%een the !e%!'in o! punishin stimulus n' !esponse& but bet%een neut!l stimuli n' the

!e%!' o! punishment the" o$$u! %ith n' p!e'i$t. Hen$e& P+lo+in $on'itionin is $lle' stimulus-stimulus le!nin.



8o! e(mple& P+lo+*s 'o sli+te' to the soun' of the bell be$use tht soun' h' been p!e+iousl"

sso$ite' %ith foo'. The 'o 'i' nothin to obtin the foo'& %hi$h simpl" ppe!e' %hen the bell soun'e' 2this is

stimulus-stimulus sso$ition3. On the othe! hn'& if the 'o h' le!ne' tht %lkin o+e! to $e!tin spot n'

p!essin le+e! %ith its p% %hen the bell soun'e' %oul' le' to !el pie$e of foo'& tht beh+io! %oul' be n in-

st!umentl !esponse& !e%!'e' b" its su$$ess in obtinin foo' 2this %oul' be stimulus-!esponse sso$ition3.

Toethe!& these t%o fo!ms of le!nin be$me the foun'tion of beh+io!l ps"$holo"& n' beh+io!ists like John7tson& B. 8. Skinne!& n' Hull hope' to e(plin ll of humn beh+io! in su$h te!ms.

Hull*s p!ti$ul! $ont!ibution to the fiel' %s to !einte!p!et the l% of effe$t in te!ms of '!i+e !e'u$tion& !uin

tht ne% inst!umentl beh+io!s& ne% hbits& !e le!ne' n' !epete' be$use the" !e'u$e '!i+es. But fo! Hull& '!i+e

onl" $ti+te' o! !ouse' beh+io!C it 'i' not 'i!e$t beh+io! to%!' spe$ifi$ stimuli tht %oul' !e'u$e the '!i+e.

Beh+io!l 'i!e$tion in the p!esen$e of '!i+e-eli$ite' beh+io!l $ti+tion %s inste' bse' on le!ne' hbits&

!esponses tht h' been su$$essful in !e'u$in '!i+es in p!e+ious $i!$umstn$es.

)n this f!me%o!k& %ht %s the '!i+e tht %s !e'u$e' in the lst p!t of 0ille!*s stu'"& %he!e the!e %s no

sho$k= 7ht mo+e' the !ts to le!n the ne% !esponse= Bein '!i+e theo!ist& 0ille! ssume' some '!i+e must h+e

been !e'u$e'& sin$e le!nin o$$u!!e'. Be$use the sho$k %s ne+e! p!esente' 'u!in the lst phse of le!nin&

ho%e+e!& pin p!e+ention $oul' not h+e been the '!i+e bein stisfie'. 0ille! !ue' tht the '!i+e bein !e'u$e'

must h+e been fe!. 8e!& in his +ie%& %s le!ne' o! $@ui!e' '!i+e& s oppose' to bioloi$l one 2tht is& n

unle!ne'& innte o! instin$tul '!i+e3.

The notion of $@ui!e' '!i+e ''e' t!emen'ous fle(ibilit" to '!i+e theo!"& sin$e most humn beh+io! is not

moti+te' b" pin o! 'ep!i+tion of essentil nut!ients. 0one"& fo! e(mple& hs no int!insi$ +lue& n' $@ui!es its

+lue onl" f!om mutul $$eptn$e of its %o!th b" those %ho use it. Simil!l"& %o!'s of p!ise o! s$o!n !e not

inntel" moti+tin& n' $hie+e thei! !esults onl" b" $on+ention.

But '!i+e theo!"C e+en %ith 0ille!*s $le+e! ''ition& !emine' p!oblemti$ fo! +!iet" of !esonsA One of the

min 'iffi$ulties $me f!om stu'ies sho%in tht !ts %oul' le!n m,e p!oblems to obtin s$$h!in. S$$h!in hs

in$enti+e +lue 2!ts %ill %o!k to obtin it3 'ue to its s%eet tste& but it is non-nut!iti+e n' thus $nnot stisf" hune!

n' !e'u$e the suppose' '!i+e $ti+te' b" the bioloi$l nee' fo! foo'. /s !esult of this n' othe! !ese!$h& '!i+e

theo!" e+entull" %s !epl$e' b" the in$enti+e theo!". 7hile '!i+es push us f!om %ithin& in$enti+es pull us f!om

%ithout.

The '+nte of n in$enti+e +ie% is tht it +oi's the postultion of h"potheti$l '!i+e stte tht hs to be

!e'u$e' in o!'e! fo! le!nin to o$$u!. 7hile in$enti+e theo!ies !e the!efo!e less $umbe!some& the" h+e thei! o%n

sho!t$ominthe" often !epl$e the '!i+e p!oblem %ith the $!e'ibilit" p!oblem 2$hp. G3. Tht is& the" ssume tht

sub>e$ti+e he'oni$ e(pe!ien$es& emotionl feelins& !e %ht moti+te beh+io!.

The i'e ) %nt to 'e+elop he!e is tht moti+tion $n be thouht of in te!ms of in$enti+es %ithout ssumin

tht feelins !e ne$ess!" to t!nslte in$enti+es into $tions. ) belie+e tht ll %e nee' to $$ept is tht in the p!es-

en$e of $on'itione' 2le!ne'3 o! un$on'itione' 2innte3 in$enti+es& emotion s"stems !e $ti+te'& pl$in the b!in in

stte %he!e n inst!umentl !esponse be$omes hihl" p!obble out$ome. )n this +ie%& %e 'on*t h+e to postulte

the e(isten$e of h"potheti$l $on$epts like '!i+es o! sub>e$ti+e sttes to e(plin moti+te' $tion. /ll %e nee' to tlk

bout is !el b!in s"stems n' thei! fun$tions.

The b!in $n be thouht of s h+in +!iet" of s"stems tht it uses to inte!$t %ith the en+i!onment n'

keep itself li+e. )*+e use' the te!m emotion systems to $h!$te!i,e mn" of these& but %ht*s !ele+nt he!e is not the

lbel %e i+e them but the p!ti$ul! fun$tion the" pe!fo!m. )n$lu'e' !e s"stems tht 'ete$t n' !espon' to p!e'to!s

n' othe! 'ne!s& to se(ul p!tne!s& to suitble foo' n' '!ink& to sfe shelte!& n' so on. The stimuli 2in$enti+es3

tht $ti+te these s"stems 'o so eithe! be$use of bioloi$ll" p!e'ete!mine' f$to!s o! be$use of pst le!nin b"

the in'i+i'ul. 7hen the b!in is $ti+te' b" eithe! n un$on'itione' o! $on'itione' in$enti+e& nimls& in$lu'in

people& !e moti+te' to pe!fo!m inst!umentl !esponses. These emotionll" p!ime' inst!umentl !esponses h+e s

thei! ol& thei! moti+e& the lte!tion of the b!in stte& the emotionl stte& tht the o!nism is in.



So lon s %e !esist the tempttion to think of emotionl sttes in sub>e$ti+e te!ms& n' inste' $on$ei+e of

them in te!ms of b!in sttes& %e !emin on soli' !oun' n' +oi' the pe!ilous $!e'ibilit" p!oblem 'is$usse' in the

lst $hpte!.

8E/48UL H/B)TS )1 THE B4/)1

)n the "e!s follo%in 0ille!*s $lssi$ stu'ies& !ese!$he!s use' +e!si+e inst!umentl $on'itionin

p!o$e'u!es to stu'" the b!in me$hnisms of fe!.

)n su$h stu'ies& !ts o! othe! nimls le!n to 'o thins tht +oi' the 'eli+e!" of sho$k. On$e the" le!n

ho% to +oi' the sho$k& the" pe!fo!m the !esponse hbitull". 9i+en tht the hllm!k of fe! o! n(iet" 'iso!'e!s is

hbitul +oi'n$e of situtions tht miht le' to h!m o! n(iet"& this pp!o$h seeme' to offe! the oppo!tunit" to

un'e!stn' the neu!l bsis of $lini$ll" !ele+nt kin' of le!nin. Ho%e+e!& s mentione' p!e+iousl"& stu'ies of

+oi'n$e $on'itionin file' to le' to $le! un'e!stn'in of the neu!l bsis of fe!. Little effo!t %s m'e to

'istinuish the $ont!ibution of neu!l s"stems to the t%o kin's of le!nin tht tke pl$e in these tsks initill"& the

sub>e$t un'e!oes $lssi$l fe! $on'itionin& %he!e $ues in the pp!tus $ome to be sso$ite' %ith the sho$k&

then n inst!umentl +oi'n$e hbit is le!ne' on the bsis of its bilit" to !emo+e the niml f!om the sitution in

%hi$h sho$k is likel".#W The notion of multiple memo!" s"stems h' not "et eme!e'& n' it %sn*t full" pp!e$ite'

tht 'iffe!ent kin's of le!nin in+ol+e 'iffe!ent b!in s"stems. On$e !ese!$he!s st!te' fo$usin on fe! $on'itionin

on its o%n& st!ippe' out of the $onte(t of +oi'n$e $on'itionin& p!o!ess %s s%ift. /n' s the popul!it" of fe!

$on'itionin in$!ese'& the mo!e $omple( +oi'n$e-$on'itionin p!o$e'u!es& %hi$h %e!e mo!e 'iffi$ult to !elte to

b!in me$hnisms& fell out of f+o!.

But fe! $on'itionin tells us onl" bout ho% fe! !e$tions %o!k. )f %e %nt to un'e!stn' ho% the !ousl of

n emotion s"stem moti+tes beh+io!& %e nee' to tu!n to inst!umentl tsks& like +oi'n$e& %he!e the b!in le!ns

to tke $tion. 7ith tht in min'& fte! seein the Ol"mpi$ bombin +i'eo& n' bein !emin'e' of 0ille!*s !ts fi!st

f!ee,in n' then es$pin& ) 'e$i'e' se+e!l "e!s o to !e+isit the @uestion bout ho% fet-moti+te' inst!umentl

le!ninfe! hbit le!nin%o!ks in the b!in. ) 'i'n*t& ho%e+e!& %nt to stu'" >ust n" fe! hbit-le!nin tsk& but

one tht %oul' enble us to buil' upon ou! e(tensi+e kno%le'e of the neu!l bsis of $on'itione' fe!& espe$ill"

$on'itione' fe! eli$ite' b" tone p!e+iousl" pi!e' %ith sho$k.

5!im 1'e!& P!in /mo!pnth& n' ) $hose to stu'" this usin tsk $lle' es$pe f!om fe!. )n this

p!o$e'u!e& the !ts fi!st un'e!%ent fe! $on'itionin to tone-sho$k $ombintion. /s in ou! othe! stu'ies& %e use' the

e(tent to %hi$h the" f!o,e in the p!esen$e of the tone s n in'e( of le!nin in the fe!-$on'itionin phse. The ne(t

'"& the nimls %e!e pl$e' in ne% $hmbe!. /fte! 'el"& the tone $me on. /t fi!st& the" f!o,e to the tone. But&

e+entull"& the" mo+e' !oun' bit& n' th!ouh t!il n' e!!o!& the" 'is$o+e!e' tht mo+ement to the othe! si'e of

the $hmbe! te!minte' the tone. O+e! mn" t!ils& the !ts le!ne' to es$pe to the othe! si'e imme'itel" to

minimi,e the e(posu!e to the soun'. The !ts thus le!ne' to tke $tion on the bsis of h+in fi!st le!ne' tht tone

%s sso$ite' %ith sho$k. The sho$k& b" the %"& %s ne+e! p!esente' in the ne% $hmbe!. The tone h' be$ome

neti+e se$on'!" in$enti+e& n' beh+io!s tht eliminte' this stimulus %e!e !einfo!$e' n' le!ne' s hbit.

The 'esin of this e(pe!iment %s +e!" simil! to tht of 0ille!*s stu'"& e($ept tht %e use' tone s the fe!-

!ousin stimulus !the! thn $onte(tul $ues in the pp!tus itself. 7e %e!e no% !e'" to e(plo!e the b!in

me$hnisms th!ouh %hi$h fe! s"stem $ti+tion moti+tes $tion.

4e$ll f!om e!lie! $hpte!s tht in o!'e! fo! tone $on'itionin to o$$u!& the tone hs to be t!nsmitte' to the

lte!l nu$leus of the m"'l. This !eion then sen's sinls to the $ent!l nu$leus& %hi$h $ont!ols fe! !esponses.

So the fi!st @uestion %e ske' %s %hethe! 'me to the lte!l o! $ent!l nu$leus %oul' lso 'is!upt the

$on'itionin of the inst!umentl es$pe !esponse. The !esults %e!e $le!. Dme to the lte!l nu$leus p!e+ente'

the le!nin of the es$pe !esponse& but $ent!l nu$leus lesions h' no effe$t. Thus& the outputs of the $ent!l

nu$leus to the b!in stem& !e@ui!e' fo! fe! !e$tions& !e not use' to le!n to 'o ne% beh+io!s& to tke $tion& on the



bsis of fe! s"stem $ti+tion. 7e the!efo!e ske' %hethe! 'me to one of the othe! t!ets of the lte!l nu$leus

nmel"& the bsl nu$leus%oul' h+e n effe$t. This lesion inte!fe!e' %ith the bilit" of the !ts to use the info!-

mtion le!ne' 'u!in fe! $on'itionin to initite p!ote$ti+e $tion. )t*s impo!tnt to note tht bsl nu$leus 'me

h' no effe$t on the niml*s bilit" to f!ee,e to the tone in the fi!st p!t of the stu'". This ptte!n of suits is %ht

neu!os$ientists $ll 'ouble 'isso$ition& %he!e the !oles of t%o b!in !es in t%o beh+io!s !e sho%n to be

'istin$tA the $ent!l nu$leus %s foun' to be in+ol+e' in fe! !e$tion but not fe! $tion& n' the bsl nu$leus in thefe! $tion but not !e$tion.

So e($tl" ho% 'oes $on'itione' stimulus& $on'itione' in$enti+e& p!o$esse' b" the m"'l moti+te

n' !einfo!$e beh+io!= To ns%e! this @uestion& %e nee' to $onsi'e! the ntu!e of !einfo!$ement fu!the!.

JUST 4E7/4DS

)n the e!l" Fs& stu'ies b" Jim Ol's n' Pete! 0ime!& t%o !ese!$he!s in Donl' Hebb*s 'ep!tment t

0$9ill& foun' tht !ts %oul' !etu!n to the lo$tion in $hmbe! %he!e the" !e$ei+e' bu!st of ele$t!i$l pulses to

thei! b!ini. The nimls& in othe! %o!'s& seeme' to be $omin b$k fo! mo!e. Ol's n' 0ime! kne% !iht %" tht

the" %e!e on to somethin. The stimultion stmpe' in the beh+io!& >ust s !e%!'s 'o. /t the time& beh+io!ism still

'ominte' ps"$holo"& n' b!in stimultion !e%!' seeme' to be %" to fiu!e out the b!in me$hnisms

un'e!l"in the topi$ most impo!tnt to beh+io!ismA ho% !esponses tht le' to !e%!'s !e le!ne'.

Ol's n' 0ime! 'e+ise' %" to test %hethe! b!in stimultion $oul' !einfo!$e ne% !esponses. Ele$t!o'es

%e!e implnte' in the !ts* b!ins n' $onne$te' to le+e! tht the sub>e$ts themsel+es $oul' p!ess. E$h time the"

p!esse'& the" ot fe% pulses. The !ts ben to p!ess like $!,". This so-$lle' self-stimultion %s $le!l"

!e%!'init moti+te' the $@uisition of n !bit!!" beh+io! 2p!essin b!3.

This fs$intin !esult %s 'ue to mistke. The !ese!$he!s %e!e t!"in to stimulte the !eti$ul! fo!mtion

in the b!in stem& !eion in+ol+e' in !ousl& le!tness& n' +iiln$e. This %s in the he"'" of '!i+e theo!"& %hi$h

p!opose' tht '!i+es le' to le!nin b" !ousin the o!nism& n' Ol's n' 0ilne! %nte' to in+estite %hethe! n

in$!ese in !ousl& p!o'u$e' b" !eti$ul! fo!mtion stimultion& %oul' enhn$e le!nin. The ele$t!o'e& thouh&

$$i'entll" en'e' up some%he!e in the fo!eb!in !the! thn in the b!in stem. /lthouh the e($t !e tht the

ele$t!o'e %s in is not kno%n& in subse@uent stu'ies& Ol's n' 0ilne! n' othe!s i'entifie' mn" sites f!om %hi$h

self-stimultion $oul' be eli$ite'&# the most potent of %hi$h %e!e in the h"pothlmus. The !eson these sites %e!e so

effe$ti+e %s not be$use the h"pothlmus is the !e%!' $ente! of the b!in& but be$use m>o! ne!+e pth%"

psses th!ouh the h"pothlmus. This pth%"& $lle' the me'il fo!eb!in bun'le& %s $tull" the sou!$e of the

!e%!'in effe$t& s )*ll e(plin lte!.

)t %sn*t lon fte! the phenomenon of b!in stimultion !e%!' %s 'is$o+e!e' tht the i'e !ose tht its

effe$ts %e!e 'ue to the stimultion of “plesu!e $ente!s# in the b!in.# This notion %s fu!the! fuele' %hen su!eon

in 1e% O!lens& 4obe!t Heth& !epo!te' tht s$hi,oph!eni$ ptients foun' su$h stimultions plesu!blei* /!oun' the

sme time& 0i$hel :!i$hton*s lite!!" $!ee! %s >ump-st!te' %hen he popul!i,e' plesu!e $ente!s in The Terminal

$an)< 7hile mn" !ese!$he!s lso t!ete' b!in stimultion !e%!' in te!ms of sub>e$ti+el" e(pe!ien$e' plesu!e&

Pete! Shi,ll& le'in thinke! in this fiel'& hs !ue' tht the bilit" of !e%!'s to moti+te beh+io! n' to i+e

!ise to plesu!ble feelins !e sep!te.# This is moti+tionl +e!sion of m" notion tht emotionl beh+io!s !e not

ne$ess!il" $use' b" emotionl feelins& s Shi,ll pointe' out.

)n spite of its immense popul!it"C b!in stimultion !e%!' !ese!$h e+entull" !n out of stem. One !eson

%s tht the moti+tionl ntu!e of b!in stimultion !e%!' %s ne+e! @uite fiu!e' out. Di' it $ti+te '!i+es&

enhn$e in$enti+es& o! both= 7s it the sme s ntu!l !e%!'& n' $oul' it e(plin le!nin= These issues

!emine' un!esol+e'& n' b" the lte Fs& b!in stimultion !e%!'& like othe! topi$s !elte' to moti+tion n'

emotion& %s '"in out s the influen$e of $oniti+e s$ien$e %s in$!esin. D!i+es& in$enti+es& n' !e%!'s %e!e >ust

not s impo!tnt to $oniti+e s$ientists s the" h' been to beh+io!ists.



PLE/SE 4ELE/SE 0E

Pe!hps the most sinifi$nt out$ome of b!in stimultion !ese!$h %s the 'is$o+e!" of %h" me'il

fo!eb!in bun'le stimultion %s !e%!'in.# 7hen this pth%" is stimulte' in the !eion of the h"pothlmus&

fibe!s he'e' f!om the fo!eb!in to the b!in stem !e $ti+te'. The min t!ets of these fibe!s !e neu!ons tht

mke 'opmine&Q %hi$h !e lo$te' in !eion of the b!in stem $lle' the +ent!l tementl !e. These $ells& in

tu!n& sen' thei! (ons th!ouhout the fo!eb!in. /s !esult& %hen the 'opmine $ells !e $ti+te' b" inputs f!om the

me'il fo!eb!in bun'le& the" !elese 'opmine %i'el" in the fo!eb!in.#

Dopmine hs lon been belie+e' to be $!iti$l f$to! in !e%!' p!o$esses. /lthouh the!e !e !e%!'in

$on'itions tht 'o not 'epen' on 'opmine&# mu$h of %ht %e kno% bout !e%!'s $ente!s !oun' the !ole of

'opmine. 8o! e(mple& t!etin !ts %ith '!us tht blo$k the effe$ts of 'opmine t its !e$epto!s in the b!in

elimintes the !e%!'in effe$ts of b!in stimultion tht is& !ts !e mu$h less in$line' to p!ess to et the b!in >olts

un'e! su$h t!etment. 8u!the!& if hun!" !ts !e i+en foo' in one $omp!tment of t%o-$hmbe!e' pp!tus& o! if

stite' !ts !e i+en !e%!'in b!in stimultion in one of the $omp!tments& the" %ill lte! spen' mo!e time in tht

$omp!tment. This is $lle' pl$e p!efe!en$e. T!etment of !ts %ith '!us tht blo$k the $tion of 'opmine

p!e+ents the fo!mtion of the pl$e p!efe!en$e. / pl$e p!efe!en$e $n lso be estblishe' b" i+in !ts shot of

mphetmine o! $o$ine& both of %hi$h mimi$ the $tion of 'opmine t its !e$epto!s. )t*s no $$i'ent tht these

%i'el" buse' '!us %o!k like !e%!'s in le!nin situtions& n' the !eltion of 'opmine to '!u ''i$tion %s im-

po!tnt in sustinin inte!est in !e%!' n' moti+tion 'u!in the "e!s of $oniti+e 'omintion in neu!os$ien$e.

Just s b!in stimultion !e%!' %s initill" thouht to be 'ue to $ti+tion of plesu!e $ente!s& 'opmine

%s belie+e' to be the $hemi$l of plesu!e. Ho%e+e!& s %e*+e seen& the he'onisti$ 2sub>e$ti+e plesu!e3 +ie% of

b!in stimultion !e%!' is in$o!!e$t& n' the he'onisti$ inte!p!ettion of 'opmine*s !ole in !e%!' is in$o!!e$t s %ell.

8o! e(mple& blo$k'e of 'opmine inte!fe!es %ith inst!umentl !esponses moti+te' b" s%eet !e %!' but 'oes not

lte! the $tul $onsumption of the tst" stuff %hen it is obtine'the nimls still “like# the !e%!' %hen the"

$onsume it& but the" !e no lone! moti+te' to %o!k fo! it. Dopmine is thus mo!e in+ol+e' in nti$ipto!" beh+io!s

2lookin fo! foo' o! '!ink o! se(ul p!tne!3 thn in $onsummto!" !esponses 2etin& '!inkin& h+in se(3. But

bein hun!" o! thi!st" is unplesnt. Plesu!e& to the e(tent it is e(pe!ien$e' 2see 'is$ussion of the $!e'ibilit"

p!oblem in $hpte! G3& %oul' not $ome 'u!in the nti$ipto!" stte but inste' 'u!in $onsummtion. Sin$e

'opmine is in+ol+e' onl" in the nti$ipto!" phse& n' not in the $onsummto!" phse& its effe$ts 2t lest in the

$se of p!im!" nee' sttes3 $nnot be e(pline' in te!ms of plesu!e.

The e($t !ole of 'opmine in moti+tion& !e%!'& n' hbit le!nin is still bein 'ebte'. /lthouh it seems

$le! tht 'opmine is not in+ol+e' in sub>e$ti+e plesu!e o! in the e(p!ession of $onsummto!" !esponses& the!e is

less !eement bout the $on'itions tht 'epen' on 'op!nine. Some 'he!e to the $lssi$ h"pothesistht it is the

bsis of !e%!'. /nothe! +ie% is tht 'opmine !elese is impo!tnt fo! the initition n' mintenn$e of nti$ipto!"

beh+io!s in the p!esen$e of se$on'!" in$enti+e stimuli. Othe!s !ue tht 'opmine !elese notifies the fo!eb!in

tht somethin no+el o! une(pe$te' hs o$$u!!e'& but not tht !e%!' pe! se hs o$$u!!e'. Still othe!s p!opose tht

'opmine is in+ol+e' in the s%it$hin of ttention n' sele$tion of $tion. These !e not mutull" e($lusi+e +ie%s&

n' in f$t e$h ppe!s to $o!!e$tl" $h!$te!i,e $e!tin spe$ts of %ht 'opmine $ont!ibutes to moti+tion.

/ 0OT)6E :)4:U)T

7hile $ti+tion of 'opmine neu!ons in the +ent!l tementl !e le's to the !elese of 'opmine in mn"

p!ts of the fo!eb!in& n !e $lle' the nu$leus $$umbens is p!ti$ul!l" e!mne to !e%!' n' moti+tion. 0n"

of the effe$ts of 'op!nine-!elte' '!us 'es$!ibe' bo+e $n be $hie+e' b" ppl"in the '!us 'i!e$tl" to the

nu$leus $$umbens& !eion of the st!i

tu!n lo$te' in f!ont of the m"'l ne! the bottom of the fo!eb!in. 8o! e(mple& nimls %ill p!ess b!

to 'ministe! 'opmine o! !elte' '!us 2$o$ine o! mphetmine3 into the nu$leus $$u!nbens. /lso& 'opmine le+-



els !ise in the nu$leus $$umbens in !esponse to ntu!l !e%!'s 2foo'& %te!& n' se(ul stimuli3& $on'itione'

in$enti+es 2stimuli sso$ite' %ith !e%!'s3& n' b!in stimultion !e%!'. 8inll"& blo$k'e of 'opmine !e$epto!s in

the nu$leus $$umbens !etl" !e'u$es the !e%!'in effe$ts of me'il fo!eb!in bun'le stimultion n' of ntu!l

!e%!'s& n' lso p!e+ents the 'e+elopment of pl$e p!efe!en$es.

So ho%& p!e$isel"& 'oes n ele+tion of 'opmine in the nu$leus $$umbens $$omplish ll of this= 0o!e

thn t%ent" "e!s o& /nn 9!"biel n' 9o!'on 0oenson sueste' tht the nu$leus $$umbens sits t the$!oss!o's of emotion n' mo+ement& n' tht 'opmine !elese in this !eion pl"s $!u$il !ole in moti+te' o!

ol-'i!e$te' beh+io!. This $on$lusion %s bse' on fou! min sets of obse!+tion. 8i!st& the nu$leus $$umbens

!e$ei+es mssi+e 'opmine inputs f!om the tementum. Se$on'& in>e$tion of mphetmine o! $o$ine into the

nu$leus $$umbens le's to beh+io!l $ti+tionnimls st!t e(plo!in thei! en+i!onment s if in se!$h of

somethin. Thi!'& the $$umbens lso !e$ei+es inputs f!om !es in+ol+e' in emotionl p!o$essin& su$h s the

m"'l. 8ou!th& the $$umbens sen's output to !es in+ol+e' in the $ont!ol of mo+ement 2su$h s the plli'um&

n !e tht $onne$ts %ith the mo+ement-$ont!ol !eions in the $o!te( n' b!in stem3. To'"& it is %i'el" $$epte'

tht the nu$leus $$umbens n' !es %ith %hi$h it is $onne$te' $onstitute ke" elements of $i!$uit th!ouh %hi$h

emotionl stimuli 'i!e$t beh+io! to%!' ols. Let*s $onsi'e! the fun$tion of this moti+e $i!$uit in the b!o'e! $onte(t

of emotionl info!mtion p!o$essin b" the b!in.

)n the p!esen$e of n emotionll" !ousin stimulus& the b!in is pl$e' in stte& sometimes $lle' moti+e

stte& tht le's to $oo!'inte' info!mtion p!o$essin %ithin n' $!oss !eions& n' !esults in the in+io!tion n'

ui'n$e of beh+io! to%!' positi+e ols n' %" f!om +e!si+e. 0ost of %ht %e kno% bout ho% in$enti+es !e

le!ne' n' !e$te' to $omes f!om stu'ies of +e!si+e $on'itionin& but most of %ht %e kno% bout ho% $on'itione'

in$enti+es !e use' to in+io!te n' ui'e beh+io! $omes f!om stu'ies of positi+e moti+tion. )*m the!efo!e oin to

ppl" to neti+e moti+tion %ht is kno%n bout the !ole of the $$umbens in positi+e moti+tion in n effo!t to mo+e

fo!%!' f!om ou! un'e!stn'in of +e!si+e $on'itionin into moti+tion $i!$uits 2the 'etils m" the!efo!e nee' to be

!e+ise' fte! mo!e !ese!$h is pe!fo!me' on the !ole of the $$umbens in neti+e moti+tion3.

The p!o$essin beins in the senso!" s"stem tht !e$ei+es the stimulus 2the u'ito!" s"stem& in the $se of

tone tht*s been pi!e' %ith n +e!si+e sho$k3 n' then flo%s fo!%!' to the m"'l& espe$ill" the lte!l nu$leus&

%hi$h& in tu!n& $ti+tes the $ent!l nu$leus of the m"'l 2$hps. 4 n' G3. Outputs of the $ent!l nu$leus initite

the e(p!ession of spe$ies-t"pi$l 'efense !esponses 2like f!ee,in n' sso$ite' utonomi$ $hnes3 s %ell s $-

ti+te !ousl s"stems in the b!in stem& in$lu'in the 'opmine neu!ons in the +ent!l tementl !e. The tementl

$ells then !elese 'opmine f!om thei! (on te!minls in the nu$leus $$umbens 2s %ell s in othe! !es of the

fo!eb!in3.

/s note' bo+e& nimls be$ome $ti+e o! in+io!te' %hen 'opmine is in>e$te' into the $$umbens. This

o$$u!s be$use 'opmine f$ilittes s"npti$ t!nsmission in the pth%" f!om the $$umbens to the plli'um& %hi$h

in tu!n $onne$ts %ith mo+ement-$ont!ol !eions in the $o!te( n' b!in stem. 7ith the plli'l output mplifie'& the

moto! !eions !e st!onl" $ti+te'& n' mo+ement is initite'. Beh+io! $n potentill" be in+io!te' b" n"thin

tht $ti+tes tementl $ells n' $uses them to !elese 'opmine in the $$umbens. 1o+el stimuli& n' $on'itione'

n' un$on'itione' in$enti+es& !e p!ime e(mples of in+io!tin stimuli.

But in+io!tion lone is not suffi$ientA beh+io! lso nee's to be ui'e' o! 'i!e$te'. 9ui'n$e of beh+io! is

the >ob of $on'itione' in$enti+es p!o$esse' b" the m"'l. The bsl nu$leus of the m"'l& s %e*+e seen&

!e$ei+es info!mtion bout $on'itione' in$enti+e f!om the lte!l nu$leus. )t then t!nsfe!s this $on'itione' in$enti+e

to the $$umbens. ;7hen 'opmine is ele+te' in the $$umbens 2s !esult of the $ent!l nu$leus*s $ti+tion of

'opmine neu!ons in the tementum tht !elese 'opmine in the $$umbens3& the !!i+l of n in$enti+e stimulus in

the $$umbens f!om the bsl nu$leus %ill h+e bie! effe$t on the $ti+it" of $$umbens $ells&s, n' p!esumbl"

on neu!ons in the +ent!l plli'um tht !e 'o%nst!em f!om the $$umbens. The in$enti+e thus le's to the !elese

of 'opmine& n' 'opmine f$ilittes the bilit" of the in$enti+e to both in+io!te n' 'i!e$t beh+io!.

:on'itione' in$enti+es !e se$on'!" !einfo!$e!s n' $n stmp in !esponses tht le' to them. /nimls %ill



%o!k to obtin $on'itione' in$enti+es& e+en %hen the" 'o not le' to p!im!" in$enti+es. /s %e*+e seen& fte! le!nin

tht tone p!e'i$ts sho$k& nimls %ill tke $tions to stop the tone. Simil!l"& nimls %ill pe!fo!m tsk 2p!ess

b!3 to tu!n on tone tht %s p!e+iousl" p!e'i$ti+e of some tst" foo'& e+en if the tone no lone! le's to foo' 2this is

$omp!ble to lookin t pi$tu!es of lo+e' one %hen he o! she is %"3.

The mnne! in %hi$h $on'itione' in$enti+es !einfo!$e !esponses is not full" un'e!stoo'. Ho%e+e!& LTP

o$$u!s in $$umbens $i!$uits& n' 'opmine is essentil fo! the s"npti$ $hnes to o$$u!.

/ !esonble h"pothesisis tht 'opmine f$ilittes Hebbin plsti$it" bet%een $ti+e p!es"npti$ n' posts"npti$ $ells n' the!eb"

st!enthens t!nsmission bet%een $$umbens pth%"s tht p!o$ess the in$enti+e n' tht $ont!ol !esponses.

0" $on$eption of the !ole of the m"'l n' $$umbens in moti+tion bo!!o%s he+il" f!om the %o!k of

B!!" E+e!itt n' T!e+o! 4obbins t :mb!i'e Uni+e!sit". These !ese!$he!s h+e e(tensi+el" stu'ie' ho%

inte!$tions bet%een the m"'l n' nu$leus $$umbens $ont!ibute to moti+tion& espe$ill" moti+tion b" positi+e

in$enti+es. The"*+e sho%n tht 'me to the bsl m"'l elimintes the bilit" of $on'itione' in$enti+es to f$ili-

tte the le!nin of ne% !esponse b" se!+in s se$on'!" !e%!'. This 'is!uption o$$u!s fo! $on'itione'

in$enti+es $!ete' b" pi!in neut!l stimuli 2like tones3 %ith +!iet" of p!im!" !e%!'s& in$lu'in tst" foo' items&

'!us like $o$ine n' mphetmine& n' e(posu!e of mle !t to se(ull" !e$epti+e femle. Th!ouh

$le+e! $ombintion of lesions& %he!e the bsl m"'l is lesione' on one si'e of the b!in n' the nu$leus

$$umbens on the othe!& E+e!itt n' 4obbins h+e sho%n tht $onne$tions bet%een the m"'l n' $$umbens

!e ke" to the bilit" of $on'itione' in$enti+e to moti+te ne% le!nin. Thei! %o!k is p!t of lon t!'ition of

!ese!$h on the !ole of the m"'l in stimulus-!e%!' le!nin. Some of the othe! ke" !ese!$he!s in this !e !e

0o!t 0ishkin& E'mun' 4olls& Tketoshi Ono& 1o!mn 7hite& 0i$hel 9llhe!& n' D+i' 9ffn.#

On$e n emotionl hbit is %ell le!ne'& the b!in s"stems in+ol+e' in e(p!essin it be$ome simple!. The

m"'l& fo! e(mple& '!ops out of the $i!$uit. /fte! "ou kno% ho% to su$$essfull" +oi' spe$ifi$ 'ne!& "ou no

lone! nee' the m"'l& be$use fe! is no lone! !ouse'. / 'o nee's its m"'l to le!n tht pl"in !oun'

in the !o' is 'ne!ous& but on$e the le!nin hs o$$u!!e'& he $n hppil" pl" in the "!' ne(t to the !o'. 2)n this

$se& +oi'n$e of 'ne! 'oesn*t !ouse fe!& it p!e+ents fe!.3 :h!$te!isti$ll"& m"'l-'epen'ent sins of

emotionl !ousl& su$h s ele+tions of he!t !te& o$$u! 'u!in the initil phse of +oi'n$e le!nin but 'isppe!

s the +oi'n$e !esponse is le!ne'. The $$umbens like%ise '!ops out on$e the !esponse is le!ne'C %hile it*s

nee'e' to 'o the le!nin& it is not ne$ess!" to pe!fo!m %ell-le!ne' !esponses. The e($t s"stems tht tke o+e! in

le!ne' 'efensi+e hbits !e not full" un'e!stoo'. Pe!hps the $$umbens& like othe! !es of the st!itum& t!ins

p!ef!ontl $o!ti$l $i!$uits& espe$ill" !es of the moto! $o!te(& ho% to !espon'. The le!nin& in othe! %o!'s& miht

be t!nsfe!!e' f!om the st!itum 2$$umbens3 to the $o!te(. This %oul' be simil! to %ht o$$u!s in 'e$l!ti+e o!

e(pli$it le!ninA initill"& both the hippo$mpus n' neo$o!te( !e in+ol+e'& but on$e the hippo$mpus hs slo%l"

tuht the neo$o!te( the memo!"& the memo!" pe!sists %ithout the i' of the hippo$mpus.

)nte!$tions bet%een the $$umbens n' m"'l thus o lon %" to%!' $$ountin& in neu!l te!ms&

fo! some of the ke" spe$ts of moti+tion. But the moti+e $i!$uit $onsists of othe! !es s %ell. The hippo$mpus

p!ti$iptes b" %" of its $onne$tions to the m"'l n' $$umbens& n' m" %ell be in+ol+e' in the ui'n$e of

beh+io! on the bsis of sptil n' othe! kin's of !eltionl $ues in the en+i!onmentA in o!'e! to fin' oo' thins n'

+oi' b' ones& "ou h+e to kno% %he!e "ou !e& %he!e "ou nee' to o& ho% to n+ite f!om %he!e "ou !e to

%he!e "ou nee' to o& n' %ht so!ts of stimuli lon the %" %ill be useful in ui'in "ou. This info!mtion& '!%n

f!om lon-te!m memo!"& is essentil. )t is lso impo!tnt to keep the o+e!ll ol in min'& n' to $onstntl" up'te

"ou! p!o!ess to%!' the ol. 7o!kin-memo!" fun$tions of the p!ef!ontl $o!te( p!obbl" !e impo!tnt fo! this

bilit" The p!ef!ontl $o!te( !e$ei+es 'opmine inputs& n' is $onne$te' %ith the $$umbens& m"'l& n'

hippo$mpus. :e!tinl"& %hen moti+tion is bse' on 'e$isions& the p!ef!ontl $o!te(& s %e %ill no% see& %ill often be

in+ol+e'.

DE:)S)O1S U1DE4 8)4E



The stu'" tht 1'e!& /mo!pnth& n' ) $on'u$te'& in %hi$h !ts le!ne' to es$pe f!om soun' tht h'

been sso$ite' %ith sho$k& %s 'esine' to ''!ess the @uestion of ho% emotionl !ousl moti+tes $tion. The

pp!o$h %e took in+ol+e' hbit le!nin. But in !el-life situtions& %e 'on*t l%"s h+e hbits to fll b$k on& o!

time to le!n ne% one. 7e !en*t onl" impelle' b" '!i+es& pulle' b" in$enti+es& n' shpe' b" !einfo!$e!s. 7e li+e in

$omple( %o!l' %he!e the ph"si$l n' so$il en+i!onment $hnes f!om moment to moment n' %e often inte!te

imme'ite nee's n' pst le!nin %ith p!e'i$tions bout the best $ou!se of $tion to tke. 7e use ou! $p$it" tothink& !eson& n' e+lute. 7e mke 'e$isions.

De$ision-mkin $omp!esses t!il-n'-e!!o! le!nin e(pe!ien$es into n instntneous mentl e+lution

bout %ht the $onse@uen$e of p!ti$ul! $tion %ill be fo! i+en sitution. )t !e@ui!es the on-line inte!tion of in-

fo!mtion f!om 'i+e!se sou!$esA pe!$eptul info!mtion bout the stimulus n' sitution& !ele+nt f$ts n'

e(pe!ien$es sto!e' in memo!"& fee'b$k f!om emotionl s"stems n' the ph"sioloi$l $onse@uen$es of emotionl

!ousl& e(pe$ttions bout the $onse@uen$es of 'iffe!ent $ou!ses of $tion& n' the like. This so!t of inte!ti+e

p!o$essin& s %e*+e seen& is the business of %o!kin memo!" $i!$uits in the p!ef!ontl $o!te(. )n $hpte!s = n' G& %e

'is$usse' the !ole of the p!ef!ontl $o!te( in %o!kin memo!" n' $onsi'e!e' the $ont!ibution of the lte!l n' me'il

p!ef!ontl $o!te(. He!e& %e %ill fo$us on t%o of the sub!es of the me'il p!ef!ontl $o!te( in liht of thei! !eltion to

the moti+e $i!$uits outline' bo+e.

The nte!io! $inulte $o!te( !e$ei+es inputs f!om the 'opmine $ells in the tementum& s %ell s f!om the

bsl m"'l& +ent!l plli'um& n' hippo$mpus. )n ''ition& it sen's outputs to the $$umbens n' to the motot

$o!te(. )t is thus in position to !e$ei+e info!mtion bout beh+io!l !ousl 2'opmine $onne$tions f!om the

tementum3 n' bout $on'itione'

in$enti+es n' thei! mplifi$tion b" 'opmine 2$onne$tions f!om the m"'l n' plhi'um3. )t $n then

inte!te this info!mtion %ith 't f!om lon-te!m memo!" 2$onne$tions %ith the hippo$mpus3 n' %ith the tem-

po!!" $ontents of %o!kin memo!" 2$onne$tions %ith othe! p!ef!ontl !es3 in the p!o$ess of $ont!ollin mo+ement

2$onne$tions to the moto! $o!te(3. Tht the nte!io! $inulte is lso in+ol+e' in p!o$essin un$on'itione' in$enti+es

is sueste' b" stu'ies sho%in $ti+tion of this !eion in humns !e$ei+in pinful stimultion.

The o!bitl $o!te(& n !e of the +ent!l p!ef!ontl $o!te(& lo$te' t the bottom of the f!ontl lobe >ust bo+e

the e"e so$kets& is lso impo!tnt in moti+tion n' 'e$ision-mkin. Stu'ies of monke"s b" D+i' 9ffn n' E'-

mun' 4olls h+e impli$te' this !eion in emotionl p!o$essinin the p!o$essin of in$enti+es 2!e%!'s n'

punishments3 n' in the tempo!!" sto!e of in$enti+e info!mtion. This !eion is $onne$te' %ith the nte!io!

$inulte& n'& like the nte!io! $inulte& it lso !e$ei+es info!mtion f!om the m"'l n' hippo$mpus.

The 'or1 of Antonio /amasio has (een especially si!nificant in dra'in! attention to the critical nature of

emotional information in human decision%ma1in!, and especially the role of the or(ital corte in this process) $uch of

/amasio9s recent 'or1 on this topic is summari:ed in his t'o (oo1s, /esca rtes9 Error and The Feelin! of "hat

#appens)> #e and his collea!ues ha+e sho'n that patients 'ith dama!e to the or(ital prefrontal re!ion ha+e poor

.ud!ment and often ma1e decisions that lead to socially inappropriate courses of action) sin! a cle+er eperimental

tas1, called the !am(lin! tas1, they demonstrated that patients 'ith or(ital corte lesions are insensiti+e to chan!es in

the incenti+e +alue of stimuli, despite the fact that they ha+e relati+ely normal 'or1in! memory, as assessed in purely

co!niti+e 'ays) /amaand collea!ues interpreted their results in terms of an ina(ility of patients

%ith o!bitl $o!te( 'me to use emotionl info!mtion to ui'e $tion& n' h+e p!opose' tht emotionl

info!mtion o! kno%le'e no!mll" bises !esonin bilit" b" influen$in ttention n' %o!kin memo!" p!o$esses.

/lthouh the" !ue' tht thei! !esults 'isso$ite' 'e$ision-mkin f!om %o!kin memo!" p!o$esses& in liht of the

suestion bo+e tht the o!bitl $o!te( is p!t of the %o!kin memo!" $i!$uit!"& n' is espe$ill" in+ol+e' in %o!kin

memo!" bout emotionl info!mtion& n lte!nte $on$lusion is tht the !esults sho% 'isso$ition bet%een $oniti+e

n' emotionl spe$ts of %o!kin memo!".

The lte!l& nte!io! $inulte& n' o!bitl p!ef!ontl !eions !e s"npti$ll" inte!$onne$te' in +!ious %"s

n' shoul' be thouht of not s sep!te& in'epen'ent mo'ules& but s $omponents of n inte!te' %o!kin memo!"



s"stem 2$hps. = n' G3. /lthouh in'i+i'ul !eions m" mke !elti+el" !ete! $ont!ibution to 'iffe!ent spe$ts of

%o!kin memo!"& espe$ill" in $ont!olle' lbo!to!" e(pe!iments& in mo!e ntu!l settins& %he!e 'e$isions in+ol+e the

inte!tion of $oniti+e n' emotionl info!mtion& it is likel" tht inte!$tions !the! thn 'isso$itions bet%een the

!es %ill be $ommonpl$e.

But %e h+e to be $!eful not to >ump to the $on$lusion tht 'e$ision-mkin is simpl" somethin $!!ie' out

b" the p!ef!ontl $o!te( on its o%n. 4e$ent stu'ies b" Pul 9lim$he! t 1YU h+e pointe' to the $ont!ibution of !eion in the p!ietl $o!te( tht ppe!s to be $omponent of the 'e$ision-mkin p!o$ess b" %hi$h e"e mo+ements

!e $ont!olle'. This !eion is p!t of the “%he!e# pth%" 2$hp. N3& is st!onl" $onne$te' %ith the lte!l p!ef!ontl

$o!te(& n' hs lon been impli$te' in e"e-mo+ement $ont!ol. But 9lim$he! hs uppe' the nte in this fiel' b"

pe!fo!min sophisti$te' mthemti$l nl"sis tht suests tht p!ietl neu!ons p!ti$ipte in 'e$ision-mkin.

Bsi$ll"& he*s pp!o$he' the p!oblem of ho% popultions of neu!ons in the b!in mke 'e$isions in mnne! simil!

to the %" tht e$onomists pp!o$h the beh+io! of popultions of peopleio His nl"sis suests tht these $ells

!e ble to inte!te info!mtion bout i+en stimulus n' its impli$tions fo! the mount of !e%!' tht sub>e$t

niml $n e(pe$t on p!ti$ul! t!il& i+en %ht hs been e(pe!ien$e' in the pst. )t %ill be inte!estin to see

%hethe! this kin' of nl"sis lso %o!ks fo! $ells in the p!ef!ontl $o!te( n' %hethe! the!e !e 'iffe!en$es bet%een

p!ietl n' p!ef!ontl in+ol+ement. /lso impo!tnt to e(mine is %hethe! the!e miht be 'iffe!en$es %ithin p!ef!ontl

$i!$uits. )t miht be e(pe$te' tht the me'il o! o!bitl !es %oul' be mo!e in+ol+e' %hen emotionl info!mtion is

ui'in 'e$isions n' the lte!l p!ef!ontl !es %hen emotionl info!mtion is less impo!tnt thn $oniti+e

info!mtion.

0n" in the fiel' h+e tken noti$e of 9lim$he!*s %o!k. P!ti$ul!l" inte!estin is his $lim tht his pp!o$h

$n put Des$!tes*s 'ulism to !est the!e*s no mentl stuff li+in in the neu!ons n' mkin 'e$isions& it*s >ust the

neu!ons $!!"in out mthemti$l $l$ultions. 7hile mn" h+e !ue' tht p!o$ess of this t"pe must un'e!lie the

min'-b!in !eltion& 9lim$he! hs $tull" e+es'!oppe' on neu!ons %hile the" 'o the $l$ultions tht %e $ll

'e$isions.

0OT)6/TED 0/1

0u$h of the %o!k on moti+tion tht %e*+e $onsi'e!e' he!e hs been bse' on stu'ies of nimls. Ho% f!&

"ou miht sk& $n this pp!o$h tke us in un'e!stn'in moti+tion in the 'il" life of humn beins= The ns%e!

is& ) think& fi!l" f!. To un'e!stn' %h" this is so& %e nee' to $onsi'e! t%o b!o' pp!o$hes to humn moti+tion

%ithin ps"$holo" to'".

The fi!st& n' most p!ominent& is the $oniti+e pp!o$h. )n the Fs& the so$il ps"$holoist Leon 8estine!

fuse' the ne%l" eme!in $oniti+e +ie% of the min' %ith the $lssi$ notion of '!i+e in n ttempt to $$ount fo! the

moti+tion of humn beh+io!& espe$ill" in $onfli$t situtions. The theo!"& $lle' $oniti+e 'issonn$e& ssume' tht

h+in in$onsistent o! $onfli$tin thouhts 2fo! e(mple& “7ntin mo!e mone" is !ee'"=* n' “H+in mo!e mone"

is oo'#3 puts one in n un$omfo!tble stte& '!i+e stte& %hi$h 'emn's !e'u$tion b" $hnin one of the thouhts

2fo! e(mple& “Bein !ee'" is not so b'# o! “H+in lots of mone" is not so oo'#3. This theo!" +e !ise to

t!emen'ous mount of !ese!$h in so$il ps"$holo" n' sp%ne' mn" othe! !elte' theo!ies*

So$il ps"$holoists %e!e one of the fe% !oups of ps"$holoists %ho !emine' inte!este' in moti+tion

'u!in the $oniti+e !e+olution. But& o+e! the "e!s& thei! +ie%s lost thei! link to t!'itionl notions of moti+tion n'

%ent f!the! n' f!the! in the $oniti+e 'i!e$tion. 5no%le'e& beliefs& e(pe$ttions& n' self-%!eness !epl$e'

'!i+es n' emotions in e(plntions of ho% beh+io! is !ouse' n' 'i!e$te'.

8o! e(mple& 1n$" :nto! n' H,el 0!kus& le'in $ontempo!!" $oniti+e moti+tionl theo!ists& +ie%

moti+tion s p!o'u$t of self-kno%le'eA* Self-kno%le'e ob+iousl" in$lu'es kno%le'e bout one*s emotions n'

thei! moti+tionl $onse@uen$es& but fo! :nto! n' 0!kus moti+es !e p!o'u$ts of the self s mu$h s $ont!ibuto!s

to it. 5e" to thei! theo!" is the notion of %o!kin self& n on-the-fl" $onst!u$tion bout %ho %e !e tht !efle$ts %ho



%e*+e been 2pst sel+es3& n' %ho %e %nt n' 'on*t %nt to be 2futu!e sel+es3. )n $ont!st to e!lie! self theo!ists&

su$h s /lf!e' /'le! %ho +ie%e' the self s stti$ n' en'u!in entit" :nto! n' 0!kus +ie% the self s

'"nmi$ n' mutble $onst!u$tion tht $hnes in 'iffe!ent situtions%e h+e 'iffe!ent ols %hen t home thn

%hen on the >ob& fo! e(mple& n' the %o!kin self in e$h sitution !efle$ts su$h 'iffe!en$es. One*s %o!kin self is

thus subset of the uni+e!se of possible self-$on$epts tht $n o$$u! t n" one timeit is the subset tht is

+ilble to the thinkin $ons$ious pe!son t p!ti$ul! moment& n' is 'ete!mine' in p!t b" memo!" n'e(pe$ttion& n' in p!t b" the imme'ite sitution. These fetu!es of the %o!kin self e(plin ho% one $n h+e both

stble n' mutble moti+es& n' ho% moti+es $n be $onfli$tin o! 'issonnt. The %o!kin self is $ent!l p!t of

ones mentl pp!tus. )t influen$es pe!$eption& ttention& thinkin& memo!" !et!ie+l& n' sto!e& n' ui'es $tion.

Buil'in on 7illim Jmes& the $oniti+e ps"$holoist John 5ihlst!om hs !ue' tht $!iti$l $omponent of

n" $ons$ious e(pe!ien$e is the !eltion& in %o!kin memo!"& of the ob>e$t of the e(pe!ien$e to one*s sense of self.

:ombinin Jmes n' 5ihlst!om %ith :nto! n' 0!kus le's to the $on$lusion tht the %o!kin self is $onst!u$te'

in %o!kin memo!" n' the $onst!u$tion of the moment $ont!ibutes in sinifi$nt %"s to on-line p!o$essin& 'e$ision-

mkin& n' beh+io!l $ont!ol.

The se$on' m>o! pp!o$h to humn moti+tion lso o!iinte' in the Fs %hen D+i' 0$:lelln'

p!opose' his nee'-$hie+ement theo!". /$$o!'in to 0$:lelln'& humns h+e limite' numbe! of inbo!n moti+es

2'!i+es o! nee's3 tht !e sensiti+e to ntu!l in$enti+es 2hune!& thi!st& n' se(& fo! e(mple3& n' moti+tion o$$u!s

%hen pe!son 'oes somethin to mke these ol ob>e$ts +ilble& usull" b" pe!fo!min some beh+io! tht hs

been le!ne' in the pst. 7hen the beh+io! le's to the in$enti+e& emotion is !ouse'& n' the beh+io!l se@uen$e

tht le' to the in$enti+e is !einfo!$e'. Th!ouh e(pe!ien$e& people lso le!n to !e$oni,e $ues tht sinl the

+ilbilit" of ntu!l in$enti+es. These $ues lso !ouse emotions. Be$use positi+e emotionl sttes !e !einfo!$in&

people seek out situtions in %hi$h le!ne' o! ntu!l in$enti+es !e p!esent. 0oti+es& in 0$:lelln'*s +ie%& !e thus

emotionll" $h!e' sttes tht nti$ipte ol ob>e$ts. Upon this @usi-bioloi$l foun'tion of inbo!n moti+es n'

le!ne' in$enti+es& 0$:lelln' hs built theo!" of humn beh+io! fo$use' on positi+e moti+tionl sttes like

ffilition n' $hie+ement. 0$:lelln' 'oes not 'en" the impo!tn$e of neti+e moti+tion& but pl$es this topi$

outsi'e the !e $o+e!e' b" his theo!". 4ese!$h on humns b" 0$:lelln' n' othe!s $$umulte' o+e! se+e!l

'e$'es hs ten'e' to suppo!t m>o! spe$ts of $hie+ement theo!".

So ho% 'o %e !e$on$ile the t%o +ie%s of humn moti+tion= 0$:lelln'*s theo!" emphsi,es non+e!bl

moti+tionl s"stems& some of %hi$h !e bioloi$ll" o!ni,e'. These %o!k impli$itl" n' fun$tion mo!e o! less

simil!l" in humns n' othe! mmmls& thouh e$h spe$ies $n h+e its o%n spe$ili,e' moti+e s"stems s %ell.

0$:lelln'*s +ie%s fit %ell %ith the '!i+el in$enti+eK!einfo!$ement t!'ition. But this pp!o$h 'oes not $o+e! the full

!ne of humn moti+tion& s 0$:lelln' himself hs note'. :ons$iousl" $$essible& +e!bll" en$o'e'&

e(pli$it moti+es $@ui!e' th!ouh the use of lnue !e lso n impo!tnt p!t of humn mentl life& espe$ill" in

so$il situtions. The self-$ons$iousness +ie% of moti+tion thus $omplements !the! thn $ont!'i$ts the impli$it

+ie%.

/nth!opoloists :lu'i St!uss n' 1omi ?uinn h+e use' 0$:lelln'*s !pp!o$hement bet%een impli$it

bioloi$l n' e(pli$it ps"$holoi$l moti+es to $$ount fo! moti+tionl simil!ities n' 'iffe!en$es bet%een $ultu!es.

She points out tht some moti+es !e uni+e!sl n' +!" onl" in intensit" bet%een $ultu!es& %he!es othe!s !e

uni@ue to spe$ifi$ $ultu!es. 0 ob+ious %" to !e$on$ile these theo!ies is to pl$e 0$:lelln'*s bioloi$ll" bse'

moti+es in the fo!me! $teo!" n' the e(pli$it& self-$ons$ious& in'i+i'ull" $onst!u$te' moti+es of :nto! n' 0!kus

into the ltte!. Ho%e+e!& not ll le!ne' moti+es !e !elte' to e(pli$it kno%le'e. 0ost moti+tionl theo!ies %e*+e

'is$usse'& f!om Tho!n'ike to Hull n' 0ille! to 0$:lelln'& emphsi,e the le!nin of moti+tionl hbits. Hbit

le!nin ene!ll" is +ie%e' s n impli$it fo!m of le!nin. St!uss points out tht hbits !e le!ne' not >ust th!ouh

en$ounte!s %ith !einfo!$e!s 2p!im!" o! se$on'!"3 but lso in $ommon so$il situtions in %hi$h %e obse!+e the

su$$esses n' filu!es of othe!s. )n'ee'& in spite of the pst emphsis of so$il ps"$holo" on self-$ons$ious

moti+es& mo!e n' mo!e !ese!$h on so$il beh+io! is beinnin to emphsi,e impli$it o! un$ons$ious spe$ts of



humn moti+tion. P!ti$ul!l" note%o!th" is John B!h*s %o!k on automoti+es n' Tim 7ilson*s theo!" of hi''en

sel+es.So )t lso nee's to be pointe' out& thouh& tht %hile hbit s"stems m" in'ee' le!n impli$itl"& %hen

moti+tionl hbits !e le!ne' un'e! $on'itions in %hi$h %o!kin memo!" tten's to the p!esent $i!$umstn$es& the

$onse@uen$es of hbit le!nin $n be e(pli$itl" !ep!esente' n' $ons$iousl" kno%ble& n' onl" lte!& on$e

!outini,e'& sent to the 'epths of the min'. Be$use hbits $n be both useful n' ptholoi$l 2hbitul +oi'n$e of

the outsi'e %o!l' b" ptient %ith pni$ 'iso!'e!& fo! e(mple3& the" !e n espe$ill" impo!tnt fo!m of beh+io!lle!nin.

Both impli$it n' e(pli$it s"stems thus $ont!ibute to moti+tion. 7o!kin memo!" is impo!tnt in the ui'n$e

of beh+io! to%!' ols tht !e e(pli$itl" !ep!esente' the!e n' $n be $!!ie' out un'e! e(e$uti+e $ont!ol fun$tions.

But& t the sme time& %e lso h+e b!in s"stems tht %o!k impli$itl" in the p!o$essin of in$enti+es n' the

ui'n$e of beh+io! to%!' ols. Sometimes& impli$it n' e(pli$it moti+tion %ill be in s"n$& in %hi$h $se %o!kin

memo!" n' impli$it s"stems ui'e beh+io! %ith $ommon put pose. 8o! e(mple& follo%in the e(plosion of

bomb& it is likel" tht both e(pli$it n' impli$it s"stems %ill initite beh+io!s tht tke "ou %" f!om !the! thn

to%!' the sou!$e of the e(plosion& ll othe! thins bein e@ul. But othe! thins !e not l%"s e@ul. )f "ou! spouse

h' one to the $on$ession stn' to et sn$k& n' the stn' is in the 'i!e$tion of the e(plosion& "ou m"& th!ouh

n e(e$uti+e 'e$ision& o+e!!i'e the ten'en$" to flee n' inste' !un to%!' the e(plosion. )n'ee'& fun$tionl-imin

stu'ies b" Jonthn :ohen suest tht the p!ef!ontl $o!te(& espe$ill" the nte!io! $multe& is in+ol+e' in !esol+in

moti+tionl $onfli$t. This !eion n' its s"npti$ $onne$tions m" the!efo!e pl" $!u$il !ole in o+e!$omin fe! o!

othe! emotionl sttes %hen %e nee' to tke n $tion tht oes inst ou! innte o! le!ne' $ompulsions. 20iht

this $i!$uit!" lso un'e!lie $oniti+e 'issonn$e=3

/n info!me' $on$eption bout the b!in !eions n' $i!$uits un'e!l"in p!ti$ul! fun$tion is the best %"

to bein to 'ete!mine ho% the b!in $tull" pe!fo!ms tht fun$tion. The!efo!e& on$e %e*+e t!nslte' bsi$ moti+-

tionl $on$epts into plusible neu!l $i!$uits& the tsk of !eltin the eno!mousl" $omple( topi$ of humn moti+tion to

the b!in be$omes less 'untin.

THE 0E1T/L T4)LO9Y )1 /:T)O1

Th!ouh the topi$ of moti+tion& %e bein to see the mentl t!ilo" in $tion. / min' is not& s $oniti+e

s$ien$e hs t!'itionll" sueste'& >ust thinkin 'e+i$e. )t*s n inte!te' s"stem tht in$lu'es& in the b!o'est

possible te!ms& s"npti$ net%o!ks 'e+ote' to $oniti+e& emotionl& n' moti+tionl fun$tions. 0o!e impo!tnt& it

in+ol+es inte!$tions bet%een net%o!ks in+ol+e' in 'iffe!ent spe$ts of mentl life.

Often the thins %e tten' to n' !emembe! !e the thins tht !e impo!tnt to us. )n su$h situtions&

$oniti+e p!o$essin %ill be $$ompnie' b" emotionl !ousl. /n' emotionl !ousl 'oes not stop %ith simple

!e$tion& fo! %e often use it to ui'e ou! beh+io! to%!' o! %" f!om the sitution tht the emotionll" !ousin

stimulus sinifies. )n the p!o$ess of 'oin so& %e sometimes h+e to mke 'e$isions bout %ht to 'o in o!'e! to keep

%o!kin to%!' ou! ol. The ol hs to be kept in min'& e+en %hen 'etou!s h+e to be tken. But the s"stem lso

nee's to be !eset if mo!e impo!tnt ol eme!es lon the %". This !e@ui!es !ello$tion of $oniti+e& emotionl&

n' moti+tionl !esou!$es& n' '>ustments %ithin n' bet%een the $omponent p!o$essin s"stems.

Self-kno%le'e is $e!tinl" sinifi$nt spe$t of humn moti+tion& but e+en nimls tht !e not self-

%!e& o! t lest not !obustl" %!e of %ho the" !e the %" humn is& !e moti+te' to 'o thinsthe" seek foo'

n' shelte! n' +oi' p!e'to!s n' in>u!". 0u$h of %ht %e humns 'o is lso influen$e' b" p!o$esses tht

pe!$olte lon outsi'e of %!eness. :ons$iousness is impo!tnt& but so !e the un'e!l"in $oniti+e& emotionl&

n' moti+tionl p!o$esses tht %o!k un$ons$iousl".



:H/PTE4 TE1

SY1/PT): S):51ESS

:/1ST THOU 1OT 0)1)STE4 TO / 0)1D D)SE/SED&PLU:5 84O0 THE 0E0O4Y / 4OOTED SO44O7&

4/E OUT THE 74)TTE1 T4OUBLES O8 THE B4/)1& /1D 7)TH SO0E S7EET OBL)6)OUS /1T)DOTE

:LE/1SE THE STU88*D BOSO0 O8 TH/T PE4)LOUS STU887H):H 7E)9HS UPO1 THE HE/4P

Shkespe!e& $ac(eth)

)n spite of Shkespe!e*s insiht tht mentl p!oblems !e “t!oubles of the b!in&# hun'!e's of "e!s lte!&

p!oponents of ph"si$l bsis fo! mentl illness still h' little e+i'en$e %ith %hi$h to mke thei! $se. B" the lte

nineteenth $entu!"& it %s %i'el" $$epte' tht $tul 'est!u$tion of the b!in 2the !esult of 'iseses like s"philis3

$oul' $hne mentl fun$tion '!sti$ll"&* but the lte!tions of moo' n' thouht tht h' $ome to be kno%n s

neu!oses n' ps"$hoses %e!e still !esistnt to ph"si$l e(plntion. Youn Simun' 8!eu' souht neu!oloi$l$$ount of mentl illness& but !eli,in tht su$h ol %s unttinble in his lifetime& tu!ne' to ps"$holoi$l

e(plntions n' ps"$holoi$l t!etments inste'. The!e %s no “s%eet obli+ious nti'ote&# to use Shkespe!e*s

ph!se& fo! h"ste!i& meln$holi& o! n(iet".

Ob+iousl"& the sitution hs $hne' $onsi'e!bl" in the pst fe% 'e$'es. 0entl ml'ies h+e& in the

e"es of mn"& $ome to be !e$oni,e' s “t!oubles of the b!in&# n' nti'otes h+e eme!e' s the t!etment of

$hoi$e mo!e often thn not. 4e!'less of ho% one feels bout the bioloi$l o!ienttion of ps"$hit!" to'" 2n' it

hs mn" $!iti$s3 t%o f$ts must be $kno%le'e'. The essen$e of %ho %e !e is en$o'e' in ou! b!ins& n' b!in

$hnes $$ount fo! the lte!tions of thouht& moo'& n' beh+io! tht o$$u! in mentl illness. The ke" issue is not

%hethe! mentl illness is !ell" neu!l in ntu!e. )t is inste' the ntu!e of the neu!l $hnes tht un'e!lie mentl

p!oblems& n' the mnne! in %hi$h t!etment shoul' p!o$ee'.

Bioloi$l ps"$hit!" %s foun'e' on& n' still l!el" 'he!es to& the ssumption tht mentl 'iso!'e!s !e'ue to $hemi$l imbln$es in the b!in. The b!in& in this +ie%& is like 'eli$te soup. To mintin its $h!$te!isti$

fl+o!& >ust the !iht mi( of ke" in!e'ients is !e@ui!e'. Too little o! too mu$h of one o! nothe! item& n' its $h!$te!

is lte!e'. But the no!ml $h!$te! $n sometimes be !esto!e' %ith the !iht mi( of ''itionl in!e'ients tht eithe!

!epl$e missin in!e'ient o! 'mpen the effe$ts of n o+e!l" bun'nt one. Like mste! $hef*s& the bioloi$l

ps"$hit!ist*s >ob is to '>ust the blen'& to bln$e the $hemist!"& so tht the 'esi!e' $h!$te! is !esto!e'.

The soup mo'el e+ol+e' in ps"$hit!" fo! t%o !esons. One %s p!$ti$l numbe! of mentl 'iso!'e!s

%e!e foun'& sometimes $$i'entll"& to be helpe' b" lte!in b!in $hemist!". /nothe! %s $on$eptul



neu!os$ientists h' $ome to think of $hemi$ls s n impo!tnt $ont!ibuto! to the %" in %hi$h mentl life is $!ete'

b" the b!in. The p!$ti$l >ustifi$tion !emins& but& s %e*ll see no%& the $on$eptul one hs $hne'.

/lthouh it seeme' in the e!l" Fs tht the!e miht be p!ti$ul! $hemi$l $o'e fo! 'iffe!ent mentl

sttes mole$ules of plesu!e& fe!& n' !ession %e!e p!opose'this notion is no% +ie%e' b" mn" s ni+e.

0entl sttes !e not !ep!esente' b" mole$ules lone& o! e+en b" mi( of mole$ules. /s %e*+e seen& the" !e

inste' $$ounte' fo! b" int!i$te ptte!ns of info!mtion p!o$essin %ithin n' bet%een s"npti$ll" $onne$te'neu!l $i!$uits. :hemi$ls p!ti$ipte in s"npti$ t!nsmission& n' in the !eultion o! mo'ultion of t!nsmission& but

it is the ptte!n of t!nsmission in $i!$uits& mo!e thn the p!ti$ul! $hemi$ls in+ol+e'& tht 'ete!mines the mentl

stte. The ol' bttle $!" “1o t%iste' thouht %ithout t%iste' mole$ule nee's !epl$in. S"npti$ $hnes& not

mole$ules& un'e!lie mentl illness. The impo!tn$e of $i!$uits hs been illust!te' !epete'l" in the p!e+ious $hpte!s.

)n this $hpte!& ) %nt to emphsi,e the impli$tions of $i!$uit point of +ie% fo! un'e!stn'in the ntu!e of

ps"$hit!i$ 'iso!'e!s.

Bioloi$l ps"$hit!ists 'o !eli,e tht $i!$uits !e sinifi$nt& n' it*s not out of ino!n$e tht the" 'he!e to

the soup mo'el. The" %oul' lo+e to h+e sm!t '!us& kin to sm!t missiles& tht& %hen tken o!ll"& %oul' o

st!iht fo! the $i!$uits tht un'e!lie p!ti$ul! 'iso!'e! n' +oi' ll othe!s. 7ith this so!t of '!u& '!e'e' si'e

effe$ts %oul' be eliminte'. But $hie+in su$h p!e$ision %oul' !e@ui!e tht the e($t $i!$uits lte!e' in p!ti$ul!

mentl 'iso!'e!s be kno%n& n' tht '!us be +ilble to '>ust sele$ti+el" the $hemist!" of the !ele+nt $i!$uits.

/lthouh not ll of the pie$es of the pu,,le !e in pl$e to'"& !ese!$h effo!ts !e un'e! %" to obtin the info!mtion

tht %oul' mke this possible. /s Ste+e H"mn& 'i!e$to! of the 1tionl )nstitute of 0entl Helth& hs note'&

ps"$hit!"& !m in !m %ith neu!os$ien$e& is poise' to ns%e! mn" of its $ent!l @uestions. H"mn& in f$t& !efe!s to

the time he' s “the millennium of min'& b!in n' beh+io!.# To f$ilitte the $hie+ement of his ol& the 1tionl

)nstitute of 0entl Helth !e$entl" hs estblishe' se+e!l 4ese!$h :ente!s fo! the 1eu!os$ien$e of 0entl

Diso!'e!s 2) se!+e s the 'i!e$to! of one of these& the :ente! fo! the 1eu!os$ien$e of 8e! n' /n(iet"& %hi$h )*ll

'es$!ibe lte! in the $hpte!3.

0ost $!iti$s of bioloi$l ps"$hit!" %ill not be stisfie' b" the shift in p!'im f!om soup to $i!$uits. The"

%ill !ue tht the impo!tnt @uestion is not %hethe! %e shoul' fo$us on $onne$tions inste' of $hemi$ls& but

%hethe! %e shoul' fo$us on the b!in t ll in ou! effo!ts to un'e!stn' n' t!et mentl illness. Ps"$holoi$l

p!oblems& su$h $!iti$s insist& !e !oote' in life e(pe!ien$es !the! thn in mlfun$tionin b!in h!'%!e& n' shoul'

be t!ete' b" helpin the ptient $ome to te!ms %ith the un'e!l"in p!oblem !the! thn b" t!"in to lte! b!in $i!$uits.

But s the !uments p!esente' in this book mke $le!& life*s e(pe!ien$es le+e lstin effe$ts on us onl" b" bein

sto!e' s memo!ies in s"npti$ $i!$uits. Be$use the!p" is itself le!nin e(pe!ien$e& it& too& in+ol+es $hnes in

s"npti$ $onne$tions. B!in $i!$uits n' ps"$holoi$l e(pe!ien$es !e not 'iffe!ent thins& but !the!& 'iffe!ent %"s

of 'es$!ibin the sme thin. Still& the mnne! in %hi$h b!in $hnes !e effe$te' b" ps"$hothe!p" is not

ne$ess!il" the sme s the %" in %hi$h the" !e b" '!us& %hi$h is %h" the!p" %o!ks in some $ses %he!e '!us

'on*t n' +i$e +e!s& o! %h" $ombintion of '!us n' ps"$hothe!p" $n sometimes be mo!e p!o'u$ti+e thn

eithe! lone.

Enouh ene!litieslet*s e(mine %ht is kno%n bout the biolo" of mentl illness. ) $n*t $o+e! ll$teo!ies of mentl illness he!e& n' so %ill fo$us on s$hi,oph!eni& 'ep!ession& n' n(iet" 'iso!'e!sA )nssemblin $ohe!ent $$ount of the histo!" of '!u the!p" fo! these 'iso!'e!s& )*+e bo!!o%e' f!om books b" SmuelB!on'es 6$olecules and $ental Illness7 n' Elliot 6lenstein 6Blamin! the Brain7)

T4)PP)1* UTE4USES

The mi'-t%entieth $entu!" %s n e($itin time in neu!os$ien$e !ese!$h. 7ith the en' of 7o!l' 7! ))&

ntionl s$ientifi$ !esou!$es %e!e shifte' to pe$etime effo!ts& n' one !e tht boome' %s b!in stu'ies. The

neu!on 'o$t!ine h' lon sin$e p!e+ile'& n' s"npti$ t!nsmission bet%een neu!ons %s %i'el" $$epte' s the

$u!!en$" of the b!in. But the ntu!e of s"npti$ t!nsmission %s still the topi$ of mu$h in+estition& the inte!p!e-



ttion of %hi$h %s hotl" 'ebte'. Si! John E$$les pushe' the notion of ele$t!i$l t!nsmission& %hile Si! Hen!" Dle

emphsi,e' the $hemi$l ntu!e of s"npti$ $ommuni$tion )n the en'& both %e!e !ihtsome s"npses !e

$hemi$l n' othe!s ele$t!i$lio 1e+e!theless& $hemi$l t!nsmission is belie+e' to be the 'ominnt fo!m of s"npti$

$ommuni$tion& fin'in to %hi$h e+en E$$les $me !oun'. Still& it is lon lep f!om the i'e tht tin" mounts of

neu!ot!nsmitte! !e s@ui!te' $!oss in'i+i'ul s"npses to the notion tht mentl sttes n' mentl 'iso!'e!s !e

$hemi$ll" $o'e'. /nothe! set of e+ents& $ulmintin !oun' the sme time& pl"e' n impo!tnt !ole in $losin thep.

)nestion of +!iet" of substn$es f!om ntu!e& like pe"ote o! $e!tin mush!ooms& h' lon been kno%n to

in'u$e hllu$intions& n' b" FQN& it h' been p!opose' tht the hllu$intions in'u$e' b" pe"ote !esemble' the

s"mptoms of s$hi,oph!eni. But it %s the $$i'entl 'is$o+e!" of no+el hllu$inoen& '-l"se!i$ $i'& o! LSD& tht

helpe' >ump-st!t the ps"$hoph!m$oloi$l in'ust!" in the Fs.#

:hemists h' 'ete!mine' in the )FQs tht e!ono+ine %s the $ti+e in!e'ient in the funus e!ot& %hi$h

h' been use' b" mi'%i+es to in'u$e ute!ine $ont!$tions n' $ont!ol blee'in 'u!in $hil'bi!th. )n the p!o$ess of

t!"in to fo!multe ne% '!u tht %oul' be useful fo! obstet!i$ins& /lbe!t Hoffmn %s $$i'entll" e(pose' to one

of the $hemi$l $ompoun's %ith %hi$h he %s %o!kin n' ente!e' “'!em-like stte# in %hi$h he e(pe!ien$e'

“klei'os$opi$ pl" of $olo!s.# Suspe$tin tht the $ulp!it %s LSD 2the t%ent"-fifth mo'ifi$tion of n $i'i$ e(t!$t of

e!ono+ine3& he 'e$i'e' to tke smll mount to see if the e(pe!ien$e %oul' !e$u!. /in& he h' po%e!ful

hllu$intions. 8u!nitu!e in the !oom “ssume' !otes@ue& th!etenin fo!ms&# n' the %omn ne(t 'oo! be$me

“mle+olent& insi'ious %it$h %ith $olou!e' msk.# His feelin tht 'emon h' in+'e' him lste' fo! bout

fou!teen hou!s. Othe!s t the $ompn" t!ie' the substn$e s %ell& ll %ith the sme !esult. 1e%s ot out& n' so 'i'

the '!u. The ke" e+ent fo! ou! sto!" %s not the popul!i,tion of LSD b" fiu!es like 5en 5e se" n' Timoth" Le!"&

but !the! the 'is$o+e!" in FQ b" John 9''um& S$ottish s$ientist& tht LSD blo$ke' ute!ine $ont!$tions in'u$e'

b" the $hemi$l s-h"'!o("t!"ptmine& othe!%ise kno%n s se!otonin. Se!otonin subse@uentl" %s foun' in the b!in&

n' sho%n to be neu!ot!nsmitte!. These f$ts +e 9''um n i'e. )f LSD p!o'u$e' ps"$hoti$ sttes 2hllu$i-

ntions3 b" lte!in neu!ot!nsmission in the b!in& snit" miht !e@ui!e $e!tin le+el of b!in neu!ot!nsmitte!s& n'

$hnin t!nsmitte! le+els miht be %" of t!etin mentl illness.

Tht '!us miht be useful in t!etin mentl illness %s not no+el i'e. 7ht %s ne% %s the notion tht

bno!ml mentl fun$tion miht !esult f!om lte!tions in s"npti$ t!nsmission& n' tht '!us tht ffe$te' s"npti$

t!nsmission miht the!efo!e be use' to t!et mentl illness. 9''um*s h"pothesis thus m!ks the beinnin of the

mo'e!n pp!o$h to bioloi$l ps"$hit!".

84O0 SED/T)O1 TO :O44E:T)O1 )1 PSY:HOS)S

/s mn" ps"$hit!ists !e %!e& the neo-8!eu'in H!!" St$k Sulli+n en$ou!e' his ptients to p!tke

of l$ohol to loosen them up befo!e st!tin ps"$honl"sis. This %s not '!u the!p" pe! se& s it %s not inten'e'

s $u!e. )n f$t& 'u!in the fi!st hlf of the t%entieth $entu!"& the non$u!ti+e

use of '!us %s $ommon& not so mu$h to f$ilitte the!p" s to se'te itte' o! mni$ ptients n'

mke them mo!e mneble& espe$ill" in institutionl settins.

)nsulin %s one of the fi!st '!us $on$ei+e' of s helpin to $u!e mentl 'iso!'e!. Like mn" othe! '!us&

its the!peuti$ effe$ts %e!e 'is$o+e!e' b" $hn$e. )n FQQ& 6iennese ph"si$in nme' 0nf!e' Skel +e smll

'ose of insulin& %hi$h lo%e!s bloo' su! le+els n' the!eb" stimultes ppetite& to some of his itte' s$hi,oph!eni$

ptients %ho h' not been etin. Su!p!isinl"& thei! ps"$hoti$ s"mptoms %e!e some%ht !elie+e'. 7hen Skel t!ie'

l!e! 'ose& the e(t!eme lo%e!in of bloo' su! put the ptients in $om fo! se+e!l '"s& but %hen the"

!e$o+e!e'& thei! ps"$hoti$ s"mptoms %e!e mu$h imp!o+e'. /lthouh the !eson this t!etment %o!ke' %s $om-

plete m"ste!"& insulin $om the!p" $me to be %i'el" use'& in spite of its 'ne!s& sin$e the!e %s no othe! +ible

t!etment fo! s$hi,oph!eni.

)n the Fs& thouh& t%o ne% ps"$hoti$ t!etments eme!e'& both of %hi$h %e!e e(pline' in te!ms of ne%



'is$o+e!ies bout neu!ot!nsmissson. One of these %s !ese!pine& '!u isolte' f!om plnt $lle' 0au'olfia ser%

pentina) 0au'o?fia h' been use' to t!et insomni n' insnit" in )n'i sin$e n$ient Hin'u times. 7hen )n'in

'o$to!s in the FQs foun' tht 0au'olfla $oul' !e'u$e hih bloo' p!essu!e& '!u $ompnies %e!e moti+te' to

isolte !ese!pine& the $ti+e substn$e in the plnt. )n the mentime& 1thn 5line& 1e% Yo!k ps"$hit!ist %ho kne%

of the use of 0au'olfia to t!et insnit" in )n'i& obtine' !ese!pine n' 'ministe!e' it to s$hi,oph!eni$ ptients. He

note' tht the '!u m'e the ptients less suspi$ious n' mo!e $oope!ti+e. Soon the!efte!& 5line $on+in$e' theo+e!no! of 1e% Yo!k tht !ese!pine shoul' be i+en to the FM& ptients in the mssi+e 1e% Yo!k Stte

Ps"$hit!i$ Hospitl s"stem. 5lein*s !epo!t $me !iht !oun' the time tht 9''um h' m'e the $onne$tion

bet%een se!otonin n' snit"& n' it %sn*t lon fte!%!' tht s$ientists 'ete!mine' tht !ese!pine !e'u$e' the le+el

of monomines 2in$lu'in se!otonin& no!epineph!ine& n' 'opmine3 in the b!ins of e(pe!imentl nimls. B" the

mi'-Fs& it seeme' tht ps"$hosis %s in'ee' !elte' to lte!tions in monomine le+els in the b!in& n' tht

!esto!tion of monomine fun$tion miht the!efo!e be %" of t!etin this $on'ition.

This $on$lusion %s suppo!te' n' !efine' b" the ne!-simultneous 'is$o+e!" of the benefi$il effe$ts of

$hlo!p!om,ine& phenothi,ine '!u m!kete' s Tho!,ine. This '!u %s isolte' be$use its $hemi$l st!u$tu!e

%s simil! to tht of ntihistmines. / 8!en$h su!eon t!ie' 'ministe!in $hlo!p!om,ine to some of his ptients to

test %hethe! it miht be mo!e effe$ti+e thn othe! ntihistmines in se'tin ptients n' !e'u$in !espi!to!" $om-

pli$tions in su!e!". The '!u tU!ne' out to h+e po%e!ful $lmin o! t!n@uili,in effe$t& %hi$h le' the su!eon to

p!opose usin it %ith ps"$hoti$s. T%o 8!en$h ps"$hit!ists& Jen Del" n' Pie!!e Denike!& t!ie' 'ministe!in

$hlo!p!om,ine to fe% s$hi,oph!eni$ ptients %ho %e!e !esistnt to ll othe! fo!ms of t!etment. 1ot onl" %e!e the"

t!n@uili,e'& thei! ps"$hoti$ s"mptoms 2p!noi n' hllu$intions3 %e!e lso !e'u$e'.

One of the si'e effe$ts of both !ese!pine n' $hlo!p!om,ine& ho%e+e!& %s the 'e+elopment of mo+ement

'iso!'e! $lle' t!'i+e '"skinesi& in+ol+in mus$le !ii'it" simil! to tht t"pi$l of P!kinson*s 'isese. Sin$e

P!kinsonism h' been foun' to be sso$ite' %ith !e'u$tion in 'opmine in the b!in& the suestion tht

ntips"$hoti$ '!us %e!e useful in t!etin s$hi,oph!eni be$use the" lte!e' 'opmine t!nsmission !ose& s 'i'

the !elte' notion tht s$hi,oph!eni %s 'ue to e($ess 'opmine. )n f$t& it $me to be belie+e' tht the poten$" of

ntips"$hoti$ '!us %s 'i!e$tl" !elte' to thei! bilit" to p!o'u$e t!'i+e '"skinesi. The +ie% tht s$hi,oph!eni

in+ol+e' 'opmine t!nsmission %s st!enthene' b" the $omplement!" obse!+tion tht ps"$hoti$ s"mptoms !e

b!ouht on b" too hih 'ose of L-'op& %hi$h in$!eses 'opmine le+els n' is use' to t!et P!kinson*s ptients&

o! b" mphetmine 2spee'3& %hi$h !tifi$ill" stimultes 'opmine !e$epto!s.

/n e(pe!iment pe!fo!me' b" S%e'ish s$ientist& /!+i' :!lsson& helpe' to !elte the effe$ts of !ese!pine

n' $hlo!p!om,ine to 'opmine. He e(mine' the effe$ts of e$h '!u on the le+el of the +!ious monomines in

!ts. 7hile !ese!pine $use' !e'u$tion& $hlo!p!om,ine h' no effe$t. This %s t!oublin fin'in fo! the eme!in

'opmine theo!" of s$hi,oph!eni. But in follo%-up e(pe!iment& he foun' tht the b!ek'o%n p!o'u$ts of 'opmine&

n' not the othe! monomines& %e!e in$!ese'. This implie' tht mo!e 'opmine %s bein !elese'& possibl" to

$ompenste fo! the blo$k of 'opmine !e$epto!s b" $hlo!p!om,ine. The loi$ is $omple(& but the impo!tnt point

he!e is tht this stu'" sueste' tht both ntips"$hoti$ '!us $te' b" !e'u$in 'opmine t!nsmission in the b!in.

7hile !ese!pine %o!ke' b" !e'u$in 'opmine !elese f!om p!es"npti$ te!minls& $hlo!p!om,ine*s effe$t %s 'ue to

blo$k'e of posts"npti$ 'opmine !e$epto!s. :!lsson sh!e' the 1obel P!i,e in fo! this n' !elte' %o!k.

The i'e tht s$hi,oph!eni miht be e(pline' t the le+el of 'opmine !e$epto!s %s st!onl" suppo!te' b"

!ese!$h $!!ie' out b" the Dut$h s$ientist J. 0. +n 4oussum 4ts i+en mphetmine 'ispl"e' in$!ese' lo$o

moto! $ti+it". 6n 4oussum sho%e' tht both the ntips"$hoti$ '!us $hlo!p!om,ine n' !ese!pine

blo$ke' this in$!ese' $ti+it". /lthouh these t%o '!us ffe$t ll monomines& thi!' potent ntips"$hoti$ '!u&

hlope!i'ol 2Hl'ol3& %hi$h onl" ffe$te' 'opmine& %s p!ti$ul!l" po%e!ful in !e'u$in the lo$omotion.

:onse@uentl"& +n 4oussum p!opose' tht nti-ps"$hoti$ '!us 'o thei! %o!k b" blo$kin 'opmine !e$epto!s& n'

tht o+e!stimultion of 'opmine !e$epto!s %s t the he!t of s$hi,oph!eni.

Still& the e+i'en$e linkin 'opmine neu!ot!nsmission to s$hi,oph!eni %s $i!$umstntil. /n ''itionl



'is$o+e!" st!enthene' the $onne$tion $onsi'e!bl". B" the mi'-FNs& numbe! of ntips"$hoti$ '!us h' been

'e+elope'. Stu'ies b" Philip Seemn in To!onto n' b" )n :!eese n' Solo-mn Sn"'e! in Bltimo!e !nk-o!'e!e'

the '!us b" thei! $lini$l effe$ti+eness n' then e(mine' the bilit" of e$h to blo$k 'opmine !e$epto!s.* F Both

stu'ies foun' tht the $o!!eltion %s ne!l" pe!fe$tA the mo!e potent its 'opmine-!e$epto!-blo$kin bilit"& the mo!e

effe$ti+e the '!u %s in t!etin s$hi,oph!eni. The 'emonst!tion tht the sme !eltion 'i' not hol' bet%een

$lini$l effe$ti+eness n' blo$k'e of se!otonin o! no!epineph!ine bolste!e' the +ie% tht it %s 'opmine& n' notthe othe! monomines& tht %s in+ol+e'# Dopmine !e$epto!s $ome in t%o !oupsA Di-like n' D-like. The f$t tht

ll of the $lssi$ 'opmine-!e$epto!-blo$kin '!us %e!e foun' to p!o'u$e thei! ntips"$hoti$ effe$ts b" $tin on the

D $lss ''e' fu!the! spe$ifi$it" to the !ole of 'opmine in s$hi,oph!eni*

The bottom-line $on$lusion f!om the e!l" %o!k on the !eltion of monomines to s$hi,oph!eni %s thisA Too

mu$h 'opmine in'u$es ps"$holoi$l 'iso!'e!& n' too little& mo+ement 'iso!'e! simil! to P!kinson*s 'isese.

/ bln$e must be mintine'. 7hen it is tippe'& the b!in 'oes not fun$tion no!mll". Subse@uent %o!k& s %e*ll see

in the follo%in se$tion& hs '!%n mo!e $omple( pi$tu!e of the neu!l bsis of s$hi,oph!eni. Dopmine is still

belie+e' to be in+ol+e'& but not @uite in so simple %" s the o!iinl imbln$e h"pothesis sueste'.

4ETH)15)19 PSY:HOS)S

/lthouh blo$kin the $tion of 'opmine t its !e$epto!s in the b!in is n effe$ti+e %" to t!et ps"$hoti$

s"mptoms& n' lthouh !tifi$il stimultion of 'opmine !e$epto!s 2%ith L-'op& mphetmine& o! $o$ine3 $n b!in

on ps"$hoti$ s"mptoms& the 'opmine !e$epto! h"pothesis of ps"$hosis !n into t!ouble fo! se+e!l !esons. 8i!st& the

the!peuti$ effe$ts of 'opmine '!us !e f! too slo% to be $$ounte' fo! b" simple !e$epto! p!o$ess. The '!us

bin' to !e$epto!s s soon s the" !e !elese' f!om the p!es"npti$ te!minl& n' h+e thei! ph"sioloi$l effe$ts

moments the!efte!. But $tul the!peuti$ effe$ts of these substn$es tke %eek o! t%o 2o! lone!3 to bein. The

the!peuti$ effe$t is the!efo!e mo!e like lon-te!m '>ustment to the !e$epto! blo$k'e thn 'i!e$t n' imme'ite

effe$t of the blo$k'e. Se$on'& ttempts to 'emonst!te tht 'opmine le+els !e ele+te' in s$hi,oph!eni p!o+e'

unf!uitful& in $ont!st to the !elti+e ese %ith %hi$h 'e$!eses in 'opmine %e!e foun' in P!kinson*s 'isese. The

se!$h fo! $hnes in 'opmine !e$epto!s& !the! thn n in$!ese in 'opmine itself& %s mo!e su$$essful but the

e+i'en$e %s $ont!o+e!sil& sin$e most of the !ese!$h %s pe!fo!me' on ptients %ho h' been on ntips"$hoti$

me'i$tion& %hi$h mkes it 'iffi$ult to kno% %hethe! the $hne in !e$epto!s %s 'ue to the 'iso!'e! itself o! %s

$onse@uen$e of the t!etment. Thi!'& stn'!' mnifesttions of s$hi,oph!eni in$lu'e positi+e o! ''e' s"mptoms

2hllu$intions& bno!ml thouht ptte!ns& p!noi& 'elusions& ittion& hostilit"C bi,!!e out-of-$onte(t beh+io!3

n' neti+e s"mptoms o! 'efi$ien$ies 2blunte' emotions& $oniti+e 'efi$its in ttention n' %o!kin memo!"& poo!

h"iene& po+e!t" of spee$h& so$il isoltion& loss of moti+tion3. The $lssi$ o! t"pi$l ntips"$hoti$ me'i$tions& D

!e$epto! blo$ke!s& !e minl" useful in t!etin positi+e s"mptoms& n' !e less helpful in t!etin neti+e ones&

suestin tht the 'opmine theo!" is t best in$omplete. 8inll"& !e$ent stu'ies h+e sho%n tht s$hi,oph!eni $n

lso be helpe' b" '!us tht t!et othe! s"stems& in$lu'in se!otonin n' no!epineph!ine". These so-$lle' t"pi$l

nti-ps"$hoti$ me'i$tions tu!n out to be mo!e useful fo! neti+e s"mptoms& fu!the! $hllenin the suffi$ien$" of the

o!iinl 'opmine theo!".

4e$ent effo!ts to e(plin s$hi,oph!eni n' othe! mentl 'iso!'e!s h+e tu!ne' to mo!e $omple(

$on$eptions tht fo$us on lte!tions of fun$tion in spe$ifi$ b!in !eions n' $i!$uits !the! thn lobl $hnes in the

le+el of monomines. 8o! e(mple& numbe! of stu'ies h+e 'emonst!te' st!u$tu!l 'iffe!en$es bet%een the b!ins

of s$hi,oph!eni$s n' no!ml $ont!ol sub>e$ts. )n$lu'e' !e $hnes in si,e o! +olume of $e!tin b!in !eions& n'

the numbe! of $ells n' thei! shpe n' !!nement in 'iffe!ent !eions. Some of the ke" !es in %hi$h st!u$tu!l

$hnes h+e been 'is$o+e!e' in$lu'e the p!ef!ontl $o!te( n' me'il tempo!l lobe 2hippo$mpus n' m"'l3.

:hnes in the numbe! of 'opmine !e$epto!s h+e lso been foun' in the p!ef!ontl $o!te( n' bsl nli. The

p!ef!ontl $o!te(& hippo$mpus& n' m"'l lso e(hibit fun$tionl nomlies in bloo' flo%

n'Ko! neu!l $ti+it"& s 'ete!mine' b" PET n' fun$tionl 04) s$nnin te$hni@ues



The st!u$tu!l n' fun$tionl 'iffe!en$es in the p!ef!ontl $o!te( h+e tt!$te' $onsi'e!ble ttention n'

h+e le' to !e+ise' 'opmine theo!" of s$hi,oph!eni. :lssi$ o! t"pi$l ntips"$hoti$ '!us !e belie+e' to $hie+e

thei! benefi$il effe$ts on positi+e s"mptoms b" blo$kin D !e$epto!s in the bsl nli. )n'ee'& numbe! of

stu'ies h+e foun' tht D !e$epto!s !e ele+te' in the bsl nli of s$hi,oph!eni$s&Q in$lu'in ptients not

p!e+iousl" me'i$te'* Ho%e+e!& s %e "e seen& D blo$k'e hs little effe$t on neti+e s"mptoms. Some of the

most p!ominent neti+e s"mptoms in$lu'e $oniti+e $hnes& n' the 'e!ee of $oniti+e 'efi$it is 'i!e$tl" !elte' tot!etment p!onosis. )t hs been p!opose' tht 'efi$its in %o!kin memo!" un'e!lie the $oniti+e $hnes in

s$hi,oph!eni. 7o!kin memo!"& "ou*ll !e$ll& $!u$ill" in+ol+es the p!ef!ontl $o!te(. 9i+en tht the!e !e !elti+el"

fe% D !e$epto!s in the p!ef!ontl $o!te(& it is not su!p!isin tht D-!elte' '!us h+e little effe$t on $oniti+e

neti+e s"mptoms.

/t the sme time& the Di $lss of !e$epto!s is bun'nt in the p!ef!ontl $o!te( of no!ml pe!sons but is

!e'u$e' in s$hi,oph!eni$s. 8u!the!& %o!kin memo!" pe!fo!mn$e in s$hi,oph!eni$s is !elte' to the numbe! of Di

!e$epto!s in the p!ef!ontl $o!te(the fe%e! the numbe! of !e$epto!s& the poo!e! ptient pe!fo!ms. 0o!eo+e!&

$oniti+e tests tht !e@ui!e tempo!!" sto!e n' e(e$uti+e fun$tion t"pi$ll" !esult in in$!ese' fun$tionl $ti+it" in

the p!ef!ontl $o!te( in no!ml humns& but not in s$hi,oph!eni$sY :onsistent %ith these !esults is the f$t tht

blo$k'e of Di& but not D& !e$epto!s in the p!ef!ontl $o!te( of iiionke"s impi!s 'el"e' !esponse pe!fo!mn$e 2

$oniti+e test of the tempo!!" sto!e spe$t of %o!kin memo!"3.

The !e+ise' +e!sion of the 'opmine theo!" thus p!oposes tht s$hi,oph!eni in+ol+es o+e!$ti+it" of the D

$lss of !e$epto!s in the bsl nli n' un'e!$ti+it" of Di !e$epto!s in the p!ef!ontl $o!te(. The h"pe!$ti+it" of

D !e$epto!s in the bsl nli $$ounts fo! positi+e s"mptoms& n' the un'e!$ti+it" of Di !e$epto!s in the

p!ef!ontl $o!te( $$ounts fo! neti+e s"mptoms. This e(plins %h" '!us tht blo$k D !e$epto!s onl" t!et positi+e

s"mptoms& but le+es open the @uestion of ho% t"pi$l ntips"$hoti$ '!us& %hi$h minl" t!et se!otonin o!

no!epineph!ine s"stems& t!et neti+e s"mptoms.

The imp!o+ement in neti+e s"mptoms is belie+e' to $ome bout be$use the t"pi$l me'i$tions $use

n ele+tion in the mount of 'opmine !elese' f!om te!minls in the p!ef!ontl $o!te( n' the!eb" help o+e!$ome

the 'efi$its $use' b" Di un'e!stimultion. The site of the '!us* $tion is not in the p!ef!ontl $o!te( itself& but in the

+ent!l tementl !e& %hi$h is the home of the neu!ons %hose te!minls !elese 'opmine in the the p!ef!ontl

$o!te(. 8o! e(mple& some +e!" effe$ti+e t"pi$l ntips"$hoti$ '!us blo$k the se!otonin / !e$epto!s& %hi$h !elo$te' on +ent!l tementl 'opmine neu!ons. 7hen the se!otonin !e$epto!s !e stimulte'& the" inhibit the bilit"

of the tementl $ells to !elese 'opmine in the p!ef!ontl $o!te(& n' othe! !es. B" blo$kin se!otonin !e$epto!s&

t"pi$l ntips"$hoti$ '!us blo$k the inhibition no!mll" p!o'u$e' b" se!otonin. This le's to n in$!ese' fi!in of

the tementl $ells n' thus mo!e 'opmine !elese in the $o!te(. The e(t! 'opmine !elese' helps $ompenste

fo! the !e'u$e' numbe! of Di !e$epto!s in the s$hi,oph!eni$ b!in.

4ese!$h on ntips"$hoti$ '!us is $u!!entl" '+n$in in mn" 'i!e$tions. )n ''ition to %o!k on '!us tht

t!et monomines& mu$h %o!k is ttemptin to 'ete!mine %hethe! lte!tions in lutmte n'Ko! its !e$epto!s&

espe$ill" 10D/ !e$epto!s& m" help t!et s$hi,oph!eni. Othe! stu'ies !e e(minin the !ole of 9/B/

t!nsmission.

)n ene!l& the!e is !o%in inte!est in the i'e tht lte!tions in s"npti$ $onne$ti+it" in neu!l $i!$uits&

!the! thn >ust le+els of neu!ot!nsmitte!s o! !e$epto!s& !e impo!tnt. 1eu!ot!nsmitte!s n' !e$epto!s still fiu!ep!ominentl" in this pp!o$h& but in the $onte(t of $onne$tions %ithin n' bet%een !es. 8o! e(mple& 8!n$>ne

Benes& notin tht the numbe! of 9/B/ $ells is 'e$!ese' in the hippo$mpus of s$hi,oph!eni$s& hs p!opose' tht

the 'iso!'e! in+ol+es shift of 'opmine $onne$tions f!om e($itto!" lutmte $ells to 9/B/ $ells in the

hippo$mpus to $ompenste fo! loss of inhibito!" $ells& n' D+i' Le%is hs p!opose' tht spe$ifi$ $lss of 9/B/

$ells lo$te' in spe$ifi$ l"e! of the p!ef!ontl $o!te( pl"s $!iti$l !ole in $oniti+e !eultion n' is lte!e' in

s$hi,oph!eni. )n imin stu'ies& !ese!$he!s su$h s D+i' Silbe!s%ei n' Emil" Ste!n !e beinnin to e(mine

$hnes in neu!l $ti+it" in net%o!ks in+ol+in inte!$onne$tions of the p!ef!ontl $o!te( %ith othe! $o!ti$l n'



sub$o!ti$l !es.

Pe!hps the most sophisti$te' $i!$uit theo!" of s$hi,oph!eni to 'te hs been the %o!k of /nthon" 9!$e.

Bse' on his stu'ies of 'opmine in +!ious fo!eb!in $i!$uits& he hs p!opose' $omple( theo!" tht ttempts to e(-

plin ho% s"npti$ inte!$tions bet%een the p!ef!ontl $o!te(& hippo$mpus& n' m"'l $$ount fo! $e!tin

spe$ts of s$hi,oph!eni. 4e$ll f!om ou! 'is$ussion of moti+tion $i!$uits in $hpte! F tht the p!ef!ontl $o!te( sen's

$onne$tions to the nu$leus $$umbens& %hi$h $onne$ts b$k %ith p!ef!ontl!es b" %" of the +ent!l plli'um. This is potentill" sinifi$nt set of $onne$tions& sin$e it in$lu'es the

ke" !es in+ol+e' in both neti+e n' positi+e s"mptoms. The p!ef!ontl $o!te(& s %e*+e seen& hs bun'nt Di

!e$epto!s tht seem to be in+ol+e' in neti+e s"mptoms. Simil!l"& the nu$leus $$umbens is one of the ke" !eions

of the bsl nli tht !e$ei+e 'opmine inputs f!om the +ent!l tementl !e n' is lo'e' %ith D !e$epto!s&

%hi$h& s %e*+e lso seen& !e in+ol+e' in positi+e s"mptoms.

9!$e sho%e' tht the bilit" of the p!ef!ontl $o!te( to $ti+te the $$umbens %s !eulte' b" the

hippo$mpus n' m"'l. Tht is& %hen the!e %s s"npti$ $ti+it" f!om the hippo$mpus o! the m"'l to the

$$umbens& the p!ef!ontl $o!te( $oul' fi!e $$umbens $ellsC othe!%ise& it $oul' not. The hippo$mpus n' m"'l

thus te o! !eulte the p!ef!ontl $ti+tion of $$umbens. 9i+en the !ole of the hippo$mpus in $onte(tul

p!o$essin of the en+i!onment& n' the !ole of the m"'l in emotionl p!o$essin& 9!$e p!opose' tht these

$onne$tions llo% p!ef!ontl $ti+it" to be '>uste' in !esponse to $hnes in the lobl en+i!onmentl sitution s

%ell s to spe$ifi$ emotionl stimuli. )n s$hi,oph!eni& lte!tions in the hippo$mpus n' m"'l 2both of %hi$h

h+e been foun'3 $oul' ffe$t p!ef!ontl p!o$essin in the $$umbens& !e'u$in the bilit" of the ptient to p!o'u$e

!esponses pp!op!ite to the imme'ite $oniti+e n' emotionl sitution.

)n 9!$e*s theo!"& 'opmine mo'ultes the s"npti$ inte!$tions in ll of the !eions. Spe$ifi$ll"& 9!$e hs

p!opose' tht the!e !e t%o 'iffe!ent pools of 'opmine& %hi$h h+e 'iffe!ent !oles. The most ob+ious pool is the

'opmine tht is !elese' b" (on te!minls in the st!itum o! p!ef!ontl $o!te( %hen 'opmine $ells in the b!in stem

fi!e $tion potentils. This is $lle' the phsi$ pool of 'opmine. Some of the 'opmine !elese' phsi$ll" 'oes not

et b!oken 'o%n o! su$ke' b$k up but inste' 'iffuses %" f!om the imme'ite !e of the s"npses n' $olle$ts

o+e! time. This $h!oni$ pool of 'opmine %ill ffe$t 'opmine !e$epto!s tht !e in its +i$init" e+en if the" !e not t

the moment !e$ei+in phsi$ 'opmine f!om the b!in stem $ells. 9!$e !ues tht the $h!oni$ 'opmine is %ht is

lte!e' o+e! the $ou!se of lon-te!m '!u t!etment& %hi$h is %h" it tkes so lon fo! su$h t!etment to be effe$ti+e.

These lte!tions& in tu!n& '>ust the phsi$ $tions of 'opmine n' influen$e p!o$essin in the $i!$uits >ust

'es$!ibe'.

:le!l"& !ese!$h in this !e hs m'e mu$h p!o!ess. /lthouh the sitution hs !o%n mo!e $ompli$te'

no% tht s$hi,oph!eni is no lone! thouht of s simpl" p!oblem of too mu$h 'opmine& the pu,,le is mo!e likel" to

be sol+e' b" $$eptin $omple(ities thn b" ino!in them. :i!$uit mo'els& fo! e(mple& !e mo!e $onsistent %ith the

f$t tht s$hi,oph!eni is not sinle 'iso!'e! but fmil" of $on'itions tht $n be mnifeste' in 'iffe!ent %"s in

'iffe!ent people. The p!ti$ul! $i!$uits ffe$te'& in$lu'in t!nsmitte! lte!tions& m" %ell 'ete!mine the e(tent to

%hi$h positi+e n' neti+e s"mptoms ppe! n' the mnne! in %hi$h the" %ill be e(p!esse'. 5e" to futu!e

b!ekth!ouhs m" be the bilit" to !elte spe$ifi$ s"mptoms to spe$ifi$ $i!$uits& n' the bilit" to 'e+elop '!us tht

t!et those $i!$uits.

B/L/1:)19 DEP4ESS)O1

/!oun' the sme time tht '!us %e!e bein 'e+elope' to t!et s$hi,oph!eni in the Fs& 'ep!ession& too&

%s p!o+in sus$eptible to $hemi$l melio!

tion. /lthouh it %s not !eli,e' t fi!st& monomines %e!e lso in+ol+e' in this illness.

One of the fi!st '!us su$$essfull" use' in t!etin 'ep!ession %s ip!oni,i'. This $ompoun' %s

'e+elope' f!om h"'!,ine& %hi$h %s o!iinll" use' s !o$ket fuel b" the 9e!mns in 7o!l' 7! L). /fte! the %!&

othe! $ompoun's bse' on h"'!,ine %e!e 'e+elope' n' teste' fo! me'i$l ppli$tions. One of these& ip!oni,i'&



%s foun' to inhibit the b$te!i tht i+e !ise to tube!$ulosis. Then TB ptients %e!e t!ete' %ith the '!u& the" %e!e

lso obse!+e' to be$ome eupho!i$. On the bsis of this effe$t& ip!oni,i' %s i+en to 'ep!esse' ptients. /lthouh

the !esults %e!e not $on+in$in& 1thn 5line& the mn %ho +e !ese!pine to s$hi,oph!eni$s in the 1e% Yo!k Stte

s"stem& 'e$i'e' to i+e ip!oni,i' t!". He put 'i+e!se !oup of ptients on the '!u& n' 'ep!esse' ones

imp!o+e'. The ke" 'iffe!en$e bet%een 5line*s stu'" n' the e!lie! one %s tht he kept the ptients on the '!u fo!

fi+e %eeksC it is no% $ommonl" $$epte' tht nti'ep!essnt '!us tke some time to ki$k in& so 5line*s 'e$ision toe(ten' t!etment %s $!u$il. /$$o!'in to 5line& %ithin "e! of !epo!tin his !esults& M& 'ep!esse' ptients

h' been t!ete' %ith ip!oni,i'.

The me$hnism b" %hi$h ip!oni,i' %o!ke' %s unkno%n& but stu'ies of niml b!ins soon !e+ele' tht

monomines %e!e in+ol+e'. 1o!mll"& the en,"me monomine o(i'se $uses monomines to be 'e!'e' fte!

the" !e !elese' f!om (on te!minls& helpin to en' the $tion of the monomines t posts"npti$ !e$epto!s

2stoppin t!nsmission is s impo!tnt s st!tin it3. Jp!oni,i' %s foun' to p!e+ent the b!ek'o%n of monomines

fte! the" !e !elese'. /s !esult& the monomines !emin !oun' the s"npse lone!& n' h+e !ete! effe$t.

Be$use ip!oni,i' $hie+es its effe$ts b" inhibitin monomine o(i'se& it is $lle' monomine o(i'se inhibito!

20/O inhibito!3.

The 0/O inhibito!s @ui$kl" be$me $ommon fo!m of t!etment fo! 'ep!ession. But the t!etment&

su$$essful o! not& h' $ost. 0/O is pl"e! in mn" b!in !es& not >ust those tht !e lte!e' in 'ep!ession& n'

lso p!ti$iptes in +!ious fun$tions outsi'e the b!in. 7hen '!u is tken o!ll"& it ffe$ts ll !ele+nt fun$tions n'

not >ust those the ptient %nts $o!!e$te'. One of the !oles of 0/O is the b!ek'o%n of the mino $i' t"!mine&

%hi$h ente!s the bo'" f!om ineste' foo' substn$es 2fo! e(mple& $e!tin $heeses3. Un$he$ke'& !ise in t"!mine in

the bo'" $n le' to su''en n' life-th!etenin !ise in bloo' p!essu!e.

The othe! m>o! t!etment fo! 'ep!ession tht eme!e' in the Fs in+ol+e' $lss of '!us kno%n s

t!i$"$li$s 2'ue to the th!ee !ins of thei! $hemi$l st!u$tu!e3. One of these substn$es& imip!mine& %s initill" t!ie' s

t!etment fo! s$hi,oph!eni& 'ue to some simil!it" to phenothi,ines. Ho%e+e!& be$use the '!u seeme' not to

$lm the ptients but to ene!i,e them n' ele+te thei! moo'& it %s teste' s t!etment fo! 'ep!ession& n'

positi+e !esults %e!e obtine'. This $lss of '!us h' fe%e! si'e effe$ts thn the 0/O inhibito!s& n' t!i$"$li$s %ith

b!n' nmes like Tof!nil n' El+il be$me %i'el" use' to t!et 'ep!ession.

Like the 0/O inhibito!s& the t!i$"$li$s %o!k b" mintinin ele+te' le+els of monomines t posts"npti$

sites. But the me$hnism of thei! $ti+it" is 'iffe!ent. The $tion of monomines& on$e !elese'& is te!minte' not >ust

b" the substn$es* bein b!oken 'o%n& but lso b" bein t!nspo!te' f!om the s"npti$ sp$e b$k into the

p!es"npti$ te!minl. T!i$"$li$s blo$k the t!nspo!ttion step& the!eb" llo%in the monomines to !emin +ilble to

bin' to posts"npti$ !e$epto!s fo! lone! pe!io's of time. Thei! effe$t %s 'is$o+e!e' b" Julius /(el!o'& %ho !e$ei+e'

1obel P!i,e fo! this n' othe! %o!k on monomine $hemist!". Be$use the si'e effe$ts of t!i$"$li$s %e!e less

se+e!e thn those of 0/O inhibito!s& the" soon $me to be the fi!st line of tt$k inst 'ep!ession.

B" the mi'-FNs& it seeme' tht 'ep!ession %s 'ue to too little monomine t!nsmission& >ust s

s$hi,oph!eni %s 'ue to too mu$h. This $on$lusion implie' !the! simple& in f$t simplisti$& pi$tu!e of the illness.

7e no% kno% tht its me$hnism is mu$h mo!e $ompli$te'. 7hen $onsi'e!e' f!om the point of +ie% of %hethe!

ptients %e!e helpe'& !the! thn %hethe! the un'e!l"in theo!" %s $o!!e$t& the monomine h"pothesis %s

su$$ess. But the su$$ess $me not f!om the f$t tht the monomine '!us tht %e!e 'e+elope' in the 2345s, Fs&

n' FNS %e!e the ultimte ns%e!. )nste' it %s be$use the" helpe' p+e the %" fo! loi$l pp!o$h fo!

futu!e '!u 'e+elopmentb" mkin effe$ti+e '!us mo!e spe$ifi$& si'e effe$ts miht be !e'u$e'. /s in the $se of

s$hi,oph!eni t!etment& !e$ent ttempts to 'e+elop '!us fo! 'ep!ession !e mo!e p!omis$uous in thei! fli!ttions

%ith t!nsmitte! s"stems in n ttempt not >ust to !e'u$e si'e effe$ts but to $!ete mo!e effe$ti+e t!etments. This hs

se+e!el" $omp!omise' the monomine theo!"& but hs f$ilitte' the se!$h fo! ne% n' mo!e effe$ti+e pp!o$hes to

t!etin 'ep!ession.



D4U9S TH/T T/L5

)n the lte FGs& ne% $hpte! in the t!etment of 'ep!ession ben %ith the 'e+elopment of '!us tht

sele$ti+el" enhn$e' the +ilbilit" of se!otonin&

in $ont!st to the e!lie! ene!tion of '!us& %hi$h umente' both se!otonin n' no!epineph!ine. Offe!in

the !elief of 'ep!ession %ith fe%e! si'e

effe$ts& n' possibl" e+en mkin “no!ml# people hppie!& the sele$ti+e se!otonin !euptke inhibito!s

2SS4)s3 took the %o!l' b" sto!m. :o+e! sto!ies in m,ines like Ne's'ee1 n' best-sellin book& Pete! 5!me!*s

Listenin! to Pro:ac, helpe' mke them popul! phenomenon. SS4)s h+e been p!es$!ibe' to millions n' millions

of people !oun' the %o!l'& not >ust fo! 'ebilittin 'ep!ession but lso fo! +!ious sh'es of unhppiness& b$k pin&

n(iet"& st!ess& P0S& n' +!iet" of othe! 'is$ontents. P!o,$ $me to be seen s the ti$ket to hppie! life& f!ee of

st!ess n' fille' %ith f!ien's n' su$$ess. /s Ne's'ee1 put it& “Sh"= 8o!etful= /n(ious= 8e!ful= Obsesse'= Ho%

S$ien$e 7ill Let You :hne You! Pe!sonlit" %ith Pill.#

O+e! the pst 'e$'e o! so& numbe! of 'iffe!ent SS4)s h+e been m!kete'& in$lu'in P!o,$& oloft&

P(il& Lu+o(& n' :ele(. These '!us !e s effe$ti+e s t!i$"$li$s in helpin 'ep!esse' people& but p!obbl" not

mo!e so. This is to be e(pe$te'& sin$e both $lsses of '!u bsi$ll" 'o the sme thinmke mo!e se!otonin

+ilble t s"npses. But the SS4)s 'o the >ob %ith fe%e! si'e effe$tsthe" !e sele$ti+e fo! se!otonin& so the si'e

effe$ts $use' b" enhn$in no!epineph!ine !e eliminte'.

0o!e people h+e tken SS4)s thn n" othe! p!es$!iption me'i$tion. /bout Q. million p!es$!iptions %e!e

%!itten in one "e! lone. Be$use the si'e effe$ts !e less se+e!e thn those of 0/O inhibito!s o! t!i$"$li$s& ptients

'on*t h+e to be monito!e' so $losel"& n' mn" p!es$!iptions !e i+en out b" ene!l p!$titione!s !the! thn

ps"$hit!ists.

The!e is& ho%e+e!& !o%in mo+ement inst the use of SS4)s n' othe! ps"$hit!i$ me'i$tions. )n

books like Tal1in! Bac1 to Pro:ac n' Toic Psychiatry, Pete! B!ein hs mounte' n tt$k inst the %i'esp!e'

use of '!us& !uin fo! n pp!o$h to ps"$hit!" bse' on lo+e& t!ust& un'e!stn'in& n' t!'itionl

ps"$hothe!p".# His 7ebsite $lims tht the si'e effe$ts of SS4)s in$lu'e +iolent n' sui$i'l ten'en$ies& n' $ites ll

so!ts of lite!tu!e on the topi$& in$lu'in !ti$les %ith titles like “P!o,$ n' Xn( 8oun' b" :ou!t to :use :!iminl

:on'u$t# n' “7s S$hool Shoote! E!i$ H!!is Tkin Lu+o(=# Si'e effe$ts of SS4)s& in$lu'in f$il ti$s n' se(ul

'"sfun$tion& !e lso emphsi,e' in Pro:ac Bac1lash, b" Joseph 9lenmullen. 7hile these !e leitimte $on$e!ns& it

is impo!tnt tht the" be e+lute' in the sme %" s the positi+e effe$ts of the '!us& tht is& th!ouh $ont!olle'

stu'ies !the! thn on the bsis of ne$'otes.

Yet nothe! !oup of books mkes pe!sonl $se fo! the use of su$h '!us. )t*s h!' not to be mo+e' b"

the utobio!phi$l $$ounts of people %ho& fte! "e!s of suffe!in %ith 'ep!ession& h+e been i+en ne% lese

on life b" '!u the!p". 5" 4e'fiel' Jmison*s An n@uiet $ind< is espe$ill" note%o!th"& but the!e !e othe!s.

/in& thouh& $!eful !ese!$h is the best %" to e+lute '!u effi$$".

7ht& then& !e the $hn$es tht these '!us $tull" %ill help n in'i+i'ul= S$ientifi$ stu'ies sho% tht

mn" $lini$ll" 'ep!esse' ptients 2bout to pe!$ent3 imp!o+e %hen i+en SS4Js o! t!i$"$li$s& but some people

i+en pl$ebos 2sometimes s mn" s Q pe!$ent of the smple3 et bette! s %ell. The most $"ni$l +ie% of su$h

't is tht '!us 'on*t $$omplish mu$h mo!e thn pl$ebos. The mo!e positi+e +ie%tht some people !ell" are

helpe' b" '!usis sueste' b" the f$t tht in $ont!st to SS4)s& pl$ebo effe$ts ten' to be smlle! n' sho!te!-

lstin n' h!' to inte!p!et. 8u!the!& !e$ent !epo!t hs $hllene' the +li'it" of pl$ebo effe$ts.

But %ht bout the notion& p!omote' b" $!iti$s& tht mn" of the people tkin SS4)s !e not !ell" $lini$ll"

'ep!esse' but >ust out fo! little moo' boost o! pe!sonlit" mkeo+e!= ) ske' 9!e Sulli+n& ps"$hit!ist f!ien' of

mine f!om :olumbi Uni+e!sit"C %ht he thouht of this $!iti$ism& n' he !espon'e' s follo%sA

In my eperience I do not 1no' of anyone for 'hom this is true) In !eneral, these dru!s are not fun to ta1e



6it9s (othersome to remem(er a daily pill, they often cause seual dysfunction, they can lead to slo' 'ei!ht !ain, and

friends and family sometimes imply that ta1in! dru!s for depression is a si!n of mental 'ea1ness7) If someone is

pleased 'ith the effects of an SS0I, that9s usually an indicator that the dru! has had a si!nificant impact on serious

symptoms, includin! those caused (y a chronic lo'%le+el depression 6dysthymia7) Such people are ama:ed once they

learn that lo' ener!y, chronic sleep distur(ance, and a pessimistic approach to .ust a(out e+erythin! doesn9t ha+e to

(e the norm for the rest of their life) But SS0s are not &happy pills,< and people 'ithout si!nificant mood or anietydistur(ance do not !enerally !et anythin! (eneficial from them, certainly nothin! that 'ould ma1e them sustain the

use) This is a sharp contrast to psychiatric dru!s that are sometimes a(used such as 0italin, 'hich ma1es people

hi!h if they administer enou!h, or (en:odia:epines, 'hich some people use in order to (ecome num( to their

difficulties and to life in !eneral)

The bottom line seems to be tht& if "ou !e se!iousl" 'ep!esse'& '!u t!etment& espe$ill" in $on>un$tion

%ith ps"$hothe!p"& is p!obbl" "ou!

best hope& espe$ill" if ps"$hothe!p" lone hs been unhelpful. The!e !e likel" to be si'e effe$ts& n' "ou

h+e to 'e$i'e %hethe! the si'e effe$ts !e oin to be %o!se thn li+in %ith 'ep!ession. But this is @uestion tht

hs to be pose' bout lmost n" me'i$tion& sin$e the!e !e fe% mi$ bullets in me'i$ine.

B" no%& SS4)s h+e been in the spotliht fo! o+e! 'e$'e n' h+e been +e!" p!ofitble fo! '!u

$ompnies. Some s$ientists h+e sueste'& %ith !eson& tht the su$$ess of these '!us hs tken some of the

impetus out of 'e+elopin othe!s. /t the sme time& the best %" to mke mone" in the '!u business is b" $!etin

bette! '!us. 0u$h of the effo!t in this !e in !e$ent "e!s hs one into mkin se!otonin-!elte' '!us mo!e

spe$ifi$& fo$usin on sele$ti+e !e$epto!s !the! thn on p!es"npti$ uptke in ene!l. The!e !e nume!ous se!otonln

!e$epto!s& n' the mo!e spe$ifi$ the '!u $n be m'e n' still $hie+e the!peuti$ effe$t& the fe%e! the si'e effe$ts

shoul' be.

Be$use 'ep!ession is not sinle $lini$l $on'ition& the sme t!etment 'oesn*t %o!k in ll 'ep!esse'

people. One st!te" bein pu!sue' is to fin' ne% t!etments tht in+ol+e no+el $ombintions of '!us. 8o! e(mple&

in some $ses !esistnt to eithe! t!i$"$li$s o! SS4)s& $o$ktil in+ol+in mi(tu!e of n SS4) n' t!i$"$li$ is useful.

The !eson fo! this is not $le!& but this is not unusul in ps"$hit!i$ '!u the!p"& sin$e so little is kno%n bout the

un'e!l"in b!in mlfun$tion. )n f$t& one of the obst$les to the 'e+elopment of bette! '!us fo! ps"$hit!i$ 'iso!'e!s

hs been tht the min insihts into the un'e!l"in b!in mlfun$tions h+e $ome f!om fin'ins& often $$i'entl ones&

bout effe$ti+e t!etments. This is ho% the monomine pp!o$h eme!e'& n' %h" it $ontinues to be m>o! fo$us

of t!etment st!teies. Ho%e+e!& the!e is !o%in !e$onition tht& %hile monomines !e in+ol+e'& the fun'mentl

p!oblem un'e!l"in 'ep!ession is not in the monomine s"stem pe! se. D!u 'e+elopment is& s !esult& mo+in in

othe! 'i!e$tions& t!etin othe! t!nsmitte!s& mo'ulto!s& ho!mones& se$on' messene! s"stems& n' neu!ot!ophi$

f$to!s. Some of these effo!ts !e 'es$!ibe' belo%. /s mole$ul! bioloi$l pp!o$hes be$ome bette! inte!te'

%ith $i!$uit-le+el pp!o$hes to b!in fun$tion& ne% n' bette! i'es bout the ntu!e of 'ep!ession n' its t!etment

!e likel" to eme!e.

ST4ESS )S DEP4ESS)19

One of the most $onsistent bioloi$l fin'ins bout 'ep!ession is tht the '!enl $o!te( se$!etes mo!e of

the st!ess-!elte' ho!mone $o!tisol in 'ep!esse' people. This simple f$t& %hi$h $n be 'ete!mine' f!om $otton

s%b $ontinin sli+& links 'ep!ession to the biolo" of st!ess. O+e! the "e!s& !et 'el of !ese!$h hs one

into un'e!stn'in the !eltion bet%een st!ess n' 'ep!ession& both th!ouh stu'ies of 'ep!esse' ptients n'

e(pe!imentl niml mo'els of 'ep!ession. Ho%e+e!& !e$ent fin'ins bout the '+e!se $onse@uen$es of st!ess on

the b!in h+e le' to po%e!ful ne% h"pothesis bout the o!iin of 'ep!ession.

/s %e s% m $hpte! G& in st!essful situtions& the $on$ent!tion of $o!tisol !ises in the bloo'st!em. This

o$$u!s be$use 'u!in st!ess& the m"'l n' othe! b!in !eions le!t h"pothlmi$ neu!ons to !elese pepti'e



f!om thei! te!minls in the pituit!" ln'. The pepti'e& $lle' $o!ti$ot!ophin-!elesin f$to! 2:483& $uses the

pituit!" ln' to !elese the ho!mone /:TH 2'!eno$o!ti$ot!ophin ho!mone3& %hi$h t!+els in the bloo'st!em n'

le's to the !elese of $o!tisol f!om the '!enl ln'. The $o!tisol is then t!nspo!te' th!ouh the bloo' to +!ious

bo'il" o!ns n' tissues 2it e+entull" !e$hes the sli+!" ln's& %hi$h is %h" it $n be mesu!e' in sli+3. )n the

b!in& $o!tisol bin's to !e$epto!s in the hippo$mpus& mon othe! !eions. ;7hen suffi$ient numbe! of !e$epto!s

!e o$$upie' in the hippo$mpus& sinls !e sent to the h"pothlmus tellin it to stop !elesin 94E )n this %"& thehippo$mpus !eultes the st!ess !esponse t!ie!e' b" the m"'l& keepin the !elese of $o!tisol %ithin no!ml

sfe !ne.

)n the sho!t !un& st!ess !esponses !e useful in mobili,in bo'il" !esou!$es to $ope %ith 'ne!. But if the

st!ess is se+e!e n' $ontinuous& the $onse@uen$es $n be se!ious. You! $!'io+s$ul! s"stem $n be $omp!omise'&

"ou! mus$les $n %eken& n' "ou $n 'e+elop ul$e!s n' be$ome mo!e sus$eptible to $e!tin kin's of infe$tions.

But none of these shoul' hppen if the hippo$mpus is %o!kin p!ope!l" to shut 'o%n the st!ess !e$tion. /s %e 'is-

$usse' in $hpte! G& 'u!in p!olone' n' se+e!e st!ess& the bilit" of the hippo$mpus to 'o its st!ess-$ont!ol >ob

flte!s.

Stu'ies b" 4obe!t Spolsk"& B!u$e 0$E%en& n' othe!s h+e sho%n tht st!ess 'mes the hippo$mpus&

le'in to sh!inke of 'en'!ites n' ultimtel" to $ell 'eth. 1ot su!p!isinl"& fun$tions tht 'epen' on the hip-

po$mpus& like e(pli$it o! 'e$l!ti+e memo!"C be$ome se+e!el" $omp!omise'. St!ess ho!mones 'o not 'me the

hippo$mpus 'i!e$tl"& but inste' 'eplete its neu!ons of lu$ose& thei! min sou!$e of ene!"& n' mke them less

$pble of pe!fo!min thei! >ob in the f$e of st!inent 'emn's. /s !esult& the" be$ome espe$ill" sensiti+e to

ele+tions of e($itto!" t!nsmitte!s like lutmte 'u!in pe!io's of in$!ese' neu!l $ti+it"& su$h s o$$u!s in

st!ess.

Spe$ifi$ll"& hippo$mpl $ells h+e to(i$ !e$tion to s"npti$ll" !elese' lutmte in the p!esen$e of

'eplete' lu$ose.

9ell sh!inke n' $ell 'eth minl" tke pl$e in one !e of the hippo$!npus the :/Q !eion. )n nothe!

!e& the 'entte "!us& $ell 'eth is f! less likel" to o$$u!& but st!ess lso tkes its toll the!e. This is one of the fe%

!eions of the b!in tht is kno%n to un'e!o neu!oenesis& the p!o'u$tion of ne% neu!ons& in 'ult o!nisms.

1eu!oenesis in$!eses %hen nimls le!n ne% thins& n' 'e$!eses %hen the" !e un'e! st!ess& o! %hen the" !e

i+en ste!oi' ho!mones tht mimi$ the ele+tions of $o!tisol tht o$$u! in st!ess. Toethe! the $ell sh!inke n' $ell

'eth in the 9/Q !e n' the loss of ne% neu!on p!o'u$tion in the 'entte "!us p!obbl" $$ount fo! the f$t tht

the +olume of the humn hippo$mpus is smlle! in people %ho h+e ele+te' le+els of $o!tisol 'ue to st!ess o! othe!

$on'itions.

8o! e(mple& s %e*+e seen& $o!tisol is ele+te' in 'ep!esse' ptients& %ho often h+e smlle!

hippo$mpus n' %ho $$o!'inl" suffe! memo!" p!oblems. 9o!tisol is lso ele+te' in el'e!l" people& espe$ill"

those %ith memo!" p!oblems n' 'ep!ession. 8u!the!& the!e*s $on'ition kno%n s 9ushin*s 'isese in %hi$h the

'!enl $o!te( se$!etes e($ess $o!ttsoli 9ushin*s ptients lso h+e smlle! hippo$mpus n' memo!" p!oblems&

n' mn" 'e+elop 'ep!ession. 4e'u$tion of $o!tisol le+els %ith '!us often !e+e!ses these st!u$tu!l n' fun$tionl

$onse@uen$es. Simil!l"& people %ho !e$ei+e p!olone' ste!oi' t!etment fo! inflmmtion 'e+elop memo!" p!oblems

n' 'ep!ession& $on'itions tht !e !e+e!se' %hen the t!etment is 'is$ontinue'. One of the $u!!ent t!en's in the

t!etment of 'ep!ession is the 'e+elopment of '!us tht lte! the bilit" of 94E to le' to !ise in $o!tisol. Sin$e

$o!tisol is belie+e' to be m>o! $hemi$l $ulp!it in st!ess 2thouh pe!hps not the onl" one3& p!e+entin $o!tisol f!om

!isin $n sometimes help 'e$!ese st!ess n' !e+e!se 'ep!ession.

The bo'" s"stem in+ol+e' in $ont!ollin st!ess-ho!mone !elese is $lle' the h"pothlmi$-pituit!"-'!enl

(is 2HP/ (is3. This s"stem 'i' not e+ol+e its bilit" to se$!ete $o!tisol fo! the pu!pose of mkin us 'ep!esse'& but

$me bout to help o!nisms 'el %ith sho!t-te!m ph"si$l 'ne!s situtions tht 'is!upt the no!ml ph"sioloi$l

bln$e of the bo'"& su$h s foo' o! %te! 'ep!i+tion& in>u!"& o! en$ounte!s %ith p!e'to! o! n enem" of "ou! o%n

spe$ies. The >ob of $o!tisol is to mobili,e bo'" !esou!$es in the sho!t !un& fte! %hi$h ph"sioloi$l no!mlit"& o!



homeostsis& is !esto!e'. /s st!ess u!u 4obe!t Spolsk" notes& nimls in the %il' 'o not h+e to 'el %ith thi!t"-

"e!-lon es$pin sp!ints f!om lions& but humns h+e thi!t"-"e! mo!tes n' othe! lon-lstin p!oblems. )t is

the !elentlessness of humn st!ess& the lon-te!m 'is!uption of homeostsis& tht in$!eses ou! !isk of 'isese&

in$lu'in mentl 'iso!'e!s like 'ep!ession.

4on Dumn& Yle !ese!$he!& hs p!opose' theo!" tht e(plins ho% st!ess $n p!e'ispose one to

'e+elop 'ep!ession. /$$o!'in to Dumn& 'ep!ession !esults f!om n inbilit" to mke the pp!op!ite 'pti+e!esponse to st!ess. Dumn*s theo!" bo!!o%s he+il" f!om the bsi$ s$ien$e fin'ins of Spolsk"& 0$E%en& n' othe!s

n' emphsi,es the effe$ts of st!ess on the initition of $ell 'eth in the :/ Q !e n' on the supp!ession of neu!o-

enesis in the 'entte !e. )n the most ene!l sense& he p!oposes tht st!ess ele+tes '!enl ste!oi's n'

'e$!eses neu!ot!ophi$ f$to!s& like BD18& mole$ule tht is essentil fo! $ell !o%th n' su!+i+l 2$hp. M3 n' fo!

the mintenn$e of s"npti$ $onne$ti+it" 2$hp. 3. )n the p!esen$e of in$!ese' neu!l $ti+it" n' lutmte !elese&

:/Q n' 'entte $ells 'eplete' of lu$ose n' l$kin BD18 !e en'ne!e'. )n :/Q& the" t!oph" n' 'ie. )n the

'entte& ne% $ell !o%th n' $onne$ti+it" of ne% $ells %ith e(istin net%o!ks is supp!esse'. 8ollo%in nti'ep!essnt

t!etment& thouh& these $hnes $n be o+e!$ome'en'!ites of :/Q $ells e(pn' n' the $ells su!+i+e& n' 'entte

$ells $ontinue to be ene!te' n' inse!te' into net%o!ks.

Ho%& then& 'oes nti'ep!essnt t!etment $hie+e these ols= )t hs lon been kno%n tht nti'ep!essnt

'!us 'o not t!et 'ep!ession b" simpl" lte!in s"npti$ le+els of monomines& sin$e& s %e s% e!lie!& thei! effe$ts

on s"npti$ le+els !e !pi' but the t!etment effe$ts themsel+es tke %eeks. Dumn p!oposes tht the ke" to the

'!u effe$ts !e to be foun' in the se$on' messene! $s$'es $ti+te' b" the '!us. 8o! e(mple& %hen n SS4J

in$!eses the mount of se!otonin +ilble t se!otonin !e$epto!s& these !e$epto!s !e stimulte' fo! lone! pe!io's

of time. /s !esult& st!one! int!$ellul! !esponse is ene!te' n' mo!e intense $ti+tion of se$on' messene!

s"stems o$$u!s& le'in to enhn$e' ene $ti+tion n' p!otein s"nthesis. The lon-lstin effe$ts of '!us& then&

m" be 'ue to ne% !o%th p!o$esses& %hi$h tke time to be put in pl$e n' to lte! s"npti$ net%o!ks.

Let*s look little mo!e $losel" t ho% this miht %o!k. 4e$ll f!om e!lie! $hpte!s tht 'u!in memo!"

fo!mtion& $l$ium ele+tion insi'e $ells !ises $/0P le+els& %hi$h $ti+tes p!otein kinses 2P5/ n' 0/P kinse3

tht phospho!"lte the t!ns$!iption f$to! :4EB. :4EB then in'u$es enes to mke p!oteins tht be$ome ne% tools

of s"npti$ t!nsmission 2ne% !e$epto!s& ne% $hnnels tht pss $l$ium o! othe! ions& ne% t!ns$!iption f$to!s o!

kinses& n' so on3. /nti'ep!essnt t!etment ski!ts !el-%o!l' le!nin e(pe!ien$e n' 'i!e$tl" in$!eses the mount

of $l$ium insi'e the $ell& t!ie!in othe! se$on' messene!s tht in'u$e enes to mke p!oteins. / b!in on

nti'ep!essnts $n be b!ouht b$k f!om its stte of isoltion f!om the outsi'e %o!l' n' en$ou!e'& e+en fo!$e'&

to le!n. The b!in& in othe! %o!'s& is 'upe' into bein plsti$ b" these t!etments.

/nti'ep!essnt me'i$tion thus enhn$es plsti$it" n' the!eb" mkes the b!in mo!e 'pti+e& bette! ble

to o+e!$ome the en'ne!e' stte into %hi$h it %s pl$e' b" e($ess $o!tisol. 7hile the t!etment itself 'oes not

'i!e$tl" substitute fo! 'i!e$t e(pe!ien$e 2it 'oesn*t i+e "ou ne% memo!ies3& b" pl$in the b!in in stte in %hi$h

ne% memo!" fo!mtion is f$ilitte'& 'ep!esse' pe!sons m" be ble to le!n ne% mentl sttes n' beh+io!s tht

o+e!!i'e the mo'es tht the" h' been lo$ke' into b" 'ep!ession. / the!pist %ho un'e!stn's the ptient n' the

un'e!l"in effe$ts of the '!us m" be ble to se!+e s ui'e to the !e$o+e!" p!o$ess& helpin the ptient tu!n to

ne%& positi+e li+e e(pe!ien$es& o! to tu!n b$k to ol' ones& t >ust the !iht time of nti'ep!essnt t!etment.

Befo!e le+in the topi$ of st!ess n' 'ep!ession& it*s impo!tnt to point out tht the hippo$mpus is not the

onl" !eion of the b!in tht is lte!e' in 'ep!esse' people. )min stu'ies in humns sho% $hnes in si,e n' in

fun$tionl $ti+it" in the p!ef!ontl !eions s %ell. 8u!the!& niml stu'ies sho% tht this b!in !eion hs bun'nt

!e$epto!s fo! '!enl ste!oi' ho!mones n'& like the hippo$mpus& is impli$te' in the !eultion of HP/ (is fun$tion.

The ele+te' $o!tisol tht o$$u!s in 'ep!ession the!efo!e lso tt$ks the p!ef!ontl $o!te(& %hi$h miht help $$ount

fo! othe! $oniti+e $hnes sso$ite' %ith 'ep!ession& in$lu'in poo! sho!t-te!m 2%o!kin3 memo!"& 'ist!$tibilit"&

n' lte!e' 'e$ision-mkin n' e(e$uti+e fun$tions. :hnes lso o$$u! in the m"'l. 0o!e stu'ies !e

nee'e' to 'ete!mine the e(tent to %hi$h nti'ep!essnt t!etment !e+e!ses st!u$tu!l n' fun$tionl $hnes



sso$ite' %ith 'ep!ession in these !es.

Dep!ession& like s$hi,oph!eni& is thus no lone! simpl" +ie%e' s monomine imbln$e. )t is inste'

belie+e' to in+ol+e lte!e' $i!$uits tht lo$k one into stte of neu!l n' ps"$holoi$l %ith'!%l in %hi$h the

b!in*s bilit" to tten' to& ene& n' le!n bout the %o!l' is !e'u$e'. /n" t!etment tht $n !eene pe!son

%ith the %o!l' is likel" to help. 7hethe! ps"$hothe!p" lone $n $hie+e this %ill likel" 'epen' on ho% f! the ml -

'pti+e $hnes h+e p!o!esse'& s %ell s on f$to!s pe$uli! to the in'i+i'ul& su$h s eneti$ mkeup n' pstle!nin e(pe!ien$es.

0OTHE4*S L)TTLE HELPE4

/n(iet" 'iso!'e!s !e the most p!e+lent fo!m of mentl illness. S$hi,oph!eni ffli$ts bout t pe!$ent of the

popultion n' 'ep!ession bout pe!$ent& but !ouhl" pe!$ent of ll 'ults !e si' to suffe! f!om some

mnifesttion of $lini$l n(iet". E+e!"one is little n(ious t times& but n n(iet" 'iso!'e! is si' to e(ist %hen

'"-to-'" ps"$holoi$l fun$tionin n' inte!pe!sonl !eltionships !e 'is!upte' b" s"mptoms su$h s %o!!"&

tension& sleep 'istu!bn$es& i!!itbilit"& n' somti$ $omplints. /n(iet" is not sinle 'iso!'e! but spe$t!um of

$on'itions tht in$lu'es nonspe$ifi$ o! ene!li,e' n(iet"& phobis& pni$ tt$ks& postt!umti$ st!ess 'iso!'e!& n'

obsessi+e-$ompulsi+e 'iso!'e!.

Ps"$hothe!p" is mo!e effe$ti+e in t!etin n(iet" 'iso!'e!s thn n" othe! !oup of mentl p!oblems. This

is t!ue both of ene!li,e' n(iet" n' of the mo!e spe$ifi$ $on'itions. The most effe$ti+e fo!ms of ps"$hothe!p" fo!

n(iet" in+ol+e beh+io!l n' $oniti+e-beh+io!l pp!o$hes& %hi$h help the ptient $ope %ith n' eliminte the

unplesnt s"mptoms tht $$ompn" n' pe!petute n(iet".

0e'i$inl pp!o$hes to n(iet" h+e lso been +luble. /l$ohol is the ol'est n' most %i'el" use'

n(iet"-!e'u$in '!u. 0n" un%in' f!om the tensions of the %o!kin %o!l' b" stoppin off fo! “hpp" hou!# t thei! f-

+o!ite %te!in hole& o! %ith “$o$ktil hou!# t home. But be$use l$ohol is into(i$tin n' ''i$ti+e& it is not

p!$ti$l solution fo! se+e!e n' $h!oni$ n(iet".

The fi!st %i'el" use' me'i$l t!etment fo! n(iet" in+ol+e' b!bitu!tes& lon-$tin '!us tht 'ep!ess

b!in $ti+it". /t lo% 'oses& the" !e'u$e tension n' n(iet" %ithout p!o'u$in into(i$tion& n' t hihe! 'oses& the"

in'u$e sleep. Ho%e+e!& these '!us !e hihl" ''i$ti+e& n' the 'iffe!en$e bet%een 'ose tht in'u$es sleep n'

one tht is ftl 2b" supp!essin b!ethin3 is @uite smll. The 'e+elopment of ne% $lss of n(iet" '!us in the

Fs %s thus %el$ome'.

0ep!obmte %s i'entifie' in the p!o$ess of s$!eenin +!itions of mephenesin& '!u tht !elie+e'

n(iet" but h' +e!" sho!t-lstin effe$t. One metho' tht '!u $ompnies use' to test the +lue of ntin(iet"

'!us %s to i+e them to monke"s& %hi$h ten' to be %il' n' !essi+e in $pti+it". 0ep!obmte m'e them $lm&

less +i$ious. 7hen i+en to humns& it !e'u$e' n(iet" %ithout p!o'u$in '!o%siness. This $ompoun' %s then m'e

+ilble b" p!es$!iption un'e! the b!n' nmes E@unil n' 0ilto%n&

n' $me to be kno%n& in the popul! p!ess& s “hpp" pills.# Thouh initill" belie+e' to be sfe&

non''i$tin !epl$ement fo! b!bitu!tes& lte! !epo!ts %e!e less f+o!ble. /''i$tion 'i' !esult& n' sometimes

me'i$l $ompli$tions o$$u!!e' %hen the '!u %s stoppe'.

The ne(t ene!tion of '!us fo! n(iet" eme!e' %hen $hemist %ho h' %o!ke' 'e+elopin '"es in

Poln' mo+e' to the Unite' Sttes n' >oine' '!u $ompn". He teste' numbe! of the $ompoun's he h' %o!ke'

%ith in his '"e !ese!$h in Poln' n' foun' tht one of them& n' onl" one& %s ef fe$ti+e in $lmin %il' monke"s.

Upon fu!the! in+estition& it tu!ne' out tht this $ompoun' %s 'iffe!ent f!om ll the !est. :hlo!'i,epo(i'e& s the

$ompoun' %s $lle'& be$me the fi!st of ne% $lss of '!us& the ben,o'i,epines.

The effe$ts of $hlo!'i,epo(i'e %e!e fu!the! teste' in !ts usin the $onfli$t test. The !ts %e!e m'e hun!"&

n' then %e!e llo%e' to obtin foo' b" p!essin b!. Ho%e+e!& if the" p!esse' %hile liht %s on& the" %e!e

sho$ke'. The liht itself $me to be fe!-!ousin stimulus n' le' to out%!' sins of ne!+ousness 2f!ee,in&



'efe$tion& et$.3. 7hen t!ete' %ith $hlo!'i,epo(i'e& thouh& the" p!esse' mo!e n' %e!e less +isibl" f!i' e+en

%hile the liht %s on. The '!u llo%e' them to e!n thei! 'il" b!e' n' to be less fe!ful in 'oin sope!fe$t

effe$ts fo! t!etment of humn n(iet". The $onfli$t test in !ts hs& in f$t& be$ome one of the ke" metho's fo!

'ete!minin %hethe! ne% $ompoun's !e likel" to be effe$ti+e in !elie+in n(iet" in humns.

:hlo!'i,epo(i'e %s sol' s Lib!ium. Then $me 'i,epm& bette! kno%n s 6lium& n' lp!,olm&

m!kete' s Xn(. B" FN& pe!$ent of the U.S. popultion %s si' to h+e tken t some point +e!sion of“mothe!*s little helpe!.# Thouh hihl" effe$ti+e in !elie+in n(iet"& n' f! less p!oblemti$ thn b!bitu!tes n'

mep!obmte& ben,o'i,epines !e like%ise ''i$ti+e& n' $n be 'ne!ous %hen mi(e' %ith l$ohol. Ju'" 9!-

ln'& fo! e(mple& is belie+e' to h+e 'ie' f!om this $ombintion.

)n $ont!st to most othe! '!us use' to t!et mentl illness& ll the ntin(iet" '!us %o!k imme'itel". Tht

is %h" '!ink $n $lm "ou! ne!+es& n' %h" 6lium n' othe! ben,o'i,epines !e useful in $ute n(iet". )n

Startin! -+er, !omnti$ $ome'" f!om the lte FNs& the $h!$te! pl"e' b" Bu!t 4e"nol's is h+in se+e!e

n(iet" tt$k in Bloomin'le*s %hile $!o%' the!s !oun' him. Someone $lls out fo! 6lium& n' essentill"

the enti!e $!o%' !e$hes into thei! pu!ses o! po$kets n' pulls out +il. 6lium >okes !e& in f$t& still popul! in

$ome'ies. Huh 9!nt*s $h!$te! in 7oo'" /llen*s !e$ent film Small Time Croo1s kept !unnin to the bth!oom fo!

6lium %hen thins 'i'n*t o his %".

7hile ben,o'i,epines !e lso useful s sleepin pills on n s-nee'e' bsis& these '!us $n p!o'u$e

tempo!!" memo!" loss fte! %kin. The!e !e infmous sto!ies of businessmen tkin ben,o'i,epine to sleep on

n o+e!niht t!ip to Eu!ope n' then %kin up n' not bein ble to !emembe! %h" the" h' flo%n o+e!ses. / ne%

$lss of '!us& imi',op"!i'ines& !e mo!e useful fo! in'u$in sleep. /mbien is p!ime e(mple. Thouh thei!

$hemi$l st!u$tu!e is some%ht 'iffe!ent f!om ben,o'i,epines& the" %o!k simil!l" 2thouh mo!e spe$ifi$ll"3 t the

$hemi$l le+el. Be$use these '!us h+e sho!te! life spn in the bloo'& n' be$use the" !e not mus$le !el(-

nts& the" h+e fe%e! line!in effe$ts the ne(t '" on $oniti+e n' beh+io!l fun$tionin.

The $lssi$ ntin(iet" '!us %o!k p!im!il" b" f$ilittin 9/B/ inhibito!" t!nsmission in the b!in& mkin

it h!'e! fo! lutmte to eli$it e($ittion t its posts"npti$ !e$epto!s. This is t!ue fo! l$ohol& b!bitu!tes& n'

ben,o'i,epines 2n' imi',op"!i'ines3. Ho%e+e!& e$h $hie+es its effe$ts 'iffe!entl". 4e$ll f!om $hpte! Q tht

%hen neu!ot!nsmitte! bin's to its !e$epto!& the !e$epto! opens& llo%in ele$t!i$ll" $h!e' $hemi$l ions to flo%

f!om the e(t!$ellul! sp$e into the $ell. )n the $se of 9/B/ !e$epto!s& the flo% of $hlo!i'e ions mkes the insi'e of

the $ell mo!e positi+e& %hi$h mens tht mo!e neti+el" $h!e' ions h+e to flo% into the $ell th!ouh lutmte

!e$epto!s to initite n $tion potentil. B!bitu!tes enhn$e inhibition b" $tin 'i!e$tl" on 9/B/ !e$epto!s& keepin

the $hlo!i'e $hnnel open lone!& llo%in mo!e positi+e ions to ente! the $ell. /l$ohol hs simil! effe$t& but t

'iffe!ent 9/B/ !e$epto! f!om the one ffe$te' b" b!bitu!tes. Ben,o'i,epines& ho%e+e!& %o!k 'iffe!entl"& s the"

h+e thei! o%n !e$epto!s& %hi$h !e linke' to 9/B/ !e$epto!s. So %hen ben,o'i,epine !e$epto!s !e o$$upie'&

linke' 9/B/ !e$epto!s bin' 9/B/ mo!e esil". /s !esult& the sme mount of 9/B/ !elese' f!om 9/B/

te!minl %ill h+e !ete! inhibito!" effe$t on the posts"npti$ $ell. The ben,o'i,epines the!efo!e %o!k onl" t

those sites %he!e 9/B/ is bein !elese' ntu!ll". )mi',op"!i'ines %o!k like ben,o'i,epines& but t mo!e

sele$ti+e p!t of the 9/B/ !e$epto!& %hi$h is p!obbl" %h" the" h+e fe%e! si'e effe$ts. 2P!entheti$ll"& the f$t tht

ben,o'i,epine !e$epto!s e(ist in the b!in mens tht the b!in lso hs ntu!l suppl" of ben,o'i,epines. )t m"

be tht $lm& %o!!"-f!ee people h+e mo!e of this $hemi$l& n' n(ious people less.3

Be$use 9/B/ n' ben,o'i,epine !e$epto!s !e 'ispe!se' th!ouhout the b!in& '!us tht bin' to them

'o not ffe$t n(iet" e($lusi+el". /n(iet" m" %ell be ene!te' b" spe$ifi$ net%o!ks& but '!us tht t!et it ffe$t the

enti!e b!in. This $$ounts fo! some of the si'e effe$ts of ntin(iet" '!us& su$h s '!o%siness n' mus$le

!el(tion. D!o%siness& of $ou!se& is not $onsi'e!e' si'e effe$t %hen the '!u is use' fo! sleep in'u$tion !the! thn

fo! n(iet" !e'u$tion %hile %ke.

1e%e! t!etments fo! ene!li,e' n(iet" !e lso +ilble. Thouh these '!us p!o'u$e fe%e! si'e effe$ts&

the" h+e the 'is'+nte of not %o!kin imme'itel". 0ost of them enhn$e se!otonin fun$tion. BuSp!



%e!e enen'e!in in the septum n' hippo$mpus %ill in tu!n be eliminte'& 'e$!esin !ousl n' +iiln$e&

the!eb" !e'u$in n(iet".

/lthouh 9!"*s theo!" %s tou! 'e fo!$e of neu!ops"$holoi$l loi$& it !n into t!ouble. 8i!st of ll& it

fo$use' e($lusi+el" on 9/B/ t!nsmission& sin$e this %s point of $on+e!en$e bet%een ll the $lssi$ ntin(iet"

'!us. The eme!en$e of '!us tht su$$essfull" t!ete' n(iet" %ithout ffe$tin 9/B/ t!nsmission the!efo!e

$hllene' the theo!". Buspi!one n' SS4)s& fo! e(mple& !e both effe$ti+e in !elie+in n(iet" n' both %o!k t thele+el of !e$epto!s posts"npti$ to se!otonin te!minls !the! thn t $ell bo'ies in the b!in stem. )n'ee'& these '!us

!e some%ht effe$ti+e %hen in>e$te' 'i!e$tl" into the hippo$mpus& %he!e the" sele$ti+el" enhn$e se!otonin t!ns-

mtssion. ;7hile this helps sl+e p!t of the theo!"& it %ekens the $o!e $on$ept tht f$ilittion of 9/B/

t!nsmission in the b!in stem is ke". Se$on'& the theo!" 'i' not llo% !ole fo! the m"'l& %hi$h s %e*+e seen

pl"s n impo!tnt !ole in p!o$essin 'ne! n' th!ets.

)n !e$ent !e+ision of the theo!"C 9!" n' his lontime $ollbo!to! 1eil 0$1uhton ttempte' to ''!ess

both of these sho!t$omins. Thei! ne% fo!multion $on$ei+es of n(iet" s ps"$holoi$l stte eme!in out of

s"npti$ll" $onne$te' net%o!k in+ol+in& mon othe! !eions& the septohippo$mpl !e& m"'l& n' p!ef!ontl

$o!te(& ll mo'ulte' b" b!in stem monomine s"stems. /lthouh the ne% theo!" is b!o'e! in its $o+e!e& in m"

opinion& it still i+es the septum n' hippo$mpus too p!ominent !ole& t the e(pense of the m"'l n' p!ef!ontl

$o!te(.

/n(iet"& in m" +ie%& is $oniti+e stte in %hi$h %o!kin memo!" is monopoli,e' b" f!etful& %o!!"in

thouhts. The 'iffe!en$e bet%een n o!'in!" stte of min' 2of %o!kin memo!"3 n' n n(ious one is tht& in the

ltte! $se& s"stems in+ol+e' in emotionl p!o$essin& su$h s the m"'l& h+e 'ete$te' th!etenin sitution&

n' !e influen$in %ht %o!kin memo!" tten's to n' p!o$esses. This in tu!n %ill ffe$t the mnne! in %hi$h

e(e$uti+e fun$tions sele$t info!mtion f!om othe! $o!ti$l net%o!ks n' f!om memo!" s"stems n' mke 'e$isions

bout the $ou!se of $tion to tke.

) belie+e tht the hippo$mpus is in+ol+e' in n(iet" not be$use it p!o$esses th!ets& s 9!" suests& but

inste' be$use it supplies %o!kin memo!" %ith info!mtion bout stimulus !eltions in the $u!!ent en+i!onmentl

$onte(t& n' bout pst !eltions sto!e' in e(pli$it memo!". 7hen the o!nism& th!ouh %o!kin memo!"C $on$ei+es

tht it is f$in th!etenin sitution n' is un$e!tin bout %ht is oin to hppen o! bout the best $ou!se of

$tion to tke& n(iet" o$$u!s.

)n m" fo!multion& the m"'l pl"s !ete! !ole in th!et p!o$essin thn the hippo$mpus. ) h+e

'es$!ibe' the !ole of the m"'l in p!o$essin n' !espon'in to th!ets in e!lie! $hpte!s n' in The Emotional

Brain, n' %ill onl" b!iefl" !e$ount it he!e. 7hen senso!" info!mtion bout th!etenin stimulus is 'ete$te' b" the

m"'l& output $onne$tions to !esponse-$ont!ol s"stems in the b!in stem initite the e(p!ession of 'efense

!esponses 2f!ee,in3 n' suppo!tin ph"sioloi$l $hnes in the bo'" 2!ises in bloo' p!essu!e n' he!t !te& st!ess

ho!mone !elese& n' so on3& some of %hi$h i+e !ise to sinls tht !e fe' b$k to the b!in n' influen$e onoin

p!o$essin. /lthouh 9!"*s theo!" 'i' not ''!ess the @uestion of ho% monomine s"stems !e $ti+te' b" th!et&

one of the ke" %"s this o$$u!s is th!ouh 'i!e$t $onne$tions f!om the m"'l to the monomine $ells. Thus& 'u!in

th!ets& se!otonin n' no!epineph!ine 2n' 'opmine3 !e !elese' in %i'esp!e' fo!eb!in !es 2in$lu'in the

p!ef!ontl $o!te(& hippo$mpus& n' m"'l& s %ell s othe! !es3. Di!e$t $onne$tions f!om the m"'l to

p!ef!ontl !es 2in$lu'in nte!io! $inulte n' o!bitl $o!te(3 llo% the 'ete$tion of th!ets b" the m"'l to

'i!e$tl" influen$e %o!kin memo!" p!o$essin. But the p!ef!ontl $o!te( n' its %o!kin memo!" fun$tions !e lso

influen$e' th!ouh othe! !outes& in$lu'in the m"'l-initite' !elese of monomines n' the fee'b$k f!om

ho!monl n' othe! bo'il" !esponses. 7hen the m"'l 'ete$ts th!et& it t!ie!s $onse@uen$es tht ultimtel"

pl$e %o!kin memo!" in +iilnt p!o$essin stte& $usin it to $ontinue to tten' to %hte+e! it is o$$upie' %ith t

the moment& bisin thouhts& 'e$isions& n' $tions. 8u!the!& output $onne$tions of the m"'l to the nu$leus

$$umbens& s %e s% in the lst $hpte!& llo% th!etenin stimuli to moti+te the o!nism to +oi' the sou!$e of

the th!et. This is n impo!tnt f$to!& i+en tht ptholoi$l +oi'n$e of possible th!et sou!$es is p!mount



beh+io!l s"mptom of n(iet" 'iso!'e!s.

Up to this point in the 'is$ussion& )*+e not m'e $le! 'istin$tion bet%een fe! n' n(iet". :lssi$ll"&

thouh& fe! is +ie%e' s !e$tion to spe$ifi$ n' imme'itel" p!esent stimulus& %he!es n(iet" is $on$e!n

bout %ht mi!ht hppen. One possible !esolution of the 9!"-0$1uhton theo!" %ith the m"'l theo!" %oul' be

if m"'l net%o!ks took $!e of fe! n' hippo$mpl net%o!ks took $!e of n(iet". This miht h+e been n $ -

$eptble thesis some "e!s o& but the!e is no% st!on e+i'en$e sho%in tht in>e$tion of ben,o'i,epines 'i!e$tl"into the lte!l n' bsl m"'l& the input stes of the m"'l& !e'u$es n(iet" beh+io!s in se+e!l 2thouh

not ll3 of the $lssi$ tsks use' to test the effi$$" of ntin(iet" '!us. Tht fin'in is $onsistent %ith the f$t tht

ben,o'i,epine !e$epto!s !e $on$ent!te' in these input !eions of the m"'l. 8u!the!& t"pi$l ntin(iet"

'!us tht t!et se!otonin !e$epto!s lso !elie+e n(iet" in niml mo'els %hen in>e$te' into the m"'l. Both

$lssi$l n' t"pi$l ntin(iet" '!us m" the!efo!e $hie+e thei! n(iet"-!e'u$in effe$ts& t lest in p!t& t the

input stes of m"'l p!o$essin& mkin it h!'e! fo! th!etenin stimuli to initite $ti+it" in the m"'l&

the!eb" p!e+entin m"'l $ti+tion f!om !ousin the !est of the b!in.

But nothe! theo!" hs been p!opose' tht 'istinuishes fe! n' n(iet" in 'iffe!ent %". 0i$hel D+is

hs pe!fo!me' e(pe!iments suestin tht n(iet" miht be fun$tion of the be' nu$leus of the st!i te!minlis&

b!in !eion tht is $onsi'e!e' n e(tension of the m"'l n' %hose output $onne$tions !e !em!kbl" simil! to

those of the m"'l. Be$use of thei! simil! outputs& the m"'l n' be' nu$leus $n ffe$t mn" of the sme

t!et b!in !es 2p!ef!ontl $o!te(& monomine s"stems& n' so on3 in $omp!ble %"s n' p!o'u$e the sme

kin's of bo'il" !esponses 2mus$le tension& fst-betin he!t& s%et" plms& tiht stom$h& n' so on3. But be$use

the inputs to the t%o st!u$tu!es !e 'iffe!ent& the" miht be $ti+te' un'e! 'iffe!ent $on'itionsthe m"'l in

!esponse to imme'itel" p!esent th!ets& the be' nu$leus to nti$ipte' ones. This 'istin$tion bet%een the !ole of the

m"'l in fe! n' the be' nu$leus in n(iet" is ppelin be$use it potentill" e(plins %h" people on ntin(iet"

me'i$tion $n be ene!ll" less %o!!ie' 2tht is& less n(ious3& n' still be $pble of !espon'in to n imme'ite

th!et. Ho%e+e!& mu$h %o!k !emins to be 'one to $l!if" the !ole of these t%o !eions n' thei! !eltion to the

b!o'e! $i!$uits in+ol+e' in n(iet".

)n summ!"& ene!li,e' n(iet" is n !ouse' stte of min' initite' n' mintine' b" emotionl

p!o$essin. /s !esult& it !e@ui!es& t minimum& net%o!ks in+ol+e' in !ousl 2monomine s"stems3& emotionl

2m"'l& pe!hps in$lu'in the e(ten'e' m"'l3& n' $oniti+e 2p!ef!ontl $o!te(& hippo$mpus3 fun$tions. /n'

%hile in'i+i'ul b!in !eions n' net%o!ks mke 'istin$t $ont!ibutions to the p!o$esses tht toethe! $onstitute

n(iet" n(iet" itself is best thouht of s p!ope!t" of the o+e!ll $i!$uit!" !the! thn of spe$ifi$ b!in !eions.

THE SPE:T4U0 O8 /1X)ETY

So f!& this o+e!+ie% hs fo$use' on f!ee-flotin o! ene!li,e' n(iet". But the n(iet" 'iso!'e!s lso

in$lu'e phobis& pni$ 'iso!'e!& postt!umti$ st!ess 'iso!'e!s& n' obsessi+e-$ompulsi+e 'iso!'e!. These !e

'istin$t $on'itions %ith 'iffe!ent $uses n' s"mptoms& n' the t!etments tht %o!k fo! one 'o not ne$ess!il" %o!k

fo! the othe!s.

Ben,o'i,epines !e of little help in t!etin the so-$lle' simple phobis 2ptholoi$ fe! of snkes& spi'e!s&

heihts& n' so fo!th3. )n f$t& the most effe$ti+e t!etment fo! these $on'itions is ps"$hothe!p"& espe$ill" $oniti+e

beh+io!l the!p"& in %hi$h the s"mptoms !e !e'u$e' b" e(posu!e to the fe!e' stimulus un'e! +!ious $on'itions

2see the bo( entitle' “:oniti+e Beh+io!l The!p"#3. /nothe! kin' of phobi& so$il phobi& $ente!s !oun' fe! of

bein neti+el" e+lute' b" othe!sfo! e(mple& b" people %ith %hom one %o!ks o! sh!es inte!ests. Some fo!ms

of so$il phobi in+ol+e fe! of bein the $ente! of ttention in publi$. E(mples of the ltte! in$lu'e n e(t!eme

'ebilittin fe! of publi$ spekin o! pe!fo!mn$e& n' fe! of etin in publi$ o! usin publi$ bth!ooms.

/nti'ep!essnt me'i$tions& in$lu'in $e!tin SS4Js n' monomine o(i'se inhibito!s& !e often use' in t!etin

these $on'itions. :oniti+e beh+io!l the!p" is lso useful. D!us like p!op!nolol& %hi$h !e'u$e the bo'il" sins of

fe! 2hih he!t !te n' so fo!th3 but tht 'o not ffe$t the b!in 'i!e$tl"& !e sometimes use' to i' in publi$ spekin



n' ste f!iht. /s %ith so$il phobi& the p!efe!!e' t!etment fo! pni$ 'iso!'e! n' postt!umti$ st!ess 'iso!'e!

to'" is the use of n SS4J in $ombintion %ith some fo!m of ps"$hothe!p" in+ol+in n(iet" mnement n'

$oniti+e beh+io!l the!p". / +!iet" of othe! '!us 2in$lu'in monomine o(i'se inhibito!s& t!i$"$li$s& n'

ben,o'i,epines3 lso

h+e some positi+e effe$ts in these 'iso!'e!s& but the SSP)s h+e bette! si'e-effe$t p!ofile. Obsessi+e-

$ompulsi+e 'iso!'e! like%ise !espon's to SS4)s to some 'e!ee.Be$use the 'iffe!ent fo!ms of n(iet" !e mnifeste' in 'iffe!ent mentl& beh+io!l& n' ph"sioloi$l

s"mptoms n' often un'e! 'istin$t $on'itions 2h+in to i+e spee$h m" h+e little effe$t on spi'e! phobi$ but

%ill be sou!$e of fe! n' n(iet" to one %ho hs fe! of publi$ spekin3& the!e is somethin unstisf$to!" bout

the use of simil! me'i$tions to t!et them ll. /n' be$use the p!efe!!e' me'i$tions !e nti'ep!essnts& !the!

thn '!us 'e+elope' fo! spe$ifi$ n(iet" 'iso!'e!s& one $n*t help but feel tht f!om the point of +ie% of '!u

'e+elopment n' t!etment& %e h+e h!'l" tou$he' these mentl p!oblems some of %hi$h !e %i'esp!e' n'

'e+sttin. :e!tinl"& follo%in the st!te" of usin info!mtion bout effe$ti+e t!etments to i+e $lues to the

un'e!l"in bioloi$l 'istu!bn$e is not oin to !e+el 'iffe!en$es bet%een +!ious n(iet" 'iso!'e!s& sin$e the sme

t!etment 2SS4)s3 is use' fo! 'iffe!ent n(iet" 'iso!'e!s& s %ell s fo! 'ep!ession.

E!lie!& ) mentione' tht ) m the 'i!e$to! of the :ente! fo! the 1eu!os$ien$e of 8e! n' /n(iet"

6http;;''')cns)fly)Cd;CNFA;7) This $ente! b!ins toethe! s$ientists t ll of the m>o! biome'i$l !ese!$h

institutions in 0nhttn& in$lu'in 1e% Yo!k Uni+e!sit" 2Eli,beth Phelps& 0on" 'e Leon& n' me3& 4o$kefelle!

Uni+e!sit" 2B!u$e 0$E%en3& :o!nell Uni+e!sit" 0e'i$l :ollee 2D+i' Silbe!s%ei n' Emil" Ste!n3& 0t. Sini

0e'i$l S$hool 2John 0o!!ison n' Pt!i$k Hof3& n' :olumbi Uni+e!sit" 2J$k 9o!mn3. The !ese!$h in+ol+es

stu'ies of nimls n' of ptients %ith n(iet" 'iso!'e!s. Ou! imme'ite ol is to elu$i'te the %"s in %hi$h the

b!in is $hne' in n(iet" 'iso!'e!s& in the hope of f$ilittin& o+e! the lon !un& the 'e+elopment of mo!e sele$ti+e

n' mo!e effe$ti+e t!etments %ith fe%e! si'e effe$ts. The ptient %o!k in+ol+es the use of stte-of-the-!t fun$tionl

00 imin te$hni@ues n' the niml %o!k tkes '+nte of the +st !senl of neu!os$ien$e tools tht hs been

'is$usse' th!ouhout this book.

Be$use n(iet" 'iso!'e!s in+ol+e lte!tions in the p!o$essin n'Ko! !e$tion to th!et n' 'ne!& n'

fe! me$hnisms !e to l!e e(tent $onse!+e' in the b!ins of humns n' othe! mmmls& !ese!$h on the ps"-

$holo" n' neu!os$ien$e of fe! $n info!m i'es bout the un'e!l"in 'istu!bn$e in 'iffe!ent n(iet" 'iso!'e!s.

/lthouh the!e h+e been se+e!l imin stu'ies of ptients %ith n(iet" 'iso!'e!s of +!ious t"pes& the im of ou!

$ente! is to use the eno!mous p!o!ess tht hs been m'e in elu$i'tin the neu!l pth%"s un'e!l"in fe!

$on'itionin in nimls to t!" n' un'e!stn' the ntu!e of the b!in $hnes tht tke pl$e in n(iet" 'iso!'e!s&

espe$ill" pni$ 'iso!'e! n' postt!umti$ st!ess 'iso!'e! 2PTSD3.

Pni$ 'iso!'e! n' PTSD both in+ol+e lte!tions in the p!o$essin of th!ets& but the $uses n' s"mptoms

!e 'istin$t. )n pni$ 'iso!'e!& fe! is e(p!esse' in the fo!m of 'is$!ete n' su''en pni$ tt$ks tht !ise %ithout

n ob+ious en+i!onmentl stimulus n' le' to $h!oni$ nti$ipto!" n(iet" n' +!ious 'e!ees of +oi'n$e

beh+io!. 8e! in pni$ ptients hs no pp!ent !eltionship to n" $tul th!et n' often in+ol+es bno!ml

sensiti+it" to un$omfo!tble somti$ senstions. )n PTSD& fe! is e(p!esse' s in$!ese' sensiti+it" to stimuli

!eminis$ent of n o!iinl& life-th!etenin t!umti$ e+ent n' in$lu'es flshb$ks n' in$!ese' st!tle !esponse.

Diffe!ent neu!l me$hnisms shoul' the!efo!e be lte!e' in these ptients.

/s %e*+e seen !epete'l"& the m"'l is ke" b!in !eion in the $@uisition n' e(p!ession of fe!

eli$ite' b" stimuli sso$ite' %ith th!etenin e(pe!ien$es. /n' se+e!l stu'ies of no!ml humns h+e no% sho%n

m"'l $ti+tion 'u!in fe! $on'itionin& e+en %hen the $on'itione' stimulus is p!esente' subliminll"& tht is&

un$ons$iousl".# 7e the!efo!e $n use fe! $on'itionin to $ti+te the m"'l n' 'ete!mine %hethe! the ptte!n of

$ti+tion the!e is lte!e' in ptients %ith n(iet" 'iso!'e!s. Ou! e(pe$ttion is tht be$use $hnes in the %" fe!-

!ousin stimuli !e pe!$ei+e' n' !espon'e' to $h!$te!i,e ll n(iet" 'iso!'e!s& %e shoul' see in$!ese' le+els of

$ti+it" in the m"'l in both pni$ n' PTSD ptients.



But the m"'l is not the onl" !e impli$te' in fe! $on'itionin. /s %e*+e seen& the hippo$mpus is

in+ol+e' in p!o$essin fe!-!ousin situtions o! $onte(ts& n' the me'il p!ef!ontl $o!te( in the '>ustment of fe!

!e$tions in !esponse to $hnin en+i!onmentl $on'itions& s in e(tin$tion 2the p!o$ess %he!eb" $on'itione'

stimulus loses its fe!-!ousin p!ope!ties %hen it no lone! p!e'i$ts 'ne!3. 4e$ent stu'ies b" Li, Phelps h+e $on-

fi!me' the !ole of the humn hippo$mpus in p!o$essin $onte(tul fe! stimuli&oo n' %e !e $u!!entl" testin

%hethe! $ti+tion of the humn me'il p!ef!ontl $o!te( %ill be lte!e' 'u!in e(tin$tion.The use of fe! $on'itionin llo%s us to ssess %hethe! ptte!ns of neu!l $ti+it" %ithin n' bet%een the

m"'l& hippo$mpus& n' me'il p!ef!ontl $o!te( 'iffe! in pni$ n' PTSD ptients f!om no!ml $ont!ols. 8u!the!&

%e $n 'ete!mine %hethe! su$$essful t!etment 2e..& the use of SS4)s n' $oniti+e beh+io!l the!p"3 %ill $use

the b!ins of these ptients to look mo!e like those of no!ml $ont!ols. B" testin ptients fte! t!etment

%ith eithe! SS4)s o! $oniti+e beh+io!l the!p" lone& %e shoul' be ble to 'ete!mine %hethe! the t%o

kin's of the!p" $hie+e thei! !esults b" lte!in the sme o! 'iffe!ent $omponents of the $i!$uits.

On$e %e h+e some sense of ho% the b!ins of pni$ n' PTSD ptients 'iffe! f!om e$h othe! n' f!om

those of no!ml pe!sons& %e $n tu!n to niml stu'ies n' e(plo!e %ht kin's of life e(pe!ien$es n' bioloi$l

$on'itions miht p!e'ispose the b!in to $hne in these %"s. 8o! e(mple& suppose %e fin' tht the m"'l is

h"pe!$ti+e in both pni$ n' PTSD& but tht the hippo$mpus n' p!ef!ontl $o!te( $hne in 'iffe!ent %"s in e$h

$on'ition. 7e $oul' look fo! st!essful e(pe!ien$es tht p!o'u$e these ptte!ns of $hne in the !t b!in. )f su$h

ptte!ns $n be i'entifie'& then the $hnes $n be pu!sue' t the le+el of s"npti$ lte!tions n' e(pline' in bi-

oloi$l te!msA s neu!ot!nsmitte! $tions on !e$epto!s tht open $hnnels n' llo% $l$ium to flo% insi'e the $ell

n' t!ie! kinses tht phospho!"lte t!ns$!iption f$to!s tht in'u$e enes to mke p!oteins tht stbili,e s"npti$

$hnes. To the e(tent tht n" one of these mole$ul! steps 'iffe!s bet%een n(iet" 'iso!'e!s& $lues bout futu!e

'!u 'e+elopment %oul' be +ilble.

B" no% "ou*+e su!el" noti$e' t!en'. 1eu!os$ientists h+e p!opose' tht the p!ef!ontl $o!te(&

hippo$mpus& n' m"'l !e lte!e' in some %" in ll fo!ms of mentl illness %e*+e $onsi'e!e' so f!. )t seems

tht mentl 'iso!'e!s !e i+in us messe& tellin us tht these th!ee b!in !eions !e espe$ill" $!iti$l to

un'e!stn'in %ho %e !e n' %h" %e !e tht %". But %e shoul' !emembe! tht the sme b!in !es $n be

in+ol+e' in 'iffe!ent 'iso!'e!s fo! 'iffe!ent !esons. /t fi!l" !oss le+el of e(plntion& neu!l $ti+it" in p!ti$ul!

!e miht be up in one 'iso!'e! n' 'o%n in nothe!. But in o!'e! fo! neu!l $ti+it" to $hne in this %"& mo!e

bsi$ $hnes h+e to be tkin pl$e %ithin n' bet%een in'i+i'ul $ells in the !e in @uestion. Sin$e these 'eepe!

$hnes $n be !e+ele' onl" b" e($tin neu!obioloi$l stu'ies& %hi$h $n be 'one onl" in e(pe!imentl nimls& it

is essentil tht !ese!$h on ps"$hit!i$ 'iso!'e!s in humns n' bsi$ s$ien$e in+estitions of b!in fun$tion in

nimls be $oo!'inte'.

7e h+e >ust beun this !ese!$h p!o!m& n' it is too e!l" to kno% >ust %ht %e*ll tu!n up. Ho%e+e!&

be$use of the s"stemti$ ntu!e of the !ese!$h p!o!m& %e %iii lmost $e!tinl" be ble to point to 'iffe!en$es in

the b!ins of pni$ n' PTSD ptients& e+en if the" !e not the ones %e e(pe$te'. But& in mn" %"s& une(pe$te'

fin'ins !e the most inte!estin& s the" fo!$e thinkin bout p!oblems in ne% %"s.

B4/)1S 9E1ES& /1D THE4/PY

7e*+e otten ll the %" to the en' of this $hpte! on bioloi$l pp!o$hes to mentl illness %ithout

'is$ussin enes. To mn"& espe$ill" to $!iti$s& bioloi$l pp!o$h to mentl 'iso!'e!s implies n emphsis on

eneti$s. But ) hope )*+e p!esente' $!e'ible lte!nti+e +ie%. /s in ll othe! spe$ts of mentl life& enes $n

p!e'ispose people in $e!tin 'i!e$tions %ithout ltoethe! p!e'ete!minin thei! 'estin". 9enes $ont!ibute to& !the!

thn solel" 'i$tte& s"npti$ $onne$ti+it".

:!iti$s su$h s :ohn 4oss n' /l+in Pm !e $on$e!ne' tht bioloi$l pp!o$h to mentl 'iso!'e!s

implies tht “the in'i+i'ul %ith beh+io! p!oblems must suffe! in some %" f!om 'efe$ti+e p!otoplsm& $onstitutionl

p!e'isposition to mentl illness&# n' tht the bo'" o! b!in is !esponsible fo! mentl illness !the! thn the fmil" o!



so$iet". The" st!onl" e@ute bioloi$l ps"$hit!" %ith eneti$s. Ho%e+e!& %hile eneti$ pp!o$h to mentl

'iso!'e!s is b" 'efinition bioloi$l in o!ienttion& the !e+e!se is not ne$ess!il" t!ueA bioloi$l pp!o$h is not

e($lusi+el" o! e+en p!im!il" eneti$. Let*s fi!st tke look t the eneti$ pp!o$h& n' then $onsi'e! the b!o'e!

pi$tu!e.

/ mssi+e effo!t is no% un'e! %" to 'ete!mine the e(tent to %hi$h enes $ont!ibute to mentl illness. 8o!

e(mple& "e!s of !ese!$h h+e one into pe'i!ee stu'ies of fmilies o! !oups of people %ith ten'en$" to%!' mentl 'iso!'e!& n' into $on$o!'n$e stu'ies of i'enti$l t%ins& %hi$h 'ete!mine the likelihoo' tht the p!esen$e of

the 'iso!'e! in one p!e'i$ts the 'iso!'e! in the othe!. S$hi,oph!eni& 'ep!ession& n(iet" 'iso!'e!s& l$oholism& n'

+!iet" of othe! ps"$hit!i$ n' neu!oloi$ $on'itions !e bein stu'ie' this %".

8o! illust!ti+e pu!poses& $onsi'e! the %o!k on s$hi,oph!eni. The !ese!$h sho%s st!on $o!!eltion

bet%een the numbe! of enes sh!e' n' the likelihoo' of 'e+elopin the 'iso!'e!. S$hi,oph!eni o$$u!s in bout i

pe!$ent of the ene!l popultion. )n $ont!st& in i'enti$l t%ins 2ioo pe!$ent ene o+e!lp3& if one $hil' hs

s$hi,oph!eni then the!e*s !ouhl" $hn$e the othe! %ill 'e+elop it t some point. But in f!te!nl t%ins 2 pe!$ent

ene o+e!lp3& the likelihoo' '!ops to N pe!$ent. )n siblins 2 pe!$ent ene o+e!lp3& the fiu!e flls to F pe!$ent&

n' in fi!st $ousins 2. pe!$ent ene o+e!lp3 to pe!$ent. The o+e!ll pi$tu!e tht eme!es is tht s$hi,oph!eni is

st!onl" tie' to eneti$ f$to!s. Tht is& in eneti$ te!ms& the!e*s $on$o!'n$e mon i'enti$l t%ins. But one $n

+ie% this $up s hlf full o! hlf empt"the!e*s lso 'is$o!'n$e. )f enes full" “e(pline'# s$hi,oph!eni&

$on$o!'n$e %oul' be ioo pe!$ent.

The 'is$o!'n$e bet%een i'enti$l t%ins is 'ue to se+e!l f$to!s. One is tht ene e(p!ession is n

epl!enetic phenomenonit in+ol+es the inte!$tion of the ene %ith en+i!onmentl f$to!s. /n e(t!eme e(mple of

epienesis is the 'isese phen"lketonu!i 2P5U3& eneti$ fo!m of mentl !et!'tion tht is not e(p!esse' unless the

essentil mino $i' phen"llnine is ineste'. 2)t is p!esent in 'i!" p!o'u$ts& +o$'o& $e!tin nuts& n' in the su!

substitute sp!tme.3 )n this $se& e!l" 'ete$tion n' t!etment $n p!e+ent the s"mptoms of the 'isese. )n most

eneti$ $on'itions& thouh& the en+i!onmentl $o-$onspi!to!s !e not kno%n. /nothe! f$to! %o!kin inst

$on$o!'n$e is the pol"eneti$ ntu!e of the eneti$ $ont!ibution. )n the '"s %hen ps"$hit!i$ 'iso!'e!s %e!e thouht

to be 'ue to simple imbln$e in p!ti$ul! b!in $hemi$l& it %s plusible tht the 'iso!'e! miht be $use' b"

sinle ene 2one tht mkes t!nsmitte! o! !e$epto! mole$ules3. But s %e*+e seen& ps"$hit!i$ 'iso!'e!s in+ol+e

$omple( $i!$uits in the b!in& n' the!efo!e n" eneti$ $ont!ibution is likel" to in+ol+e inte!$tions mon multiple

enes. Be$use the e(p!ession of e+e!" ene lso in+ol+es inte!$tions %ith en+i!onmentl f$to!s& pol"eneti$

inhe!itn$e !etl" e(pn's the mnne! in %hi$h the en+i!onment $n influen$e eneti$ p!e'ispositions. 8u!the!& in

some $ses& people %ith the ene fo! 'isese sho% little o! no e+i'en$e of h+in the s"mptoms of the 'isese.

This is $lle' nonpenetrance) )n othe! instn$es& eneti$ 'iseses !e +!ibl" e(p!esse'& %he!e some fmil"

membe!s m" h+e the full-blo%n 'isese n' othe!s onl" mil' s"mptoms. 8inll"& mentl 'iso!'e!s $n p!obbl"

h+e multiple un!elte' $uses. )t is belie+e'& fo! e(mple& tht in some instn$es& s$hi,oph!eni $n be in'u$e' b"

en+i!onmentl f$to!s& like b!in in>u!" o! infe$tion& in pe!sons %ith little o! no eneti$ lenin to%!' the 'iso!'e!. So

'is$o!'n$e bet%een i'enti$l t%ins miht sometimes be 'ue to the f$t tht the ffli$te' t%in $@ui!e' s$hi,oph!eni

fo! noneneti$ !esons.

Bioloi$l ps"$hit!ists !e inte!este' in the possibilit" tht enes $ont!ibute to mentl 'iso!'e!s be$use

eneti$ p!oblems miht in the futu!e be fi(ble. / ene %o!kin o+e!time n' the!eb" $usin mlfun$tion miht&

%ith pill& be tu!ne' 'o%n o! off& n' one tht is sluish miht be en$ou!e' to %o!k h!'e!. 7hethe! these fets

%ill e+e! be su$$essfull" $$omplishe' is unkno%ble t the p!esent. But if the" !e& mn" people !e likel" to be

helpe'.

)t shoul' be note' tht su$$ess o! filu!e fo! one ps"$hit!i$ 'iso!'e! %ill not p!e'i$t the su$$ess o! filu!e in

t!etin othe!s. E$h 'iso!'e! %ill h+e its o%n pe$uli! '+ntes n' 'is'+ntes fo! eneti$ pp!o$h& n'

e$h hs to be tt$ke' in'i+i'ull". /t the sme time& !ese!$h st!teies 'e+elope' fo! one p!oblem m" help in the

pu!suit of the othe!s. 7ith the humn enome !e$entl" p!onoun$e' s “kno%ble&# this kin' of %o!k is likel" to



e(pn' in the $omin "e!s.

But pe!hps )*m not bein $ompletel" fi! to the $!iti$s. One of thei! $on$e!ns is tht fo$us on enes o!

othe! spe$ts of biolo" puts too mu$h blme on the bo'"& 'is$ou!in mentl p!ofessionls f!om usin non'!u

fo!ms of the!p"& insu!n$e $ompnies f!om p"in fo! non'!u the!p"& n' ptients f!om tkin !esponsibilit" fo!

thei! o%n helin. But these $on$e!ns& ) belie+e& !efle$t misun'e!stn'in of the ims of bioloi$l ps"$hit!" )n

spite of the $u!!ent enthusism fo! eneti$ nl"ses of mentl 'iso!'e!s& most bioloi$l ps"$hit!ists +ie% enes in !elisti$ %". 4"mon' DePulo& bioloi$l ps"$hit!ist t Johns Hopkins Uni+e!sit"& e(p!esses %ht is p!obbl" the

most $ommon +ie%A “) 'on*t think 'ep!ession is ll eneti$. )f "ou $n nil 'o%n one en' of the tent& ho%e+e!& it*s

esie! to fiu!e out b" st!et$hin out the !est of the tent %ht it shoul' look like.# )n othe! %o!'s& on$e "ou kno% the

eneti$ $omponent of 'iso!'e!& it shoul' be esie! to fiu!e out %hi$h kin's of en+i!onmentl e(pe!ien$es inte!$t

%ith it to t!ie! the 'iso!'e! n' mke it %o!se. 9enes !e p!t of the sto!"& n' if tht p!t of the sto!" $n be

inte!p!ete'& %e shoul' be bette! off thn if %e ino!e it.

E(pe!ien$e is often $onsi'e!e' the $ounte!point to enes. But eperience is $omple( notion %ith mn"

possible menins n' en'less impli$tions. /s !esult& the !ole of e(pe!ien$e is p!obbl" oin to be e+en mo!e

'iffi$ult to un'e!stn' thn the !ole of enes. But the mo!e %e un'e!stn' bout ho% e(pe!ien$e $hnes the b!in&

the bette! off %e*ll be in 'is$o+e!in ho% it $ont!ibutes to mentl 'iso!'e!s. /s %e*+e seen& e(pe!ien$es ffe$t the

b!in %hen the" !e sto!e' s s"npti$ $hnes in one o! mo!e s"stems 'u!in le!nin& %hi$h is %h" !ese!$h on

s"npti$ plsti$it"& n' on le!nin n' memo!"& is so impo!tnt.

7he!e 'oes bioloi$l pp!o$h to mentl helth n' mentl 'iso!'e!s le+e ps"$hothe!p"= E!i$ 5n'el&

the !eno%ne' neu!os$ientist& st!te' his $!ee! s ps"$hit!ist. 4e$entl"& he bol'l" p!opose' “ne% intelle$tul

f!me%o!k fo! ps"$hit!"&# one foun'e' on bioloi$l p!in$iples. He !ue' tht %e !e on the th!eshol' of

un'e!stn'in memo!" n' emotion s"stems in the b!in& n' tht this info!mtion& $ombine' %ith $ontinue'

'+n$es in mole$ul! neu!os$ien$e& offe!s %elth of oppo!tunities fo! ps"$hit!".

/s ) pointe' out t the beinnin of this $hpte!& ps"$hothe!p" is fun' mentll" le!nin p!o$ess fo! its

ptients& n' s su$h is %" to !e%i!e the b!in. )n this sense& ps"$hothe!p" ultimtel" uses bioloi$l me$hnisms

to t!et mentl illness. This 'oes not men& ho%e+e!& tht ps"$hothe!p" in+ol+es le!nin %hile '!u the!p" in+ol+es

somethin else& like $o!!e$tion of eneti$ll" 'i$tte' $hemi$l imbln$es. E+en if $hemi$l imbln$es %e!e to

$$ount fo! mentl 'iso!'e!s& the imbln$e $oul' !esult pu!el" f!om en+i!onmentl f$to!s& like some intensel"

st!essful e(pe!ien$e& o! f!om en+i!onmentl e+ents tht t!ie! n' mplif" eneti$ p!e'isposition. The the!pist*s

>ob& %hethe! usin '!us o! not& is to !esto!e mentl %ell-bein. )f the ptient*s p!oblem in+ol+es neu!l $hnes tht

!e lo$kin the b!in in n !ouse' stte& !elief %ill $ome onl" %hen the !ouse' stte is !e'u$e'& eithe! b"

ps"$hothe!p" o! '!u the!p"& o! b" some $ombintion of the t%o. 4e!'less of %hethe! the initil $use is so$il

st!ess o! eneti$ time bomb& unless the $hnes in the b!in tht $$ompn" the 'iso!'e! $n be !e+e!se' o!

$i!$um+ente'& the p!oblem is unlikel" to 'issipte.

:ontempo!!" pp!o$hes to the t!etment of mentl 'iso!'e!s !e not 'istinuishe' f!om ol'e! ones so

mu$h b" n emphsis on '!us s b" n emphsis on effecti+e t!etment. J$k 9o!mn of :olumbi Uni+e!sit"&

le'in bioloi$l ps"$hit!ist& puts it this %"A “)n the Ol' Ps"$hit!"& e$h $lini$in le!ne' set of te$hni@ues f!om

one s$hool of thouht n' insiste' on ppl"in them to ll $o!ne!s. )n the 1e% Ps"$hit!" $lini$ins m" still feel most

$omfo!tble %ith the tools of one s$hool& but the" !e'il" 'mit %hen the" 'on*t h+e the !iht skill fo! p!ti$ul!

ptient. To'"& ps"$honl"sts !e %illin to !efe! ptients %ho nee' me'i$tion to ps"$hit!ist %ith skills in

ps"$hoph!m$olo"& >ust s those t!ine' in ps"$hoph!m$olo" in$!esinl" sen' ptients to ps"$hothe!peuti$

spe$ilist. “The 1e% Ps"$hit!"&# $$o!'in to 9o!mn& “is onl" inte!este' in p!o+i'in sfe n' effe$ti+e t!etment. )f

tht mens bo!!o%in f!om 'iffe!ent points of +ie% to offe! ptient $ombintion of the!pies& then tht is %ht must

be 'one.#

On$e 'iso!'e! e(ists& n' the b!in hs $hne'& the $hnes h+e to be 'elt %ith in some %" in o!'e!

fo! ptient to !e$o+e!. D!us $n in'u$e 'pti+e $hnes in neu!l $i!$uits& o! put neu!l $i!$uits in stte %he!e



'pttion n' le!nin !e p!omote'. But the!e*s no u!ntee tht& left to its o%n 'e+i$es& the b!in %ill le!n the

!iht thins. Ptients& in othe! %o!'s& !e likel" to benefit most f!om '!u the!p" %hen the '!u-in'u$e' 'pti+it" of

thei! b!ins is 'i!e$te' in meninful %". This is p!obbl" best $hie+e' b" t!+elin 'o%n the ph!m$oloi$l

!o' to !e$o+e!" %ith some one %ho un'e!stn's not >ust the '!u o! the pe!son& but the '!u& the pe! son& n' the

life sitution the pe!son is e(pe!ien$in. H0Os m" not like it& but the '!u& the!pist& n' ptient !e p!tne!s in the

s"npti$ '>ustment p!o$ess $lle' the!p"& %ith '!us tt$kin the p!oblem f!om the bottom up& the the!pist f!omthe outsi'e in& n' %ith the ptient !e$hin up n' 'o%n

f!om his o! he! o%n s"npti$ self.

:H/PTE4 ELE6E1

7HO /4E YOU=

7HO /4E YOL7HO 7HO& 7HO 7HO=

The 7ho

8iu!in out ho% the b!in %o!ks is 'untin tsk. 8o! tht !eson& neu!os$ientists usull" %o!k onl" on

pie$es of the pu,,lelike spe$ts of $onition& emotion& o! moti+tion!the! thn on the %hole o!n n' its

s"stems t on$e. But if %e %nt to un'e!stn' ho% ou! b!ins mke us %ho %e !e& %e h+e to fiu!e out ho% these

in'i+i'ul p!o$esses blen' toethe! to $use pe!son to eme!e effo!tlessl" f!om the ele$t!o$hemi$l $ti+ities of the

p!otoplsmi$ mss tht is his o! he! b!in. )t*s time fo! me to bite the bullet n' e(plin ho% ) think the b!in&

spe$ifi$ll" its s"npses& mkes us %ho %e !e.

B4/)1S /1D OTHE4 P/4/LLEL :O0PUTE4S

) on$e h' f!ien' %ho suppo!te' bohemin life in 'o%nto%n 0nhttn %ith >ob s $ompute!

p!o!mme! in neu!os$ien$e lb. He %s e(t!emel" tlente'& too tlente' fo! su$h %o!k& n' e+entull" ot position mo!e suite' to his bilities. He %s hi!e' b" $ompn" in Boston tht m'e po%e!ful $ompute!s $lle'“$onne$tion m$hines.# )t %s th!ouh him tht ) fi!st he!' bout p!llel $ompute!s.

P!llel $ompute!s %o!k 'iffe!entl" f!om the stn'!' mo'el %ith %hi$h %e*!e fmili!. 4the! thn 'oin$omputtions one t time in se@uen$e 2in othe! %o!'s& $!!"in out the steps of p!o!m line b" line in se!ilo!'e!3& the" p!o$ess mn" steps simultneousl". P!llel $ompute!s $n fun$tion this %" be$use& in $ont!st to "ou!'esktop P: o! 0$& the" h+e mn" p!o$essin units tht $n be 'e+ote' to the e(e$ution of i+en tsk. B" 'ist!ib-utin the %o!klo' $!oss the +!ious p!o$esso!s& the" $n pe!fo!m the tsk mu$h fste! thn se!il $ompute!s. 2Don*tpln on ettin one fo! "ou! home o! offi$e& ho%e+e!A the" $ost millions of 'oll!s.3

The b!in is lso sometimes 'es$!ibe' s p!llel $ompute!& but it $tull" fun$tions 'iffe!entl" f!om n off-

the-shelf $onne$tion m$hine. The b!in is o!ni,e' into p!o$esso!s 2neu!l s"stems3 tht fun$tion in'epen'entl" of



one nothe! 2t lest to some e(tent3. Sin$e e$h of these s"stems hs spe$ifi$ >ob ssinment& se+e!l t"pes of

tsks $n be 'one b" the b!in simultneousl"& tht is& in p!llel. This !$hite$tu!e enbles "ou to $he% um n'

%lk 'o%n the st!eet& ui'in "ou!self to%!' "ou! 'estintion %hile feelin hpp" n' !ehe!sin the phone numbe!

"ou! f!ien' +e "ou blo$k b$k& ll t the sme time s "ou! postu!e is mintine' up!iht& "ou! bloo' p!es su!e is

kept t sfe le+el& n' "ou! !te of b!ethin is p$e' to the o("en nee's impose' b" ll the $ti+ities in %hi$h

"ou*!e ene'.:onne$tion m$hines $n& like b!ins& be 'i+i'e' up in su$h %" tht 'iffe!ent !oups of p!o$esso!s !e

!esponsible fo! p!ti$ul! tsks. /lthouh e$h tsk is then pe!fo!me' less effi$ientl" thn it %oul' be if ll the p!o$es-

so!s %e!e 'e+ote' to it& o+e!ll this $n be mo!e effi$ient use of the m$hine sin$e multiple tsks $n be %o!ke' on

t the sme time. 4e+e!sin the loi$& if %e h' fe%e! neu!l s"stems usin up the sme o+e!ll $omputin po%e! in

ou! b!ins the s"stems %oul' e$h be mo!e po%e!ful. Ho%e+e!& be$use %e h+e to 'o lots of 'iffe!ent thins e$h

'" to st" li+e n' %ell 2et& sleep& %lk& +oi' 'ne! n' pin& he!& see& smell& tste& tlk& n' think& to nme

some3& %ith fe%e! b!in s"stems %e %oul' lmost $e!tinl" be less $pble& e+en if the !eminin s"stems %e!e e$h

mo!e p!ofi$ient t thei! p!ti$ul! tsks.

O+e! the lon& slo% e+olution!" p!o$ess of buil'in the b!ins of +e!teb!tes& n' then of mmmls& n'

e+entull" of ou! o%n spe$ies& the neu!l s"stems %e h+e %e!e spe$ifi$ll" 'esine' to tke $!e of impo!tnt >obs.

7e 'on*t h+e e(t! ones tht %e $n esil" i+e up n' $ontinue to le' life s befo!e. Simil!l"& ne% s"stems !en*t

esil" $@ui!e'. 8o! e(mple& the ''ition of lnue n' !elte' spe$ts of $onition to the p!imte b!in %s not

t!i+il p!o$essthe b!in %s b" tht point in its e+olution l!e'" full" booke'. /''in %hole ne% set of fun$tions&

the!efo!e& !e@ui!e' eithe! loss

of sp$e 'e+ote' to some fun$tions o! n in$!ese in b!in si,e. )n f$t& both seem to h+e o$$u!!e'. The

humn b!in is bie! thn tht of othe! nimls 2!elti+e to ou! bo'" si,e3 n' lso seems to h+e un'e!one some

!eo!ni,tion. 8o! e(mple& the neu!l me$hnism un'e!l"in the pe!$eption of sptil !eltions is p!esent in both

hemisphe!es of othe! p!imtesC it is minl" on the !iht si'e in humns. This implies tht sptil pe!$eption %s fo!$e'

f!om the left 'u!in the lnue in+sion of humn s"npti$ te!!ito!".

Life !e@ui!es mn" b!in fun$tions& fun$tions !e@ui!e s"stems& n' s"stems !e m'e of s"npti$ll"

$onne$te' neu!ons. 7e ll h+e the sme b!in s"stems& n' the numbe! of neu!ons in e$h b!in s"stem is mo!e o!

less the sme in e$h of us s %ell. Ho%e+e!& the p!ti$ul! %" those neu!ons !e $onne$te' is 'istin$t& n' tht

uni@ueness& in sho!t& is %ht mkes us %ho %e !e.

THE P/4/DOX O8 P/4/LLEL PL/ST):)TY

7e*+e met numbe! of the b!in*s neu!l s"stems th!ouhout this book. )n$lu'e' !e net%o!ks in+ol+e' in

senso!" fun$tion& moto! $ont!ol& emotion& moti+tion& !ousl& +is$e!l !eultion& n' thinkin& !esonin& n'

'e$isionmkin. 7ht is !em!kble is tht s"npses in ll of these s"stems !e $pble of bein mo'ifie' b"

e(pe!ien$e. :onsi'e! fe% e(mples.

Emotion s"stems& s %e*+e seen& !e p!o!mme' b" e+olution to !espon' to some stimuli& so-$lle' innte

o! un$on'itione' stimuli& like p!e'to!s o! pin. Ho%e+e!& mn" of the thins tht eli$it emotions in us o! moti+te us

to $t in $e!tin %"s !e not p!ep!o!mme' into ou! b!ins s p!t of ou! spe$ies he!ite but h+e to be le!ne' b"

e$h of us. Emotion s"stems le!n b" sso$ition%hen n emotionll" !ousin stimulus is p!esent& othe! stimuli

tht !e lso p!esent $@ui!e emotion-!ousin @ulities 2$lssi$l $on'itionin3& n' $tions tht b!in "ou in $ont$t

%ith emotionll" 'esi!ble stimuli o! p!ote$t "ou f!om h!mful o! unplesnt ones !e le!ne' 2inst!umentl

$on'itionin3. /s in ll othe! t"pes of le!nin& emotionl sso$itions !e fo!me' b" s"npti$ $hnes in the b!in

s"stem in+ol+e' in p!o$essin the stimuli. Some of the b!in*s plsti$ emotionl p!o$esso!s in$lu'e s"stems in+ol+e'

in 'ete$tin n' !espon'in to 'ne!& fin'in n' $onsumin foo'& i'entif"in potentil mtes n' h+in se(.Senso!" s"stems !e like%ise plsti$. Until +e!" !e$entl"& it %s belie+e' tht pe!$eptions !e stble f!om '"

to '" n' "e! to "e! be$use senso!" s"stems !e immutble fte! $hil'hoo'. But stu'ies b" 1o!mn 7einbe!e!&



:h!les 9ilbe!t& 0ike 0e!,eni$h& n' othe!s h+e sho%n tht these s"stems !e !em!kbl" sus$eptible tomo'ifi$tion in !esponse to e(te!nl stimultion. 0e!,en>$h& fo! e(mple& hs sho%n in +!iet" of %"s ho%e(pe!ien$e %ith p!ti$ul! stimulus lte!s the net !e& n' thus the un'e!l"in s"npti$ te!!ito!"C 'e+ote' top!o$essin tht stimulus. 8ollo%in mputtion of fine!& fo! e(mple& the !e in the somtosenso!" $o!te( 'e+ote'to tht fine! sh!inks& %hile e(tensi+e stimultion of p!ti$ul! fine! e(pn's the !e of $o!te( 'e+ote' to it.

0oto! s"stems !e lso plsti$. This is ob+ious f!om the f$t tht %e $n le!n skills n' $n imp!o+e ou!

bilit" to pe!fo!m $e!tin mo+ements %ith p!$ti$e. /s %e s% in $hpte! & $hnes in s"npti$ t!nsmission in the

$e!ebellum !e impo!tnt fo! some fo!ms of moto! skill le!nin. S"npti$ plsti$it" lso o$$u!s in the moto! $o!te(&bsl nli& n' othe! b!in !eions in+ol+e' in moto! $ont!ol.

Be$use s"npti$ plsti$it" o$$u!s in most if not ll b!in s"stems& one miht be tempte' to $on$lu'e tht the

m>o!it" of b!in s"stems !e memo!" s"stems. But s ) !ue' in $hpte! 4, bette! %" of thinkin bout this is tht

the bilit" to be mo'ifie' b" e(pe!ien$e is $h!$te!isti$ of mn" b!in s"stems& !e!'less of thei! spe$ifi$ fun$tion.

B!in s"stems& in othe! %o!'s& %e!e fo! the most p!t not 'esine' s sto!e 'e+i$esplsti$it" is not thei! min >ob

ssinment. The" %e!e inste' 'esine' to pe!fo!m p!ti$ul! tsks& like p!o$essin soun's o! sihts& 'ete$tin foo'

o! 'ne! o! mtes& $ont!ollin $tions& n' so on. Plsti$it" is simpl" fetu!e tht helps them 'o thei! >ob bette!.

The f$t tht plsti$it" 'oes o$$u! in so mn" b!in s"stems& ho%e+e!& !ises )nte!estin @uestions. Ho%

'oes pe!son %ith $ohe!ent pe!sonlit" fi!l" stble set of thouhts& emotions& n' moti+tionse+e! eme!e=

7h" 'on*t the s"stems le!n 'iffe!ent thins n' pull ou! thouhts& emotions& n' moti+tions in 'iffe!ent 'i!e$tions=

7ht mkes them %o!k toethe!& !the! thn s n un!ul" mob=

LESSO1S 84O0 D)S:O11E:T)O1

Befo!e %e e(mine %ht hol's the self toethe!& let*s $onsi'e! ho% f!ile pt$h >ob it is. The bottom line is

simpleA 8un$tions 'epen' on $onne$tionsC b!ek the $onne$tions& n' "ou lose the fun$tions. This is t!ue of the

fun$tion of sinle s"stem 2 lesion of the +isul thlmus& fo! e(mple& %ill p!e+ent info!mtion f!om the e"es f!om

!e$hin the $o!te(& n' thus %ill p!e+ent the $o!te( f!om bein ble to pe!$ei+e the +isul %o!l'3 s %ell s of

inte!$tions bet%een s"stems 2 lesion in $e!tin p!t of the tempo!l lobe %ill p!e+ent info!mtion bout +isul

ob>e$ts f!om !e$hin the p!ef!ontl $o!te( n' thus %ill p!e+ent tht stimulus f!om bein hel' in %o!kin memo!"& n'

hen$e f!om bein use' s the bsis fo! thinkin n' 'e$ision-mkin3.

The most st!ikin instn$e of b!oken $onne$tion )*+e e+e! pe!sonll" %itnesse' in+ol+e' teene bo"

%ho un'e!%ent split-b!in su!e!" fo! the $on-t!ot of epileps". )n this ope!tion& the ne!+es bet%een the t%o si'es of

the b!in !e se+e!e' to p!e+ent the sei,u!es f!om mo+in bet%een the left n' !iht hemisphe!es. One of its

un%nte' $onse@uen$es is tht the t%o hemisphe!es be$ome some%ht in'epen'ent. Se+e!l '"s fte! the su!e!"C

the bo" %s obse!+e' pullin his pnts 'o%n %ith his !iht hn' n' up %ith his left. Sin$e the !iht hn' is un'e! the

$ont!ol of the left hemisphe!e& n' the left hn' of the !iht hemisphe!e& the no!ml inte!tion of moto! $ont!ol tht

e(ists so effo!tlessl" in e$h of us b!oke 'o%n in this bo" be$use the b!in s"stems tht h' finl s" o+e! %ht the

t%o hn's 'o %e!e no lone! $onne$te'. 2This so!t of $onfli$te' beh+io! hs been 'es$!ibe' fo! mn" su$h ptients

but %s m,in to see fi!sthn'.3

/nothe! e(mple in+ol+es $on'u$tion phsi. Ptients %ho suffe! f!om this $on'ition $n spek %ithout

t!ouble n' $n un'e!stn' spoken %o!'s 2fo! e(mple& the" $n point to the pi$tu!e of n ob>e$t nme' b" someone

else3& but $nnot& upon he!in spoken %o!' o! senten$e& !epet it& o! ns%e! @uestion pose' to them. The

!eson fo! this& $$o!'in to the lte 1o!mn 9es$h%>n'& one of the !et neu!oloists of the t%entieth $entu!"C is tht

the neu!l pth%" tht t!nsmits info!mtion bet%een the !es of the b!in !esponsible fo! the $omp!ehension n'

p!o'u$tion of spee$h is $ut. :on'u$tion bet%een the b!in !es is thus 'is!upte'.

9es$h%in' use' the ph!se disconnection syndromes to $h!$te!i,e $on'itions in %hi$h spe$ifi$ beh+io!l

o! mentl $onse@uen$es !esult f!om 'is!uptin $ommuni$tion bet%een b!in !eions. 7ht is st!ikin bout these

'iso!'e!s is tht the 'efi$it !esults not f!om the loss of p!ti$ul! fun$tion& but f!om the inbilit" to e($hne

info!mtion bet%een b!in !es. Dis$onne$tion s"n'!omes illust!te ho% $!iti$l inte!nl $oo!'intion bet%een b!in



s"stems is in mintinin the unit" of min' n' beh+io!.

7hile the effe$ts of b!in lesions !e not in+!ibl" inte!p!ete' s 'is$onne$tion s"n'!omes& 'is$onne$tions

l%"s o$$u! %hen the b!in is 'me'. 8o! e(mple& lesions of the p!ef!ontl $o!te(& espe$ill" the +ent!l o! o!bitl

f!ontl $o!te(& h+e& sin$e the nineteenth $entu!" been kno%n to '!sti$ll" lte! pe!sonlit". /fte! n i!on !o' psse'

th!ouh the he' of Phines 9e in !il!o' $$i'ent& this upstn'in $iti,en su''enl" be$me fitful& i!!e+e!ent&

n' un!est!ine'. /s one $ontempo!!" obse!+e! put it& “The e@uilib!ium bet%een his intelle$tul f$ulties n' nimlu!es seems to h+e been 'est!o"e'.## Buil'in on this $se n' nume!ous othe!s& /ntonio Dms>o hs sueste'

tht 'me to the +ent!l p!ef!ontl $o!te( $n le' to loss of so$il $ont!ol& n' in the e(t!eme $n $use

so$iopthi$ beh+io!. But it %oul' be %!on to think of the +ent!l p!ef!ontl !eion s the $ente! of so $il !$e.

/$$o!'in to Dmsio& the $onse@uen$es of 'me to the +ent!l p!ef!ontl $o!te( $n be $on$ei+e' of s

b!ek'o%n in the bilit" to use emotionl info!mtion to ui'e thouhts n' $tions. This seems !esonble i+en tht

some of the ke" $onne$tions of the +ent!l p!ef!ontl $o!te( in$lu'e !es in+ol+e' in hihe! $oniti+e p!o$esses

2othe! p!ef!ontl !eions su$h s the lte!l p!ef!ontl $o!te( n' nte!io! $inulte $o!te(& s %ell s the

hippo$mpus3 n' emotionl n' moti+tionl fun$tions 2the m"'l n' nu$leus $$umbens3. 6ent!l p!ef!ontl

'me thus 'oes mo!e thn >ust $!ete hole in this p!t of the b!in. )t !emo+es tht b!in !eion f!om the $i!$uits in

%hi$h it p!ti$ipte'. 4e!'less of %hethe! it is ob+ious o! not& b!in lesions l%"s p!o'u$e 'is$onne$tions.

:onne$ti+it" $hnes lso tke pl$e in ps"$hit!i$ 'iso!'e!s& but the" !e t"pi$ll" mo!e subtle thn those in

neu!oloi$l ptients %ith o+e!t b!in le

sions. /s !esult& ps"$hit!i$ 'iso!'e!s miht be best thouht of s ml$onne$tion !the! thn 'is$onne$tion

s"n'!omes. 8o! e(mple& s 'es$!ibe' in the p!e+ious $hpte!& !o%in bo'" of e+i'en$e suests tht $e!tin

fo!ms of 'ep!ession ppe! to in+ol+e lte!tions in the %" $i!$uits in the hippo$mpus& s %ell s in the p!ef!ontl

$o!te( n' m"'l& 'pt to the $onse@uen$es of lon-te!m ele+tions of st!ess ho!mones. /n' >ust s b!in

lesion in one !e $n ffe$t the fun$tions me'ite' b" othe! !eions o! s"stems %ith %hi$h it is $onne$te'& so& too&

$n lte!tions in the s"npti$ ope!tion of !eion. The onl" thin one b!in !e kno%s bout nothe! is the stte of

its s"npses. :hne the s"npses in one !e& n' like 'ominoes in line& s"npses in othe!s %ill be lte!e' s

%ell.

0ost of the time the b!in hol's the self toethe! p!ett" %ell. But %hen $onne$tions $hne& pe!sonlit"& too&

$n $hne. Tht the self is so f!ile n entit" is 'is$on$e!tin. /t the sme time& if the self $n be 'isssemble' b"

e(pe!ien$es tht lte! $onne$tions& p!esumbl" it lso $n be !essemble' b" e(pe!ien$es tht estblish& $hne& o!

!ene% $onne$tions. /n impo!tnt $hllene fo! the fiel' of neu!os$ien$e is to fiu!e out ho% to mnipulte the b!in in

%" tht ptients %ith mentl 'iso!'e!s $n& eithe! lone o! %ith the help of the!pist& t!" to put the self*s s"npses

b$k toethe!.

SEL8-/SSE0BLY

/s 'es$!ibe' in $hpte!& "ou! b!in %s ssemble' 'u!in $hil'hoo' b" $ombintion of eneti$ n'

en+i!onmentl influen$es. 9enes 'i$tte' tht "ou! b!in %s humn one n' tht "ou! s"npti$ $onne$tions&

thouh mo!e simil! to those of membe!s of "ou! fmil" thn to those of membe!s of othe! fmilies& %e!e ne+e!theless

'istin$t. Then& th!ouh e(pe!ien$es %ith the %o!l'& "ou! s"npti$ $onne$tions %e!e '>uste' 2b" sele$tion n'Ko!

inst!u$tion n' $onst!u$tion3& fu!the! 'istinuishin "ou f!om e+e!"one else.

S"npti$ $onne$tions !e '>uste' b" en+i!onmentll" '!i+en neu!l $ti+it" in spe$ifi$ neu!l s"stems. 7hen

these $hnes o$$u! 'u!in e!l" life& the" !e si' to in+ol+e 'e+elopmentl plsti$it"C %hen the" o$$u! lte!& the" !e

$onsi'e!e' s le!nin. But the line bet%een 'e+elopmentl plsti$it" n' le!nin is fine one n' pe!hps

none(istent. ) %ill the!efo!e ino!e this 'istin$tion& n' plune !iht into the @uestion of ho% s"npti$ plsti$it" o$$u!-

!in in multiple neu!l s"stems is $oo!'inte' in the p!o$ess of ssemblin& n' mintinin& the self. The mnne! in

%hi$h this o$$u!s $n& ) think& be un'e!stoo' in te!ms of se+en p!in$iples.



P4)1:)PLE D)88E4E1T SYSTE0S EXPE4)E1:E THE S/0E 7O4LD.

/lthouh the 'iffe!ent neu!l s"stems h+e 'iffe!ent fun$tions& be$use the" !e p!t of the sme b!in the"

%ill be in+ol+e' in en$o'in the sme life e+ents. One s"stem p!o$esses the sihts& nothe! the soun's& n' still

nothe! the smells in i+en s$ene. /''itionl s"stems %ill 'ete!mine %hethe! those sihts& soun's& o! smells

in'i$te tht 'ne! is p!esent& o! tht the!e miht be somethin tst" to et out the!e. 8!om the point of +ie% of the

o!nism& n' the %o!l' %ith %hi$h it is inte!$tin& these !e not 'iffe!ent e(pe!ien$es& but !the! 'iffe!ent spe$ts of

sinle e(pe!ien$e. /n' lthouh e$h s"stem is plsti$& n' $n thus le!n n' sto!e info!mtion& e$h is le!nin

n' sto!in info!mtion bout the sme e(pe!ien$e. Just s people li+in in 'iffe!ent to%ns of $ount!" %ho ne+e!

meet f$e-to-f$e $n sh!e $ultu!e be$use the" h+e simil! en+i!onmentl influen$es 2simil! $limte& simil!

eo!ph"& simil! m"ths n' leen's& simil! politi$l histo!ies& simil! $u!!ent politi$l sitution& simil! so$il

institutions3& %ithin the b!in& kin' of sh!e' $ultu!e 'e+elops bet%een the +!ious s"stems be$use the" !e

e(pose' to simil! en+i!onmentl $i!$umstn$es.

To mke this p!in$iple mo!e e(pli$it& )*+e put it in pi$to!il fo!m in fiu!e .. P!t / sho%s h"potheti$l

b!in %ith th!ee neu!l s"stems. E$h s"stem !e$ei+es inputs f!om the outsi'e %o!l'. )n this mo'el b!in& the s"stems

'o not $ommuni$te 'i!e$tl" %ith one nothe!. But be$use the" h+e the sme inputs& the" $ome to kno% e($tl" the

sme thins bout the %o!l'. The" !e thus $ompletel" !e'un'nt p!o$esso!s.

P!t B ''s bit of $omple(it". 1o% the th!ee s"stems !e 'istin$t n' non!e'un'nte$h en$o'es the

%o!l' 'iffe!entl" 2s !ep!esente' b" the 'iffe!ent fills in the shpes3. These $n be thouht of& fo! e(mple& s 'iffe!ent

senso!" s"stems+isul& u'ito!"& n' olf$to!"& if "ou like. )n spite of the f$t tht e$h p!o$esses @ulitti+el"

'iffe!ent info!mtion& be$use the" e(pe!ien$e the sme e+ents& the!e is still st!on 'e!ee of o+e!lp in %ht the"

!ep!esent bout the %o!l'. The soun's& sihts& n' smells tht o$$u! 'u!in n e(pe!ien$e !e 'iffe!ent pie$es of

info!mtion f!om the point of +ie% of e$h of the th!ee s"stems& but !e ll p!t of the sme e(pe!ien$e f!om the point

of +ie% of the b!in n' pe!son.

1o%& imine tht ou! h"potheti$l b!in +isits th!ee 'iffe!ent pl$es %he!e it hs th!ee 'iffe!ent e(pe!ien$es.

E$h e(pe!ien$e %ill be en$o'e' in p!llel b" the th!ee s"stemss sihts& soun's& n' smells. :ont!st this to %ht

%oul' tke pl$e if& 'u!in e$h of the th!ee e(pe!ien$es& onl" one of the neu!l s"stems %s $ti+e& n' the one tht

%s $ti+e 'iffe!e' in e$h sitution.

)n this $se& lthouh the o!nism n' its b!in h' th!ee uni@ue e(pe!ien$es& e$h s"stem h' onl" one.

/s !esult& this b!in hs info!mtion bout one en+i!onment in the fo!m of sihts& the se$on' in soun's& n' the thi!'

in smells& but be$use no p!llel en$o'in took pl$e& the!e is no sh!e' info!mtion bout the th!ee e(pe!ien$es

$!oss the th!ee s"stems.

1o!mll"& this $on'ition 'oes not o$$u!. The +!ious s"stems of "ou! b!in sh!e the sme e(pe!ien$es.

The" en$o'e them 'iffe!entl"& but the" en$o'e the sme e(te!nl e+ents. The" %ill not l%"s fo$us on the sme

'etils& n' e$h m" not l%"s p!ti$ipte in e+e!" e(pe!ien$e. But to the e(tent tht neu!l s"stem en$o'es n

e(pe!ien$e& it is likel" tht some othe! s"stems of the b!in !e en$o'in the sme e(pe!ien$e. /s !esult of p!llel

en$o'in b"& n' p!llel plsti$it" %ithin& neu!l s"stems& sh!e' $ultu!e 'e+elops n' pe!sists mon the

s"stems& e+en if the" ne+e! $ommuni$te 'i!e$tl".

P4)1:)PLE SY1:H4O1Y :OO4D)1/TES P/4/LLEL PL/ST):)TY.

)n !el b!ins neu!l net%o!ks 'o not e(ist in isoltion. The" $ommuni$te %ith othe! net%o!ks b" %" of

s"npti$ t!nsmission. 8o! e(mple& in o!'e! to see n pple& inste' of !oun'ish& !e''ish blob& the +!ious fetu!es

of the stimulus& e$h p!o$esse' b" 'iffe!ent +isul subs"stems& h+e to be inte!te'. /s %e s% in $hpte! N& the

p!oblem of un'e!stn'in the mnne! in %hi$h this o$$u!s is $lle' the (indin! pro(lem) One popul! solution to this



p!oblem is bse' on the notion of neu!onl s"n$h!on". S"n$h!onous 2simultneous3 fi!in& n' thus bin'in& hs

been p!opose' s n e(plntion of $ons$iousness 2$hp. N3& but ou! inte!est he!e is mo!e in the bilit" of s"n-

$h!onous fi!in bet%een $ells in 'iffe!ent inte!$onne$te' !eions to $oo!'inte plsti$it" $!oss the !eions.

7olf Sine! is one of the m>o! p!oponents of s"n$h!on" s mens of inte!tin plsti$it" $!oss !eions&

espe$ill" %ithin the +isul s"stem. )n b!ief& his bsi$ i'e is tht info!mtion p!o$essin $!oss 'iffe!ent inte!$on-

ne$te' !eions is $oo!'inte' %hen $ells in the in'i+i'ul !eions fi!e $tion potentils s"n$h!onousl"tht is& t thesme time. 8o!m n' $olo!& fo! e(mple& !e b!ouht toethe! fo! n imme'itel" p!esent ob>e$t b" the f$t tht the

$ells p!o$essin the p!ti$ul! fo!m n' p!ti$ul! $olo! !e $ti+e t the sme time. B" %" of the s"npti$

inte!$onne$tions bet%een $ells in the $olo! n' fo!m !eions& Hebbin plsti$it" o$$u!s 2sin$e the $ells %ill be

$ti+tin e$h othe! t the sme time the" !e bein $ti+te' b" the e(te!nl +isul stimulus3. Hebbin plsti$it"

thus bin's simultneousl" $ti+e $ells toethe! so tht the ne(t time the sme o! simil! stimulus o$$u!s& the sme

$ells n' $onne$tions %ill be $ti+te'. Tht s"n$h!onous fi!in $n le' to Hebbin plsti$it" 2s oppose' to

$ons$ious pe!$eption3 is in$ont!o+e!tible. )n f$t& simultneous 2o! ne! simultneous3 $ti+tion of inputs is %ht $-

$ounts fo! Hebbin plsti$it" 2$hp. 3.

Unfo!tuntel"& little is kno%n bout %hethe! $hnes of this t"pe $tull" tke pl$e bet%een net%o!ks in the

b!in 2s oppose' to %ithin in'i+i'ul net%o!ks3. Ho%e+e!& !e$ent stu'ies usin $ompute! simultions h+e beun to

e(plo!e ho% plsti$it" o$$u!!in in in'i+i'ul s"stems lte!s info!mtion p!o$essin in inte!$onne$te' s"stems. This

%o!k p!o+i'es foun'tion fo! pu!suin simil! stu'ies in !el b!ins.

)nte!tion $!oss b!in !eions 2bin'in3 is usull" 'is$usse' in the $on te(t of pe!$eption. Ho%e+e!&

un'e!stn'in lon-'istn$e $ommuni$tion in the b!in is lso impo!tnt fo! memo!"C emotion& moti+tion& n' othe!

s"stems. E(plo!tion of inte!$tions $!oss s"stems is oin to be espe$ill" $!u$il s %e t!" to $ome to !ips %ith

the !eltion of the self to the b!in. / !i'i$ulousl" simple e(mple is the f$t tht ou! pe!$eption of n pple is not >ust

bse' on the inte!tion of the shpe n' fo!m n' othe! +isul fetu!es of the ob>e$t& but lso on the inte!tion of

these fetu!es %ith info!mtion sto!e' in memo!" bout the ob>e$t n' ou! e(pe!ien$es %ith it& n' its sinifi$n$e fo!

us t the moment& in the pst& n' in the futu!e.

P4)1:)PLE Q P/4/LLEL PL/ST):)TY )S /LSO :OO4D)1/TED BY 0ODUL/TO4Y SYSTE0S.

P!llel p!o$essin in 'iffe!ent b!in s"stems is fu!the! $oo!'inte' b" mo'ulto!s. /s %e*+e seen& these !e

!elese' th!ouhout the b!in in the p!esen$e of sinifi$nt stimuli& in$lu'in no+el& une(pe$te'& o! pinful stimuli& o!

stimuli tht othe!%ise sinl emotionl !ousl. )n the lst $hpte!& %e e(mine' the !ole of one $lss of mo'ulto!s&

the monomlnes& in mentl 'iso!'e!s. He!e %e e(mine thei! !ole in no!ml b!in fun$tion. These !e t%o si'es of the

sme $oin.

)n the mi''le of the t%entieth $entu!"& !ese!$he!s 'is$o+e!e' !eion of the b!in stem tht %s !e@ui!e'

fo! le!tness n' !ousl. Dme to this !eion put nimls n' people into $omtose stte. Stimultion of the

sme !eion $oul' %ken n niml f!om 'eep sleep& n' if n niml %s l!e'" %ke& le!tness n' ttention

%e!e enhn$e' b" the stimultion. This !e $me to be $lle' the “!eti$ul! $ti+tin s"stem# o! the “!eti$ul! fo!-

mtion.# Subse@uentl"& it %s 'is$o+e!e' tht !ousl fun$tions %e!e l!el" $$ounte' fo! not b" sinle inte!te'

s"stem in the b!in stem but b" the $ti+ities of se+e!l 'iffe!ent !oups of neu!ons in the +i$init"& %ith e$h !oup

h+in uni@ue $hemi$l sintu!e 2'iffe!ent neu!ot!nsmitte! mole$ules !e p!esent in the 'iffe!ent !oups3. The

$hemi$ls in @uestion !e ll mines& n' spe$ifi$ll" in$lu'e the monomines'opmine& no!epineph!ine&

epineph!ine& se!otoninn' $et"l$holine.

The $ells tht p!o'u$e mo'ulto!s !e lo$te' p!im!il" in the b!in stem&

but thei! (ons !e 'ist!ibute' th!ouhout the b!in. :onse@uentl"& %hen these $ells !e $ti+te'& mn"

b!in !es !e ffe$te'. The %i'esp!e' $tion of mo'ulto!s mkes them espe$ill" useful in b!o'$stin tht



somethin sinifi$nt hs hppene'& but the" !e less suite' to i'entif"in e($tl" %ht it is tht*s hppenin. The

mo'ulto!" s"stem fun$tions some%ht like n l!m soun'e' b" the fi!ehouse in the $ente! of smll to%n. The

l!m is +e!" effe$ti+e in le!tin ll the to%n*s fi!emen to the fi!e& n' in summonin them to the sttion& but it 'oesn*t

tell them %hose house is on fi!e. This the" h+e to le!n b" othe! mens& >ust s b!in !es h+e to 'ete!mine

p!e$isel" %ht it is tht*s $usin the !ousl b" othe! mens.

The min >ob of mo'ulto!s is to !eulte neu!ot!nsmission bet%een neu!ons& but the" 'on*t %o!k t ll themn" s"npses tht the" bthe. The" !e minl" effe$ti+e in mo'ultin t!nsmission t s"npses tht !e l!e'"

$ti+e %hen the mo'ulto! !!i+es.

Be$use mo'ulto!" s"stems !e $ti+te' 'u!in sinifi$nt e(pe!ien$es& mo'ulto!s $n sele$ti+el"

f$ilitte t!nsmission t the s"npses $ti+el" p!o$essin info!mtion bout su$h e(pe!ien$es $!oss %i'el"

'ist!ibute' neu!l s"stems. Emotionl o! othe!%ise sinifi$nt e(pe!ien$es !e the ones %e ten' to fo!m memo!ies

bout& n' s 'es$!ibe' in $hpte! G& it is %ell estblishe' tht mo'ulto!s like no!epineph!ine !e in+ol+e' in the

enhn$ement of memo!" tht o$$u!s 'u!in emotionl e+ents. 1o!epineph!ine hs lso been impli$te' in the

in'u$tion of lon-te!m potentition 2LTP3& %hi$h& s %e "e seen& is lbo!to!" p!o$e'u!e fo! stu'"in s"npti$

plsti$it". Thus& LTP is f$ilitte' %hen this $hemi$l is p!esent& n' 'is!upte' %hen it is bsent. So not onl" $n

mo'ulto!s p!o'u$e moment!" f$ilittion of t!nsmission in $i!$uits $ti+el" in+ol+e' in p!o$essin sinifi$nt

e+ents& the" $n lso p!omote s"npti$ plsti$it"& n' thus le!nin n' memo!"& in those $i!$uits. 4e$ll tht one of

the most p!ominent $u!!ent theo!ies suppo!tin monomine t!etment of mentl 'iso!'e!s is tht these '!us mke

mo!e se!otonin n'Ko! no!epineph!ine +ilble t s"npses n' the!eb" t!ie! int!$ellul! mole$ul! $s$'es tht

p!omote s"npti$ plsti$it". 0o'ultion of plsti$it" $!oss b!in s"stems is thus impo!tnt in both no!ml n' ptho-

loi$l mentl $on'itions.

One of the most impo!tnt fetu!es of mo'ulto!s is tht& on$e !elese'& the" h+e p!olone' $tion& t

lest %ith !espe$t to t!nsmitte!s like lutmte o! 9/B/. The p!im!" $tion of lutmte o! 9/B/ is t"pi$ll" $on-

$lu'e' %ithin mtte! of millise$on's& %he!es mo'ulto!s $n h+e effe$ts tht lst fo! se$on's. 9i+en tht not ll

b!in s"stems ope!te t e($tl" the sme !te 2some in+ol+e mo!e 'istnt pth%"s %ith mo!e $onne$tions& n'& in

ene!l& the mo!e $omple( the p!o$ess& the lone! it tkes to o$$u! be$use mo!e $onne$tions !e in+ol+e'3& the sio%

!e$o+e!" time of mo'ulto!s llo%s them to ffe$t %i'e !ne of p!o$esses& f!om the e!liest n' simplest in n

episo'e to the lst n' most $omple(& p!omotin le!nin in'epen'ent of info!mtion e(t!$te' 'u!in 'iffe!ent

$omponents of n e(pe!ien$e.

/lthouh 'iffe!ent s"stems le!n bout 'iffe!ent spe$ts of n e(pe!ien$e& the %i'esp!e' $tion of

mo'ulto!s in$!eses the likelihoo' tht %hen somethin sinifi$nt tkes pl$e& plsti$it" %ill o$$u! in p!llel t

$ti+e s"npses in ll these s"stems. /s !esult& the le!nin of multiple elements of n e(pe

!ien$e 2its sihts& soun's& n' smells& its emotionl n' moti+tionl sinifi$n$e& its mo+ement ptte!ns& n'

so on3 is f$ilitte'& llo%in the %hole e(pe!ien$e to be sto!e' t on$e& lbeit $!oss multiple s"stems. )n$lu'e'& of

$ou!se& %oul' be s"stems tht p!o$ess info!mtion both impli$itl" n' e(pli$itl"& but mo!e bout tht lte!.

1ot ll mo'ulto!s h+e the sme effe$t 2some inhibit !the! thn enhn$e plsti$it"3& n' the sme

mo'ulto! $n h+e 'iffe!ent effe$ts 'epen'in on the p!ti$ul! posts"npti$ !e$epto! %ith %hi$h it inte!$ts.

0o!eo+e!& the sme inte!$tion bet%een mo'ulto! n' its !e$epto! $n be 'iffe!ent 'epen'in on the othe! $ells in

the $i!$uit. 8o! e(mple& %hen se!otonin inte!$ts %ith one of its !e$epto!s& it p!o'u$es inhibition& n' %hen it inte!$ts

%ith nothe! !e$epto!& it p!o'u$es e($ittion. But the net effe$t 2tht is& %hethe! e($ittion o! inhibition is the out$ome3

%ill 'epen' on the kin' of neu!ons on %hi$h the se!otonin !e$epto!s !e lo$te'. Se!otonin& fo! instn$e& inhibits the

$ti+it" of m"'l p!o>e$tion $ells 2e($itto!" $ells tht t!nsfe! info!mtion f!om one !eion of the m"'l to

nothe!3. But it $hie+es this inhibition b" %" of n e($itto!" se!otonin !e$epto! lo$te' on 9/B/ $ells. Thus&

se!otonin e($ites 9/B/ inhibito!" $ells& n' these inhibit m"'l p!o>e$tion $ells. 7hile the out$ome of the

inte!$tion bet%een se!otonin n' its !e$epto! is e($itto!"& the out$ome fo! the o+e!ll $i!$uit is inhibition. 0u$h mo!e

%o!k is nee'e' to bette! un'e!stn' the $ont!ibution of mo'ulto!s to !outine t!nsmission in spe$ifi$ $i!$uits& n' to



the in'u$tion of plsti$it" 2le!nin3 n' its mintenn$e 2memo!"3. But the ps in ou! kno%le'e 'o not tke %"

f!om the estblishe' !ole of some mo'ulto!s in enhn$in plsti$it"& n' thus potentill" se!+in s !eulto!s of

plsti$it" $!oss neu!l s"stems.

P4)1:)PLE M :O16E49E1:E O1ES )1TE94/TE P/4/LLEL PL/ST):)TY.

)n the e(mples $ite' so f!& b!in s"stems le!n in p!llel. 7hile p!llel le!nin is su!el" n impo!tnt p!t

of the $omple( p!o$ess b" %hi$h the self is ssemble'& p!llel le!nin& on its o%n 2e+en %hen butt!esse' b" s"n-

$h!on" n' mo'ulto!" $hemi$ls3& is not suffi$ient to $$ount fo! the $ohe!ent pe!sonlit" of humn bein.

/nothe! impo!tnt me$hnism in self-ssembl"& espe$ill" in humns n' othe! p!imtes& is the e(isten$e of

$on+e!en$e ,ones& !eions %he!e info!mtion f!om 'i+e!se s"stems $n be inte!te'. 8iu!e . sho%s t%o

in'epen'ent p!o$essin units& the outputs of %hi$h meet up in thi!'& $on+e!en$e ,one. 0n" kin's of nimls

h+e multiple in'epen'ent le!nin s"stems tht $n be $oe!$e' into le!nin simultneousl" b" mo'ulto!"

$hemi$ls n' s"n$h!onous fi!in& but onl" some nimls h+e $on+e!en$e ,ones in thei! $o!te(. The $oniti+e

sophisti$tion of mmmlin spe$ies& in f$t& is ni$el" p!e'i$te' b" the e(tent of $on+e!en$e tht o$$u!s in its

$o!te(mo!e is p!esent in humns thn in monke"s& fo! e(mple& n' mo!e in monke"s

thn in !ts. 7hen plsti$it" o$$u!s simultneousl" in t%o !eions tht fee' into $on+e!en$e ,one&

plsti$it" is lso likel" to o$$u! in the $on+e!en$e ,one sin$e it %ill be the !e$ipient of the hih le+el of $ti+it" tht

o$$u!s %hen plsti$it" is bein estblishe' in the in'i+i'ul !eions. Ob+iousl"& s"n$h!on" n' mo'ultion lso

influen$e $on+e!en$e ,ones& fu!the! in$!esin thei! potentil to inte!te info!mtion $!oss s"stems.

:on+e!en$e tkes pl$e %ithin s"stems befo!e it tkes pl$e bet%een s"stems. This $n be illust!te' b"

$onsi'e!in ob>e$t !e$onition in the “%ht# st!em of the +isul $o!te( 2$hp. N3. The ob>e$t !e$onition s"stem& like

othe! $o!ti$l p!o$essin s"stems& is hie!!$hi$ll" o!n i,e'. The lte! stes 'epen' on the e!lie! ones& n'

info!mtion !ep!esenttion be$omes in$!esinl" $omple( s the stes !e psse' th!ouh. )n the e!liest ste& fo!

e(mple& e$h $ell p!im!il" !espon's to the o!ienttion of $ontou! o! e'e of smll p!t of the stimulus. /$!oss

mn" $ells& ll the $ontou!s tht mke up the shpe of the stimulus !e !ep!esente'. )n the ne(t ste& $ells !e$ei+e

$on+e!ent inputs f!om the e!lie!-ste $ells. /s !esult of ettin inputs f!om $ells tht !ep!esent 'iffe!ent p!ts of

tht ob>e$t& e$h $ell in the se$on' ste $n !ep!esent l!e! p!t of the ob>e$t. This so!t of $on+e!en$e $on tinues

th!ouh the hie!!$h" until t the finl ste in'i+i'ul $ells !ep!esent mu$h of the enti!e ob>e$t. These ltte! $ells %e!e

on$e ffe$tiontel" kno%n s “!n'mothe! $ells&# sin$e the" %e!e suppose' to be ble to !e$ei+e ll the info!mtion

nee'e' to !ep!esent stimulus s $omple( s "ou! !n'mothe!*s f$e. 7hile it is no lone! belie+e' tht

!n'mothe! $ells e(ist& mn" s$ientists 'o belie+e tht smll sets of s"npti$ll" $onne$te' $ells& $lle' ensembles&

!e$ei+e $on+e!ent inputs f!om lo%e! le+els in thei! p!o$essin hie!!$h"& n' !ep!esent f$es& $omple( s$enes& n'

othe! ob>e$ts of pe!$eption. This 'iffe!en$e is sometimes 'es$!ibe' s one bet%een “pontifi$l# $ells& %hi$h %oul'

mke finl 'e$isions lone bout the %" thins !e& n' “$!'inl# $ells& %hi$h 'o thins s smll !oup. /lthouh

sinle $ells h+e been sho%n to h+e !em!kble $p$ities& most !ese!$he!s $$ept tht ensembles !the! thn

sinle $ells un'e!lie mentl n' beh+io!l fun$tions.

On$e $on+e!en$e is $omplete' %ithin s"stems& it beins to o$$u! $!oss s"stems. )n FN& E. 9. Jones n'

T. P. S. Po%ell publishe' ln'm!k stu'" in %hi$h the" i'entifie' se+e!l !eions in the monke" $o!te( tht !e$ei+e

$on+e!ent inputs f!om the lst p!o$essin ste of t%o o! mo!e senso!" s"stems in the $o!te(. Some of the ke"

$on+e!en$e ,ones i'entifie' %e!e the poste!io! p!ietl $o!te(& the p!hippo$mpl !eion n' !es of the p!e-

f!ontl $o!te(. The bilit" of these !eions to inte!te 'i+e!se kin's of info!mtion e(plins %h" the" !e in+ol+e' in

the most sophisti$te' $oniti+e fun$tions of the b!in. /s %e*+e seen& !es of the p!ef!ontl $o!te( !e in+ol+e' in

%o!kin memo!" fun$tions& %hi$h un'e!lie mn" spe$ts of thinkin& plnnin& n' 'e$ision-mkin. The poste!io!

p!ietl !e pl"s n impo!tnt !ole in the $oniti+e $ont!ol of mo+ement in sp$e in nonhumn p!imtes& n' in

humns is $!u$ill" in+ol+e' in lnue $omp!ehension in the left hemisphe!e n' sptil $onition in the !iht.



4hinl $o!ti$l !es !e p!t of the me'il tempo!l lobe memo!" s"stem. The" estblish $!iti$l links bet%een

senso!" !es of the $o!te( n' the hippo$mpus& n' thus p!o+i'e the hippo$mpus %ith the !% mte!ils nee'e'

to fo!m !eltions bet%een e(te!nl stimuli in the p!o$ess of estblishin lon-te!m e(pli$it memo!ies. The

hippo$mpus& too& is $on+e!en$e ,oneC !the! thn inte!tin inputs f!om 'iffe!ent senso!" s"stems pe! Se&

!e$ei+es inputs f!om othe! $on+e!en$e ,ones& n' is thus somethin of supe!-$on+e!en$e ,one.

)n $on+e!en$e ,ones like the hippo$mpus& it is possible fo! $ompletel" in'epen'ent senso!"!ep!esenttions to be s"nthesi,e' into memo!" !ep!esenttions tht t!ns$en' the in'i+i'ul s"stems in+ol+e' in the

initil p!o$essin. Thus& %hile 'iffe!ent s"stems m" fo!m in'epen'ent memo!ies of sep!te spe$ts of n

e(pe!ien$e& memo!ies fo!me' in& o! b" %" of& $on+e!en$e ,one !e multif$ete'the" in$lu'e info!mtion

e(t!$te' f!om 'iffe!ent s"stems. Su$h memo!ies !efle$t the %hole e(pe!ien$e of the o!nism& !the! thn bits n'

pie$es of n e(pe!ien$e !e$o!'e' b" othe! s"stems. But be$use the bits n' pie$es !e the !% mte!ils& the!e is

kin' of unit" of e(pe!ien$e bet%een the memo!" estblishe' b" $on+e!en$e ,one n' b" its lo%e! $onne$tions.

/n' be$use the hippo$mpus n' othe! $on+e!en$e ,ones !e$ei+e inputs f!om mo'ulto!" s"stems& 'u!in

sinifi$nt sttes of !ousl plsti$it" in these net%o!ks is $oo!'inte' %ith the plsti$it" o$$u!!in in othe! s"stems

th!ouhout the b!in.

One impo!tnt $onse@uen$e of this !!nement is tht thouh memo!ies !e fo!me' b" s"stems tht

fun$tion both impli$itl" n' e(pli$itl" 'u!in sinifi$nt e(pe!ien$es& the memo!ies !e $oo!'inte' to some 'e!ee#

Tht is& the elements "ou !e ble to $ons$iousl" !emembe! bout n e(pe!ien$e o+e!lp often %ith some of the

elements tht %e!e lso bein sep!tel" sto!e' impli$itl" in othe! s"stems. :on+e!en$e ,ones su$h s those in the

me'il tempo!l lobe mke possible the $!etion of $ons$iousl" $$essible memo!ies tht inte!te elements bein

en$o'e' sep!tel" n' impli$itl" in the othe! s"stems. But& !emembe!& %hile the me'il tempo!l lobe s"stem fo!ms

memones in %" tht llo%s them to be $ons$iousl" $$essible& these memo!ies onl" ente! $ons$iousness %hen

the" !e pl$e' in %o!kin memo!". /n' on$e in %o!kin memo!"& memo!ies n' thouhts $n& s %e see ne(t&

influen$e $ti+it" b$k 'o%n the p!o$essin hie!!$h".

P4)1:)PLE DO717/4DLY 0OB)LE THOU9HTS :OO4D)1/TE P/4/LLEL PL/ST):)TY.

So f!& )*+e pl$e' mu$h of the bu!'en of ssemblin the self on p!o$esses tht %o!k mo!e o! less

utomti$ll"& f!om the bottom up. But this is onl" p!t of the sto!". :on+e!ent !ep!esenttions built f!om the bottom

up !e lso use' to 'i!e$t $ti+it" b$k 'o%n the p!o$essin hie!!$hies. Thouhts n' memo!ies pl$e' in %o!kin

memo!"& fo! e(mple& $n influen$e %ht %e tten' to& the %" %e see thins& n' the %" %e $t. These e(e$uti+e

$ont!ol fun$tions of %o!kin memo!"& %hi$h %e!e 'is$usse' in $hpte! N& !e possible be$use the p!ef!ontl $o!te(&

like othe! $on+e!en$e ,ones& !e$ip!o$tes p!o>e$tions. Tht is& $onne$tions !e sent b$k to the !eions tht p!o+i'e

the $on+e!ent inputs. B" pullin the !iht st!ins 2$ti+tin the !iht (ons3& %o!kin memo!" $n 'i!e$t t!ffi$ in the

!es %ith %hi$h it is $onne$te'& enhn$in the p!o$essin of stimuli tht !e !ele+nt to the tsk on %hi$h it is

ene' n' supp!essin the p!o$essin of othe! stimuli#

The p!o$ess b" %hi$h thouht $n $use the b!in to issue $e!tin o!'e!s is kno%n s 'o%n%!'

$ustion. 7e p!o+e tht 'o%n%!' $ustion e(ists e+e!" time %e $!!" out n intention. Do%n%!' $ustion is

onl" min'-bolin if "ou belie+e tht thouhts !e one phenomenon n' b!in $ti+ities nothe!. ft*s still 'iffi$ult

p!oblem e+en if "ou +ie% thinkin s fo!m of b!in $ti+it"& but the ntu!e of the solution is f! mo!e ob+ious in this

$se.

)f thouht is embo'ie' s ptte!n of s"npti$ t!nsmission %ithin net%o!k of b!in $ells& s must be the

$se& then it stn's to !eson tht the b!in $ti+it" tht is thouht $n influen$e $ti+it" in othe! b!in s"stems in -

+ol+e' in pe!$eption& moti+tion& mo+ement& n' the like. But the!e*s one mo!e $onne$tion to mke. )f thouht is

ptte!n of neu!l $ti+it" in net%o!k& not onl" $n it $use nothe! net%o!k to be $ti+e& it $n lso $use nothe!



net%o!k to $hne& to be plsti$.

/ll tht is !e@ui!e' to in'u$e plsti$it" t s"npse is the !iht kin' of s"npti$ $ti+it". )f $ells p!o$essin

senso!" e+ents $n un'e!o plsti$it" s !esult of the kin' of $ti+it" those e+ents t!ie! in senso!" s"stems& then

%h" $n*t $ells p!o$essin thouht $hne the $onne$tions of the $ells %ith %hi$h the" $ommuni$te= Ob+iousl"&

the" 'oC %e simpl" nee' to le!n mo!e bout p!e$isel" ho% this hppens.

The 'o%n%!' mobilit" of thouht p!o+i'es po%e!ful mens b" %hi$h p!llel plsti$it" in neu!l s"stems is$oo!'inte'. The mo!e elbo!te the $on+e!en$e ,ones p!esent in spe$ies& the mo!e elbo!te %ill be the $oniti+e

$p$it" of the spe$ies n' the mo!e sophisti$te' %ill be the bilit" of info!mtion $on+e!en$e to $oo!'inte

plsti$it" in tht spe$ies. 7ith thouhts empo%e!e' this %"& %e $n bein to see ho% the %" %e think bout ou!-

sel+es $n h+e po%e!ful influen$es on the %" %e !e& n' %ho %e be$ome. One*s self-ime is self-pe!petutin.

P4)1:)PLE E0OT)O1/L ST/TES 0O1OPOL)E B4/)1 4ESOU4:ES

Emotions& too& pl" ke" !ole in o!ni,in b!in $ti+it". 7e*+e l!e'" h' hint of this %hen %e

'is$usse' the fun$tion of mo'ulto!s in $oo!'intin p!llel plsti$it"& sin$e emotionl stimuli !e some of the most

potent $ti+to!s of mo'ulto!" s"stems. But the influen$e of emotions is mu$h b!o'e! thn simpl" $ti+tin

mo'ulto!" s"stems& n' $n be illust!te' b" !e$onsi'e!in the +!ious %"s tht the m"'l ffe$ts othe! b!in

s"stems %hen it 'ete$ts 'ne!.

)n the p!esen$e of th!etenin stimulus& the m"'l sen's 'i!e$t fee'b$k b" %" of neu!l $onne$tions

to senso!" !es of the $o!te(& en$ou!in these !es to st" fo$use' on those spe$ts of the stimulus %o!l' tht

!e $!iti$l. /m"'l fee'b$k lso !e$hes othe! $o!ti$l !es ene' in thinkin n' e(pli$it memo!" fo!mtion&

en$ou!in them to think $e!tin thouhts n' to fo!m $e!tin memo!ies bout the $u!!ent sitution. )n ''ition& the

m"'l sen's $onne$tions to !ousl net%o!ks& $usin them to !elese thei! mo'ulto!" $hemi$ls th!ouhout the

b!in. The s"npses tht !e $ti+el" in+ol+e' in p!o$essin the e(te!nl %o!l'& in thinkin bout the %o!l'& in fo!min

memo!ies bout it& n' in !e$ei+in the m"'l*s fee'b$k %ill thus be enhn$e'. )n ''ition& plsti$it" %ill be

f$ilitte' t these $ti+e s"npses. 0' inte!$onne$tions bet%een $ti+e $ells in 'iffe!ent !eions n' s"stems tht fi!e

s"n$h!onousl" %ill be linke' b" the plsti$it" tht is in'u$e'. /t the sme time& bo'il" !esponses $ont!olle' b" the

m"'l %ill be e(p!esse'& n' these %ill p!o+i'e ''itionl fee'b$k to the b!in& not onl" in the fo!m of bo'il"

senstions tht !e p!t of the “felt# !esponse of the emotion& but lso in the fo!m of ho!mones tht fu!the! ffe$t

s"npti$ $ti+it"& o+e! lone! time s$le thn e+en mo'ulto!s. The net !esult is tht emotionl !ousl penet!tes

the b!in %i'el"& n' pe!petutes itself

/s %e*+e seen& the b!in hs numbe! of emotion s"stems& in$lu'in net%o!ks in+ol+e' in i'entif"in se(ul

p!tne!s n' foo' sou!$es& s %ell s 'ete$tin n' 'efen'in inst 'ne!. 7hen one of these is $ti+e& the

othe!s ten' to be inhibite'. 8o! e(mple& othe! thins bein e@ul& nimls %ill ten' to spen' time in !es %he!e the"

!e sfe. So %hen it $omes time to se!$h fo! foo'& thei! fe! of $e!tin pl$es& like %i'e-open sp$es o! pl$es %he!e

the"*+e p!e+iousl" en$ounte!e' p!e'to!& hs to be o+e!$ome if tht*s %he!e foo' is likel" to be foun'. The hun!ie!

the niml is& the mo!e it %ill tole!te fe! n' n(iet" n' tke !isks to obtin nou!ishment. Simil!l"& both etin n'

se(ul !ousl !e 'e$!ese' b" $ti+tion of s"stems in+ol+e' in fe! n' st!ess. But& on$e !ouse'& se(ul 'esi!e

$n o+e! !i'e mn" othe! b!in s"stemspeople !isk ll so!ts of '+e!se $onse@uen$es fo! n 'ulte!ous flin. 1ot

onl" 'oes the !ousl of n emotionl stte b!in mn" of the b!in*s $oniti+e !esou!$es to be! on tht stte& it lso

shuts 'o%n othe! emotion s"stems. /s !esult& le!nin is $oo!'inte' $!oss s"stems in +e!" spe$ifi$ mnne!&

ensu!in tht the le!nin tht 'oes o$$u! is !ele+nt to the $u!!ent emotionl sitution.

Be$use emotion s"stems $oo!'inte le!nin& the b!o'e! the !ne of emotions tht $hil' e(pe!ien$es

the b!o'e! %ill be the emotionl !ne of the self tht 'e+elops. This is %h" $hil'hoo' buse is so 'e+sttin. )f

sinifi$nt p!opo!tion of the e!l" emotionl e(pe!ien$es one hs !e 'ue to $ti+tion of the fe! s"stem !the! thn

positi+e s"stems& then the $h!$te!isti$ pe!sonlit" tht beins to buil' up f!om the p!llel le!nin p!o$esses $oo!-



'inte' b" the emotionl stte is one $h!$te!i,e' b" neti+it" n' hopelessness !the! thn ffe$tion n'

optimism.

The %i'e influen$e of emotionl !ousl !esults in mn" b!in s"stems bein $ti+te' simultneousl"& mn"

mo!e thn if one is ene' in @uiet $oniti+e $ti+it"& like l"in b$k musin bout somethin& o! e+en %hen

+io!ousl" thinkin bout the solution to p!oblem. /n' be$use mo!e b!in s"stems !e t"pi$ll" $ti+e 'u!in

emotionl thn 'u!in nonemotionl sttes& n' the intensit" of !ousl is !ete!& the oppo!tunit" fo! $oo!'inte'le!nin $!oss b!in s"stems is !ete! 'u!in emotionl sttes. B" $oo!'intin p!llel plsti$it" th!ouhout the

b!in& emotionl sttes p!omote the 'e+elopment n' unifi$tion of the self.

P4)1:)PLE N )0PL):)T /1D EXPL):)T /SPE:TS O8 THE SEL8 O6E4L/P& BUT 1OT :O0PLETELY.

)n spite of the multipli$it" of $he$ks n' bln$es tht help keep the +!ious s"stems of the b!in on one

t!$k& le!nin bout the sme e(pe!ien$es n' bout the sme thins in e$h e(pe!ien$e& the >ob pe!fo!me' is not

l%"s pe!fo!me' pe!fe$tl". Sometimes& the thins le!ne' e(pli$itl" !e not the thins tht %e!e fo$use' on b" the

impli$it s"stems& espe$ill" emotionl s"stems!e$ll the bilit" of the m"'l to le!n in'epen'ent of the $o!te(

2$hp. G3. /lthouh the!e !e p!obbl" mn" !esons %h" this is so& the most ob+ious one is tht the!e is n impe!fe$tset of $onne$tions bet%een $oniti+e n' emotionl s"stems in the $u!!ent ste of e+olution of the humn b!in. This

stte of ffi!s is p!t of the p!i$e %e p" fo! h+in ne%l" e+ol+e' $oniti+e $p$ities tht !e not "et full" inte!te'

into ou! b!ins. /lthouh this is lso p!oblem fo! othe! p!imtes& it is p!ti$ul!l" $ute fo! humns&

sin$e the b!in of ou! spe$ies& espe$ill" ou! $o!te(& %s e(tensi+el" !e%i!e' in the p!o$ess of $@ui!in

ntu!l lnue fun$tions.

Lnue both !e@ui!e' ''itionl $oniti+e $p$ities n' m'e ne% ones possible& n' these $hnes

took sp$e n' $onne$tions to $hie+e. The sp$e p!oblem %s sol+e'& s %e s% e!lie!& b" mo+in some thins

!oun' in e(istin $o!ti$l sp$e& n' lso b" ''in mo!e sp$e. But the $onne$tion p!oblem %s onl" p!till"

sol+e'. The p!t tht %s sol+e'& $onne$ti+it" %ithin $o!ti$l p!o$essin net%o!ks& m'e the enhn$e' $oniti+e

$p$ities of the homini' b!in possible. But the p!t tht hsn*t been full" sol+e' is $onne$ti+it" bet%een $oniti+e

s"stems n' othe! p!ts of the mentl t!ilo"emotionl n' moti+tionl s"stems. This is %h" b!illint mthe-

mti$in o! !tist& o! su$$essful ent!ep!eneu!& $n like n"one else fll +i$tim to se(ul se'u$tion& !o' !e& o!

>elous"& o! be $hil' buse! o! !pist& o! $n h+e $!ipplin 'ep!ession o! n(iet". Ou! b!in hs not e+ol+e' to the

point %he!e the ne% s"stems tht mke $omple( thinkin possible $n esil" $ont!ol the ol' s"stems tht i+e !ise to

ou! bse nee's n' moti+es& n' emotionl !e$tions. This 'oesn*t men tht %e*!e simpl" +i$tims of ou! b!ins n'

shoul' >ust i+e in to ou! u!es. )t mens tht 'o%n%!' $ustion is sometimes h!' %o!k. /oin! the !iht thin

'oesn*t l%"s flo% ntu!ll" f!om 1no'in! %ht the !iht thin to 'o is.

)n the en'& then& the self is mintine' b" s"stems tht fun$tion both e(pli$itl" n' impli$itl". Th!ouh e(pli$it

s"stems& %e t!" to %illfull" 'i$tte %ho %e !e& n' ho% %e %ill beh+e. But %e !e onl" p!till" effe$ti+e in 'oin so&

sin$e %e h+e impe!fe$t $ons$ious $$ess to emotionl s"stems& %hi$h pl" su$h $!u$il !ole in $oo!'intin

le!nin b" othe! s"stems. )n spite of thei! impo!tn$e& thouh& emotion s"stems !e not l%"s $ti+e n' h+e onl"

episo'i$ influen$e on %ht othe! b!in s"stems le!n n' sto!e. 8u!the!mo!e& be$use the!e !e multiple in'epen'ent

emotion s"stems& the episo'i$ influen$e of n" one s"stem is itself but $omponent of the totl imp$t of emotions on

self-'e+elopment.



YOU /4E YOU4 SY1/PSES

S"npti$ $onne$tions hol' the self toethe! in most of us most of the time. Sometimes& thouh& thouhts&

emotions& n' moti+tions $ome un$ouple'. )f the mentl t!ilo" b!eks 'o%n& the self is likel" to bein to 'isinte!te

n' mentl helth to 'ete!io!te. 7hen thouhts !e !'i$ll" 'isso$ite' f!om emotions n' moti+tions& s in

s$hi,oph!eni& pe!sonlit" $n& in f$t& $hne '!sti$ll". 7hen emotions !un %il'& s in n(iet" 'iso!'e!s o! 'e-p!ession& pe!son is no lone! the pe!son he o! she on$e %s. /n' %hen moti+tions !e sub>ute' b" '!u

''i$tion& the emotionl n' intelle$tul spe$ts of life suffe!.

Tht the self is s"npti$ $n be $u!seit 'oesn*t tke mu$h to b!ek it p!t. But it is lso blessin& s

the!e !e l%"s ne% $onne$tions %itin to be m'e. You !e "ou! s"npses. The" !e %ho "ou !e.

THE E1D.

TH)S H/S BEE1. THE SY1/PT): SEL8. BY JOSEPH LEDOUX.

joseph ledoux_synaptic self

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