neurofisiologia e patologia dei processi … · funzioni visuospaziali, apprendimento e memoria....

NEUROFISIOLOGIA E PATOLOGIA DEI PROCESSI COGNITIVI: Il Lobo Temporale

What are we doing with our

brains at this moment?’

• Feeling your chair

• Squirming (moving)

• Watching

• Listening

• Remembering

• Paying attention

• Writing

• Feeling anxious

• Feeling hungry

• What happens when you ask a question?

• Learning

What are we doing with our

brains at this moment?’

• Feeling your chair

• Squirming (moving)

• Watching (me, slides, mobile, the lady on the right)

• Listening

• Remembering

• Paying attention

• Writing

• Feeling anxious

• Feeling hungry

• What happens when you ask a question?

• Learning

Lobi e solchi degli emisferi cerebrali

Localizzazione dell’insula , visibile aprendo la scissura di Silvio ( solco laterale)

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insula and Sylvian fissure

Insula is responsible for: ‘gut feelings’ like sense of nausea and disgust,

interoception (feeling internal organs), emotional awarness.

Sylvian fissure runs between parietal and temporal lobes horizontaly

towards junction with occipital lobe. It contains supratemporal plane that

hosts primary and secondary auditory cortex and part of Wernicke’s area

for speech comprehension.

Major lobes – hidden and visible

AREE CORTICALI

MONOMODALI PRIMARIE: sensitive primarie, motoria primaria

MONOMODALI SECONDARIE : sensitive secondariemotorie secondarie

AREE ETEROMODALI : aree associative frontali, parietali, temporali

Aree motorie, uditive, somatosensitive, visive , olfattive e associative negli emisferi di 3 diversi mammiferi.

Si può notare l’enorme aumento nelll’uomo delle aree associative

Le aree corticali motorie, uditive, somatosensitive, visive , olfattive sono aree primarie strettamente correlate con il mondo esterno

( sensitivo-motorie)

Nell’uomo le aree associative consentono un elaborazione avanzata degli stimoli interni/esterni

Vengono divise in unimodali ( es aree 18-19 corteccia visiva)e eteromodali o multimodali che sono correlate a funzione di

integrazione

AREE ASSOCIATIVE ETEROMODALI

• CORTECCIA PREFRONTALE

• CORTECCIA PARIETALE POSTEROINFERIORE

• CORTECCIA TEMPORALE LATERALE

• GIRO PARAIPPOCAMPALE

• convergenza di tutti gli stimoli dalle aree unimodali

• controllo sistema limbico e centri sottocorticali

LOBO TEMPORALE

giro temporale superiore

giro temporale medio

giro temporale inferiore

giro fusiforme ( occipito-temporale)

Funzioni: integrazione uditiva, linguaggio (porzione posteriore del giro

superiore, area di Wernicke)

funzioni visuospaziali, apprendimento e memoria

Sylvian fissure-

Post central

sulcus posterior

limit of primary sensory area in parietal lobe

Gyrus supra marginalis ( parietal lobe)

Wernicke’s

area belongs to

superior temporal gyrus

Superior temporal gyrus

Superior temporal sulcus

Inferior temporal sulcus

Middle temporal gyrus Inferior

temporal gyrus

Terminal branch sylvian fissure

External part of the temporal lobe on a dissected brain

With a blue arrow: gyrus

With a red arrow: sulcus

Heschl’s

gyrusexternal part of primary auditive area

Central sulcus limit

between frontal and parietal lobe and posterior limit of primary motor area

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Lingual gyrus and fusiform gyrus belong to the temporo occipital area

Collateral sulcus

Collateral sulcus

Ento rhinal sulcus

Temporal pole

Amygdaloid nucleus

Arbitrary delineation between parahippocampal gyrus and lingual gyrus

Parahippocampal gyrus

Lingual gyrus

Fusiformgyrus

MidbrainMRI on horizontal plane of the temporal lobe

The course of the collateral sulcus may be interrupted in some part of its course

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Fasci di associazione tra le diverse aree corticali (DTI)

A, arcuate (superior longitudinal) fasciculus; C, cingulum; EC, extreme capsule; F, fornix and stria

terminalis ; H, hippocampus; IL, inferior longitudinal fasciculus; IO, inferior occipitofrontal

fasciculus; P, putamen; SO, superior occipitofrontal fasciculus (combined with the subcallosal

fasciculus adjacent to it); Th, thalamus; U, uncinate fasciculus.

I sistemi di connessione

SINDROMI DA DISCONNESSIONE:

INTERRUZIONE DELLE CONNESSIONI

TRA AREE UNIMODALI/ ETEROMODAI DIVERSE( es.: anomia per i colori)

http://www.nfos.org/degree/opt41/3

Dalle connessioni tra le diverse aree cerebrali nascono reti specifiche.

• Linguaggio

• Attenzione spaziale

• Funzioni esecutive e comportamento

• Emozioni e memoria

• Riconoscimento di facce e oggetti

Localization of function in the nervous

system: Functional networks

5 major brain systems subserving

cognition and behavior

Left perisylvian language network

Parieto-frontal network for spatial attention

Occipitotemporal network for object/face recognition

Medial temporal/limbic network for learning & memory

Prefrontal network for attention & comportment

Lateralization of functions(approximate)

• Left-hemisphere:

– Sequential analysis

• Analytical

• Problem solving

– Language and

communication – Emotional functions

• Recognizing emotions

• Expressing emotions

– Music Competence

• Right-hemisphere:– Simultaneous analysis

• Synthetic

– Visual-Spatial skills

• Cognitive maps

• Personal space

• Facial recognition

• Drawing

– Emotional functions

• Perceiving emotions

• Showing emotions

– Music perception

SUONI E LINGUAGGIO

Onward to the Brain!

• Organ of Corti transmits signals to the cochlear nerve

• Medulla

– Cochlear Nucleus to Superior Olivary Complex

• Lateral Lemniscus fiber bundle carries information to the inferior colliculus

• Proceeds to the Medial Geniculate Nucleus of the thalamus and on to the auditory cortex

http://www.neuroreille.com/promenade/english/ptw/zoom1.htm

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Auditory cortex• In humans primary auditory

cortex is located within Heschl’s gyrus.

– Heschl’s gyrus corresponds to Brodmann’s area 41.

• Another important region in auditory cortex is planum temporale located posterior to Heschl’s gyrus.

– Planum temporale is much larger in the left hemisphere (up to 10 times) in right handed individuals.

– It plays important role in language understanding.

• Posterior to planum temporale is Broadmann area 22 that Carl Wernicke associated with speech comprehension (Wernicke area).

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Binder and colleagues (1997) studied activation of brain areas to words, reverse speech and pseudowords and found that Heschl’s gyrus and the planum temporale were activated similarly for all stimuli.

This supports the notion of hierarchical processing of sounds with Heschl’s gyrus representing early sensory analysis.

Speech signals activated larger portion of auditory cortex than non-speech sounds in posterior superior temporal gyrus and superior temporal sulcus, but there was no difference in activation between words, pseudowords and reversed speech.

The conclusion is that these regions do not reflect semantic processing of the words but reflect phonological processing of the speech sounds.

Speech perception

Brain response to: Words

Pseudowords

Reversed speech

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The planum temporale (PT) location close to Wernicke’s area for speech comprehension, points towards its role as the site for auditory speech and language processing.

However neuroimaging studies of PT provide evidence that functional role of PT is not limited to speech.

PT is a hub for auditory scene analysis, decoding sensory inputs and comparing them to memories and past experiences.

PT further directs cortical processing to decode spatial location and auditory object identification.

Planum temporale and its major associations: lateral superior temporal gyrus (STG), superior temporal sulcus (STS), middle temporal gyrus (MTG),

parieto-temporal operculum (PTO), inferior parietal lobe (IPL).

Functional mapping of auditory processing

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Auditory objects are categorized into human voices, musical instruments, animal sounds, etc.

Auditory objects are learned over our lifetime, and associations are stored in the memory.

Auditory areas in superior temporal cortex are activated both by recognized and unrecognized sounds.

Recognized sounds also activate superior temporal sulcus and middle temporal gyrus (MTG).


Fig. (c) shows difference between

Activations for recognized sounds

and unrecognized sounds

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Binder and colleagues propose that middle temporal gyrus (MTG) is the region that associates sounds and images.

This is in agreement with case studies of patients who suffered from auditory agnosia (inability to recognize sounds).

Research results showed that auditory object perception is a complex process and involves multiple brain regions in both hemispheres.


Brain activities in auditory

processing – cross sections at

different depth

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Function source : Palmer & Hall, 2002

• Numerous bilateral regions are

frequency-dependent

• Overlapping regions are

sensitive to intensity and to the

temporal changes in sound

• One region is sensitive to the

spatial properties of sound

(R>L)

• Speech also activates these

regions, but neurons are

probably responding to the

complex acoustic properties in

the sound.

•Perceptual attributes may be

important

Slow-rate temporal pattern in sound

L

L

L

H LH H

Right hemisphere

Auditory Cortex

• Tonotopic Organization

– Different frequencies

of sound are mapped to

different regions of the

auditory cortex

– Extends to the level

of the cochlea

Zhou, X. and M. M. Merzenich (2007).

"Intensive training in adults refines A1

representations degraded in an early

postnatal critical period." Proceedings of the

National Academy of Sciences 104(40):

15935-15940.

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• Sound intensity and activation

• Loud sounds (90 dB) activated posterior and medial temporal gyrus (red)

• Soft (70 dB) sounds activated area (yellow) is found most laterally of TTG

• Medium intensity (82 dB) sounds activated intermediate area (green). (NeuroImage 2002;17: 710)

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Auditory agnosia

• A deficit in recognition

Acoustical analysis RepresentationsAuditory

input

Perception Recognition

“Apperceptive

agnosia”

“Associative

agnosia”

Auditory agnosia is of this type

• sordità verbale pura ( lesione bitemporale o sinistra, area 22)

• agnosia acustica ( area acustica secondaria)

What is Language?

• Grammar– Phonetics, morphology, syntax, semantics

• Symbol usage• Ability to represent real-world situations• Ability to articulate something new• Intention to communicate• Duality, productivity, arbitrariness, interchangeability,

specialization, displacement, and cultural transmission (Linden 1974)

“An infinitely open system of communication” Rumbaugh, 1977

W. W. Norton

Schematic representation of the

components that are involved in

spoken and written language

comprehension.

Input can enter via either auditory

(spoken word) or visual (written word)

modalities.

The flow of info is bottom up, from

Perceptual identification to

“higher-level” word and lemma

activation.

Interactive models of language

Understanding would predict top-down

influence to play a role as well.

Adap

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.M., T

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, G

., D

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., M

arsh

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., a

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. (E

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), L

inguis

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Speech Production

Outline of the theory of

speech production developed by

William Levelt (1999)

Brain areas involved in Language

Wernicke-Geschwind Model1. Repeating a spoken word

• Arcuate fasciculus is the bridge from the Wernicke’s

area to the Broca’s area

Wernicke-Geschwind Model2. Repeating a written word

• Angular gyrus is the gateway from visual cortex to Wernicke’s

area

• This is an oversimplification of the issue:

– not all patients show such predicted behavior (Howard, 1997)

Functional neuroimaging of the language

network

One to many, many to oneCJ Price, J Anat 2002

Language function: Using neuroimaging

to test hypotheses

CJ Price, J Anat 2002

fMRI:Record during

language tasks

– Activated brain areas

consistent with temporal

and parietal language

areas

– More activity than

expected in nondominant

hemisphere

Brain Imaging

Generate words from a category

Silently repeat a heard sentence

Listen to a story

A functional MRI protocol for localizing language comprehension in

the human brainGary W. Thickbrooma ,*, Michelle L. Byrnesa, David J. Blackerb, Ian T. Morrisc,

a,b,d Frank L. Mastaglia

Brain Research Protocols 10 (2003) 175–180

TONE DECISION TASK

Semantic decision

PET by Damasio’s

• Different areas of left hemisphere (other than Broca’s and Wernicke’s regions) are used to name (1) tools, (2) animals, and (3) persons

• Stroke studies support this claim

• Three different regions in temporal lobe are used

• ERP studies support that word meaning are on temporal lobe (may originate from Wernicke’s area):– “the man started the car engine and stepped on

the pancake”

– Takes longer to process if grammar is involved

LETTURA

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Neural systems for reading

• Converging evidence indicates three important systems in reading, all primarily in the left hemisphere-

– Some right hemisphere activation now implicated;

• These include an anterior system and two posterior systems:

1) anterior system in the left inferior frontal region;

2) dorsal parietotemporal system involving angular gyrus, supramarginal gyrus and posterior portions of the superior temporal gyrus;

3) ventral occipitotemporal system involving portions of the middle temporal gyrus and middle occipital gyrus

Dorsal (Green) and Ventral Pathways (Purple)

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Written language neural

pathway

• Visual input transmitted from lateral geniculate to primary cortex in striate areas and secondary extrastriate cortex.

• From here 2 streams-

– Ventral (what): unimodal visual area of fusiform gyrus (may contain ortho reps of words)

– Dorsal (where): superior parietal lobule for spatial aspects of reading.

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Heteromodal areas

• Wernicke’s including angular gyrus, supramarginal gyrus

– Likely responsible for integration of written & spoken word

forms.

– Wernicke’s is massively connected to inferior temporal

category specific areas for faces animals, tools

– Also with frontal areas for overt speech production

(Broca’s), and reciprocal connections for memory and

manipulating verbal information.

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Confirmed two systems for reading

• word analysis

– operating on individual units of words such as phonemes, requiring attentional resources and processing relatively slowly

• Parietotemporal area

and

• visual word attention

– an obligatory system that does not require attention and processes very rapidly, on the order of 150 msec after a word is read; Price et al 1996.

• Occipitotemporal area

• visual word form area appears to respond preferentially to rapidly presented stimuli (Price et al 1996) and is engaged even when the word has not been consciously perceived (Dehaene et al 2001).

Due sistemi corticali: dorsale e ventrale

Cellular responses in ventral stream

• V2-V4 especially orientation & color sensitive

– V4 contains color sensitive cells

– some have complex preferred stimuli

• Inferior temporal cortex (IT) is form sensitive

– big receptive fields (up to entire visual field)

– face selective cells in some regions

– others respond best to complex, 3D stimuli (Tanaka)

www.cnbc.cmu.edu/~mgilzen/85219/slides/Week8a.ppt

Effects of lesions to ventral stream

• Animal studies– Damage to P pathway inputs abolishes color

perception

– Damage to IT impairs discrimination between objects and identification

• Human patients– Achromatopsia

• Loss of color perception

• Associated with damage to lingual and fusiform gyri

– Agnosia• Apperceptive

• Associative

• Prosopagnosia

www.cnbc.cmu.edu/~mgilzen/85219/slides/Week8a.ppt

PERCEZIONE VISIVA

Visual processing streams: Confirmation

of hypotheses using neuroimaging

Ungerleider LG, PNAS 1998

Visual processing: Attention influences

which stream is used

Ungerleider LG, PNAS 1998

Encoding & recall of category-

specific information

Encoding of category-specific information activates

relevant areas of cortex

Polyn SM et al., Science, 2005

Faces: Fusiform gyrus Places: Parahippocampal gyrus

Visual object recognition: Faces & places

Kanwisher N, Science, 2006

Fusiform Face Area (FFA)

• functional brain imaging investigations of the normal human brain show that a region in the fusiform gyrus is not only activated when subjects view faces, but is activated twice as strongly for faces as for a wide range of non-face stimuli (Kanwisher et al., 1997)

IL LOBO LIMBICO TEMPORALEL’altra faccia della luna

Functions of The Limbic System

LOBO LIMBICOgiro del cingologiro paraippocampalegiro paraterminale ( lamina terminalis)giro subcallosaleippocampo, paraippocampo, uncus

Emozioni, apprendimento , memoria

Medial Temporal Lobe (MTL)

• Hippocampus

• Connected areas

– Entorhinal cortex

– Perirhinal cortex

– Parahippocampal cortex

Bird & Burgess, Nature Reviews Neuroscience 9, 182-194

Function of MTL• Principally concerned with memory

• Operates with neocortex to establish and maintain long-term memory

• Ultimately, through a process of consolidation, becomes independent of long-term memory

MTL

Simons & Spiers (2003) Nature Reviews Neuroscience 4; 637-648

STRUTTURA DELL’IPPOCAMPOA: ricostruzione dell’ippocampo e del fornice.

B : struttura del giro dentato e del corno d’Ammone

C, sezione coronale del giro dentato, ippocampo e subiculum

D, diagramma delle cellule e fibre dell’ippocampo Le fibre efferenti dall’ippocampo si originano da cellule piramidali . La maggior parte delle efferenze originano dal subiculum.Il flusso di informazioni proviene maggiormente dalla corteccia entorinale > giro dentato> cellule piramidali dell’ippocampo e subiculum> fornice

Nel giro dentato dono presenti cellule staminali.

(B, modified from Duvernoy HM: The human hippocampus: functional anatomy, vascularization and serial sections with MRI, ed 3, Berlin, 2005, Springer-Verlag. C, modified from Nolte J, Angevine JB Jr: The human brain in photographs and diagrams, ed 3, St. Louis, 2007, Mosby.)

• CA1 > CA4 = zone del corno d’Ammone ( ippocampo = corno d’Ammone + giro dentato)

• Paraippocampo = subiculum + corteccia entorinale

Settore CA1 del C.Ammone = settore di SOMMER : compostoa da grandi cellule piramidali,

Con metabolismo molto attivo, alta densita di recettori NMDA, estrema sensibillità all’ipossia,

Marcato potenziamento post-sinaptico ( 2 ore per singolo stimolo in arrivo)

Memoria sinaptica

Neuroplasticità

Crisi epilettiche

Connessioni anatomiche dell’ippocampo

Input e out

dell’ippocampo:è una struttura nervosa

della regione

temporale mediale

Gli input

all’ippocampo:arrivano tramite

stazioni di

ritrasmissione nelle

corteccie peririnali,

paraippocampali ed

entorinali

Le uscite

dall’ippocampo:seguono il percorso

opposto. Gli input-

output sotto-corticali

dell’ippocampo

viaggiano nel fornice

AFFERENZE DELL’IPPOCAMPO:

• corteccia entorinale ( bulbo olfattorio)

• amigdala

• nuclei settali

• ippocampo controlaterale

• locus coerulus

. (Modified from an illustration in Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.)

EFFERENZE DELL’IPPOCAMPO

• Fornice ( attraverso il fornice le informazioni provenienti dall’ippocampo

raggiungono i corpi mammilari,il nucleo anteriore e mediodorsale del talamo,

il cingolo)

Papez Circuit (memory)

Mammillary bodies

Other hypothalamic nuclei

Septal nuclei

Substantia innominata

(Basal nucleus of Meynert)

Hippocampal Formation

(hippocampus

and dentate gyrus)

Anterior Thalamic

nuclear group

Cortex of Cingulate GyrusParahippocampal Gyrus

Neocortex

FornixMammillothalamic

tract

The Papez circuit.

The shortcut from the hippocampus directly to the anterior thalamic nucleus,

not part of the circuit as originally proposed, is indicated by a dashed line. A,

anterior thalamic nucleus; CA, hippocampus proper; D, dentate gyrus; MB,

mammillary body. (Modified from an illustration in Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.)

IPPOCAMPO E MEMORIA

Nel 1957 un paziente di nome H.M. fu trattato chirurgicamenteper epilessia resistente alla terapia farmacologica con asportazione bilateraledell’ippocampo e dell’amigdala.

HM soffri da quel momento di un grave disturbo della memoria episodica

Dopo molti anni dall’intervento il paziente fu sottoposto a RM encefalo.

Il suo caso dimostrò in modo conclusivo il ruolo fondamentale dellaparte mediale del lobo temporale nella memoria

HM

AMIGDALA

L’amigdala è un insieme di circa 12 nuclei situati in prossimità dell’uncus, vicino alla parte anteriore dell’ippocampo, e accanto al corno temporale del ventricolo laterale .

Origina dalla corteccia periamigdaloidea , che forma parte della superficie del’uncus.

I nuclei dell’amigdala vengono classificati in 3 principali gruppi : mediale, centrale e basolaterale, ognuno con diverse funzioni.

Nucleo mediale: è connesso con il sistema olfattorio ed è piuttosto piccolo negli esseri umani.

Nucleo centrale : collegato all’ipotalamo e alla sostanza grigia periacqueduttale ha funzioni emozionali

Nucleo basolaterale: è il nucleo più grande negli esseri umani, contiene cellule piramidali ed è strettamente collegato agli altri nuclei

Suddivisione dell’amigdala nei

principali nuclei (basolaterale,

centrale e mediale) con le

principali connessioni.

( PH, parahippocampal gyrus)

Amygdala Connections

Cerebral cortex

Olfactory system

Thalamus

Brainstem reticular formation

Hypothalamus

AMYGDALA

Stria

terminalis

Ventral Amygdalofugal

fibers

Amygdala Inputs

AMYGDALA

Corticomedial Nuclear

Group

Basolateral Nuclear

Group

Central Nucleus

Olfactory

System

Temporal Lobe

(associated with visual,

auditory, tactile senses)

Brainstem (viscerosensory relay

Nuclei: solitary nucleus

and parbrachial nucleus)

Ventral

Amygdalofugal

Fibers

Maggiori input ai nuclei basolaterale(blu), centrale(rosso) e mediale

(verde) dell’amigdala.

Sono evidenziati gli input dalle aree visive , ma simili proiezioni

esistono dalle principali aree unimodali e dalle altre aree limbiche.

B, brainstem (periaqueductal gray, parabrachial nuclei, other nuclei);

Hy, hypothalamus; S, septal nuclei; T, thalamus (multiple nuclei). (Modified from Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.)

Principali efferenze dai nuclei dell’amigdala ( blu= basolaterale;rosso=centrale; verde=

mediale)

(1) stria terminalis: verso i nuclei del setto e l’ipotalamo

(2) Via amigdalofugale e Via amigdalofugale ventrale ( ipotalamo e talamo MD)

(3) proiezioni diffuse alla corteccia frontale ventromediale , corteccia insulare, striato

ventrale, aree olfattorie , tronco encefalico .

(4) connessioni dirette con l’ippocampo e il lobo temporale.(Modified from Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.)

Riepilogando:

L’amigdala riceve una gran quantità di input :

1. Molti di questi sono semplici e famigliari, riguardando stimoli visivi,

suoni, stimoli tattili, odori e.

Gli stimoli olfattivi raggiungono direttamente il nucleo mediale , dalla

corteccia e bulbo olfattorio ( tratto olfattorio).

Gli altri tipi di stimoli raggiungono il nucleo basolaterale dal talamo e

dalle cortecce unimodali visiva, uditiva, gustativa e somatosensitiva.

2. Un altro tipo di stimolo arriva all’amigdala dall’insula, dal cingolo e dalla

corteccia orbitofrontale ( via amigdalofugale)

3.Infine l’amigdala riceve input viscerali provenienti dall’ipotalamo ( stria

terminalis) e dal tronco encefalico ( grigio periacqueduttale ,

n.parabrachiale)

Le efferenze dall’amigdala raggiungono le stesse aree da cui l’amigdala

riceve degli input

Limbic System and Basal Nuclei

Medial and lateral temporal lobe

Hippocampus

Amygdala

Entorhinal cortex (24)

Ventral Striatum

(nucleus accumbens)

Caudate Nucleus

(head)

Anterior Cingulate Gyrus

Orbitofrontal Areas (10, 11)

Ventral Pallidum

Medial Globus Pallidus

Pars Reticularis

(Substantia nigra)

Ventral Anterior Nucleus

Dorsomedial Nucleus

Functions of the Amygdala

• Relate environmental stimuli to

coordinated behavioral autonomic and

endocrine and motor responses seen in

species-preservation.

• Responses include:Feeding and drinking

Agnostic (fighting) behavior

Mating and maternal care

Responses to physical or emotional stresses.

La connessione limbica tra amigdala e gangli della base influenza le decisioni riguardo al movimento e, più in generale, è necessaria per l’associazione stimolo-ricompensa.

Qualsiasi cosa possa apparire piacevole determina un aumento di rilascio di dopamina nello striato che si traduce successivamente in un’azione; avviene il contrario per ciò che consideriamo spiacevole

Neuro-anatomy of hedonic regulation of food intake; reward (or pleasure) seeking areas of the brain control orexigenic neurons of LHA

L’amigdala, attraverso le sue connessioni , in particolare con la corteccia frontoventromediale e l’ipotalamo, svolge un ruolo fondamentale nella vita emotiva.

Quando l’amigdala di un animale viene stimolata l’animale si ferma e rimane attento: a ciò può far seguito una risposta di difesa, rabbia, aggressione, o di fuga

La stimolazione dell’amigdala nell’uomo evoca più spesso paura accompagnata dalle reazioni vegetative corrispondenti .

La distruzione bilaterale dell’amigdala determina un assenza di paura e di aggressività con mancanza di reazioni vegetative .

L’assenza congenita dell’amigdala impedisce l’apprendimento di reazioni comportamentali complesse in risposta a determinate situazioni

LA PATOLOGIA

Symptoms of Temporal-Lobe Lesions

Pathologies (lesions)

• Voracious appetite

• Increased (perverse) sexual activity

• Docility:

Loss of normal fear/anger response

• Memory loss:

Damage to hippocampus portion:Cells undergoing calcium-induced changes associated with memory

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Temporal lobectomy• Brown and Schäfer (1888) reported

behaviour of monkey ‘Tame one’ after bilateral temporal lobectomy.

• Preop: wild, fierce

• Postop: – Does not retaliate or escape if slapped,

tame

– Poor memory and intelligence

– Evidence of hearing and seeing, but ‘no longer clearly understands meaning of sights, sounds.’

– Does not select raisins from other food in dish: does not seem to visually recognize items.

Kluver-Bucy Syndrome:

• Results from bilateral destruction of

amygdala.

• Characteristics:

Increase in sexual activity.

Compulsive tendency to place objects in mouth.

Decreased emotionality.

Changes in eating behavior.

Visual agnosia.

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Delusional Misidentification

Syndromes• 3 DMS:

1. Pick [1903] “reduplicative paramnesia”• Misidentifies familiar places as replica

2. Capgras Syndrome [1923] • Familiar people described as doppelgangers

– visual but not emotional recognition

3. Frégoli Syndrome [1927]• Person misidentified as someone else with totally different

appearance.

• DMS are rare– Rare enough to be of little clinical importance

– Yet, may still reveal how emotions are processed

100

Hirstein and Ramachandran

[1997] • H&R postulate that DMS is caused by

disconnection between visual recognition

system and emotional system.

• E.G. Capgras syndrome due to

disconnection between fusiform gyrus

[face area] and amygdala [limbic system]

101

Hudson and Grace

• 71 women suffered lesion to anterior fusiform gyrus (between face area and amygdala)– Frégoli Syndrome

• Identified husband as elder sister (who had died 3 years previously)

• Only visual misidentification (fine on phone)

• Home was ‘replica’ would pack bags to return to ‘real’ home.

• Support for H&R

102

Pain asymbolia

• Patient’s report they can feel pain, but it no

longer hurts.

• Ramachandran (1998): speculates

disconnection of insula from cingulate

(part of limbic system)

– Insula identifies pain

– Cingulate does not receive signal, so

discounts threat

I DISTURBI ACUSTICI E DI LINGUAGGIO

104

Auditory agnosia source : Griffiths et al. 1999

• Normal brainstem processing

• Midbrain impairment questionable

• Cortical deficit in perception- Preserved hearing (pure tones)

- Disordered perception of certain sounds :

Speech - word deafness

Music - amusia

Environmental sounds - environmental sound agnosia

105

A case of word deafness source: Ellis & Young, 1988

• Hemphill and Stengel (1940) “I can hear you dead plain, but I cannot get what you say. The noises are not quite natural. I can hear but not understand”

- Normal pure tone audiometry

- Fluent speech “no errors of grammar beyond what is common for hisparticular dialect and standard of education”

- Normal reading

- Normal writing and spelling

- Poor spoken word repetition

- Gross asymmetry between spoken and written word comprehension

106

Word deafness source : Ellis & Young, 1988

• Associated symptoms- Some hearing loss (> 20 dB HL)

- Production (Broca’s) aphasia

- Perception of melody

- Perception of environmental sounds

• Lesion site- Generally large bilateral infarcts

- When unilateral, it’s more often the left hemisphere

- Involves superior temporal lobe (non-primary auditory cortex)

- May or may not involve Heschl’s gyrus (primary auditory cortex)

107

A case of amusia source : Peretz, 1993

Patient CN

• Symptoms- Unable to recognise even simplest tune

- Unable to sing children’s songs that she had known well

- No deficit in everyday verbal communication

- No deficit in everyday recognition of environmental sounds

• Lesion site- Bilateral temporal lobe damage

- When unilateral, it’s more often the right hemisphere

108

Amusia source : Peretz, 1993

• Dissociation within musical perception- Right injury - Deficit in melody perception: the variations in pitch

- Left injury - Deficit in rhythmperception: the temporalorganisation of melody over 100s ofmilliseconds or seconds time scale

109

Environmental sound agnosia

• Deficit rarely occurs in isolationsource : Griffiths et al. 1999

Environmental sounds contain fewer changes in acoustic structure over time

than an equivalent length segment of speech or music

110

A common deficit? No! source : Peretz, 1993

• Word deafness, amusia and environmental sound agnosia are distinct- speech and music can dissociate after brain damage

- music and environmental sounds can dissociate after brain damage

- environmental sound perception can be selectively spared

- recovery can follow different patterns (e.g. environmental sounds, then music then speech or in the reverse order)

111

A common deficit? Yes! source : Griffiths et al. 1999

• Word deafness, amusia and environmental sound agnosia probably co-occur- May not always be report because not all abilities are tested

• All 3 types of sound contain a mixture of acoustic features

• Deficit in an intermediate level of analysis, which is rarely tested- Analysing the spectro-temporal pattern in sound

112

Symptoms

(a) Rightward biases in sound localization

(b) Poor relative judgements for sounds on the contralesional side

(c) Poor elevation judgements for sounds on the contralesional side

Failure to detect contralesional sound, when presented concurrently

Poor allocation of attention to sounds separated in time

Auditory neglect source : Pavani et al., 2003

113

Lesion site – usually right hemisphere

- inferior parietal lobe

- superior temporal gyrus

- temporo-parietal junction

Auditory neglect source : Pavani et al., 2003

Quadro riassuntivo

Summary: Correlations of symptomswith areas of lesion

Broca’s Broca’s area

Wernicke’s Wernicke’s area

ConductionSMG, Insula,

Arcuate fasciculus

Transcortical motorAreas anterior and/or

superior to Broca’s area

Transcortical sensoryAreas posterior and/or

superior to Wernickes a.

Aphasic Syndrome Area of Damage

Cf. H. Damasio 1998: 43-44

Two different patients with anomia

Deficit in retrieval of animal names

(Damage from stroke)

Inability to retrieve words for unique entities

(Left temporal lobectomy)

Two more patients with anomia

Deficit in retrieval of words for man-made manipulableobjects

(Damage from stroke)

Severe deficit in retrieval of words for concrete entities

(Herpes simplex encephalitis)

I DISTURBI AGNOSICI

Ishyhara plates

Cerebral Achromatopsia

Color Agnosia

• What causes it?

– Damage to the extrastriate visual cortex, specifically the V4 area.

– The visual area 4 (V4) is cut off from sending information to the lingual gyrus, fusiform gyrus and inferior temporal gyrus.

– Without the ability to send that information to the “What” pathway of the temporal lobe, the color cannot be recognized.

Achromatopsia is not:

a) due to peripheral damage (e.g. retina)

b) due to primary visual area damage

c) colour agnosia: disorder of colour categorization

d) colour anomia: disorder of colour naming

Cerebral Achromatopsia

Usually caused by bilateral damage to V4

(lingual and fusiform gyri (occipitotemporal junction))

characterized by an inability to identify or discriminate colour

Usually full field deficit but hemiachromatopsia possible if

damage is unilateral

Still able to perceive form and motion - dissociation with

akinetopsia and visual form agnosias

Damasio et al., (1989b) in Heilman and Rothi (1993)

42 patients.

achromatopsia associated with lesions below

calcarine sulcus that damaged middle third of lingual

gyrus, but not fusiform gyrus

Calcarine sulcus

Lingual Gyrus

Fusiform Gyrus

Which part of V4?

Prosopagnosia

• Special nature of face processing originates from reports of patients who are reportedly unable to recognize familiar faces while maintaining the ability to recognize objects. – This impairment is often accompanied by focal

damage to the ventral occipitotemporal and temporal cortices.

– Reported to process faces similar to objects (sometimes absence of inversion effects).

Prosopagnosia

Why just faces? What about objects? Fusiform gyrus responds to faces

Parahippocampal gyrus responds to inanimate objects

Double Dissociation- The areas for recognizing faces and

inanimate objects are separate therefore agnosia for objects and

prosopagnosia do not occur together

Face Processing:

Cognitive and Neural Components

Bruce & Young

(1986)

Haxby et al., (2000)

Importance of Facial Configuration

• the importance of the overall configuration of the face can help us understand why face recognition can be remarkably robust despite a variety of natural (change in expression, orientation etc) as well as unnatural (cartoons) transformations in faces.

Prosopagnosia

• Marotta, Genovese, & Behrmann (2001)

– fMRI of prosopagnosic patient did not show

normal activation of fusiform.

– Did show left hemisphere posterior fusiform

activation, suggesting faces are being processed

featurally.

Fig. 4-18, p. 83

Prosopagnosia

George et al. (1999).fMRI study of positive and reverse contrast faces.

Bilateral fusiform gyriresponse to facesRight fusiform gyrus only when face became familiar(Note contrast to Alexia)

Brain region involved

Image of Left Fusiform Gyrus (Visual Word Form Area -VWFA) and Right Fusiform Gyrus (Weiner et al, 2004.)

The left fusiform gyrus

( referred to as the

visual word form area)

is responsible for

word recognition.

The right fusiform gyrus

is (referred to as the

fusiform face area)

responsible for facial

recognition.

What Causes Prosopagnosia?

• Damage to occipitaltemporal regions of the brain

– Specifically the fusiform gyrus of the interior temporal cortex

– The cause of damage can be from head injury, degenerative diseases (ex. Alzheimer’s and Parkinson’s disease), right temporal lobe atrophy, encephalitis, or strokes (ex. Posterior cerebral artery stroke or transient ischemic attack).

• There is also a genetic form of prosopagnosia that can be passed down from a parent to child. Prosopagnosia can also be the result of a developmental disorder.

• Evolutionarily facial recognition is important – There must be an adaptive benefit for facial recognition. Newborns

show great preference for human faces despite their poor visual acuity. Newborns use eye contact and facial expressions to engage caretakers to take care of their needs. Socially facial recognition became essential to survival because it provides self-identity, identity for group members, and identity for non-group member (could be an enemy?).

LA MEMORIA

Memory and Forgetting

Classificazione dei tipi di memoria.

Memoria

Esplicita

(dichiarativa) Implicita

Episodica Semantica Procedurale Emotiva

Vegetativa(condizionamento)

• cos’è una bicicletta memoria semantica

• ieri sono andato in bicicletta memoria episodica

• andare in bicicletta dopo 10 anni memoria procedurale

• ho paura della bicicletta ( non so perché) memoria emotiva

Brain regions in Learning and Memory

Patient H.M.

• Bilateral temporal lobe resection for treatment of epilepsy.

• Included removal of hippocampus and amygdala from both sides.

• Various etiologies lead to symptoms like H.M.'S, including stroke and herpes

Case of Patient H. M.

• Age 9, knocked over by a bicycle rider, sustained brain damage

• Age 16, suffered bilateral temporal lobe seizures which became uncontrollable– Unable to work and lead a normal life

• Age 27, underwent bilateral removal of hippocampal formation, amygdala, parts of multimodal association areas of temporal cortex (1953)

Consequences of Psychosurgery for H.M.

• Positive - seizures better controlled- IQ unaffected; bright- good long term memory for events before the surgery- good command of language including vocabulary- remembered his name and job he held

• Negative • suffered anterograde amnesia -

unable to transfer new short-term memory into long term memory– unable to retain for more than a

minute new people, places or objects

– unable to recognize people he met during surgery including his neurosurgeons

– took a year to learn his way around a new house

- suffered retrograde amnesia for information acquired a few years before surgery

Patient HM

• Revealed declarative/ nondeclarative distinction

– Declarative memories (explicit memories) involve conscious recollection of events and information.

• H.M. Lost this ability.

– Nondeclarative memories (implicit memories) involve ability to acquire and perform new behaviors or associations.

• H.M. Retained this ability.

– could perform mirror-tracing after training but could not remember doing the task before

Semantic Dementia (Snowden 1989)

• Semantic memory (Warrington 1975):

• Term applied to the component of long-term memory which contains the permanent representation of our knowledge about things in the world: facts, concepts and words

• Culturally shared, acquired early in life.

Semantic Dementia (Snowden 1989)

• Affects fundamental aspects of language, memory and object recognition.

Semantic Dementia

• Progressive anomia, not an aphasia, but a loss of semantic memory.

• Impaired: naming, word comprehension, object recognition and understanding of concepts.

• characterized by preserved fluency and impaired language comprehension: “phonologically and syntactically correct”

Assessement

• Category fluency

• Generation of definitions– Lion: ” it has little legs and big ears, they sleep a lot, see them in

shops”

• Word-picture matching

• Famous faces test

• Normal episodic memory, normal visuospatial skills

• Nature of errorSemantic-type naming errors:initially within-category, “elephant” for hippopotamus, then superordinate “dog” for everything, then “animal”…

• Profound and complete anomia

• Circumlocutions and semantic paraphasias

– semantic paraphasias, in which the wrong word is produced, one that is usually related to the target (eg, "pliers" for "hammer").

• In semantic dementia the most context-free levels of knowledge (constituting traditional notions of semantic memory) are most compromised.

• In contrast, patients may retain knowledge tied to specific experiences or routines

SD and memory

• Can relate details ( in a rather anomic fashion) of recent events, but there is impaired recall of distant life events.

SD

• In most cases, neuroradiological studies reveal selective damage to the inferolateral temporal gyri(inferior and middle) of one or both temporal lobes, with sparing of the hippocampi, parahippocampal gyri, and subiculum.

• Note: AD: inferior and middle temporal gyri

Semantic dementia patient with severe focal atrophy of the left temporal lobe see arrow, right-hand side of MRI scan) involving the pole, inferior, and middle temporal gyri with relative sparing of the hippocampal complex (H) and of the superior temporal gyrus.

Grazie per l’attenzionefine

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