AP PSYCH Unit 3B.2The Cerebral Cortex & Our Divided Brain

The Cerebral Cortex

• Cerebrum – the 2 large hemispheres (85% of brain’s weight)• Not basic life functions (like lower level brain)• Thinking, perceiving, speaking (higher level)

´ Cerebral Cortex – thin surface layer of brain• Thinking, info-processing, language, body’s ultimate control center• Humans have larger cerebral cortex than animals

Structure of the Cortex´ Glial cells / Neuroglia

´ (“glue cells”)´spidery ´provide nutrients & myelin to neurons´primitive “chatting” with neurons & might be responsible for brain function

(information transmission, memory)´Outnumber neurons 10 to 1´Einstein didn’t have a bigger brain, but had more glial cells

Structure of the Cortex

´ Lobes´Frontal lobes, Parietal lobes, Occipital lobes, Temporal lobes´There are 2 brain hemispheres, so 2 of each lobe (1 on each side

of the brain)

Frontal Lobe´Most important part of the brain for defining “us”, who we are´Decision-making center, problem solving, planning´Personality, higher level emotions´ Speech, language, social behavior, what makes us human´Contains motor cortex, too´Memory hint: Thinking (touching forehead)

Parietal Lobe´Receives & processes sensory information´ Integrates in the visual senses from the occipital lobe´Contains sensory cortex´Memory hint: Act like you’re washing your hair, and feel

the shampoo

Occipital lobe

´Vision – visual cortex´Back of the head´Memory hint: Eyes in the

back of your head

Temporal Lobe´Memory, language, emotion´Hearing – auditory cortex

´Schizophrenic people that are “hearing voices” aren’t hearing external factors, but their temporal lobe is malfunctioning

´Contains hippocampus´Helps recognize faces & objects´Memory hint: located near the ear

Functions of the Cortex

Motor Cortex´ In back of frontal lobe,

controls voluntary movement´ Brain has no sensory

receptors, so scientists can stimulate parts of the motor cortex and observe crazy motion!

´ Also, stimulating the right part of the cortex in the brain makes the left part of the body move

Mapping the Cerebral Cortex

´Brain has no sense of touch, so we can find exactly in the motor cortex where certain movement control centers are located by stimulating brain areas on awake people

´Body areas requiring more precise control (fingers & mouth) have larger spaces in motor cortex

´Neural prosthetics

Sensory Functions of the Cortex

Sensory Cortex: similar to motor cortex (specific parts of brain responsible for specific sensations)´ Located in parietal lobe´ Stimulate a spot here and the

body will feel a sensation in that body part

´ The more sensitive a body region, the larger the sensory cortex area associated with it

Association Areas´ Home of the “90%” of the brain we “don’t

use” ´Big areas of cerebral cortex that haven’t

been specifically labeled for anything motor or sensory

´ In all 4 lobes´ Higher level mental functions: Learning,

remembering, thinking, speaking´ Frontal lobes: Phineas Gage

Language à 1-5 Language: speaking, reading,

writing, reading & writing, having a conversation / discussion, singing

Language

´ Aphasia – impairment of language, impaired use of language´Damage to any link in that

chain of 1-5 from previous image

´Usually caused by left hemisphere damage or cortical area damage to:´ Broca’s Area (impairing speaking), or

´ Wernicke’s Area (impairing understanding)

´Studying aphasia helps determine functions of parts of brain responsible for language

Broca’s Area

´ Locatedintheleftfrontallobe.

´ Communicateswithmotorcortex.

´ Involvedwithexpressivelanguage.

´ Damagetothisarearesultsindifficultywithspokenlanguage.

´ Areadirectsmusclemovementsinvolvedinspeechproduction.´ Cansingfamiliarsongs&comprehendspeech,buttroublespeaking

Wernicke’s Area

´ Located in the left temporal lobe.´ Controls receptive language (problems understanding

what someone else says.)´ Speak meaningless words

Angular Gyrus

´ Involved in reading aloud´ Receives visual information from visual cortex (occipital lobe) and

recodes it into an auditory form, makes it an auditory code´When you read, you read silently, but aloud inside your head. ´The words you see and read turn into a sound inside your head

´ (the voice inside your head)

´ Then sent to Wernicke’s Area to derive its meaning´ Damage here means you can still speak and understand, but can’t

read aloud

Brain activity when hearing, seeing, and speaking words. Always keep in mind the lobe of the brain this activity takes place in

MnemonicDevices

´ Angular Gyrus´Turns written words into audio,

into the voice in your head´Angular Gyrus = Audio

´ Wernike’s Area´Understanding/interpreting the

audio´Wernike = What?

´ Broca’s Area´ Interacts with Motor Cortex and

makes speech muscles move (mouth, tongue, lips, etc)

´Broca = Breech Speech?´ Another way to memorize each step

is to memorize the location and function in relation to the 4 lobes

Brain Break

´ Which of your brain parts involved with language are strongest and weakest? Why?

The Brain’s Plasticity´ Plasticity – brain’s ability to change

´ Especially during childhood

´ Reorganize after damage or build new pathways based on experience

The Brain’s Plasticity

´ Constraint-induced therapy – rewire brains by restraining fully-functioning limb and forcing use of the “bad hand” or leg, etc´Damaged brain functions migrate to other brain regions

´ Blind or deaf brains make use of unused brain areas for other uses´Brain area for reading finger feeling of touch expands into unused

visual cortex´Temporal lobe in deaf picks up other jobs instead

TheBrainʼsPlasticity

´ Neurogenesis – theformationofnewneurons

´ Contrarytolong-heldbelief

´ Monkeysformthousandsofnewneuronseachday

´ Scientistsaretryingtomassproducethetechnologytoregrowbrainneurons

´Butuntilthen,healthylifestylesandstimulatingenvironmentswillhelpmakenewneuralconnections

SplitBrain/TwoBrainExaggerations

´ Noactivityinwhichonly 1hemisphereistruly,responsible

´ Logicisnotconfinedtoonlythelefthemisphere

´ Creativityisnotonly intheright´ Hemispheresaren’teducatedone

atatime

´ Nooneispurelyleftorright-brained

SplittingtheBrain

´ Thereare2sidesofthebrain´Braindamageinthelefthemispherehasmorenoticeable

impairmentsthanright´Soistherightsidelessdominant?

SplittingtheBrain

´ Vogel&Bogen:Epilepticseizuresresultfromproblemswithinfobouncingbackandforthbetweenthehemispheres

´ Cutthecorpuscallosum tofixtheseproblems

´widebandofaxonfibersconnectinghemispheres,sendingmessagesbetween

´ Createdthesplitbrain,nomoreepilepticseizures

´ Asplitbrainmakes2separatebrainsthatcouldeasilybetested

´ The2hemispherescomplimenteachother

´ Whenyoulookatpictures,informationfromlefthalfofyourfieldofvisiongoestoyourrighthemisphere;infofromrighthalfgoestoleft

´Eachreceivessensoryinfofromboththeright&leftvisualfields

´Datareceivedbyeitherhemispherearequicklytransmittedtotheotheracrossthecorpuscallosum

´Butnotinapersonwithaseveredcorpuscallosum

´ Sperry&Gazzaniga:testedsplit-brainpatients

´HE-ARTflashedonscreen´HEgoestoright

hemisphere,ARTtoleft´Patientssaid theysaw

ART(speaking/Broca’s inthelefthemisphere)

´Butpointedw/lefthandtoHE(rightvisualfieldcommunicateswithleftpartofbody)

´ Peoplewithasplit-brain,suchasJoe,candraw2separateshapesatthesametime,butyoucan’t

´ Couldheplayrock,paper, scissorsbyhimself?

´ Let’stryafewexperiments totestourleft-rightbrainrelationship

´ Lookatthecenterofoneface,thentheother´Whichfacelookshappier?

´ Researcherssaypeoplechoosetheoneontheright,becausetherighthemisphere,whichisskilledinemotionprocessing,receivesinfofromthelefthalfofeachface(thelefthalflookshappierontheoneontheright)