Memory and Cognition PSY 324 Chapter 2: Cognition and the Brain Part II: Localization of Function Dr. Ellen Campana Arizona State University.

Memory and Memory and CognitionCognition

PSY 324PSY 324

Chapter 2: Cognition and the Chapter 2: Cognition and the BrainBrain

Part II: Localization of Part II: Localization of FunctionFunction

Dr. Ellen CampanaDr. Ellen Campana

Arizona State UniversityArizona State University

The Whole BrainThe Whole Brain

Localization of functionLocalization of function - Different - Different parts of the brain serve different parts of the brain serve different functionsfunctions

Many, many ways to divide the brainMany, many ways to divide the brain Like an onion, many layersLike an onion, many layers Like a fractal, the closer you look the Like a fractal, the closer you look the

more complex it seems more complex it seems Descriptions may seem contradictory Descriptions may seem contradictory

and/or overlapping because of thisand/or overlapping because of this

Cerebral CortexCerebral Cortex Most important for CognitionMost important for Cognition

Cerebral CortexCerebral Cortex

Temporal Lobe Temporal Lobe LanguageLanguage MemoryMemory HearingHearing Perceiving formsPerceiving forms

Occipital LobeOccipital Lobe Visual information (early processing) – Visual information (early processing) –

feature detectorsfeature detectors

Cerebral CortexCerebral Cortex Parietal LobeParietal Lobe

TouchTouch VisionVision AttentionAttention

Frontal Lobe Frontal Lobe Proportionately larger in humans than Proportionately larger in humans than

in other speciesin other species LanguageLanguage ThoughtThought MemoryMemory Motor functioningMotor functioning

Subcortical StructuresSubcortical Structures

Subcortical StructuresSubcortical Structures

HippocampusHippocampus Forming memoriesForming memories

AmygdalaAmygdala Emotions, emotional memoriesEmotions, emotional memories

ThalamusThalamus Processing sensory information (vision, Processing sensory information (vision,

hearing, touch)hearing, touch)

HemispheresHemispheres

Brain separated into sides (hemispheres)Brain separated into sides (hemispheres) Corpus CollosumCorpus Collosum connects them connects them

Structurally and Structurally and functionally very functionally very similarsimilar

LateralizationLateralization – – specific functions specific functions occurring in one occurring in one hemisphere or the hemisphere or the otherother

Note: Sperry studied “split-brain patients”, who had had their corpus collosum severed as a treatment for epilepsy. He shared Hubel & Weisel’s Nobel Prize for this work.

LateralizationLateralization

Vision of left part of the world Vision of left part of the world lateralized to the right side (opposite lateralized to the right side (opposite also true)also true)

Motor Control of left side of body Motor Control of left side of body lateralized to the right side (opposite lateralized to the right side (opposite also true)also true)

Touch on left side of body lateralized Touch on left side of body lateralized to the right side (opposite also true)to the right side (opposite also true)

LateralizationLateralization Are there “right-brained” and “left-Are there “right-brained” and “left-

brained” people?brained” people? Analytical/Logical processing (syntax of Analytical/Logical processing (syntax of

language) usually on the left side (not always)language) usually on the left side (not always) Analogy and Broad Thinking usually on the Analogy and Broad Thinking usually on the

right side (not always)right side (not always) Everyone has (and uses) bothEveryone has (and uses) both Patients who have had a Patients who have had a

hemispherectomyhemispherectomy Other side usually takes over missing Other side usually takes over missing

functionalityfunctionality Coglab “Brain Assymetry” Coglab “Brain Assymetry”

Localized FunctionLocalized Function

Parietal LobeParietal Lobe Sensory HomunculusSensory Homunculus (near the front, (near the front,

somatosensory cortexsomatosensory cortex)) Motor HomunculusMotor Homunculus (near the back, (near the back,

motor cortexmotor cortex))

These guys aren’t actually IN your brain, they’re representations of how much cortex area is devoted to different body parts

Sensory HomunculusSensory Homunculus

Each side of the brain has a

copy, which processes

touch from the other side

Localized FunctionLocalized Function

Parietal LobeParietal Lobe Sensory HomunculusSensory Homunculus (near the front, (near the front,

somatosensory cortexsomatosensory cortex)) Motor HomunculusMotor Homunculus (near the back, (near the back,

motor cortexmotor cortex)) Temporal LobeTemporal Lobe

Wernicke’s AreaWernicke’s Area – metaphor, meaning – metaphor, meaning in languagein language

Broca’s AreaBroca’s Area – logical structure of – logical structure of languagelanguage

Fusiform Face Area (FFA)Fusiform Face Area (FFA) – – specialized for faces (or is it things specialized for faces (or is it things we’re experts at recognizing???)we’re experts at recognizing???)

Researching Localized Researching Localized FunctionFunction

NeuropsychologyNeuropsychology – comparing – comparing patients with localized brain damagepatients with localized brain damage Single dissociationSingle dissociation– single patient has – single patient has

some things impaired, other things not some things impaired, other things not impairedimpaired

Single Dissociation: Single Dissociation: Phineas GagePhineas Gage

Construction Construction accident – 1848accident – 1848

Harlow (doctor) Harlow (doctor) wrote a lot about wrote a lot about his conditionhis condition Gage lived, could talk, act, and do Gage lived, could talk, act, and do

all “normal” activities, but suffered all “normal” activities, but suffered impairment of emotional, social, and impairment of emotional, social, and personal traitspersonal traits

Evidence for some separation of Evidence for some separation of language and social traits, etc. language and social traits, etc.

Researching Localized Researching Localized FunctionFunction

NeuropsychologyNeuropsychology – comparing – comparing patients with localized brain damagepatients with localized brain damage Single dissociationSingle dissociation – single patient has – single patient has

some things impaired, other things not some things impaired, other things not impairedimpaired

Broca’s Aphasics, Wernicke’s aphasics, Broca’s Aphasics, Wernicke’s aphasics, ProsopagnosiacsProsopagnosiacs

Double dissociationDouble dissociation -- two (or more) -- two (or more) patients show opposite single impairmentspatients show opposite single impairments

Broca’s & Wernicke’s Aphasics considered Broca’s & Wernicke’s Aphasics considered togethertogether

Double DissociationDouble Dissociation

FormForm

““The boy was The boy was pushed by the pushed by the girl”girl”

MeaningMeaning

““The apple The apple was eaten by was eaten by the girl”the girl”

Broca’s Broca’s AphasicsAphasics

ImpairedImpaired OKOK

Wernike’s Wernike’s AphasicsAphasics

OKOK ImpairedImpaired

What can we conclude?What can we conclude?

Double dissociationDouble dissociation Two functions involve different mechanismsTwo functions involve different mechanisms Two functions involve different brain areasTwo functions involve different brain areas Mechanisms Mechanisms areare independent independent

Single dissociationSingle dissociation Two functions involve different mechanismsTwo functions involve different mechanisms Two functions involve different brain areasTwo functions involve different brain areas Mechanisms Mechanisms may not bemay not be independent independent

Limitations of Limitations of NeuropsychologyNeuropsychology

At least for human processing, brain At least for human processing, brain damage comes about from natural means damage comes about from natural means (accident, etc.)(accident, etc.) Members of groups rarely have exactly the Members of groups rarely have exactly the

same damage (location or extent)same damage (location or extent) No record of processing or brain organization No record of processing or brain organization

before the damagebefore the damage Difficult to assess all possible types of Difficult to assess all possible types of

functional impairment functional impairment Brain may actually reorganize following Brain may actually reorganize following

damage (called damage (called plasticityplasticity))

Imaging MethodsImaging Methods EEGEEG- Electrodes on outside of head continuously - Electrodes on outside of head continuously

measure electrical activitymeasure electrical activity PETPET- Radioactive dye injected, accumulates in - Radioactive dye injected, accumulates in

different regions over time and can be read by a different regions over time and can be read by a scanner. Essentially measures metabolism of neuronsscanner. Essentially measures metabolism of neurons

fMRIfMRI- Brief magnetic pulses used to give a snapshot - Brief magnetic pulses used to give a snapshot of ratio of oxygenated to deoxygenated blood of ratio of oxygenated to deoxygenated blood (metabolism)(metabolism)

TMSTMS- New measure. Magnetic field can disable - New measure. Magnetic field can disable specific portions of the brain for a short time, specific portions of the brain for a short time, simulating damage.simulating damage.

Temporal resolutionTemporal resolution: Detail with respect to time: Detail with respect to time Spatial ResolutionSpatial Resolution: Detail with respect to physiology: Detail with respect to physiology

Image from an

fMRI scanImage from a

PET scan

Imaging MethodsImaging Methods

Spatial Spatial ResolutionResolution

Temporal Temporal ResolutionResolution

EEGEEG PoorPoor GoodGood

PETPET ExcellentExcellent PoorPoor

fMRIfMRI GoodGood GoodGood

TMSTMS GoodGood GoodGood

Subtraction TechniqueSubtraction Technique

Used for fMRI studiesUsed for fMRI studies Method similar to Method similar to

Donder’s studyDonder’s study Compared two Compared two

situations that situations that included different included different cognitive processescognitive processes Data = blood glucose Data = blood glucose

levellevel Relative measureRelative measure

Visual Stimulus (light flashing)

Perception of the light

Response

Visual Stimulus (light flashing)

Perception of the light

Response

DECISION

Subtraction TechniqueSubtraction Technique Activation in Activation in

control control condition is condition is subtracted from subtracted from experimental experimental condition to get condition to get activity due to activity due to stimulation in stimulation in the the experimental experimental conditioncondition

The EndThe End

Next up: Representation in the BrainNext up: Representation in the Brain