Cognitive Neuro Exam 2
Kosslyn has proposed: LH may be specialized for categorical spatial representations because they can be represented in verbal terms (e.g., "Left", "Right," "Over," "Under") RH may be specialized for more quantitative (coordinate) spatial relations (e.g., exactly how far is it), because it is superior for visuo-spatial processing, including mathematical/quantitative processing
"Where" pathway processing of spatial relations
Study of the neurobiology of emotions -Offers new ways to test old questions, e.g., are emotion and cognition independent or dependent systems? (Answer: both) -Key areas include emotion perception and emotion production --how we process information with emotional content and how we produce it -Seeks the neural bases of individual differences in emotional processing/function --Basis of personality --Basis of social attitudes --Basis of vulnerability to psychopathology
Affective Neuroscience
-impaired "percepts"rather than vision -due to posterior right hemisphere lesion -loss of object constancy (ie changing the position of an object makes it unrecognizable) Failure of higher-level "what"system to maintain object representation
Apperceptive agnosia
-SMA/Premotor Cortex and/or parietal lesions (usually left hemisphere) -Inability to execute learned purposeful movements -Despite having the desire and the mechanical capacity to perform the movements (intact ability to move muscles). -Tested by asking subject to pantomime an action
Apraxia
-Agnosia due to "semantic" impairment -Damage to left hemisphere "what" pathway -Cannot match by function
Associative agnosia
-Multivariate Pattern Analysis indicates that emotions that feel different are indeed represented by distinct patterns of activity across the brain -Neural activity supports distinct categories (e.g., anger vs. happiness) as opposed to a continuum of arousal or pleasantness -Different patterns in the brain for different emotions --look across broad areas of the brain and see the diff patterns (instead of focusing on PARTS of the brain that do certain thing)
Broader patterns of emotional representation
-impaired initiation of movement -tremors (e.g., pill rolling of fingers) -muscular rigidity (frozen appearance) -very slow movements -problems with posture, balance -characterized by loss of dopaminergic neurons in substantia nigra -unknown cause -movement deficits are most pronounced when movement is guided by voluntary internal cues -treatments: -drugs that supply synthetic dopamine (L-dopa) -Deep brain stimulation -progressive & degenerative
Parkinson's disease
-Fusiform gyrus activity actually reflects a lot of things -Voxel analysis: look at patterns can help decode representation -These complex patterns are observed both when objects are seen and when objects are later remembered -Often distributed within a specific region (e.g., fusiform for faces) -Different categories of objects can be decoded -Voxels in the same general place of cortex -Different activity for different objects and categories --WHAT pathway, but it's distributed
Perception of objects through complex patterns of neuronal firing (Haxby et al., 2001)
-Was a railroad foreman (important job with planning etc) -Got injured with a spike: gunpowder was incorrectly prepared and the spike shot thru orbital bone -didn't die but had major brain damage there -Studied by doctor -Back and forth between flat affect and socially inappropriate behavior -Entire personality changed: this is whats so interesting about him -Such a stark change with changing brain -Out of control or affectless: unrecognizable
Phineas Gage
These were the effects of his injury
Phineas Gage Quote
Perception of movement of own body and joints -Even with our eyes closed we know what position our bodies are in and how it is moving or changing -Need signals other than visual then When our bodies are moving that signal is sent not only to the body from the brain but also to the somatosensory cortex which allows us to anticipate what we are going to feel when we move -Need to be able to distinguish which sensations caused by us and our own movement vs. by the environment -Keep us from being startled by volitional movements -This is why we can't tickle ourselves
Proprioception
The shape of sounds, feel of sounds rather than language chunks -Musicality of language Airport example: hear a bunch of languages that you do not understand but can kind of figure out emotional content based on the prosody
Prosody
Selective impairment of face recognition -Object recognition is relatively preserved -Face recognition is impaired -The fact that only face recognition can be impaired without the impairment of ID-ing other objects indicates that this process is probably special -Not all or nothing: difficulty with face recognition in high or low levels -Even in healthy cognition, faces are processed differently than objects --Therefore dissociation in brain damaged people with this condition -Healthy individuals --Diffs in response times in cog psych --Diffs in functional brain imaging
Prosopagnosia
Prosopagnosia: Can read words, but can't recognize handwriting Alexia: Recognize handwriting but cannot read -Handwriting=holistic -Reading has more to do with parts DOUBLE DISSOCIATION Neural systems between receptive processing and internal storage = shared -what we have stored can shape what we see
Prosopagnosia vs. Alexia
Semantic categories are defined by central, anchoring prototypes -not by necessary and sufficient criteria (Aristotle) -other items are judged by similarity to those prototypes -How humans represent things in their brains -People think categories are described by criteria but category criteria is not actually that clear -What humans actually do is base categories on exemplars/prototypes -We all have prepotent ideas of the best exemplars -We compare what we see to prototypes not by checking off a list of criteria
Prototype Theory
Characterized by temporal grading of memories from oldest memories to memories from just before brain damage or onset of dementia Indicates that the neural storage of memory is dynamic (changes over time). Otherwise damage would affect old and new memories equally. Gradation between more recent and older mems -ability to recall things from the more recent decades the worst -way that memory breaks down is graded -Best kept memories from much earlier in life
Retrograde Amnesia
-When we make a decision, we evaluate the various options by considering a "marker"of the physiological affective states associated with each option (i.e., "how would this feel?") --We think about how it would feel to make a certain decision --Consider how body would feel between both options --Also for non-somatic feelings (like dentist): also for other decision --Brain damage: hard to pick pen or pencil even; to Damasio that means that there is an element about how we feel that goes into every decision that we make -Somatic markers thought to be stored in Orbital VMPFC -Precursor: James-Lange Theory (reaction of the body leads to reaction of the mind/emotions) --Look at how bodies react to a stimulus then shape the narrative about how we feel about it as opposed to the other way around --James not really correct with this What happens when there is loss of somatic markers (due to brain damage): -Thought without emotion -emotional responses do not modulate patients' decision making --prolonged indecision or flat skin responses in galvanic -"flat"Galvanic Skin Response (an index of arousal) in anticipation of emotional stimuli -Somatic markers are how we imagine how things WILL feel like -Without these somatic marker, it shouldn't affect how we feel once something good or bad actually happens but how we go thru the decision making process and how we feel during that process
Role of emotions in decision making: Somatic Marker Hypothesis (Damasio)
Told participants they would receive a large, painful shock -Didn't do it but they convinced the participants they would -Looked at brain when they thought they would get shocked vs when they thought they would be unharmed Expectation of aversive stimuli (shock) activates left amygdala -indicates role in explicit emotional knowledge (i.e., expectation) -fMRI of normal subjects during "threat" vs. "safe" conditions
Role of the amygdala: explicit emotional knowledge
Lexical network: associative proximity -words that are similar in meaning are somehow closer to each other in their neural rep than words that are more unrelated in meaning -Therefore, when thinking of one thing it is less work to think of related things or things in the same category -With priming, the neural activity from doing first thing can be "borrowed" when doing the next thing if they are related -ie network of neurons that represents "car" likely overlaps with the one repping "truck" -Overlap in networks is liekly greater with words that are more similar in meaning as is the pattern of activity
Semantic organization
Semantic priming is.... -Preserved in amnesia= so not the medial temporal lobe -Preserved in Huntington's= so not the striatum/Basal Ganglia -Preserved in Patient MS= so not the visual cortex Impaired in Alzheimer's -therefore it depends on temporal-parietal-frontal cortex (not occipital lobe though)
Semantic priming and brain issue
Facilitation of word recognition due to semantic association -perception and processing of words affected by semantics -People are faster at naming and lexiscal decision task when words are semantically related/there is semantic priming
Semantic priming effect
Priming can also be based on conceptual/semantic information -Based on the actual meaning of words/word categories
Semantic/conceptual priming
-Naming game: animals ("write the name of five animals) -Several commonalities across participants and with different categories Prototype- exemplar that is most representative of a category
Semantics
Primacy effect: remember things that come first better -reduced in anterograde amnesia (if short-term memory is affected) Recency effect: remember things at the end of the list better (intact in anterograde amnesia)
Serial position effect: Primacy effect vs Recency effect
Set shifting: start thinking of one thing then need to start thinking about another thing ex: learn one sequence based on shape then learn another based on color -this shift slows people with Parkinson's down substantially (reaction time goes way up)
Set shifting impairments in Parkinson's disease
LH: better at processing high spatial frequency information -Allows perception of details (local) RH: better at processing low spatial frequency information -Allows perception of whole (global) Both hemispheres receive both high and low frequency input, but process differently Processing bias of the two hemispheres
Spatial Frequency Hypothesis
Semantic context -Prepotent meanings--interpretations of words can be altered by context (ie rose and bank) -Context matters: process words as products of semantic context
Factors in language comprehension: Semantic context
Learning transfers from one hand to another -If you learn a skill with one hand, the other hand also gets slightly better at it even if you do not practice with it -Better than if u had never practiced with it at all -This is bc planning is bilateral Applications for sports psychology -Planning motor activity and going through it in your head actually does some of the work for you when you are practicing
Implications of hierarchical (top-down) organization of motor control
-This is impaired in Huntington's disease Huntington's Disease Genetic degenerative disease affecting the basal ganglia structures (striatum: caudate and putamen -Impaired Rotary Pursuit and Implicit Sequence learning
Implicit Learning and motor skills
-Skills and learning -Conditioning -Priming
Implicit Memory Subcategories
-Preserved in amnesia Mirror drawing: something occludes hands but can see the reflection of hand (learning new way to draw) -Can learn how to fix -Initially make mistakes but then get better at it Rotary Pursuit: hold pen on a dot as it goes around -get better over time -Procedural memory Sequence learning task -Implicit pattern/sequence learning -Pick up on the pattern implicitly (not conscious) -Observe in reaction time (get faster over time)
Implicit learning: Skills and Habits
-Orbitofrontal prefrontal cortex -Ventromedial prefrontal *image is positioned from the bottom of the brain -Amygdala --Prefrontal cortex in general
Important brain structures for emotion
-object recognition by parts, not as a whole -due to damage in extra-striate cortex (higher-order visual cortex)
Integrative agnosia
Vision is thought of as TWO different kinds of processing/analyses -ANALYTICAL= process by combining parts -HOLISTIC= process as configuration Looking at individual parts and putting together but focus mostly on parts VS focus on the thing as whole Example: When learning to read you start by looking at each letter but now we look at the word as a whole/shape of the word -Faces are more holistic --We don't recognize faces based on their individual parts but as a whole/combo of all of those features -People with prosopagnosia can see and recognize different parts of a face individually but cannot put the pieces together holistically
Model by Farah: Two perceptual systems in vision
-A lot of the brain is dedicated to moving our bodies -Size of body:size of brain ratio -Moving and feeling body is complicated so it makes sense that there is a lot of brain dedicated to doing these things Ex: Motor function while playing the piano -select: match finger to key -sequence: group notes into a phrase -force: strike accented notes with greater force -timing: establish rhythm These are all really complex processes
Motor Control
-Pyramidal motor neurons originate in layer V of primary motor cortex and other cortical regions (there are 6/VI total layers) -Pyramidal axons decussate (cross over) in the medulla oblongata Outgoing info travels along particular cells: PYRAMIDAL cells -Extremely long: axons of single cells travel long distances -Axons start at the cortex and go through white matter, through brainstem, cross over at the medulla oblongata to the vertebrae -At the spinal chord, each vertebrae sends axons out to control muscles near by (ie hips and feet are lower while arms higher) Ex: axon coming from the foot area of the motor cortex will go all the way down to the vertebrae responsible for feet (connects to an interneuron at the vertebrae that connects to the actual muscle) -Because these neurons are so directly involved in in moving our bodies, we can get info out of them by using signals to read what our brain wants the body to do
Motor Pathway
-Hemisphere studies reveal insights into Local and Global levels of perception Perception at global level: House Perception at local level: Window Right = GLOBAL dominance Left = LOCAL dominance
Object processing (what pathway)
-Associated with parietal damage (where pathway) -Normal vision -Can recognize, name, and describe objects -Cannot reach for objects in space Video: patient can see that there is a lock in front of him but cannot grab it
Optic Ataxia
-How do separate features combine into one percept? -Ensemble hypothesis requires putting together diff types of information--how do we do that? -Even at early level, functional segregation separates information but how is it re-integrated? -e.g., purple + circle = purple circle -We are still unsure
The Binding Problem
Medial temporal lobe structures are important for encoding, but aren't the site of long-term memory storage. -Patient HM had medial temporal resection and this had effects on some kinds of memory but not others--so where is memory stored in the brain? Remember Lashley's experiments with rats: -memory deficit depended upon the amount of cortex removed -location of lesions did not matter -conclusion: "memories are stored in a distributed fashion"
The search for the "engram" (where is memory in the brain?)
This can be seen in lesion evidence from monkeys
The what pathway is both functionally and structurally different from the where pathway
Results: Ventral ("what") pathway object recognition regions that were activated during encoding of object pictures are re-activated when subjects remember those pictures based on word cues. -Visual system activation even though there's no picture -Thus, regions involved in perceiving an object also contribute to storing/representing the object in memory. -Based on these results, we learn that memory is modular
Vaidya, et al results (fMRI study on words and pic encoding)
Deficits in emotional/affective responses after ventromedial prefrontal damage: -"flat"affect and/or-loss of socially appropriate behavior -poor decision-making -Phineas Gage
Ventromedial prefrontal area
-Damage to the temporal cortex (what pathway) -Normal vision acuity -Cannot recognize objects or ID pics of objects -Can describe object if given name (in some cases) -Can name and describe objects if placed in hand (in some cases--this is because they are using other sensory cues) -Can often use motor-system responses as clues for what the object is --i.e, in the video the man uses his motor response to seeing the lock as a clue to correctly identify it
Visual Agnosia
Apperceptive agnosia Integrative agnosia Associative agnosia Category-specific agnosia
Visual agnosias
-Where= Dorsal;What= Ventral Dissociation between What and Where systems is supported by evidence from: --Single-cell recording --Lesion studies in monkeys --Brain damaged patients --Brain imaging studies Single cell recording -Individual neurons recorded -If record neurons in... --PARIETAL LOBE (dorsal/where): the cells are senstitive to stimulation from the periphery and fovea --TEMPORAL LOBE (ventral/what): the cells are sensitive to stimulation from the fovea (what you are looking at, i.e.) -The fovea is for detailed vision which is really important for figuring out WHAT something is (details and color). So, it makes sense that these neurons go to the What pathway -The where pathway needs to be able to track things across the retina and those things cannot be lost track of. Therefore, the Where aspect of vision needs the whole retina
Where vs What pathways
-Almond-shaped structure -Amygdala response to finger cookies in halloween -Critical role in ascribing affective meaning to stimuli --should I be afraid or disgusted? -Kluver-Bucy syndrome: damage to bilateral amygdalae: do not avoid fearful stimuli --Usually animals: gorilla won't respect dominance hierarchy --Fear is important in existence -Animal studies: neurons in amygdala respond to affective nature of stimuli--especially fear. -Human studies: critical role in emotional memory and evaluation of emotional stimuli--especially fear and disgust --Amygdala doesn't STORE memories but provides a signal for which memories should be better remembered bc they were emotionally salient (esp. if something rly good or bad happened) --Evolution: remember bad things so they can be avoided in the future
Amygdala
-Why doe we remember negative things? LEARN to remember things that we should avoid How will people respond when we pair a negative stimulus with a neutral tone? -Neutral tone paired with ugly sound -Associate neg stim with neutral stimulus -Before people learn that they are paired consciously, they implicitly learn this -Affective response to negative US even before they consciously/explicitly make that connection (implicit response) -People with damage to amygdala had lower GSR than the controls -Therefore amygdala is important in the implicit learning of emotional stimuli or IMPLICIT EMOTIONAL LEARNING -Once explicit learning begins, even people with amygdala damage can make the connection --Anterograde amnesia cannot do explicit learning Deficit in fear conditioning following amygdala damage but intact conscious knowledge of the association between CS and US -indicates role in implicit emotional learning -opposite dissociation is found in amnesia -amygdala and hippocampal damage represents a double dissociation between implicit and explicit emotional learning
Amygdala: Role in emotional learning
-In neuroimaging studies of normal subjects, amygdala activation is correlated with memory for emotional materials. -Patients with Urbach-Wiethe syndrome (bilateral amygdala calcification) show impaired memory for emotional portions of stories. *Emotional content is more salient!! Amygdala plays a modulatory role in memory: Amygdala activity alters subsequent hippocampal function --Amy tells Hip that this mem needs to be held on to! -thought to be related to consolidation of memory for emotional events -consistent with evidence that emotional memories are more strongly retained
Amygdala: Role in emotional memory
-fMRI studies of normal subjects show amygdala activation during perception of fearful faces -Right amygdala damage impairs ability to recognize fearful facial expressions; recognition of other facial expressions is intact. -Amygdala damage does not impair the ability to interpret fear in prose or in language prosody as much as facial expressions Conclusion: Amygdala is preferentially involved in perception of fearful expressions
Amygdala: Role in recognition of facial expressions
-A deficit in naming -Anomias are a subset of aphasia -Distinct from agnosia -Caused by left inferior temporal lobe lesions -Often category-specific (can't come up with the name of a certain kind of thing ie tools, animals, etc) -Tip of the tongue feeling--not an issue with recognizing things Therefore, semantic knowledge is retained but difficulty in name retrieval
Anomia
Semantic knowledge preserved but deficit in "name"retrieval -Different lesions affect diff categories -With temporal area: some areas represent different categories based on lesion effects -SOME regional specificity but still networks across these regions as more important---cannot over simplify
Anomia deficits--lesion studies
-SMA and PMC: cognitive aspects of movement (planning and sequencing ie) -Hierarchical planning (top-down) Motor cortex and somatosensory cortex relationship -Wiggle finger, ie, very simple movement so no activation in inferior prefrontal cortex--only activated in motor cortex and somatosensory cortex (M1: if moving right hand then left M1 activated) ---the somatosensory cortex activated because not just movement but FEELING the movement -Instead of wiggling, now sequence finger tapping on the right hand --need more contributors bc this action is much more complex --Requires planning and sequencing and understanding instructions --Right hand but there is bilateral activation for SMA and inferior prefrontal cortex because it is abstract, not just direct movement, and planning occurs in both hemispheres even if moving only on one side
Beyond Primary Motor Cortex
-Show participant faces and other stuff: compare fusiform gyrus activation--more interested when shown faces Is that all it can do though? Was it made for this only purpose? Or is it because we see a lot of faces Evolutionary importance for having face skills
Brain imaging evidence
-Implicit sequence learning: Activation in the caudate and putamen (Basal Ganglia) -Explicit sequence learning: motor cortex, parietal, and prefrontal areas
Brain imaging of sequence learning
Broca's aphasia (Expressive Aphasia): deficit in language production -Seen in Tan -Lesions in inferior prefrontal cortex -Classically thought of as PRODUCTION related Classical View -Damage to Broca's area (close to motor areas) -Telegraphic speech: lacking function words -Can understand language relatively well -Words are not properly formed (difficulty repeating) -Speech is slow and slurred Revised View Also includes comprehension problems: -The dog chased the cat (active, non-reversible: Broca's patients understand) -The car chased the bike (active, reversible: Broca's patients understand pretty reliably) -The ball was thrown by the girl (passive, non-reversible: Broca's patients understand pretty reliably) -The car was chased by the bike (passive, reversible: Broca's patients misinterpret 50% of time) THEREFORE THEY MAY BE USING WORD ORDER AND CONTEXT CLUES RATHER THAN SYNTAX PROPER -Comprehension problems masked to an extent by the ability to use these semantic clues
Broca's Aphasia: classical and revised conceptions
-Non-living things are manipulable and have BOTH visual and motor representations -Living things only really have the visual aspect -ie when someone sees scissors that might trigger a motor response for using scissors -There is more evidence for this explanation -Motor rep comes with visual rep especially for tools/nonliving but not really with living things
Category-Based Explanation
-Selective loss of knowledge from a specific category -Example: living vs non living things
Category-specific agnosia
Cells in visual cortex have (on / off) receptive fields that encompass the receptive fields of many lower-level cells. -Simple cells have inhibitory regions that surround the excitatory regions Narrow stimulus: Maximum response of a neuron with a small receptive field (high spatial frequencies) Wide stimulus: Maximum response of a neuron with a large receptive field (low spatial frequencies) This leads to Spatial Frequency Hypothesis
Cellular basis for differentiation
-Memory is the strengthening of synaptic interactions among regions involved in experiencing an event Hebb's Law "When an axon of cell A is near enough to excite cell B and repeatedly or persistently takes part in [exciting] it, some growth process or metabolic change takes place in one or both cells such that [the strength of the synaptic connection] is increased." -Cells that fire together, wire together Long-term Potentiation (LTP) Refers to strengthened synaptic connections between neurons that fire together over time (e.g., in hippocampus) --Important physical manifestation of memory and learning
Cellular basis of memory
Cerebellum is not only a motor structure--It represents timing information Evidence from eye blink experiments -Train rabbit to blink before air puff; pair air puff with a tone -Bunny will blink at the tone even with no air puff eventually: they learn timing between the tone and air puff -If the cerebellum is lesioned, air puff timing is off
Cerebellum and timing
-Cerebellum is widely connected to many cortical and subcortical regions to aid in timing of a variety of cognitive functions -Cerebellar and prefrontal activity are tightly linked -Timing of cognitive functions and thoughts too----not JUST timing
Cerebellum functions
-What and where can break independently: this is a clue that they are separate systems
Conclusions from describing ataxia and agnosia
Fear (emotional) and skeletal musculature
Conditioning
Damage to the arcuate fasciculus: white-matter tract connecting Wernicke's and Broca's areas -Comprehend words -Impaired repetition -Impaired production: know their speech errors but cannot repair them -Connection between processing/reception and the production of language Language depends upon concerted operation of a network
Conduction Aphasia
Memory consolidation is necessary in order to make memories last -Major consolidation in days after event, but can take years to complete -Hippocampus and other areas of Medial Temporal cortex are crucial -Sleep is important (animal studies suggest "re-playing" events) Can also be disrupted by injury or Electroconvulsive therapy
Consolidation
Can be studied by looking at disorders
Contributions of the Basal Ganglia to Motor Function--what we know from disorders
Cerebellar lesions -clumsy, irregular, erratic movements -coordination deficits, most pronounced in highly practiced movements (e.g., walking) ----affects automated timing -hypermetria- cannot smoothly terminate movements **Police use tests of these symptoms to identify drunk drivers because cerebellum is especially sensitive to alcohol
Contributions of the Cerebellum to Motor Function
Corpus callosum: thick band of fibers that connects the two hemispheres -White matter (axons) Kinds of axons that are involved in CC Ipsilateral: stay on same side of the brain Heterotropic: connect two different parts of brain on different sides Homotropic: connect same part of brain on different sides
Corpus Callosum
-Not just M1 -Various parts of the brain play at least a small role in motor function Supplementary Motor Cortex (SMA) Pre-Motor Cortex (PMC) Position: Central sulcus, then M1 just in front of that, then PMC and SMA -SMA is dorsal and almost near the inter-hemispheric fissure SMA and OMC involved in higher-order motor functioning not just sending info to the spinal column --do stuff that leads up to that signal -Posterior areas of parietal cortex also play a role
Cortical motor areas
-All of this points to the need to consider the role of emotion in decision making -Clearly emotions play a role and they are intertwined -Is this the best hyp the best way to think about it? Maybe or not Criticisms: -Inefficient to "feel" the marker for every possible option --Bc the number of options you have at any time is technically infinite --Choices aren't always this or this; difficult when there are more options bc cant rep everything distinctly -Reinforcement association learning may be sufficient (e.g., Hebbian strengthening of orbito-striatal circuits based on reward incentive learning) --If we made a decision before and it went well, that is reinforced so we have strong biases to act in ways that have worked for us before -Depression: worse at decision making bc not as much emotional feeling
Criticism of the Somatic Marker Hypothesis
Declarative -Consciously recollect past experience and learn info -Impaired in amnesia -Facts and events -"THAT" -Encoding , consolidation, and retrieval depend on hippocampus and medial temporal lobe -Storage occurs in the cortex Non-Declaritive -Unconscious change in behavior due to past experiences without awareness -Preserved in amnesia -Anticipate without awareness -"HOW"
Declarative (explicit) vs. Non-declarative (implicit)
-The brain detects semantic incongruency about 400 ms afterword presentation -Independent of modality (e.g., written vs. spoken) Language best studied using tools that tell us WHEN something is happening (ie not fMRI but EEG and ERP) -Language happens quickly -In this experiment, they were looking at what happens in the brain when presented a semantic inconsistency (think sentence is going one way but it actually goes another way) -Look at the brainwaves for unsurprising sentences vs inconsistency sentences -Control was a perceptual surprise (ie make one word look bigger) Found that: -When there is a perceptual surprise, the wave changes at P560 (wave goes down 560 ms after presentation) -When there is a semantic surprise, there is a distinct change in waveform at N400 (goes UP at 400 ms)
Detection of semantic anomaly
-Need to use ERP because timing is so specific and quick -Left frontal cortex -ERP studies show a positive peak 600 ms after syntactic violation --Called the Syntactic Positive Shift (SPS)
Detection of syntactic (grammatical) anomaly
Can tell us a lot about the contributions of different brain areas to motor function
Disorder of motor control
Agraphia: inability to write Alexia: inability to read (Pure Alexia: letter by letter reading and can write) These two conditions can co-occur after damage to angular gyrus BUT can have one without the other so double dissociation This means: Distinct systems for interpreting written language and for producing written language
Disorders of written language
-Consolidation done with activityu in medial temporal cortec Results of ECT: -2 mo following ECT and 6 mo. before= problems -Those shaded memories lost This tells us that consolidation happens for at LEAST 6 months (and maybe more than that) after an experience that you remember actually happened -At least 6 months to encode that into memory storage AND that after effects of ECT continue to disrupt electrical activity for 2 mo. after treatment
Disruption of consolidation due to ECT
Yes
Does the hemispheric distinction we find in the "what" pathway (e.g., for stimulus identification) apply to the "where" pathway? (e.g., for stimulus spatial relations)
Patient MS (lesion to visual cortex) -Impaired priming -Preserved explicit memory Amnesia -Preserved priming -Impaired explicit memory Relationship to visual cortex again indicates that there is a perceptual basis for some forms of priming
Double dissociation between priming and explicit memory
Look at the diagram
Elements of language
Subjects are slower to name colors of emotional words -Suggests automatic reading is harder to suppress because of the emotional meaning of words -Effect of emotion on cognitive function is what is being studied here -Say color of the word not word itself: harder to say emotion words -Why is the way we tested this in class not great? --Priming --Practice effect: better at doing the second list because you are more used to doing the task itself Autonmatic reading is slower because when u read a word with an emotional salience (if it matters to u) then it is harder to ignore it and only focus on color Emotion increases salience
Emotional Stroop Task
-Particular patterns of firing across an array or network of cells encodes a particular object -Different components of the network (but NOT individual neurons) reflect different aspects of the object -No single cell encodes the whole object -It all has to do with the patterns of firing, the code sequence of this firing -The network for one thing can overlap with the network for another thing but they are not identical -This theory allows for a higher degree of flexibility
Ensemble Hypothesis
-Double dissociation between optic ataxia and visual agnosia Optic Ataxia: can recognize objects but cannot use visual information to guide actions to reach object's location Visual Agnosia: impaired object recognition in the presence of preserved perception (can locate, reach); object information can be accessed through other modalities (e.g., touch)
Evidence from brain-damaged patients
-WHAT processing is inter-hemispheric (uses input from both hemispheres) -WHERE processing is intra-hemispheric (occurs within one hemisphere) This was studied through lesion work in primates too -Monkeys do WHAT task: there are no impairments if V1 is lesioned on one side and the temporal cortex is lesioned on the other (eg right V1 and left temporal) --This suggests that inter-hemispheric processing is occurring --Right V1 cannot see and left Temporal cannot process so info has to cross and the hemispheres have to communicate -The impairment occurs with ADDITIONAL lesions to the corpus callosum Conclusion: WHAT processing is inter-hemispheric
Evidence from combination lesion studies: What pathway
-Impairment after lesions to right V1 and left parietal lobe -Lesioning corpus callosum only slightly worsened performance Conclusion: WHERE processing is intra-hemispheric
Evidence from combination lesion studies: Where pathway
Recognition of upright faces is superior to recognition of inverted faces -This strong orientation-dependency cannot be seen with non-living objects like a screwdriver -So there is a specialness in the way things are represented in the brain as well as in the way we process certain parts of stimuli
Face inversion effect
Both hemispheres can do task but differ in RT
Experiment to test global/local processing
Confusing sentences but they make sense to us (ie the old lady bites the gigantic dog) Garden-path sentences: initially lead to one interpretation, but by the end of the sentence, you change your interpretation -Ex: "Fat people eat accumulates" -Ex: "The horse raced past the barn fell" -These give us head fake: think they're going one way but then actually end up going in different directions -This is because we think we will get meaning but SYNTAX forces in different direction --shows need to follow syntax in order to generate meaning
Factors in language comprehension: Syntactic structure
-Lesioning the amygdala impairs learning of the conditioned fear response Experiment: Put rodent in a box -Box plays sound then electrocutes it -After a while, the rat will respond fearfully to the sound even if it is not paired with a zap -The amygdala is near the hippocampus: link between memory and fear
Fear conditioning
-Greebles experiment -Researchers created these little creatures called Greebles and wanted people to study them and to know their characteristics/faces --Their "faces" were not like human faces but rather had learnable features -Can people become experts in visual recognition of greebles? And is the fusiform gyrus important for faces specifically or for visual expertise in general? Looked at activation when looking at human face vs greeble novice vs greeble expert There is evidence that fusiform is not just for faces... The area is predisposed to process faces This can also be observed in people with expertise in birds and cars: similar activation
Fusiform "Face Area": Faces or visual expertise?
-Show patient word/image only one side of screen (right) and asked what they saw. Patient said he saw nothing, then asked him to close his eyes and let left hand draw and the hand draws image he didn't see -If image shown on the left side, it goes to the right hemisphere and right hemisphere is not generally associated with language production so he cannot say what he saw but he can draw it because right side controls the left hand. --Left hand "does the talking"
Gazzaniga video: Behavioral testing in split brain patients
-Called the Grandmother Hypothesis because "every thing has a cell including grandma so when you see her those cells fire." -Lower level cells encode lower level components of objects; and everything has a corresponding cell -A single cell art the highest level encodes the whole object whereas lower ones encode the parts. This top cell is called the GNOSTIC or GRANDMOTHER cell. -For example: When you see a table, there are cells for lines, legs, top part of the table which all lead up to the gnostic/grandma cell that recognizes the whole.
Grandmother Hypothesis AKA Hierarchical encoding hypothesis
-Age 27 years, underwent bilateral medial temporal lobe resection (including hippocampus and parahippocampus) to control severe epilepsy -Fewer seizures after -IQ in tact -Childhood memories intact -BUT profound side effects: --Anterograde amnesia -inability to learn any new information --Retrograde amnesia- inability to remember pre-surgical information dating back to ~ 3 years before the surgery
HM-Case study of amnesia
-Hot pop psychology topic -SOME structural asymmetry (regional size, cytoarchitecture) -SOME functional asymmetry BUT there is a lot in common between both; more similar than different
Hemispheric Specialization: misconceptions
Approach Vs. Avoidance (model by Richard Davidson) *model is continually updated Two primary systems of emotional processing: affective styles -Based on lesions of prefrontal cortex -Either more approach or more avoidance -Approach: when there is a stimulus or another person etc, the approach means that that person wants to approach the thing or person and interact -Avoidance: Something new--don't wanna check it out though Left Hemisphere -Approach -Positive Emotions -Depression after LH damage Right Hemisphere -Avoidance -Negative Emotions -Mania after damage to RH (too MUCH appraoch): seen in bipolar disorder *Need some of both!! But the balance is not perf equilibrium therefore...... May be a basis of personality: left/right differences in EEG studies in normal subjects relate to self-report of personality
Hemispheric specialization for emotion
Dissociation between emotional perception and production -Some functions more left or right Emotional perception -Right hemisphere dominance -evidence from perception of emotional content of language prosody --Airport example: hear people speaking at an airport and u don't understand the language they are speaking but you can kind of tell the emotional content of what they are expressing based on cadence and rhythm -evidence from recognition of facial expression --fits with split brain studies because right hemisphere is more involved with global processing as opposed to individual words being more local --also RH more involved with face processing bc faces seen/processed more globally than as parts Emotional production -laterality is not strong -right hemisphere dominant for emotional prosody production ---To produce speech with emotional content, ie (emotional prosody) -production of facial expression: ---voluntary: left hemisphere ---spontaneous/reflexive: subcortical pathway -More to do with motor control/function
Hemispheric specialization for emotion
Why lose representation of living things and NOT non-living things? Property Based Explanation Category Based Explanation
How can we account for category-specific deficits?
Same visual presentation strategy used for split-brain patients: Visual hemi-field presentation without eye movements -Exposure duration must be under 200 ms Which visual-field yields a faster response? -LH or RH advantage -Effects are very small (~20 ms) because information is quickly shared between hemispheres in a healthy brain Interpretation: LH or RH has better access to the information/process required for the task (LH or RH dominance)
How can we study hemispheric specialization in normal cognition?
Voluntary action -Action plan (premotor cortex, SMA, inferior prefrontal) -Action execution (primary motor cortex) -Modulatory role (Basal Ganglia, Cerebellum) Reflexive Action -Reflexive circuits (spinal cord) Hierarchical because cortical processes are above subcortical processes PMC and SMA are for more abstract things; contribute to the cognitive aspects of planning -Don't tell muscles what to do directly -Motor planning -Planning more involved in making movements -Inferior prefrontal cortex also plays a role in this -When moving on purpose When it's time to actually send signals to the body from the brain this is called the action execution stage -Largely primary motor cortex -Pyramidal cells with long axons communicate Subcortical brain structures play a largely modulatory role -Don't directly plan or execute but help those processes out -Basal Ganglia- motor initiation, initiating voluntary action -Sequencing too: automatic and implicit -All subcortical areas are more involved in the more automatic part of action --Like walking, etc --Do without thinking of it --Autopilot -Cerebellum is important for coordinating and timing movements -Movements are complicated and require multiple moving parts with coordination -Need to move at the right time
How do cortical and subcortical brain regions work together to produce motor function?Hierarchical organization
Resecting parahippocampal cortex impairs performance -This was tested in an animal study in which the monkey watched food go in a place and then had to remember where it is Resecting perirhinal cortex causes additional impairment -Structures have an ADDITIVE effect: the more you take out or damage, the worse the impairment Resecting amygdala does not substantially impair performance -Amygdala does not appear to contribute to memories that are not emotional
How much do the regions in the medial temporal lobe that surround the Hippocampus participate in memory?
Task: 2 decks of cards and can win or lose money when picking a card -In pile A, can win or lose in big amounts but in pile B can only win or lose in small amounts -Intact somatic markers: when reach for card in pile A there is a bigger sort of anticipatory change in GSR because they are a bit more nervous so Auto NS more aroused BUT people with damage to the ventromedial prefrontal cortex: -Intact "reactive" GSRs but lack of "anticipatory" GSRs in ventromedial prefrontal patients -cannot guide action based on emotion This, to Damasio, distinguishes semantic markers from the ability to process affective events in a reactive way
How was the somatic marker hypothesis tested?
-loss of striatal neurons -cause is genetic; no cure -progressive degenerative -involuntary choreoform movements -cognitive problems -dementia
Huntington's disease
Category vs Property AND Modular vs Distributed -More likely that info is stored in a distributed way with some things being more modular -Semantic info can be broken up in different ways (modular vs distributed) -Patterns across networks -Distributed might be right most of the time but somethings are special: ie how we process faces
Hypotheses for how semantic knowledge is organized in cortex
Category vs property based
Hypotheses for how semantic knowledge is organized in cortex
An area in fusiform gyrus (inferior temporal lobe) has been called the Fusiform "Face Area" -Located at the bottom of the temporal lobe where the gyrus runs -Functional evidence from lesion studies and fMRI studies
Is there a brain area specialized for faces?
*Newborns prefer mother's voice over father or other women -in-utero perception of sound *Newborns prefer mother's native tongue over other languages -perception of prosody of language *Size of vocabulary at 2 years depends upon how talkative the mother is to the child Speech segmentation: detecting boundaries between words is not easy or obvious. So, this requires experience/practice. The brain set up to do certain things really well and language is one of those things. -The brain might be hardwired to learn language well but need experience to develop and experiences can increase learning
Language acquisition is a product of experience
-Apraxia can affect speech and language production -As severity of apraxia increases so does the likelihood of aphasia
Language and motor impairments can occur bc speech is a motor act
Aphasia: Broad category that includes many deficits in producing and understanding language -Broca -Wernicke -Conduction
Language breakdown due to lesions: Aphasia
Monkeys do 2 different tasks Selective deficits after parietal and temporal lobe bilateral damage -The first task involves a table with cups that are not see-through -There is a raisin in the cup closer to the landmark object: the type of object does not but the LOCATION of it or WHERE it is does -This is called the Landmark task -The monkey is supposed to get better at the task as time goes on -With a lesion to the temporal lobe and with no lesion at all, the monkeys improve -BUT with a lesion in the parietal lobe, the monkey does not improve -The second task was called the Object Discrimination task -In this task, the location of the objects didn't matter. The raisin was always located closer to a particular object -With this task, the monkeys with lesioned temporal cortex did worse DOUBLE DISSOCIATION
Lesion evidence from monkeys to support the hypothesis that what and where pathways are different
Dissociation between global and local perception: RH patients (LH processing): Local LH patients (RH processing): Global The patients with RH lesion clearly processing the local level bc they can see the Z's but not really the M. Therefore, global processing is impaired The patients with left hem lesions really focus on the global bc there are no Z's drawn at all
Lesion evidence: Unilateral lesions of temporal lobe (what pathway)
Declarative (explicit) vs. Non-declarative (implicit)
Long-term Memory
-We can measure emotion directly and/or indirectly Direct -Access a person's affective state -ie make people watch sad turtle video and then ask about emotion -Ask for a self-report (how do u feel?) eg after a manipulation of emotional state (mood induction, reward/punishment) -Recognition (eg observing facial expressions, body language) Indirect -Measuring arousal of autonomic nervous system (eg Galvanic skin response, or GSR) --GSR- Galvani zapped frogs and make legs twitch: ANYWAY look at skin conductance of electricity bc it changes with the ups and downs of the autonomic nervous system. This is because our pores get sweaty when Auto NS ramps up and that water conducts electricity better -Brain imaging of emotion related brain systems -Measuring the effect of emotion on cog function by the inhibition or facilitation of a response (eg Emotion Stroop Task)
Measures of emotion
Memory is the ability to record, retain, and retrieve experience Encode--consolidate--storage Consolidation= the process by which we take things we experienced and turn them into memories. Interesting especially because memory is dynamic so they can be reconsolidated many times
Memory
-Category-specific left temporal activation -Regions damaged in patients were active in controls -Similar layout of categories *Nice convergence of results across different methods of studying
Naming study in normal subjects (PET)
-Look at tools vs living things in an MRI -Overall, non-living things/tools are associated with activity early in the visual system as well as the motor system ---Especially in the Left-ventral-premotor area This explains the difference between living and nonliving things and the way the patient moved their hands when seeing the lock This can be used as a sort of coping mechanism for people with this condition. They can wait and see what their motor system "says" in order to distinguish things
Neuroimaging evidence for the category-based explanation
Habituation: learning to reduce or eliminate a response to a repeated stimulus -Stimulus initially triggers a response, but over time the response is reduced Over the course of repetitions, neurotransmitter release decreases in the neurons of the reflex pathways -This occurs in the spinal column--not even in the brain yet
Non-Associative Learning
-Damage to ventral (what) pathway, but dorsal (where) pathway was intact. -Unable to recognize the orientation of a slot -However, could place a letter in it when told to place it "as if mailing a letter" -Hand "knows what to do" D.F.'s performance shows that the "Where"pathway mediates knowing how to interact with objects, not just knowing where they are.
Patient DF
-Bilateral temporal lobe damage Task: tell us the ID of the thing you're seeing or hearing -Really bad at answering for living things in both visual and auditory presentations -impaired for living things -relatively intact for non-living Effect on auditory stimuli shows that underlying semantic processing is disrupted in this patient (not just the visual system) Therefore, the deficit is SEMANTIC (knowledge of things) -Far along the what pathway--so think of it as both visual and auditory systems
Patient JBR
-Motor neurons have preferred directions of movement -But motor neurons are broadly tuned (fire for a range of directions) -Each cell is a direction vector (like a tug in its preferred direction) -Summing vectors to make a population vector predicts direction of movement (compromise between all the tugs) -If you know the preferred direction of each cell and how frequently each cell is firing (the strength the tug), you can predict the direction of movement. -Ex: Jedi monkeys able to control mechanical arm when hooked to the brain The way that these cells work remind people of the way line-orientation cells work (get excited by a particular orientation) -In this case, each potential direction of movement is maximally exciting for a particular kind of neuron -Ex: for one cell, the most exciting direction is straight up --this doesn't mean the cell doesn't fire when not EXACTLY straight up. The cell will fire for some directions close to up and less is closer to down --Look at groups of neurons that we know their preferred direction: put all that info to tell us what direction an arm will move Population vector=what will all the tugs add up to? Weighted average of cell tugs With all of this information, we can figure out how brain wants body to move -Prosthetic limbs: read signals to move them
Primary Motor Cortex
Pre-central and post-central gyri on both sides of the central sulccus Pre-central = Motor function Post-central = somatic sensory function -Also called M1 and motor strip -V1 is called that because it is the first place in the cortex where visual information goes but this is not the case for M1 -Motor function goes FROM brain TO body -The layout of M1 is not the same as the layout of the body -The size of cortex dedicated to body parts is not correlated to size of the body part (prick hand vs back ie)
Primary Motor Cortex: overview
-Word list and fragments exercise Priming: improved performance speed or accuracy for previously encountered stimuli relative to new stimuli -Priming is preserved in amnesia
Priming
-Priming is somewhat dependent on the modality of information presentation -Priming is reduced when modality of presentation differsat study and testing (e.g. hear the word, "volcano," then see the written word-completion task). Therefore, priming is based in part on perceptual information
Priming and modality of stimulus presentation
-Perceptual priming: modality specific cortex (visual, auditory, tactile)
Priming in the brain
-Categories can fall apart -Need cell for every possible thing which means need cells for infinite things -Also, what is the boundary for "thing"? Can we see things even though we might not know what they are? YES BUT -The hand data is real -So it seems like there are some neurons that are very predisposed to be specialized for particular kinds of things that you would see -Therefore, maybe their are cells that are predisposed for hands for example ---Doesn't necessarily mean that's all that neuron CAN do--the cell is just sensitive to that input -The ensemble hypothesis is helpful because it provides a better way of explaining how we interact with the visual world: we can see different kinds of things that we may know or not --Distributed representation in the brain
Problems with the Grandmother Hypothesis
-Living things share more visual features than nonliving things -Sp when cat lost, harder to ID based on tail, snout, etc.
Property-Based Explanation
LH is faster at judging categorical spatial relations (e.g., L or R?) -Categorical representations RH is faster at judging distances (how close?) -Coordinate representations
Representing Spatial Relations
-Some debate over just how long vs. short true short-term memory is. -An important component of short-term memory is called Working Memory: The ability to hold and use information in mind even when there is a delay or a distraction (i.e., keeping information at the "front" of your mind) -Key characteristics of short-term memory are the primacy effect and the recency effect.
Short-term memory
-Can be seen in people playing sports, playing instruments, dance dance revolution, etc. Cerebellum activation -repeated coordinated movement -Practice again and again
Skeletal Musculature or "Muscle Memory"
More precisely, memory is stored in a distributed cortical network with some localization of information: -Hippocampus (and other medial temporal structures) are important for encoding + consolidation + retrieval ----Lashley lesioned cortex, so less disruption for recently learned tasks. -Long-term memories are stored throughout much of parietal, temporal, and frontal cortex -Evidence indicates that memory is often stored in a modality-specificmanner (e.g. visual, auditory, etc.) --Link between perceiving and remembering
So where is long term memory stored in the brain?
Contributions: -Each hemisphere can function independently -Hemispheres have separate strengths and weaknesses Limitations -Patients are not "normal"prior to surgery -Findings are from a handful of patients
Split brain studies in humans
-Pioneered by Roger Sperry in 1960s -Split-brain surgery: cut the corpus callosum for control of epilepsy -No transfer of information between the hemispheres after surgery (well, almost none) -No obvious side-effects; seem normal on the surface -However, careful behavioral testing revealed isolated functioningof each hemisphere
Split-brain studies in humans
RH superior for recognizing newly-learned (not familiar) faces Task: Participants are shown a group of faces, then shown another group with some of the same faces and asked to press a button each time they see a face that they saw before -RH better at face-processing bc better at global processing and faces are processed globally Results: If show faces to RH (left visual field) then accuracy is much higher than if presented to LH (right field)
Split-brain studies: Face processing
Once infants can parse language, do they remember words? Study: Give 6 month old babies words, after words presented, a passage (either contained presented word or note) was read. Researchers looked to see if they pay more attention to passage that had the familiar word or not. Acquisition of words -Infants can parse/segment language into words by 7.5 months Building a vocabulary -7.5 month old infants can also remember words after 24 hour delays
Study babies parsing language
High frequency sound information is important for lexical analysis (what are the words?) -LH dominant for word recognition Low frequency sound information is important for melody and prosody (global rhythm of language) -RH dominant for prosody recognition
The frequency hypothesis may also apply to auditory processing:
-By looking at patterns of activity in a group of people, we can learn the "code" for different representations and then use that to decode neural activity and "read minds." -How activity maps onto semantic space -Map onto vectors to find semantic content
We are now officially reading minds (Periera et al., 2018)
Wernicke's aphasia (Receptive Aphasia): deficit in language comprehension -Traditionally thought of as difficulty in understanding language -Production intact Classical View -Fluent speech (grammar, syntax, intonation, rate of speech) -But meaningless language (word salad), often including non-words -Difficulty knowing when their language is nonsensical -Damage to higher-order auditory areas (medial temporal cortex and temporal lobe white matter) -Classical "Wernicke's area" is often damaged as well, but this is not the critical area of lesion for this deficit Revised View -semantic comprehension preserved if patients are directly asked to make lexical decisions (e.g., word vs. non-word), even though they cannot use this comprehension in their own speech. -intact semantic priming Revised View summary: impaired processing/use of semantic comprehension rather than loss of this ability altogether
Wernicke's Aphasia: classical and revised conceptions
Priming reflects reduced activation (BOLD signal change) during processing of previously studied information -ie judge is words are man-made or natural but then if asked again the same activated regions respond less strongly --Work has already been done so save E -Activity is in the frontal, temporal, and parietal lobes
What changes in the brain during priming?
-Motor Test: act out/mime learned, purposeful movements (ie show me how you would open a door with a key) VS -Perception Test: Physician shows patient pictures of a hand (or a video) in motion and patient has to ID which looks like action of opening a door with a key -Motor test shows deficits that are fairly equivalent for anterior apraxia (issues with SMA/PMC) and posterior apraxia BUT anterior and posterior apraxia distinguishable on the perception test -less of a deficit with anterior apraxia than posterior Anterior= action planning Posterior= storage of action representations -With no rep of action (lesion to posterior) there are issues with motor AND perception--this means they can plan but no abstract rep -If anterior lesioned, only have an issue with motor test bc cannot plan
What do we learn about premotor and parietal cortex from Apraxia?
-Distinction between short-term and long-term memory in different patients with anterograde amnesia -Some amnesics (like H.M.) have relatively intact short-term memory (e.g., remember a list of numbers and then repeat them immediately), but impaired long-term memory (e.g., "what did you do yesterday").
What does amnesia reveal about the neural organization of memory?
Distinction between short-term and long-term memory --short-term memory (few seconds-a few minutes) can remain intact while long-term memory (more than a few minutes) is impaired Memory storage is dynamic (changes over time) --retrograde amnesia is temporally graded What is the site of long-term storage (engram) --Not the medial temporal lobe/Hippocampal region (damaged in H.M. -retained older stored memories)
What does amnesia reveal about the neural organization of memory?
Perception involves processing different spatial frequencies Spatial Frequency: low means that things are spaced further apart and change happens over a great space. High means the opposite -Local level based on high spatial frequencies -Global level based on low spatial frequencies Neurons in the visual pathway are sensitive to size of stimuli -neurons with large/small receptive fields Firing rate (excitation) of visual cortical neurons will vary for these two types of stimuli based on the size of their receptive fields
What is the basis of the global/local distinction?
Set shifting hypothesis -Not only motor functions -Modulates cognitive function by contributing to control of attention, especially for shifting cognitive "set" (representation of the task at hand). -Imbalances in basal ganglia dopamine (originating in substantia nigra) play a role in psychiatric conditions like obsessive-compulsive disorder.
What is the function of the basal ganglia?
-Facilitates function by pooling together resources of the two hemisphere (eg Visual cortex-visual fields) -Facilitates function by inhibiting competition between the two hemispheres--coordinate rather than compete (e.g., stuttering) --Neurons want to make connections and that sometimes leads to competition rather than coordination between the two sides --this is what happens in stuttering Anomalies in size/shape of the corpus callosum have been linked to various disorders (e.g., small CC in autism) but what this means for function is generally not well understood.
What is the function of the corpus callosum?
Memory encoding- demonstrated by anterograde amnesia Memory consolidation-as shown by retrograde amnesia (but not loss of very old autobiographical memories in LT storage)
What is the role of the medial temporal lobe (Hippocampus and surrounding cortex)?
-Temporal/ventral -Single cell recording: fovea AND some selective responses of neurons to specific shapes --This helps in determining WHAT things are --Some neurons fire when they see a particular thing/shape (i.e the more something looks like a hand, the more activity you can see in a particular cell) TWO HYPOTHESES: Grandmother hypothesis and Ensemble hypothesis
What pathway: How does it work?
-Demonstrate stimuli in either picture or word format for encoding -Always present word for the retrieval---not pic Compare at encoding and retrieval for these different stimuli Encoding -Activity during encoding near occipital cortex, temporal cortex in the WHAT pathway (occipital-temporal activation more for pics than words) -Same activation when looking at retrieval -If saw pic, when retrieving from word, usual system was activated --even though you didn't see a pic at retrieval, you represent a picture
fMRI study on memory storage
