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Cog neuro 2

pulvinar area and function- association nucleus in thalamus<br>- orienting! visual perception, eye movements<br>- has subregions involved in other aspects of attn
pulvinar cxns- receives info from superior conniculus, association cortex to integrate attn and oculomotor fxns<br>- projects to 2ndary visual areas, parieto-temporal association cortices
pulvinar lesionscause neglect syndromes to contralateral visual field, both voluntary and reflexive orienting attn issues
how attn modulates visual cortical regions- topographic map of contralateral visual field in fronto-parietal regions<br>- attn modulates V4 and FEF according to fMRI data
neglect- issue with orienting<br>- normal vision but deficits in attending to contralateral space, even in memory<br>- more severe/persistent with RH stroke
common neglect lesions- right lateralized<br>- frontal and parietal lesions (more common)<br>- FEFs<br>- especially temporo-parietal area (IPL/TPJ)
dorsal and ventral attn streams both involve ____ networks and are more ___ lateralizedfronto-parietal<br>right (esp. ventral)
dorsal attn system fxn, regions, response time- top-down, voluntary allocation to locations, features<br>- IPS, FEFs exert top-down influence on visual areas<br>- TMS to IPS and FEF modulates cortical activity<br>- earlier response in parietal, later in frontal
ventral attn system- bottom-up, detection of unexpected events and triggering attn shifts<br>- stimulus-driven attn control, recruited by behaviorally relevant unexpected or infrequent events
ventral attn system filtering- activity of VS surpressed-during top-down guided attn (ex. visual search) or under high visual short-term memory load<br>- filtering keeps on task for goal-directed behavior, stops distracting stimuli<br>- TPJ engaged during visual search when salient nontargets have info about target (contextual cuing)
TPJ fxn and hypotheses- large region engaged in many tasks (attn, theory of mind, episodic memory, etc.)<br>- hypotheses for a more general role for this area, such as switching b/w networks, triggered by external and memory-driven stimuli, distinct regions for diff tasks
regions thought to link dorsal and ventral systemsTPJ, right posterior middle frontal something, inferior frontal junction
WM dorsal/ventral system cxnsSLF I connects dorsal fronto-parietal regions<br>SLF II connects parietal ventral with dorsal frontal regions (damage predictor of spatial neglect)<br>SLF III connects ventral fronto-parietal regions
visual search task regions involved- dorsal network activated, ventral deactivated<br>- left TPJ and left IFG respond to contextual relevance of nontarget stimuli<br>- FEF inhibits TPJ when no informative stimuli present<br>- thus dorsal filters info to ventral, relying on interaction b/w systems with FEF and TPJ
executive attn systems- control systems that manage attn by organizing other attn systems<br>- attn not just sensory-driven, can also attend to thoughts, memories
examples of executive attn systeminhibition (vPFC, OFC, ACC, BG)<br>sustained attn (ACC, dlPFC)<br>self-regulation (medPFC)
interaction/balance b/w attn network and DMN- suppress each other based on task<br>sleep deprivation disregulates balance b/w - - - DMN and FP networks — lose ability to sustain/cognitively control attn
salience network fxn, core regions, info received- detection and filtering of salient stimuli<br>- anterior insula (subregions) and dACC<br>- assoc. with cingulate-opercular executive networks<br>- recieves sensory, motivation info
how movement relates to cognition- involves making predictions based on models created by current sensory data and prior knowledge<br>- rehearsal, sequencing, outcome prediciton, action selection
simple reflex circuit types- SC organization<br>- muscle contraction<br>- muscle spindle, stretch reflex, withdrawal reflex<br>- spinal circuits basic pattern generators; locomotion
voluntary movement areas- M1 and other cortical areas<br>- BG for selection of movement<br>- cerebellum for optimization of movement
population coding- M1 codes direction and force for movement by selective firing based on direction<br>- sum of single neuron contributions (population vector) describes movement direction
SMA and PMAboth in BA6 and involved in motor planning<br>fire before M1<br>lesions —> apraxia (loss of skilled movement)
SMA- sequenced actions<br>- internally-driven actions via input from medPFC
PMAsensory-driven actions via input from parietal
intraparietal sulcus- end of dorsal visual stream, involved in vis-guided movements<br>- location, visual attn (DAN), control of eye and hand movements
IPS regionsAIP - visual control for grasping/manipulating hand movements<br>LIP - visual attn and control of saccades<br>VIP - vis attn and control of saccades, vis control of reaching and pointing<br>CIP - perception of depth<br>MIP - vis control of reaching/pointing
BG pathwaysdirect<br>- excitation<br>- hyperkinetic when overactive<br><br>indirect<br>- inhibition<br>- hypokinetic when overactive
___ part of cerebellum important for cognition???lateral
domain general regionsregions that are broadly engaged during task performance
cerebellum motor fxns- control of movement/posture<br>- coordination, accuracy<br>- accurately timed sq of muscle contractions for skilled movements<br>- supervised, error-driven motor learning
cerebellum cxnsinputs from and outputs to:<br>spinal cord, sensorimotor and association cortices<br><br>connects ipsilaterally to body and contralaterally to CC
"Cisek's affordance competition hypothesis + role of cerebellum""- affordances are opportunities for action defined by constantly changing environment<br>- competition is assessment of usefulness of action — one option wins and action is selected and performed<br>basically choosing the best possible action defined by environment<br><br>cerebellum knows motor command as it's sent out, makes predictions then helps adjust movements as they're happening"
operant conditioning- respond based on outcome of reinforcement or punishment<br>- cxns b/w sensory assoc. and motor areas via episodic memory cxns, BG, thalamus<br>- BG lesions disrupt it
classical conditioning- cerebellar learning<br>- ex tone followed by eye puff causes blinking
procedural learning- cerebellum<br>- performance imporves based on practice, cues, error feedback
supervised learning- driven by error/feedback from sens. systems<br>- cerebellum receives efference copy and connects to appropriate areas to modify movement<br>- LTD/LTP enable models of movements to be acquired
what negative + fastforward feedback shows usnegative is accurate but too slow, and feedforward is fast but inaccurate<br>shows that an accurate stored program is needed —> internal model of movements
internal model (movement) definition, uses, possibilities- consistent, repeated pattern of correlated firing in cerebellum —> internal models of sensorimotor systems<br>- used to predict outcome/sensory consequences of movement<br>- with training, models become the actual movement program and can be used for feedforward control<br>- if outcome not as desired (error) the program is altered/optimized<br>- might be applicable to cognition/emotion
cognitive roles for BG and cerebellum- both connect with assoc cortices in cognitive loops<br>- also have limbic loops<br>- same computation methods might apply to the diff types of information processed in diff loops
evidence for cognitive cerebellum- lesion –> cerebellar cognitive affective syndrom<br>- anatomical cxns to cortex<br>- anatomical substrates –> diff areas of cerebellum assoc with cognitive roles
modulate motor vs cognitive aspects of language in cerebellumtCDS over medial or lateral right cerebellum more info needed
proposed ideas for cerebellar contribution to cognitionprediction, timing, error-based learning, internal speech, etc
types of memorysensory, short-term/WM, long-term declarative, long-term nondeclaractive
declarative memory descr, mechanisms of loss, and typeshigh capacity, lasts days to years, consciously aware<br>loss mostly from interference<br><br>episodic – events<br>semantic – out of context facts
nondeclarative memory descr, mechanism of loss, typesprocedural – things you know by doing<br>long-term, high capacity, not consciously aware<br>primarily lost due to interference<br><br>skill learning – riding bike<br>priming – more likely to use word you recently heard<br>conditioning - salivating when see favorite food
stages of memoryencoding – establishing neural circuits via alterations in synaptic strength<br>recognition – activation of those circuits<br>remembering – continuted activity of circuits
memory processing stagesencoding (acquisition/consolidation)<br>storage<br>retrieval
how much stuff is encoded into memory?limited capacity for sens info –> not everything is encoded<br>salient stuff is<br>some unconscious processing (ex. priming)
shadowing technique- diff sentence in each ear<br>- can shift attn to one ear or other<br>- alters response – will perceive sound, but not content, in other ear
"Broadbent's filter theory"- explains shadowing effect<br>- limited capacity to process info – salient info is processed after filtering and meaning is extracted
Atkinson and Shiffrin model- describes effect of attn on memory – info must be attended to in order to be remembered<br>- attending to one thing at expense of processing others
how does info get into/stay in LTM?- first needs to be attended to to get info into sensory memory or WM<br>- practice (memory activities, repeated testing)<br>- depth of processing (use of currency vs being able to identify counterfeit money)
how is info stored in LTM?- stored based on meaning and assoc. networks of related concepts<br>- mental representation includes many aspects, incl. visuals, sounds, behavior, etc<br>- complex and abstract ideas<br>- schemas – cognitive structures that allow us to percieve, organize, process, use info
types of amnesiasanterograde – loss of memory for events after damage<br>retrograde – loss of memory for events prior to lesion. can be extensive or limited, usually greatest for most recent events
HM- profound anterograde amnesia due to bilateral damage to hippocampus<br>- still had LTM, WM, perceptual learning, retained preference info, stimulus-response learning, implicit procedural learning
how is memory established?LT changes in brain underlie learning and memory<br>takes place at molecular and systems level
molecular mechanisms for memory- learning underlined by changes in synaptic strength<br>- LTP and LTD<br>- hippocampus and cerebellum
hippocampus inputs- sensory, motor, assoc. areas<br>- BG<br>- amygdala<br>- DA (reward)<br>- NE (arousal)<br>- hypothalamus<br>etc.
hippocampal formation location, primary input, axons- medial temporal lobe<br>- primary input from entorhinal cortex<br>- axons travel through perforant path and synapse with granule cells of dentate gyrus
long term potentiation study (Lomo)electrical stimulation of axons from entorhinal cx to dentage gyrus of hippo –> LT increase in magnitude of EPSPs
LTP-related changes- size + shape of dendritic spines<br>- growth of new spines that can then form synapses<br>- presynaptic increase in glu release via NO messenger, production of which triggered by Ca2+<br>- increase in postsynaptic receptors
NMDA receptors mediate ___explicit learning through cascade of events leading to LT diffs in synaptic strength
how do we form explicit memories?hippo receives info from sens/motor assoc cortices, BG, amygdala<br>processes info and modifies memory consolidation via projections back to these areas, linking them together in ways that will preserve all the elements + their context
without hippo, would have ___snapshots without episodes/context
____ and ____ aid in memoryschemas and other cognitive structures
stages of learning/memorylearning/encoding establishes neural circuits via alterations in synaptic strength<br><br>recognition/retrieval activates the circuits established by learning
how does perceptual memory work?activation of neural circuits in sensory areas/same set of circuits as during encoding –> readout of perceptual memory<br><br>can be trained (ex. visual word form area)
damage to ventral pathway –>visaul agnosias
stimulate visual, auditory cortex –>familiar images, sounds
how much info can be in STM?7 +/- 2 items<br>info sometimes recorded<br>chunking can increase number of bits remembered
damage to ____ disrupts ____perisylvian areas<br>verbal STM but not visuospatial info
verbal memory is ___, spatial memory is ___left lateralized<br>right lateralized
working memorylimited capacity<br>retention of info short term, using/manipulating that info
og Baddeley/Hitch modelvisuospatial sketchpad - mapping out info<br>central exec - organizing info<br>phonological loop - verbal rehearsal
updated Baddeley/Hitch modelhas episodic buffer, attn gating<br>limited capacity system that works b/w other parts of model and holds/binds multimodal info temporarily
central executive neural systemslikely to engage multiple brain regions, incl. dorsolateral PFC
attn controller Baddeley/Hitch model areaACC (part of exec attn network)
episodic buffer Baddeley/Hitch model areaparietal regions
primingprior experience/exposure to stimulus changes subsequent response<br>can be brief to long term
perceptual priming damagedamage to visual areas disrupts vis priming<br>damage to auditory areas disrupts auditory priming
conceptual priming ex and damageex. talk about different breeds of dogs then asked to name an animal<br>damage to lateral temporal and prefrontal
semantic primingprime and target from same semantic category. ex. word nurse is recognized more quickly following the word doctor than following the word bread<br>brief
declarative memory is in ___ systemmedial temporal
when is the hippocampus needed?"hippo used to set up networks so it's important early after consolidation<br>as the cxns are strengthened, the cortex has the info so the hippo is not needed anymore"
____ and ____ feed into entorhinal cortexparahippocampal cx<br>perirhinal cx
dorsal and ventral hippocampal streamsparallel routes for sens info to hippo<br><br>dorsal: parahippocampal cx, where<br>ventral: perirhinal cx, what
learning and memory figure<b>sensory info</b> —attn—> <b>short-term memory </b>—consolidsation—> LTM<br><br>also rehearsal goes backwards from LTM to STM
study on MTL and MTGsq occuring during memory formation were replayed during successful retrieval<br>coupling b/w MTL and MTG
taxi driver studyR hippo activation during simulation of route<br>R posterior hippo volume increased
____ in humans corresponds to ____ in rats where ____ are foundR posterior hippo<br>dorsal hippo<br>place cells (fire when animal in particular location)
spatial memory inputinput from parietal lobe via PHC and entorhinal cx
entorhinal cx spatial memory cell typeshead direction, border, grid (fires when animal is in space, allowing it to understand position)
place info vs recall of placesplace cells fire for same position regardless of cued object. active when individual at particular location<br>memory trace cells fire relative to retreival cue. active during memory condition, specific to cued object and its location
"____ doesn't necessarily require hippo, but ____ does"familiarity<br>recall
familiarity vs recall areashippo - recollection<br>entorhinal cx - familiarity
perirhinal cortex recognition- familiarity-based item recognition<br>- associating object features<br>- as recognition confidence increases, so does PRC activity
encoding and retrieval involverelevant areas of modality-specific cortical regions
frontal and parietal activation during ___retrieval<br>possibly a more general role for these ares?<br>involved in WM, attn
areas activated during memory retrieval for words, scenes, faces, body partsVWFA<br>PPA<br>FFA<br>EBA
frontal activation during coding and retrievalventrolateral regions<br><br>laterality might be material-dependent<br>ex. linguistic L, visuospatial R
parietal cortex and retreival- important for integration of multisensory info<br>- important role in attn (DMN)
retrosplenial regions- parietal cortex<br>- important for retreival/recollection, particularly context info<br>- both retrograde and anterograde amnesia<br>- connects to MT area — projects to PHC and posterior hippo<br>- lower than baseline activation during encoding, unless self-referential and emotional
semantic dementia- damage to lateral anterior temporal regions (near anterior pole)<br>- fluent aphasia, object aphasia<br>- both verbal and visual<br>- intact episodic memory
PHC recallspatial, context, scene info recollection