Association cortices COPY Flashcards
HIERARCHICAL ORGANISATION OF SENSORY SYS
i) how can an associative area of the cortex be defined?
ii) what is the sequence of travel from sensory receptors in the periphery to the association cortex? (5)
iii) what is received and added in each hierarchal level of the sensory system?
i) an area that is not purely sensory or motor and has higher order integrative function
ii) 1) peripheral sensory receptor 2) thalamic nuclei 3) primary sensory cortex 4) secondary cortex 5) association cortex
iii) each level receives input from the level below but adds another level of analysis before passing it on
MULTIMODALITY SYSTEM
i) what is a unimodal association area? give an example of this
ii) what is a multimodal association area? give an example of this
iii) what area does the initial stage of processing take place? which area does the final stage of processing take place?
iv) where are multimodal motor association areas found anatomically?
v) give an example of a brain area that is multimodal
i) only integrates associations from a single modality but does this to a high level eg in some areas of the visual cortex
ii) integrate signals from different sources then decide what to do with them eg hippocampus
iii) initial stage = primary sensory area and final stage = primary motor area
iv) rostral to M1
v) hippocampus
THE VISUAL SYSTEM - HIERARCHICAL NETWORK
i) which cells receive sensory signals in the visual system?
ii) which four steps does the signal then take to end up in the cortex?
iii) does communication get more or less complex the further up the hierarchy you go?
iv) what will be the result of damage to a) retinal ganglion cell, b) further up eg in LGN
i) retinal ganglion cells receive sensory information
ii) travels down magno and Parvo pathway - then to thalamus - then to LGN - then to cortex
iii) more complex
iv) a) damage to RGC will affect encoding in the whole visual system b) damage further up will affect interpretation of information
THREE MAIN MULTIMODAL ASSOC AREAS
i) what are the three main multimodal association areas and what function do they each have?
ii) does the higher the level of damage up the hierarchy cause more or less complex deficits?
iii) which four key brain areas are not multimodal?
i) 1) posterior association area = perception and language 2) temporal association area - emotion and memory 3) prefrontal = executive function
ii) the higher up the heirachy the more complex the deficit
iii) somatosensory, motor, visual, auditory
PROCESSING DISTURBANCES
i) what is agnosia?
ii) what are the two types of visual agnosia and what happens in each? which one did Dr P have?
iii) what happens in a) prosopagnosia, b) visual agnosia c) anosognosia
i) a rare disorder where a patient cant recognise objects, faces or sounds but will still respond to stimuli (light) and have no memory problems and senses work well
ii) 1) perceptive = fail to recognise things due to deficits in early stages of visual processing 2) associative = failure to recognise objects despite in tact perception of object (Dr P)
iii) a) prosopagnosia = cant recognise faces b) visual agnosia = cant recognise objects c) anosognosia = not recognising you have an illness
PRE FRONTAL CORTEX DAMAGE
i) what can damage to PFC cause? (4)
ii) who was this demonstrated in? what happened?
I) 1) personality changes 2) long term planning and judgement impairment) 3) working memory impairment 4) continuity of behavioural planning impairment eg may start making tea and forget what they are doing halfway through
ii) demonstrated in phineas gage - accident with injury to PFC - no longer himself after accident but didn’t have any physical deficits
CONVERGENCE FROM UNI TO MULTIMODAL AREAS
i) experiments in which animals demonstrated this?
ii) where does all information ultimately converge on? what does this area do?
I) macaque monkeys
ii) all info ultimately converges on pre frontal cortex which contains info from all the senses and can interpret/integrate it
SERIAL AND PARALLEL PROCESSING OF SENS INFO
i) what area of the brain is the visual system in both humans and macaque monkeys?
ii) what is seen when monkeys are showed a normal monkey face?
iii) what response is seen when the face is scrambled or part of the face is missing? why is it?
iv) what gives the optimal response?
v) will the monkey respond to irrelevant signals eg human hand?
i) inferior temporal cortex
ii) good response when recording from IT cortex
iii) scrambled/missing > responses of neurons are compromised as not ‘optimal stimulus’
iv) optimal response when seeing side profile of monkey face
v) won’t respond to irrelevant signals
LOC OF DECLARATIVE MEMORIES IN NEOCORTEX
i) what does Hebb say about the engram being based off information from a specific sensory modality? what should be possible?
ii) what effect does a lesion in the inferior temporal cortex have on monkeys performing the visual discrimination task?
iii) how is basic visual capability affected in monkeys with an IT cortex lesion?
iv) what do recordings from the IT cortex suggest about how monkeys recognise faces?
v) what do cortical areas eg IT cortex therefore process? (2)
i) if engram is based off info from one sensory modality then it should be possible to localise it in regions of the sensory cortex that respond to that modality
ii) lesion in IT cortex > animal cant perform vis discrim task
iii) basic visual capability is not affected
iv) recordings from IT cortex suggest that monkeys may encode memories of faces
v) cortical areas can therefore process sensory info (visual) and store memories of this info
INFO PROCESSING IN MOTOR SYSTEM
i) what is the difference between sequence of motor and sequence of sensory processing? give an eg
ii) in the frontal cortex - do individual neurons fire specifically for motor responses?
iii) what do movement and complex actions result from in the frontal lobe?
iv) which area of the cortex generates motor programmes? when are these neurons activated?
v) what does firing of neurons in the motor cortex principally achieve?
i) it is reversed - start with general information to get a specific motor response eg feel thirsty then grab water from the table (ending in a specific motor response from a general feeling of thirst)
ii) no - individual neurons fire for a range of related behaviours
iii) patterns of firing of large networks of neurons in the frontal lobe
iv) premotor cortex generates motor programmes neurons are activating during preparation of movement
v) producing a movement in spec direction around spec joints
SPEC LANGUAGE AREAS IN THE BRAIN
i) what is aphasia? what is not usually seen?
ii) where is brocas and werenickes area anatomically located?
iii) which two areas does language come into the brain through?
iv) which brain area was damaged in case studies with disrupted language? (Paul Broca)
i) partial or complete loss of language ability post brain damage - usually without loss of cognitive ability to move muscles for speech
ii) in the left hemisphere
iii) visual and auditory system
iv) frontal lobe in left hemisphere
ASSYMETRICAL LANGUAGE PROCESSING
i) what procedure can be used to determine which hemi is dominant for cognitive function espec speech/memory? is this done when the patient is awake or asleep?
ii) give an example of two conditions where this process may be carried out?
iii) what agent is administered in this procedure? where is it admin to? what effect does this have? what does it allow?
iv) what % of right handed people have the left hemi dominant for speech?
v) what % of left handed people have the left hemi dominant for speech?
vi) which handed people may have speech represented in both hemispheres?
i) wada procedure - done whilst awake
ii) epilepsy surgery or tumour resection
iii) administer a barbiturate (GABAa agonist) through the internal carotid and inject into one hemi at a time - causes shut down of any language or memory functions in that hemisphere which allows evaluation of the other hemisphere
iv) 96%
v) 70%
vi) left handers
APHASIA
i) which aphasia is non fluent? is comprehension good or bad?
ii) which type of aphasia has fluent speech but poor comprehension?
iii) in brocas aphasia - where is the language disturbance located? what does this cause
iv) what does the effect of aphasia in bilingual people depend on? (3)
v) what is seen in aphasia in individuals using sign language? what does this suggest?
i) brocas - difficult to speak (pause and search for words) but comprehension is good but not normal
ii) werenicke
iii) disturbance towards motor end of language system - causes language to be understood but not easily produced
iv) ailing depends on order that languages have been learnt, fluency and how often the language is used
v) sign language - analogous to speech aphasia which suggests there is some universality to language processing in the brain
APHASIA EXAMPLES
I) what type of aphasia would this be - I, errr… w, we, went.. tot,t,t, to th…e ca,…. r
ii) what type aphasia would this be car I go now thought bee you see swerve no oh
I) brocas
ii) werenickes
SPLIT BRAIN STUDIES
i) which brain area is surgically disconnected? what does this produce?
ii) is any communication maintained?
iii) which hemisphere is language comprehension mostly found in?
iv) what hemisphere controls the left hand?
v) what does the right hemisphere have? but what can it not control?
vi) what do split brain studies suggest?
i) corpus callosum > produces two independent functioning hemispheres
ii) some communication maintained
iii) left hemisphere
iv) left
v) right can do some language processing but cant control speech production
vi) suggest that two hemispheres can func as independent brains and have diff language abilities
- R hemi can understand pictures but now whole sentences and cant explain reactions to stimuli
