cognitive neuropsychology of memory & visual perception Flashcards
what is episodic memory?
- memory of specific events
what is semantic memory?
- memory of facts
what is working memory?
- short term memory
- requires rehearsal
what is procedural memory?
- motor memory
- (like getting on a bike after 10 years of not riding a bike)
what is anterograde amnesia?
- poor ability to acquire new information
- information acquired before damage = in tact
- declarative memory = episodic + semantic = impaired
- non-declarative memory = perceptual + procedural = intact
what is the brain basis for anterograde amnesia?
- hippocampus
- related structures in medial temporal lobe
identify 2 causes and anterograde amnesia
1/ Korsakoff’s syndrome
2/ temporal lobe lobectomy
what causes Korsakoff syndrome?
- thiamine (vitamin B deficiency)
- due to alcoholism -> poor diet and impaired absorption of thiamine from intestine
- produces bilateral degeneration of mammillary bodies (part of hypothalamus)
what is a temporal lobectomy?
- for patients with uncontrollable seizures
- bilateral removal of temporal lobes
outline the case of Patient HM
- suffered major seizures
- drugs failed to contain seizures
- surgical removal of anterior hippocampal regions
- pure deficits = IQ unaffected by surgery, no personality change
- only side effect = issues with forming NEW memories (old memories in tact)
what memory problems did HM have?
- complete absence of new episodic memories
- could report date and age prior to operation
- could not remember events or people after operation
- formation of new semantic memory partially disrupted
what type of memory was still intact in HM?
- working memory
- unless constant rehearsal interrupted -> had normal digit span
- rate of forgetting = normal
- could hold convo
- would forget convo happened
explain the mirror tracing task
- ppts presented with two stars drawn inside each other
- trace between the two lines of two stars
- view blocked by mirror
- asked to trace in between two lines
- only way to see star is the reflection in the mirror
what did HM doing the mirror tracing task show?
- everyday HM did task
- HM forgot he did task
- but HM made normal improvements on mirror tracing task
- shows motor memory still in tact
what is retrograde amnesia?
- loss of memory that is acquired BEFORE getting amnesia
what does the case of HM suggest about the role of the hippocampus?
- suggests hippocampus does not store memories
- old memories are preserved
- may be that hippocampus enables consolidation of new memories which are stored elsewhere
what type of amnesia did patient HM have?
- temporally graded retrograde amnesia
- old memories = ok
- memories made immediately before lesion = lost
how long does consolidation require?
(Marslen-Wilson & Teuber, 1975)
- showed HM photos of celebrities
- suggests retrograde amnesia spans decades
- but more distant memories relatively preserved
what is meant by dissociations?
- where some parts of memory = in tact
- other parts of memory = not in tact
- can be seen where some tasks are impaired but other tasks are not
- suggesting that tasks use different resources
what type of memory is impaired and what type is spared in semantic dementia patients?
- semantic memory = impaired
- episodic memory = spared
what do double dissociations studies show?
- involves two anatomical patient groups with different lesions
- repeated measures study with counterbalancing
- different groups = better at different tasks
- suggests different tasks rely on different brain structures
what is visual agnosia?
- impairment in recognising visually presented objects
what does it mean that visual agnosia is modality specific?
- patients with visual agnosia = able to name object through touch
what is apperceptive agnosia?
unable to perceive full shape of object despite intact low level processing
what is associative agnosia?
- ability to perceive shape
- inability to recognise it (name it)
identify features of apperceptive agnosia?
- inability to perceive full shape of object
- intact low-level perception
- intact visual acuity = ability of the eye to distinguish shapes and the details of objects at a given distance
- brightness discrimination
- unable to extract global structure
- evidenced in impairment in drawing, copying, visual recognition
identify features of associative agnosia
- inability to perceive whole form of shapes
- able to copy figure
- cannot draw from verbal instruction
- cannot recognise objects using vision
outline a theoretical explanation for associative agnosia
- damage to left occipital cortex
- damage to white matter
- disconnect between visual representation and language
what is prosopagnosia?
inability to recognise faces visually
patients are able to tell that a picture shows a face
unable to say who the face belongs to, even family
can identify through voice, hairstyle
what damage is involved in prosopagnosia?
- fusiform gyrus
- in inferior part of occipital/temporal lobe
- usually right sided
what does FFA stand for?
Fusiform Face Area
what area of the brain is activated by faces in healthy adults?
- fusiform gyrus
what is unique to individuals faces?
- the configuration of facial features
what does face processing involve?
- perception of configuration of facial features
- perception of facial features
what is the inversion effect?
- phenomenon where identifying inverted faces = harder to recognise than upright faces
- because configuration of features = difficult to process
- only when faces presented right way up = notice the distortion –> we use our face processing mechanisms differently
what does prosopagnosia imply about the brain processing faces?
- implies brain = specialised to process faces
what else is the FFA concerned with?
- area = activated when observing pictures of birds or cars
