Lecture 17 - Amensia and The Brain Flashcards
Outline Retrograde Amnesia
Cannot remember events prior to brain damage
Outline Anterograde Amnesia
Cannot later remember events occur after brain damage
Causes of Anterograde Amnesia
Alzheimer’s Korsakoffs Herpes encephalitis Anoxia/Ischaemja Injuries or rumours limbus system Surgeries for epilepsy Degenerative brain diseases
Outline Korsakoffs Pscyhosis
Reflecting gradual onset
Confabulation
Associated thymine deficiency - vitamin B
Make up stories
Outline Anoxia/Ischaemia
Result very selective AA
Aschemic brain damage
Interruption oxygen supply
Outline degenerative brain diseases
Schiz
Advanced multiple sclerosis
Huntington’s disease
Outline hippocampus particularly sensitive anoxia
Damage field CA1 caused anoxia
Effect oxygen deprivation hippocampus
Both rats and humans distinctive cell layering hippocampus
Structure less well defined and organised
Outline Neural substrates of Hippocampus and associated structures
Cortical connections hippocampal formation
Hippocampus lies beneath not truly sub-cortical, rather primitive-cortical infolding mamilliary bodies also implicated amnesia
Lessons similar profile memory loss
Outline HM case study by Milner et al 1968
Epileptic seizures Bilateral media temporal lobe removed Anterograde amnesia Above average IQ, normal perceptual, good memory events prior Selective
Outline pure amnestied syndrome
HM - Milner
Poor LTM for new material
Perceptual/motor learning intact
Claperede Effect
Outline the Clapered Effect
Patient amnesia testing his reflexes
Pin method - patient poked pin
Went to do re-test following session
Patient didn’t remember pin but did say researcher may have pin in his hand
Outline the nature of the deficit
- Selective effect LTM
- Global - impairments across modalities and materials
- Selective - impairments remembering new facts and events
- Selective - spares learning and expression skilled performance
- Info inflexible and expressed limited contexts
Outline effective effect on the LTM
Digit span normal 7 +- 3
Extended: multiple repetitions up to 20
HM not recall string excess normal STM even after 25 repetitions
Outline global impairments across different modalities and materials
Tests: free, cued recall, recognition
Modalities: amnesia seen information presented different modalities
Visual, auditory, olfactory - different visual agnosia
Outline selective impairments remembering new facts and events
HM unable report any personal or public events since surgery
Impaired list based tasks - paired associate learning
Task recall given first word cue
Compare learning face name pairings, new word meanings
Outline evidence impaired memory for new facts and events in HM
Take word rather obscure and measure capacity learning and remembering word 3 ways: definition, synonyms, sentences
HM amnesia affects stable, no recovery across 3 years two time points
High test retest reliability
Outline amnesia spares learning and expression skilled performance for repetition priming
Repetition priming - show something visually lager influence you. Even if don’t remember.
Picture fragment completion and word stem completion
Outline amnesia spares learning and expression skilled performance for mirror tracing
Reproducing outline Star with only visual info from mirror Amnesiacs show savings Learning draw what you can’t see only from feedback from mirror Normal people get better over time
Outline amnesia spares learning and expression skilled performance for mirror image reading task
Given word triplets read
Amnesiacs get fast and accurate with multiple presentations
Normal people enter over time
Despite: little no memory learning experience
Little recall/recognition test
Little no insight skills acquired
Outline evidence for spares skilled performance broken, degraded drawings
Earlier exposed completed image even if don’t remember be much better picture completion
Neurologically intact recognise at an even more incomplete stage
Snodgrass and Feenan 1990 picture fragmentation completion
Ppts required join up dots Which you produce influenced what saw earlier Also in amnesiac patients Procedural learning and memory in tact Repetition priming
Cohen and Squire 1980 mirror image word sets
Mirror image reading task only feedback mirror
Improved reading times over trials
For new non repeated sets words
Perceptual skill learned even those in amnesia
Outline inflexibility and having little transfer
Performance measures exactly same way show savings
Facilitation does not carry over other tasks or contexts
Outline amnesiacs dissociation between cues recall and word stem completion
Impaired cued recall
But biased previous word exposures asked complete word stems ‘1st word comes mind’ first few letters = cues
Amnesiacs so bad often recalling from previous learnt think - interference
Outline Amnesiacs being bad at knowing when paired associate task by Winocur and Weiskrantz 1976
Averaging strategy
Amnesiacs bad unrelated pairs
Ok words combined according semantic of phonetic properties
Retention 30 mins ok but couldn’t learn second paired associate list be because high number list 1 intrusions
Theoretical accounts
Procedural vs Declarative memory - Squire 1992
Semantic vs episodic - Tulving 1972
Outline if there are two or more memory systems
Declarative/episodic vs Procedural/semantic
Wider circuit not just hippocampus
Pure amnesia damage mammillary bodies
Outline if there are two or more memory systems differences Amnesiacs and Korsakoffs
Korsakoffs differ from temporal lobe amnesiacs
Maybe just additional deficits associated brain damage - frontal lobe signs
Other degenerative conditions show additional deficits - demand confusion, Schiz
