B7.060 Learning and Memory Flashcards
classes of memory
declarative (explicit)
non-declarative (implicit)
declarative memory
conscious
perceptual v executive
episodic v semantic
non-declarative memory
unconscious
motor memory
striatum & cerebellum
semantic memory
facts
episodic memory
events
your life story
cognitive psych model of memory
- immediate memory: neurons firing based on whatever is happening in environment, lasts less than 1 second
- short term memory: based on what you give attention to, can last seconds to minutes with rehearsal of info
- long term memory: transferred from short term memory, remodeled via strengthening of synaptic connections, last hours to years
what is working memory
in clinical model
immediate + short term memory from other model
clinical model of memory
- working memory: stored diffusely in cortex, maintained via rehearsal rapidly lost
- short term memory: memories that are being transferred from working to long term, located in limbic circuits
- long term memory: stored diffusely in cortex, maintained via remodeling (just like cognitive psych model), slowly lost unless there is cortical damage
preferential storage of memories
based on importance
how are working memories formed and stored
based on attention: dorsolateral prefrontal cortex
retention of info for seconds to minutes
neocortical “reverberating circuit”
directly related to intactness of cortical neurons and synapses
how are long term memories formed and stored
limbic circuits initiate retention of a memory
retention of info for hours to years
relatively few errors until 25% or more of the cortex has been damaged
based on synaptic remodeling
-long term potentiation
-NMDA receptor
components of memory consolidation process
active remembering
further long term potentiation
new synapses formed
new neurons (least important)
long term depression of memories
if you don’t continue to think about something, you are no longer using the synaptic connections
will eventually degrade
memory circuit of papez
- hippocampus
- fornix (c-shaped white fiber bundle)
- mammillary bodies of hypothalamus
- anterior nucleus of thalamus
- internal capsule
- cingulate gyrus
- cingulum
- hippocampus
what is the significance of memory processing taking place in the limbic system structures
emotional area
you are more likely to remember emotional events
how do you disrupt short term memory
bilateral damage to the memory circuits
midline lesion or diffuse lesion
how to assess working memory (attention)
digit span- immediate recall (7 normal)
5-7 unrelated words or numbers
repeating a brief story
how to assess short term memory (transfer to long term)
orientation to time and place
remember a word list for 3 min
how to assess long term memory
fund of information- long term recall
past presidents, significant dates, etc.
delirium
acute global brain failure
NOT just memory affected
amnestic syndromes
usually a component of a condition causing global cognitive problems
less commonly isolated
midline lesions that can cause an isolated amnestic syndrome
thalamic
large frontal meningioma
basilar occlusion
diffuse lesions that can cause isolated amnestic syndrome
thiamine deficiency
anoxia
trauma
manifestations of isolated amnestic syndrome
short term memory is gone (disoriented) language normal construction normal alert, attentive long term normal
what is Hollywood amnesia
severe long term memory deficits with preserved short term memory
lesion cannot do this, you’d have to knock out a ton of the cortex to destroy all long term memories, thus you’d see other manifestations of neuro dysfunction
this is psychogenic
what is subjective cognitive impairment
forget specific dates and names, but can remember what they forgot
accurately track ongoing events
memory deficit inconsistent (name forgotten yesterday, but remembered today)
remote memories forgotten more often than recent
no impairment in social/occupational functioning
normal exam
risk of SCI progressing
low
mild cognitive impairment
objective short term memory issues
higher likelihood of progression to dementia than SCI
impact of Alzheimer’s on memory
both short and long term memory affected
early: short term due to pathology in the hippocampus
late: neo-cortical damage, long term memories lost
anterograde memory loss
failure to form NEW retrievable memory
short term deficit
retrograde memory loss
failure to retrieve formerly learned information
memory gap
span of retrograde and anterograde amnesia around the incident
tends to shrink over time but will eventually reach a stable size
why do you get retrograde memory loss after trauma
don’t have time to consolidate memories after making them due to brain injury
at a certain point, cant retrieve them
Wernicke/Korsakoff
metabolic etiology acute untreated or chronic thiamine deficiency persistent lesions of -dorsal medial thalamic nuclei -mammillary bodies
korsakoffs psychosis
little or no acquisition of new information
impaired retrieval of old, historical memory
confabulation
