Amnesia Flashcards
Prefrontal lobes
important for short-term memory.
Temporal lobes
hippocampus and amygdala
processing of short-term to long-term memory
-> consolidation
Diencephalon
thalamus, hypothalamus, mammillary bodies
processing of short-term to long-term memory.
-> emotional/ tramatic memory
Retrograde
loss of memory for events prior to injury.
- cant rmbr event prior to brain damage
Anterograde
inability to form new memories.
- cant latre rmbr events that occur after brain damage
Post-traumatic Amnesia (PTA)
period of time after brain injury during which new memories can not be formed (patient is also usually disoriented in time and space).
questions like what year is it who is the PM are asked
Describe what Kent could and couldn’t remember?
good at knowing facts like why are dark colours warmer then lighter colours; semantic memory
cant remember what happened yesterday
knows where he works but doesn’t know what he does
knows process for hot to change a tire but can’t rmbr if he’s every had one
semantic memory is intact but episodic memory is affected
Who is H.M.?
Patient H.M. suffered from epilepsy thought to be caused by a head injury at age 9.
H.M.’s epilepsy could not be controlled through drug interventions.
H.M. underwent bilateral temporal lobotomies in 1958.
The medial temporal lobes (MTL)
What did the surgery lead to in HM?
Surgery successfully treated epileptic seizures, but left severe memory impairments.
His memory for the remote past was intact (could remember his childhood), but he had some retrograde amnesia and severe anterograde amnesia.
If you left H.M. for only a few minutes, upon returning he would most likely forget who you were or that you had already met!
Loss of episodic memory. Semantic memory generally intact.
Semantic
memory for factual based material
Episodic
memory for events that can be linked to a time and place.
Describe Clive’s condition
suffered an infection of brain that damaged tissue similar to areas removed in H.M
- damage to left and right temporal lobe and part of frontal lobe
- damage to hippocampus
- damage to frontal lobe causes him to repeat himself a lot
when his wife comes into the room he gets very excited saying he hasn’t seen her yet even though he just saw her a few moments ago
doesn’t rmbr writing stuff down in his diary and gets very angry when he’s told he did
has severe anterograde amnesia
has semantic but not episodic memory
has damage to areas that control emotion
Describe The case of N.A.
A small lesion in the left dorsomedial nucleus of the thalamus.
- suffered from a fencining incident
Similar pattern of deficits to H.M.
Retrograde amnesia for the 2 years preceding the accident.
Almost complete anterograde amnesia – can remember virtually nothing of events since the accident.
More verbal than visual memory deficits, although both domains affected (e.g., has spatial memory impairments).
Episodic lost but semantic intact.
What does the video in class showed about N. A tell us?
- hippocampus and amygdala are crucial to memory
- he has difficulty rmbr words he saw and repeating them
- good at telling stories from the past all the way up until the accident- no problem in retrieval
- problem in recording new memories in LTM
- brain structures damaged are involved in processing memory not storage of memory
What types of functions may be left intact in cases of severe amnesia, such as H.M., Clive and N.A.?
immediate memory – can recite back several words immediately (but within five minutes no recollection of words).
intact memory for remote events (e.g., from childhood).
factual knowledge (e.g. water boils at 100°C).
perceptual and motor memory (e.g. riding a bike, brushing teeth).
language and social skills. procedural learning (e.g. mirror drawing).
Other facets of functioning:
Personality
Intellectual Functioning
Insight into intact and impaired functions in amnesics enables us to learn much about memory processing.
H.M. – procedural learning.
Task – draw object viewed in the mirror.
- can’t see image b/c of barrier so has to look in mirror to see reflection have to learn to do opposite of what is shown
Practice makes perfect – even in H.M.
Never recalls having done the test! (explicit memory)
Implicit memory.
stem-completion also intact – e.g., DEFEND, HELIUM, MODIFY
DEF__________
DEFEND, DEFEAT, DEFINE
Free recall vs completion
free recall- explicit memory
- amnesic perform lower
completion
- implicit memory
- amnesic performs same as control
What has been H.M.’s Contribution to Memory Research
The hippocampus is NOT the location of LTM, and is NOT necessary formation of LTM.
can remember childhood.
The hippocampus is NOT the location of STM.
can carry on conversations.
The hippocampus IS responsible for converting STM into LTM.
understands new information, but a permanent record is never made.
involved in consolidating memories overtime.
What brain regions are critical in anterograde amnesia?
for H.M. the hippocampus and parahippocampal cortex were removed (as was the amygdala)
Parahippocampal cortex:
A region of limbic cortex adjacent to the hippocampal formation that, along with the perirhinal cortex, relays information between the entorhinal cortex and other regions of the brain.
flashbulb memories.
amygdala is probably only important for the emotional content of memories
Can amnesic patents do memory tests
amnesic patients can perform memory tasks, but they cannot learn anything they learned from it.
Proof the hippocampus mediates consolidation?
Patient S.M. - bilateral amygdala damage.
could not establish conditioned emotional responses.
Patient W.C. - bilateral hippocampal damage.
could not remember testing procedure.
episodic (declarative) memory impaired.
Patient R.H. - bilateral damage to both.
both kinds of learning impaired.
Korsakoff’s amnesia
severe anterograde amnesia.
destruction of parts of diencephalon (mammilo-thalamic tract).
temporally graded retrograde amnesia.
lose declarative memories but not procedural ones.
confabulation is common.
caused by thiamine deficiency due to alcoholism and poor diet
retrograde amnesia and the temporal gradient
Korsakoff’s patients show a steep temporal gradient in their remote memories
Retrograde amnesia and consolidation
temporal gradient to retrograde amnesia.
for closed head injury or even ECT (shock therapy) – memory loss is greatest for most recent events and rarely extends beyond a few years.
retrograde amnesia is quite severe in Wernicke-Korsakoff’s syndrome but still maintains a temporal gradient – suggests hippocampus is not the only structure necessary for memory.
Confabulation
more than just “filling-in-the-blanks”.
patients with Wernicke-Korsakoff’s will make up information to hide a memory deficit.
indicative of a lack of awareness of the memory impairment (frontal lobe involvements).
a plausible yet imaginary memory that fills in gaps in what is remebered
What does memory involves?
Memory involves multiple brain regions
What brain areas does memory involve?
medial temporal lobes hippocampus entorhinal cortex parahippocampal cortex amygdala
subcortical structures
mammilo-thalamic tract
neocortex
posterior superior temporal gyrus
dorsolateral prefrontal cortex
Animal Models of Memory Research
We have learned a lot about memory from case studies, but individual cases are not as statistically powerful as group studies.
We know that different brain structures have different roles in learning and memory.
Human memory research provides research direction, but animal research is needed for in depth analysis.
Delayed match to sample
Spatial memory – animal models
hippocampal lesions disrupt learning in a radial arm maze or Morris water maze.
Prefrontal cortex
output from BG – thalamus, from there to prefrontal and SMA
premotor, SMA involved in planning & execution
important for learning sequences of movements
Triple Dissociation
MacDonald & White used the radial arm maze (RAM) to examine declarative, procedural and emotional memory.
Evidence for different memory systems mediated by different brain structures.
Lesions to the hippocampus produced deficits in declarative memory.
Lesions to the basal ganglia produced deficits in procedural memory.
Lesions to the amygdala produced deficits in emotional memory.
1) People with anterograde amnesia
A) are unable to recall childhood experiences.
B) show impairments in motor memory.
C) show normal complex relational learning.
D) are unable to learn new information.
E) show facilitated stimulus-response learning.
D) are unable to learn new information.
2) The most profound symptom of Korsakoff's syndrome is A) anterograde amnesia. B) total amnesia. C) combative behavior D) delirium tremens. E) auditory and visual hallucinations.
A) anterograde amnesia.
3 ) Which of the following is true of confabulation?
A) Confabulation is seen in persons who simply mix up their memories.
B) Confabulation is intentional.
C) Patient H.M. shows severe confabulation.
D) Korsakoff’s patients fail to show confabulation.
E) Confabulation is the report of a fictitious event by a person with amnesia.
E) Confabulation is the report of a fictitious event by a person with amnesia.
4) One striking aspect of H.M.’s memory deficit is that he
A) can learn some new tasks, but is unaware of having learned them.
B) only remembers recent facts.
C) reverses word order in repeated sentences.
D) indicates he remembers things he has never seen.
E) show signs of confabulation.
A) can learn some new tasks, but is unaware of having learned them.
5) Which of the following is true of short-term memory?
A) Immediate memory precedes short-term memory.
B) Short-term memory has a limited capacity.
C) Short-term memory is impaired by repetition of verbal material.
D) Short-term memory has an unlimited capacity.
E) Immediate memory is distinct from short-term memory.
B) Short-term memory has a limited capacity.
6) When tested in an 8-arm maze, a rat with hippocampal damage will
A) repeatedly visit arms from which they have already eaten a food pellet.
B) be unable to visit all of the arms.
C) be more efficient at getting food than is an intact rat.
D) only visit arms that have never held food in the past.
A) repeatedly visit arms from which they have already eaten a food pellet.
