Lecture Outline Disorders of Memory HM Anterograde Amnesia Retrograde Amnesia Korsakoff s Syndrome Animal Models of Memory Anatomy of Memory Prefrontal lobes important for shortterm ID: 908688
Download Presentation The PPT/PDF document "Disorders of Memory Amnesia & Animal..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Disorders of MemoryAmnesia & Animal Models
Slide2Lecture OutlineDisorders of Memory
H.M.Anterograde AmnesiaRetrograde Amnesia
Korsakoff
’
s SyndromeAnimal Models of Memory
Slide3Anatomy of Memory
Prefrontal lobes
important for short-term
memory.
processing of short-term to long-term
memory.
Diencephalon
thalamus, hypothalamus, mammillary
bodies.
Temporal lobes
hippocampus and
amygdala.
processing of short-term to long-term memory.
Slide4Disorders of Memory
Retrograde – loss of memory for events prior to injury.Anterograde – inability to form new
memories.
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
).
Slide5Who 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.
coronal MR slices
H.M. Healthy control
Slide6The medial temporal lobes (MTL)
Slide7Surgery 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.
Who is H.M.?
Slide8What is it like to be H.M.?“Right now, I’m wondering, ‘Have I done or said anything amiss?’ You see, at this moment everything looks clear to me, but what happened just before? That’s what worries me. It’s like waking from a
dream.”-- H.M., 1965
“Every day is alone in itself, whatever enjoyment I’ve had, and whatever sorrow I’ve had.”
-- H.M., 1968
Slide9What Is Memory?
Classic cases of amnesiaThe case of N.A
.
A small lesion in the left
dorsomedial nucleus of the thalamus.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.
Slide10What Is Memory?
Classic cases of amnesiaWhat 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:PersonalityIntellectual FunctioningInsight into intact and impaired functions in amnesics enables us to learn much about memory
processing.
Slide11H.M. – procedural learning.
Task – draw object viewed in the mirror.Practice makes perfect – even in H.M.
Never recalls having done the test
!
Implicit memory.stem-completion also intact – e.g., DEFEND, HELIUM, MODIFYDEF__________
DEFEND, DEFEAT, DEFINE
Slide12Slide13H.M.’s Contribution to Memory ResearchThe 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.
Slide14Hypothesized Memory Processes
Incoming information
Performance
Retrieval
Working memory
Short-term storage
Encoding
Long-term storage
Consolidation
Sensory buffers
Sight
Sound
Smell
Touch
Attention
Rehearsal
Slide15Anterograde AmnesiaWhat 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
.
amygdala is probably only important for the emotional content of memories – flashbulb
memories.
amnesic
patients can perform memory tasks, but they cannot learn anything they learned from it.
Slide16Double Dissociation 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.
Slide17Korsakoff’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.
Slide18Retrograde amnesia and the temporal gradient
Korsakoff’s patients show a steep temporal gradient in their remote memories
1990
1980
1970
1960
1950
1940
Korsakoff’s
patients
MTL
amnesics
% correct
Slide19temporal 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.
Retrograde amnesia and consolidation
Slide20Confabulation
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).
Slide21The story so far…Memory involves multiple brain regions
medial temporal lobeshippocampusentorhinal cortex
parahippocampal
cortex
amygdalasubcortical structuresmammilo-thalamic tractneocortexposterior superior temporal gyrus
dorsolateral prefrontal cortex
Slide22Animal 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
.
Slide23Animal models of memory
Delayed match to sample
Delayed non-match to sample
Slide24Spatial memory – animal models
hippocampal lesions disrupt learning in a radial arm maze or Morris water maze.
Now have Virtual Reality Morris water mazes for humans
Slide25Prefrontal cortex
output from BG – thalamus, from there to prefrontal and SMApremotor, SMA involved in planning & execution
important for learning sequences of movements
Slide26Triple 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.
Slide271) People with anterograde amnesiaA) 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.2) The most profound symptom of Korsakoff's syndrome isA) anterograde amnesia.B) total amnesia.
C) combative behavior
D) delirium tremens.
E) auditory and visual hallucinations.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.
Review Questions
Slide284) One striking aspect of H.M.'s memory deficit is that heA) 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.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.6) When tested in an 8-arm maze, a rat with hippocampal damage willA) 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.E) perform more efficiently than will a rat with damage to the fornix or entorhinal cortex.
Review Questions