Chapter 5: Animal Models of Amnesia Flashcards
What was determined about amnesia through human studies?
the study of human amnesia led to a formal categorization of memory types: conceptual/cognitive differences, declarative vs. procedural
correlations of behavior with brain damage: hippocampus and medial temporal lobe, midline diencephalic structures, basal forebrain
further study: animal models, allow them to test specific aspects of amnesia
What are the advantages to studying human memory?
testing facilitated: verbal report, understand instantly if they demonstrate memory
applicability: human brain
What are the disadvantages of studying human memory?
lack of experimental control
lack of replicability: lesions are always different
lack of generalizability: lesions, second degree issues such as treatment, other illnesses and degeneration
What are the advantages of using animal models to study amnesia?
experimental control
experience pre, post surgery
specified lesions
What are the requirements of using animal models to study amnesia?
dissociative: no sensory, motor, motivational, or cognitive deficits, impaired declarative vs. procedural memories, limited only to specific forms of memory, limited to memory itself
global: impairment for multimodal information, can’t be limited to one sensory information
temporal component: short vs long term impairment, new vs. old information (intact STM, impaired LTM, vice versa)
What are the primitive models for memory?
Wisconsin testing apparatus: original, perceptual and memory abilities
touch screen display: current
delayed match, and non-match, to sample
What is the object discrimination task used for evaluating similarity of amnesic syndrome?
pick the same object when paired with a different object (S-R)
means that animals have no perceptual issues
What is the delayed matching to sample (DMS: repeated objects/patterns) task used for evaluating similarity of amnesic syndrome?
shown a cross, delay, must discriminate between the cross and a square, must choose the cross
were able to do this as long as the object didn’t change
What is the delayed non-matching to sample (DNMS: novel objects/patterns) task used for evaluating similarity of amnesic syndrome?
presented with a star, delay, shown a star and a cube, must choose the cube
damaged monkeys were okay as long as delay was short
What is the delayed spatial response task used for evaluating similarity of amnesic syndrome?
have to learn which well they have to pick in order to get reward, same object covering wells
damaged monkeys perform at chance levels
What selective and specific deficits in memory did lesions similar to H.M.’s produce in monkeys?
intact conditioning: simple visual discrimination learning, can discriminate objects and become conditioned
anterograde impairment for long-term retention of novel objects: DMNS with trial unique objects
intact motor learning: Barrier motor skill (need to learn to deviate around plexiglass to reach treat), & Lifesaver task (push lifesaver through wires and eat it off the end)
evidence for temporal gradient in retrograde loss: list learning at different time point prior to lesion
What are the two problems with using rats as models of amnesia?
similar tasks can be used for human and non-human primates; with rats, the tasks have to be adapted both physically and conceptually
neurosurgical procedures for rodents and primates different in terms of both access and techniques to lesion MTL structures
what exactly does the hippocampus do?
What is the hippocampal role in memory for rats?
no deficits in simple classical conditioning: Skinner box tasks, active avoidance, no problems with perception or procedural memory, will move into dark room instinctively but will not go if they receive a shock
no deficits in visual, olfactory, tactile discriminations
modified DNMS
deficits in reversal learning
deficits in spatial learning
deficits in “working” or “recent/episodic” memory vs. “reference/semantic” memory
What was the DNMS task used in rat models of amnesia?
The Mumby Box: rat placed in center portion, once door came up, rat can enter room and displace an object to get a froot loop, then a delay; other door opens, need to displace new object, not the similar one to get treat
deficits with MTL lesions notable, HPC lesions less so
areas around hippocampus gave rise to deficits when destroyed
What was the discrimination learning task used in rat models of amnesia?
rats had hippocampal damage
rats were placed in a Y maze and had to pick one of the arms
simple tasks: have to pick the dark arm; okay, but could not do the reversal
complicated tasks: start in stem, if both arms are white go right, if both arms are black go left, hippocampal damage showed deficit
How was the role of the hippocampus in spatial memory studied in rat models of amnesia?
“cognitive map”
Morris water maze: cloudy water, put platform below surface, swim to find platform, once they have found it will use spatial cues to remember the location, will swim directly to platform after that
hippocampus impairment decreased memory and navigation
non-specific behavior to find platform inefficiency
hippocampus can’t learn new place
equivalent time in every quadrant
How was the role of the hippocampus in “working” (recent) memory studied in rat models of amnesia?
8-arm Radial maze (Olton)
once-baited arms: learn to visit arms once to get the treat, and don’t need to go back; hippocampal damage decreased performance
once-baited and never-baited arms: only baited four arms, needed to avoid the non-baited; hippocampal damage could still determine which ones to not visit, but couldn’t remember where they had gone in the trial, could not remember the baited arms they had already been to
spatial and non-spatial versions: deficits in “recent” vs. “reference” components
episodic vs. semantic?
What us the unified theory for the role of the hippocampus in rat models?
hippocampal role in “relational” memory
HPC forms relations or associations between independent stimulus elements or associations: allows flexibility and inference
What is the “transitivity” task used in rat models of amnesia?
inferential associations
rats can make inferences based on past experiences and make associations based on relationships of past stimuli
A –> C (through B)
X –> Y (through Z)
make the inference, “fill in” missing relation
What is the “symmetry” task used in rat models of amnesia?
reverse associations
present stimulus to make them make the reverse association
C –> B
B –> A
What is the naturalistic food preference task?
another inferential associative task
eat a little bit, then see if they get sick, if they do they will not eat it again
in the litter, rats will not demonstrate fear, learn that food is safe
they learn to not eat the poison
associate breath of littermate and flavor of food so they remember it and pick
What is the hippocampus involved in?
configural learning and memory
spatial learning and memory
recent memory
