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MEMORY FOR SPATIAL LOCATIONS, MOTOR RESPONSES, AND OBJECTS
Group B2
Praveena SimonpillaiKoral NeilKatelyn PiriePavi NantheeswararSara Silva Nakul Ratra
OUTLINE
Introduction/Background Information - Pavi
Experiment 1- Methods and Results - Katelyn &
Nakul
Experiment 2- Methods and Results - Sara & Nakul
Experiment 3- Methods and Results - Praveena &
Nakul
Discussion and Conclusion - Koral
Questions
INTRODUCTIONKey Terms:Working/ declarative/ data-based
memory: memory for new incoming information
Allocentric spatial: spatial location in reference to the outside space and is independent of the viewer
Egocentric spatial: spatial location in reference to the viewer
Pavi
INTRODUCTIONKey Terms
Pavi
TWO MAJOR THEORETICAL VIEWS CONCERNING THE NEUROBIOLOGICAL BASIS OF MEMORY FOR NEW INFORMATION:
1) Working and Declarative Memory Model: Hippocampus exclusively mediates or codes all info (spatial,
temporal, response, sensory-perceptual, or affect)
2) Attribute/ Data-based Memory Model: There are different neural substrates that mediate different
attributes.
Pavi
PURPOSE OF THE CURRENT STUDY:
To determine which of the two models supports the neurobiological basis of memory for new info by testing working/data-based memory for 3 different memory tasks.
3 memory tasks: spatial location (allocentric) response (egocentric) visual object (sensory-perceptual)
Pavi
HYPOTHESIS:1) Based on Working and Declarative Memory Model: Hippocampal lesion deficits in memory for all 3 tasksBut.. Caudate or extrastriate visual cortex lesions no deficits in memory
in 3 tasks
2) Based on Attribute/Data-based Memory Model: Hippocampal lesion deficit in memory for spatial location task only
Caudate nucleus lesion deficit in memory for motor response task only
Extrastriate nucleus lesion deficit in memory for visual object task only
Pavi
OVERVIEW OF THE CURRENT STUDY
Three Experiments:
Experiment 1: spatial location memory task
Experiment 2: motor response memory task
Experiment 3: visual objects memory task
Pavi
EXPERIMENT 1:TESTING FOR SPATIAL LOCATION MEMORY
Katelyn
Step 1 – Training Phase: Familiarized with maze Trained using a delayed spatial matching-
to-sample procedure
Step 2 – Study Phase: Rats trained to enter a randomly selected
arm of the maze to obtain a small piece of cereal (reinforcement)
Rat returned to centre area, linoleum was wrapped around the central platform to cover all arms
Katelyn
Step 3 – Test Phase: Linoleum was removed and rat was given choice
between previously entered arm and a new arm After reaching criterion performance (75% correct
or better on 16 consecutive trials) rats received either hippocampal lesions, caudate nucleus lesions, extrastriate visual cortex lesions, or cortical control
After Surgery: Retested 4 times daily until reached criterion
performance again 32 trials (4 per day) with 15 second delay
between study and test phase 32 trials with 30 second delay between study and
test phase
Katelyn
RESULTS - EXPERIMENT 1
-Hippocampal lesioned rats took more trials to rereach Criterion (P<0.01)-In the delay tests, continued poor performance with expectedreduced performance withincreased delay
Nakul
EXPERIMENT 2:TESTING FOR RESPONSE RECOGNITION MEMORY
Sara
Step 1 - Training phase: Familiarized with maze
Step 2 - Study phase: Rat place in middle arm and given opportunity to
make left or right turn depending on which door was opened
Given reinforcement for making the right choice
Step 3 - Test phase: Rat was place in middle arm opposite of the study
phase arm, both left and right doors were opened and they were given the opportunity to enter one
Positive reinforcement for choosing the matching sample
Sara
Post Surgery: Rats were retested daily until they reached
criterion performance or completed 204 trials
Then rats were given 36 trials with a 15-s delay followed by 36 trials with a 30-s delay between study and test phase
All continued testing with a 30-s delay until they reached criterion or 204 trials.
Sara
RESULTS - EXPERIMENT 2
Caudate nucleus lesioned rats took more trials to rereach Criterion (P<0.01)-In the delay tests, continued poor performance with expectedreduce in performance withincreased delay
Nakul
EXPERIMENT 3: TESTING VISUAL OBJECT RECOGNITION MEMORY
Delayed nonmatching-to-sample procedure
Praveena
Step 1: Training Phase Familiarization with apparatus
Step 2: Study Phase Side one of apparatus, rat given
opportunity to push aside visual object to obtain reinforcement
On other side, rat must choose novel unique object in order to receive reward
10 trials per day are given to each rat until 75% criterion or better on 60 consecutive trials has been reached
Praveena
Step 3: Test Phase (After Surgery) Recovered rats are retested daily with 10
trials per day until 75% criterion or better on 60 consecutive trials has been reached
10s and 20s delay trials done after until criterion reached or after 260 trials
Praveena
RESULTS – EXPERIMENT 3
-Extrastriate visual cortexlesioned rats took more trials to rereach criterion (P<0.05)-In the delay tests, continued poor performance with expected reduce in performance withincreased delay
Nakul
SUMMARY OF RESULTS
Nukal
LESIONED AREAS
AFFECTED & UNAFFECTED ATTRIBUTED AREAS
SPATIALLOCATION
EGOCENTRIC MOTOR
RESPONSE
VISUAL OBJECT RECOGNITION
HIPPOCAMPUS
xCAUDATE NUCLEUS
xEXTRASTRIATE VISUAL CORTEX
x
Koral
DISCUSSION/CONCLUSIONAlso, all 3 tasks used similar S-R bonds and CMM
ie:moving towards or away from set target.
o HIPPOCAMPUS LESIONS spatial location recall deficits. Findings were consistent with previous neurobiological studies of monkeys (eg. Hunt et al 1986) and humans (eg. Cave and Squire, 1991).
o CAUDATE NUCLEUS LESIONS response recognition memory deficits. Consistent with previous studies.
o MEDIAL EXTRASTIATE VISUAL CORTEX LESION visual object recognition deficits. Consistent with previous studies (eg Farah, 1990 – visual appreceptive agnosia). MEVC – parallel function to hippocampus mediation of WM for visual objects.
Koral
KEY FINDINGS
TRIPLE DISSOCIATION of the hippocampus, caudate nucleus and areas of extrastriate visual cortex in mediation of spatial location, visual object processing and responding functions.
Each neural systems can function independently in STM and in parallel.
More than the H mediates WMM – first hypothesis refuted.
Revision of Kesner’s attribute memory model needed - multidimensional memory model
Each of the 3 lesioned rats performed well in at least 2 STM tasks - low reliability and causality of MD to GA, M, AP or pre-surgery training.
Koral
Thank you for listening!
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