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!