1. M EMORY FOR SPATIAL LOCATIONS, MOTOR RESPONSES, AND OBJECTS Group B2 Praveena Simonpillai Koral Neil Katelyn Pirie Pavi Nantheeswarar Sara Silva Nakul Ratra

2. O UTLINE 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

3. I NTRODUCTION Key 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

4. I NTRODUCTION Key Terms Pavi

5. T WO M AJOR T HEORETICAL V IEWS C ONCERNING THE N EUROBIOLOGICAL B ASIS OF M EMORY FOR N EW I NFORMATION : 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

6. P URPOSE OF THE C URRENT S TUDY : 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

7. H YPOTHESIS : 1) Based on Working and Declarative Memory Model: Hippocampal lesion  deficits in memory for all 3 tasks But.. 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

8. O VERVIEW OF THE C URRENT S TUDY Three Experiments: Experiment 1: spatial location memory task Experiment 2: motor response memory task Experiment 3: visual objects memory task Pavi

9. E XPERIMENT 1: T ESTING FOR S PATIAL L OCATION M EMORY Katelyn

10. 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

11. 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

12. R ESULTS - E XPERIMENT 1 -Hippocampal lesioned rats took more trials to rereach Criterion (P<0.01) -In the delay tests, continued poor performance with expected reduced performance with increased delay Nakul

13. E XPERIMENT 2: T ESTING FOR R ESPONSE R ECOGNITION M EMORY Sara

14. 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

15. 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

16. R ESULTS - E XPERIMENT 2 Caudate nucleus lesioned rats took more trials to rereach Criterion (P<0.01) -In the delay tests, continued poor performance with expected reduce in performance with increased delay Nakul

17. E XPERIMENT 3: T ESTING V ISUAL O BJECT R ECOGNITION M EMORY Delayed nonmatching-to-sample procedure Praveena

18. 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

19. 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

20. R ESULTS – E XPERIMENT 3 -Extrastriate visual cortex lesioned rats took more trials to rereach criterion (P<0.05) -In the delay tests, continued poor performance with expected reduce in performance with increased delay Nakul

21. S UMMARY OF R ESULTS Nukal

22. LESIONED AREAS AFFECTED & UNAFFECTED ATTRIBUTED AREAS SPATIAL LOCATION EGOCENTRIC MOTOR RESPONSE VISUAL OBJECT RECOGNITION HIPPOCAMPUS x CAUDATE NUCLEUS x EXTRASTRIATE VISUAL CORTEX x Koral

23. DISCUSSION/CONCLUSION Also, 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

24. 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

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