1. Memory for spatial locations, motor responses, and objects Group B2 PraveenaSimonpillai Koral Neil Katelyn Pirie PaviNantheeswarar Sara Silva NakulRatra

2. 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

3. Pavi Introduction 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

4. Pavi Introduction Key Terms

5. 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.

6. 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)

7. Pavi Hypothesis: 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

8. 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

9. Katelyn Experiment 1:Testing for Spatial Location Memory

10. 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

11. 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

12. Nakul Results - Experiment 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

13. Sara Experiment 2:Testing for Response Recognition Memory

14. 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

15. 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.

16. Nakul Results - Experiment 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

17. Praveena Experiment 3: Testing Visual Object Recognition Memory • Delayed nonmatching-to-sample procedure

18. 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

19. 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

20. Nakul Results – Experiment 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

21. Nukal Summary of Results

22. Koral

23. Koral DISCUSSION/CONCLUSION Also, all 3 tasks used similar S-R bonds and CMM ie:moving towards or away from set target. • 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). • CAUDATE NUCLEUS LESIONS response recognition memory deficits. Consistent with previous studies. • MEDIAL EXTRASTIATE VISUAL CORTEX LESION visualobject recognition deficits. Consistent withpreviousstudies (eg Farah, 1990 – visualappreceptiveagnosia). MEVC – parallelfunction to hippocampusmediation of WM for visualobjects.

24. 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’sattributememory model needed - multidimensionalmemory 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.

25. Thank you for listening!