| Abstract No.: | A-G1201 |
| Country: | Canada |
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| Title: | SYSTEMS CONSOLIDATION... OR THE CHANGING NATURE OF SPATIAL MEMORIES? |
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| Authors/Affiliations: | 1 Stephane Gaskin*; 1 Marilyn Tardif; 1 David Mumby;
1 Concordia University, Montreal, QC, Canada.
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| Content: | Objective: The objective was to determine whether hippocampal damage causes temporally-graded retrograde amnesia (TGRA) on a test of incidental spatial learning?
Materials and Methods: In a non-navigation spatial memory paradigm, rats were exposed to two identical objects in a circular open field for 7 minutes on 7 consecutive days. In the 1-3 days following the last day of training half the rats (n=8) received complete lesions of the HPC. Another group (n = 7) received the same lesions 3 weeks after training. The rats were then placed back in the open field with one object displaced by 90o and the time spent in each of the quadrants as well as time spent exploring the objects was recorded.
Results: Rats that received HPC lesions 3 weeks but not 1-3 days after training showed evidence of preserved remote spatial memory; however, their remote memory was expressed through different behaviour than normal rats used to express memory of the same remote event. Rats with HPC lesions spent more time with the displaced object than with the object that remained in the same place, whereas normal rats spent more time in the quadrant where the displaced object used to be.
Conclusions: These results suggest that although remote spatial memories may be preserved with a sufficiently long training-to-surgery interval before HPC ablation, the nature of these memories may differ in quantity and/or quality from that of normal rats suggesting the possibility that these memories may have never been dependent on the HPC. These results also raise the possibility that spatial memories may undergo consolidation provided the spatial paradigm does not require navigation.
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