| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
In order to elucidate the spatial information systems, especially those involved with problem solving strategies, we tried to dissociate functions of the hippocampus, dorsal striatum (DS), and parietal cortex of the rat brain.
1. Using place and cue tasks in the Morris water maze, functional dissociation of the hippocampus and DS was attempted. The results showed that the hippocampus is involved with the use of the place strategy whereas DS is concerned with the use of the cue strategy.
2. We explained the behavioral function of the medial caudate putamen (MCPu) using place and cue tasks under the win-shift and win-stay conditions in the radial arm maze. MCPu rats showed impairment with place task under the win-stay condition, but not with other task/condition. This result partly does not agree with the above-mentioned results. Considering the fact that there is a direct pathway between MCPu and the hippocampus, we pointed out the importance of the selective lesion of CPu in the future.
3. Hippocampus-lesioned rats (Hipp), parietal cortex-lesioned rats (Par), and normal rats (Cont) were tested in the water maze with or without room light. The performance of Hipp was poorest in every condition. Par also showed mild impairment, but there was not significant differences between Par and Cont. These results suggested that for spatial information processing hippocampus involvement is gross, but parietal cortex involvement is more limited;
4. Lastly, we examined differential effects of MK-801, an glutamate NMDA receptor antagonist, on acquisition and retention. We hypothesized that the difference is caused by the learning experience of the subject and the timing of drug administration, and gave the subjects place and cue tasks. It resulted that the effect of the drug is ameliorated in performing the succeeding task when the subject has experienced a task regardless of the nature of the task.
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