| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
In a previous study we investigated the effects of callosal transected lesions made 10 weeks earlier, either at 3 weeks of age or at 13 weeks of age, upon the acquisition of BW discrimination in rats either with one eye removed at birth (GEB) or in adulthood (OETs) following the CT visual cortex lesions. The CT visual lesions were perofrmed right before the training of BW discrimination. We found that the 10-week-old callosal transected lesions facilitated the acquisition in OEBs when the callosal lesions were given at 3 weeks of age, but not at 13 weeks of age, whereas the same type of callosal transected lesions did not do so in OETs, regardless of the age when the callosal lesions were made.
Since the CT visual cortex lesions inevitably result in damage of the callosal neurons, and lead to degeneration of the callosal afferents in the IP visual cortex, the present study was undertaken to investigate if the 10-week-old CT visual cortex lesions, made at either 3 weeks of age or 13 weeks of age, would affect the acquisition of BW discrimination in OEBs and OETs, like the 10-week-old callosal transected lesions employed in the previous study mentioned above. We found that the facilitation effects generally tended to be more prevailing and pronounced : the 10-week-old CT visual cortex lesions made at 3 weeks of age facilitated the acquisition of BW discrimination not only in OEBs but also in OETs, and the same type of CT visual cortex lesions, made as late as 13 weeks of age, did so in OEBs but not in OETs. The findings are discussed in relation to the possible involvement of neurotrophic factors, released when the CT visual cortex lesions were made, in synaptic reorganization.
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