1988 Fiscal Year Final Research Report Summary
Behavioral and physiological study on compensatory effects of visual system in rats.
| Project/Area Number |
61510050
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Psychology
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| Research Institution | Saga University |
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Principal Investigator |
IKEDA Yukinobu Saga University, College of Liberal Arts and Sciences, 教養部, 助教授 (50159638)
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| Project Period (FY) |
1986 – 1988
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| Keywords | monocular enucleation / visual cortex lesion / superior colliculus lesion / black-white discrimination / corpus callosum transection / アルビノラット / 片眼摘出 |
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| Research Abstract |
It has been shown that, following original training of a black-white discrimination task, rats with one eye removed at birth(OEB) relearned the task faster than rats monocularly enucleated at three months of age(OET) when relearning was conducted after extirpation of the visual cortex contralatral to the remaining eye. The aim of the present study was to examine the role of the visual pathway in mediation of original learning and relearning of OEBS in comparison with OETs. At first, the superior colliculus(SC) was destroyed bilaterally either before or after original learning. It was found that SC lesions did not affect original learning nor its retention in both OEBs and OETs, and there was no difference in the learning rate between the two. In relearning, it was also found that only when SC lesions were made before original learning, did OEBs fail to show faster relearning. Based on these findings it was suggested that enhanced functioning of the uncrossed visual pathway passing by way of SC in original learning plays an indispensable role in enabling OEBs to relearn the discrimination task faster than OETs.
Second, the experiment was undertaken to investigate the question of whether early elimination of the callosal fibers would give rise to reorganization of the visual system so that relearning is facilitated. This is because if the corpus callosum is sectioned immediately before original learning of the task, both OEBs and OETs become unable to relearn it within the stipulated 300 trials. It was found that OEBs and OETs with sections of the corpus callosum at 21 days of age relearned the task at almost the same rate as did OEBs and OETs with intact corpus callosum. This finding suggests that the early callosotmy brings out enhanced functioning of the visual system ipsilateral to the remaining eye.
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