Differential effects of unilateral optic tract transections and visual cortical lesions upon a pattern discrimination in albino rats with removal of one eye at birth.
Previously we have demonstrated that adult rats with one eye removed at birth (OEB) relearn a black-white discrimination faster than control rats monocularly enucleated at maturity (OET), when relearning is conducted after lesions of the visual cortex contralateral to the remaining eye. This faster relearning phenomenon is considered to be one behavioral expression of the functioning of the expanded uncrossed visual pathways resulting from monocular at birth. The present study was concerned with the question of whether the same phenomenon can be observed in the discrimination between alternating black and white stripes oriented horizontally and vertically. Two experiments were carried out. In the first experiment, which is a replication of one of our previous studies, relearning was conducted after the visual cortical lesions contralateral to the remaining eye. The results were consistent with those of the previous one in which neither OEBs nor OETs were found able to relearn the discrimination. In the second experiment, relearning was conducted after transections of the optic tract contralateral to the remaining eye. It was shown that under this condition both OEBs and OETs could relearn the discrimination, and furthermore, that OEBs restored the habit faster than OETs. Possible mechanisms underlying the difference in the results from the two experiments were discussed.
Sakai
M
M
Neuropsychology Laboratory, Saga Medical School, Japan.
Ikeda
Y
Y
Yagi
F
F
D000818:Animals; D001931:Brain Mapping; D004193:Discrimination Learning / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D005829:Geniculate Bodies / Q000502:physiology; D008297:Male; D011939:Mental Recall / Q000502:physiology; D009416:Nerve Regeneration / Q000502:physiology*; D009900:Optic Nerve / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012683:Sensory Deprivation / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology