Discrepant effects of unilateral and bilateral forebrain lesions on the visual performance of pigeons.

The monocular and binocular performance of pigeons with bilateral, unilateral or sham lesions in the telencephalic Wulst was tested with visual discrimination tasks. Unilateral lesions yielded a marked deficit when the animals could only use the eye contralateral to the lesion. Otherwise the accomplishments of the ablated animals did not differ from that of the controls. The reciprocal inhibition of symmetrical visual brain stem centers is thought to have been unbalanced through the one-sided interruption of a known pathway descending from the Wulst.