THE EFFECT OF DARK-REARING, STROBE-REARING AND ACUTE VISUAL-CORTEX REMOVAL ON THE VISUAL RESPONSES IN THE SUPERFICIAL SUPERIOR COLLICULUS OF THE GUINEA-PIG

Extracellular multi-unit responses to visual stimuli were recorded in the cells of the superficial layers of the superior colliculus (SC) in four groups of adult guinea-pigs: a control group, a strobe-reared gr oup, a dark-reared group and a group with the ipsilateral visual corte x removed acutely. Single unit visual responses were also recorded in a control and a dark-reared group. When guinea-pigs were either strobe or dark-reared from birth, the number of directionally selective resp onses in the superficial SC decreased significantly. Acute removal of the visual cortex had no affect on the number of directionally selecti ve cells recorded in the SC. The correlation between azimuthal visual receptive field and rostrocaudal position of the recording electrode i n the SC was not significantly different from the control group follow ing strobe, dark-rearing or acute visual cortex removal. These data im ply that, during early development, visual information is necessary fo r directional selectivity of the visual responses in the superficial S C. However, the map of visual azimuthal space is essentially unperturb ed by visual restriction (in the form of dark or strobe-rearing) or ac ute visual cortex removal.