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 group, a dark-reared group and a group with the ipsilateral visual cortex 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 responses in the superficial SC decreased significantly. Acute removal of the visual cortex had no affect on the number of directionally selective cells recorded in the SC. The correlation between azimuthal visual receptive field and rostrocaudal position of the recording electrode in the SC was not significantly different from the control group following strobe, dark-rearing or acute visual cortex removal. These data imply that, during early development, visual information is necessary for directional selectivity of the visual responses in the superficial SC. However, the map of visual azimuthal space is essentially unperturbed by visual restriction (in the form of dark or strobe-rearing) or acute visual cortex removal.