Effects of stroboscopic rearing on the response properties and laminar distribution of single units in the rabbit superior colliculus

Single neurons were recorded from the superior colliculus of rabbits reared in a stroboscopically illuminated environment, and data were compared with recordings made from the superior colliculus of normally reared rabbits. Some of the consequences of strobe rearing were observed in all laminae of the superior colliculus: direction selectivity was abolished, receptive field size was increased and there was an increase in the proportion of cells responding more strongly to the offset than to the onset of light. Other consequences of strobe-rearing were observed selectively in specific laminae of the superior colliculus. Among cells influenced by a stroboscopic stimulus, cells in SGSu were more often responsive to the strobe stimulus, whereas cells in SGS1 were more often strobe inhibited. In layers deep to SO, equal numbers of cells showed strobe responsivity and strobe inhibition. Inhibitory surround organization was more strongly affected by strobe rearing in the deep layers, and external inhibition was abolished in layers deep to SO. The results indicate that strobe rearing has significant effects on responsivity to stroboscopic illumination, and on several other receptive field characteristics including direction selectivity, receptive field size, surround inhibition and responsivity to light offset. The data are discussed with reference to the role of the cortico-collicular projection.