The geniculocortical pathways from the contralateral eye and the callosal pathway were interrupted in cats in order to study how cortical cells are influenced by changes induced in the interhemispheric transfer of visual information. Unit recording was carried out from areas 17 and 18 boundary, the callosal projection zone. The ocular dominance distribution of cortical cells showed absence of interhemispheric interaction. The visual areas in the two sides of the brain thus functioned independently, presenting a condition of visual split brain. This also has been reflected by the absence of compensatory visual inputs via an alternative commissural pathway. Furthermore, remarkable diminution in the excitability level was found as indicated by the reduction in the proportion of visually responsive cells. Finally, the results of the split brain cat reflect the condition of the individual operations from which it is composed.