The hemispheric dominance of cortical cells in the absence of direct visual pathways

Unit recording was carried out in the visual cortex of split chiasm and optic tract-sectioned adult cats. From the proportions of the visually responsive and unresponsive cells found in each hemisphere of the operated cats it was concluded that the indirect pathway via the corpus callosum becomes visually inactive under these conditions. However, the direct geniculocortical pathway remains visually active. Thus, it was assumed that unilateral or bilateral elimination of the decussating pathway has a crucial effect on the amount of interhemispheric callosal transfer of basic visual functions.