The retinotopic distribution of visual callosal projections in the suprasylvian visual areas compared to the classical visual areas (17, 18, 19) in the cat.

The distribution of the interhemispheric projection from area 17 and 18 was studied using the anterograde degeneration technique. Besides the classical visual areas (17, 18, 19), area 21 and several visual areas in the middle suprasylvian sulcus also received visual callosal input. In the four terminal areas of the middle suprasylvian sulcus the projection was found to be focused on representations of the ventrical meridian including the area centralis, as in the classical visual areas. An increase of the width of visual field represented in the zone of callosal terminations can be seen from area 17 through area 18 to area 19 and possibly this trend continues in the suprasylvian visual areas.