Spatial dissociation of visual inputs alters the origin of the corpus callosum

The distribution of the origin of corpus callosum neurons was investigated in cats reared with an optically induced strabismus by applying horseradish peroxidase (HRP) to severed callosal axons. These animals demonstrated an enlargement of the region of callosal connectivity compared to normal cats. Bilaterally there was an expanded efferent zone, with callosal cell bodies widely distributed in area 17, extending down the medial bank of the lateral gyrus halfway to the fundus of the splenial sulcus. This suggests that rearing a cat with visual spatial dissociation requires additional communication between the hemispheres in the form of increased callosal connections between cortical regions representing more peripheral portions of the visual field.