Callosal projections in the visual cortex and the vertical meridian of the visual field in the albino rat

Studies using electrophysiological and HRP-labeling techniques showed that the lateral border of physiologically determined primary visual cortex coincides with the cytoarchiectonically defined area 17/18a border. The dense callosal projections are distributed in a zone, about 1.5 mm wide, along this border, which lies in the callosal zone, about 1/4-1/3 of the zone width from its lateral limit. There are two representations of the vertical meridian of the visual field, one in the proper of area 17, about 1/3 of the zone width from its medial limit, the other in area 18a, at about the lateral zone limit.