Simultaneous anatomical demonstration of the representation of the vertical and horizontal meridians in areas V2 and V3 of rhesus monkey visual cortex

This paper describes an experiment undertaken to demonstrate anatomically the representation of the horizontal and the vertical meridian of the visual fields in areas V2 and V3 of the same hemisphere. [3H]Proline was injected into V1 in the region of horizontal meridian representation at 30° from the centre of gaze in an animal in which the corpus callosum had been sectioned. The histology of the prestriate cortex revealed two small patches of label, separated by a 500 μm gap, between two regions of callosal fibre degeneration. The centre of the 500 μm gap was taken to be the boundary between V2 and V3. This demonstration leaves no doubt that not only are the two areas topographically organized but they both receive a direct input from area 17 (V1).