Segregation of efferent connections and receptive field properties in visual area V2 of the macaque.

V2 is a visual area of the macaque monkey which is at the second level in a recently proposed hierarchy of cortical visual areas. Histochemical staining for cytochrome oxidase (CO) in V2 reveals a pattern of alternate thick and thin CO-rich stripes separated by CO-sparse interstripes. These subregions receive distinct inputs from neurones in CO-rich and CO-sparse zones arrayed within the superficial layers of V1 (refs 4, 5). Are output projections from V2 to higher visual areas also segregated? Using an anatomical double-label paradigm, we have now demonstrated that V2 cells projecting to two of its major target areas, MT and V4 (refs 6, 7), are arranged in stripe-like clusters which are largely segregated from one another and which are closely related to the pattern of CO stripes. Concomitant electrophysiological recordings from V2 indicate that groups of cells having similar receptive field properties are clustered within the subregions defined by these anatomical techniques.