The retino-geniculo-cortical pathway in Callithrix. II. The geniculo-cortical projection.

After monocular injections of tritiated tracer precursors and transneuronal transport of tritiated compounds, a continuous band of radioactivity in layer IV of striate cortex of Callithrf the crossed and uncrossed retino-cortical pathways. Comparison with the organization of these pathways in other primates suggests that a segregation of the retino-cortical pathways of opposite ocularities into alternating ocular dominance columns in striate cortex has developed independently in the different primate lines. The significance is discussed of the weak labeling of the region of area 17 representing the central retina as compared to the representation of the peripheral retina.