Organization of geniculate inputs to visual cortical cells in the cat

Neuronal connectivity between a geniculate cell and a striate cortical cell was examined by cross-correlograms between their impulse activities. Delayed positive correlations were found in 82 pairs, and the onset delay of the positivity was short enough in 65 pairs to infer that the geniculate cell monosynaptically excited the cortical cell. These monosynaptic excitations were found in both simple and complex cells. By determining connectivity of a cortical cell with multiple geniculate cells, the convergence of X and Y geniculate cells and that of on-center and off-center geniculate cells was demonstrated in several striate cells.