The retinal input to cells in area 17 of the cat's cortex.

The activity of retinal ganglion cells and cortical cells with overlapping receptive fields was simultaneously recorded. The responses to moving stimuli of individual simple cortical cells could be accounted for on the basis of the cell receiving either on-centre or off-centre afferents; instances in which it was necessary to postulate a mixed on- and off-centre input were not found. In six instances cross correlograms of ganglion cell and cortical cell activity showed that the ganglion cell was afferent, via a relay cell in the LGN, to the cortical neurone. The receptive fields of such pairs were almost completely overlapping and concentric. In three cases a sustained ganglion cell projected to a simple cortical cell. In one case a transient ganglion cell projected to a simple cell, and in one case a sustained and a transient ganglion cell projected to the same simple cell.