Responses of directional ganglion cells in the pigeon retina.

1. Extracellular single-unit records were taken from ganglion cells in the pigeon retina, and average response histograms were recorded, with base line spike counts. 2. Movements in the preferred direction in directional cells produce discharge peaks. Movements in the null direction produce spike deletion suggesting there is an inhibitory patch offset from the field centre, towards the start of the null sweep. 3. Bi-directional responses can be obtained from the preferred side of the field centre; bi-directional inhibition can be obtained at the null side. Scans orthogonal to the null-preferred direction passing through the inhibitory patch can produce deletions. 4. The latency of deletions from the inhibitory patch is slightly greater than of excitation from the field centre, judged by flashed or moving stimuli.