Ganglion cell discharge and proximal negativity in the pigeon retina.

1. Proximal negativity has been compared with the spike responses and membrane responses of pigeon ganglion cells. 2. Spike discharge peaks develop during the rising phase of proximal negativity. 3. Proximal negativity is never directional, even when recorded concurrently with directional ganglion cells. 4. To moving stimuli, on-centre cells respond in association with the leading edge of the stimulus, off-centre cells with the trailing edge, and on-off cells with the leading and trailing edges. Proximal negativity is produced in association with the leading and trailing edges. 5. Quasi-intracellular records show that discharge peaks occur in association with depolarizing potentials. The synaptic responses of on-off cells bear a closer resemblance to the proximal negative response than do the responses of on-centre cells, off-centre cells, or directional cells.