Figure 3. Antidromic activation of an off-centre unit by electrical stimulation of the optic tract.

A, light-evoked spikes initiated the traces at the arrow indicated by ‘Triggering spike’. Shocks given after a 4 ms delay evoked an antidromic spike with 1 ms latency, indicating conduction velocity group II. Several successive traces are shown superimposed. B, no antidromic spike was recorded when shocks were given at less than 1 ms delay, due to collision with the light-evoked spike.