Temporal properties of retinal ganglion cell responses to local transretinal current stimuli in the frog retina

Extracellular current stimuli have been used in both electrophysiological and clinical studies. The present study elucidates the temporal properties of the frog retinal ganglion cell response induced by local transretinal current stimuli. Two classes of spike response were recorded from the ganglion cell. One had a constant latency ranging from 1.5 to 4.5 ms after the onset of the stimulus regardless of differences in stimulus parameters. Another class had a latency that varied from trial to trial between 3.5 and 71.5 ms at the threshold even when stimulus parameters were identical. The latency became shorter and the number of spike responses increased as the charge applied via the stimulus pulse was increased by increasing the amplitude (from 50 to 200 microA) or the pulse duration (from 100 to 1000 micros). In both classes, the current stimuli with the same amount of charge induced responses of a similar latency for amplitudes between 50 and 200 microA and for pulse durations between 100 and 1000 micros.