Synchronous oscillations in the cat retina

Retinal ganglion cells exhibit oscillatory responses which are precisely sy nchronized over large distances. Here we examined, with multi-electrode rec ordings, the time course of synchronization during spontaneous and stimulus -driven oscillatory activity. Spontaneous discharges showed synchronized os cillations at similar to 30 Hz, which were occasionally associated with slo wer superimposed oscillations in the range of 1-5 Hz. Stationary stimuli or moving gratings induced synchronous oscillations at higher frequencies (me an of 79.0 +/- 20.0 Hz for OFF- and 91.7 +/- 11.7 Hz for ON-responses), wit h time lags of a few milliseconds. At response onset, the first few oscilla tory cycles were occasionally time locked to the stimulus. Thereafter, sync hronization became independent of stimulus coordination and was exclusively due to neuronal interactions. Oscillatory modulation emerged rapidly and w as sustained throughout the responses while oscillation frequency decreased gradually. This periodic patterning of responses persisted despite brief a nd local occlusion of stimuli, suggesting that synchronous oscillations eme rge from population dynamics and entrain cells even if they are intermitten tly silenced. (C) 1999 Elsevier Science Ltd. All rights reserved.