EARLY INHIBITION AND EXCITATION OF RETINAL GANGLION CELLS

Experiments were performed on anesthetized rabbits to establish the relationship of the a-wave of the electroretinogram to early inhibition of the retinal ganglion cells. Early inhibition was produced in most experiments by superimposing a brief, intense flash on a background of off firing. Measurements made from average response histograms of multiple unit ganglion cell recordings taken at the surface of the retina show that the latency of earliest inhibition is several milliseconds shorter than that of earliest excitation. The inhibition always occurred during the negative trough of the transretinally recorded a-wave; excitation always started with the sharp upswing of the b-wave. Experimental conditions leading to b-wave delay relative to the a-wave caused enhanced inhibition and delay of excitation. The shorter latency of inhibition is interpreted as indicating that the inhibition arises within the visual cells and not in the neuronal network between the visual cells and ganglion cells. A hypothesis is presented suggesting that the a-wave produces the inhibition by defacilitating the flow of excitation from visual cells to bipolar cells by inducing a hyperpolarization of the proximal endings of the visual cells. © 1969.