żŜ14-3ĦĦSignal processng in the retina. Intracellutar recordings from pr- incipal retinal elements. R, eceptor ;H,horizontal cell;B,bipolar cell; A,amacrine cell; G,ganglion cell. Left-hand diagram: the responses obtai- ned when the centre of a receptive field is illuminated. Right-hand diag- ram: the response obtained from the same elements when peripheral parts of the receptive field are illuminated. The response of the receptors and horizontal cells is hyperpolarisation. The bipolar cells are hyperpolari- sed by illumination in the center of the receptive field and depolarised by peripheral illumination. The amacrine cells are depolarised by central and peripheral illumination and are the first show spike-like discharges. The spikes are single transients and occur only at the onset and termina- tion of illumination. Finally the ganglion cells are depolarised by cent- ral and peripheral stimulation and show typical neural spike discharges. (Adapted from Dowling, Invest. Ophthalm., 9,1970.)