Fig. 18. Catfish retina. Activation of ganglion cells through light or an injection of extrinsic current into single bipolar cells. A1. On-center bipolar cell response (upper trace) and on-center ganglion cell response (lower trace) to a light stimulus. A2. Sinusoidal current passed through the bipolar cell membrane (upper trace) evokes ganglion cell spikes (lower trace) during the depolarizing phase. B1 through B4. Comparable sets of records for off-center bipolar cell and ganglion cell responses. (Naka K-I: Functional organization of catfish retina. J Neurophysiol 40:26, 1977)