Responses of retinal network to electrical stimulation.

The carp's inverted retina was stimulated by a brief electric pulse of 0.5-1 msec. 1. A negative potential less than 1 mV in amplitude appeared following the stimulating pulse and lasted about 20-30 msec. 2. This potential is a graded response, and facilitated by a suitable background illumination. 3. When the intensity of the stimulus was sufficiently high, the negative potential mentioned above could be followed by a second and/or third similar responses. A positive deflection intervened between successive negative deflections. 4. Some facilitatory effects of 3% strychnine, and 5×10-4 M d-tubocurarine were observed upon the negative slow potential. 5. A monopolar stimulating microelectrode was inserted into various depths of the retina, and it was found that the retinal network intervening between the receptor cell layer and the ganglion cell layer gave the greatest responses. 6. The relation between the slow potential and unitary discharges was investigated. The discharge of an on-element was facilitated by the negative response as well as by cathodal polarization, whereas that of an off-element suffered from suppression.