Differential recovery rates of horizontal and amacrine cell responses from intense irradiation in the isolated retina of cyprinid fish.

Recovery of light sensitivity in horizontal and amacrine cells, following desensitization of photoreceptors by localized brief laser flashes (647.1 or 488 nm) in isolated retinae of roach has been studied in a comparative approach. Spectrally matching laser irradiation suppressed light-evoked horizontal cell responses for minutes, cells only recovering on average less than 10% of their pre-irradiation response levels. In contrast, transient depolarizing responses in on-off amacrine cells recovered 80% or more of their light sensitivity within 10-20 s following laser irradiation of either wavelength. Possible neural basis of the sensitization phenomenon in amacrine cells is discussed in relation to known mechanisms of synaptic transmission in the retina.