Rod-cone interaction in carp retina: an analysis of electroretinographic B-waves

Changes in electroretinographic b-wave in the presence of background lights of increasing intensity were examined in isolated, superfused carp retinas. Within a certain range of ambient illumination b-waves elicited by red (695 nm) test flashes against dimmer background lights were smaller in size than against brighter ones. Accordingly, incremental thresholds for red flashes decreased as the intensity of background lights increased within this intensity range. The results suggest that cone pathways may be suppressed by rods in darkness and dim illumination. The phenomenon was absent for photoreceptor potentials (PIII components), indicating that the rod-cone interaction occurs in second-order retinal neurons.