Interaction between the short-wavelength cone and rod systems in the electroretinogram of the cynomolgus monkey

We recorded electroretinograms from anesthetized cynomolgus monkeys by means of three monochromatic (435, 524 or 579 nm) full-field stimuli presented with a monochromatic background light. The color of the background light was changed with 29 interference filters (400-700 nm). Waveforms were analyzed by means of principal component analysis to investigate interaction between the short-wavelength cone and other systems. With the same test lights, responses were also recorded during dark adaptation after 20,000-lux full bleach. The shape of the short-wavelength cone electroretinogram changed as a function of the wavelength of monochromatic background light. The change was clearer around 500-nm background light, to which the rod system is highly sensitive. Further, short-wavelength cone responses developed during the first 15 min in the dark; however, they became smaller with the recovery of the rod system. These findings suggest that there is interaction between the short-wavelength cone and rod systems. In addition, the results of waveform analysis confirmed the interaction between the long-wavelength and middle-wavelength cone systems.