Toshihiko Oikawa

The dual nature of the octopus electroretinogram

Abstract Micro-electrodes inserted through the octopus retina detect a sustained negative response on the anterior surface, next an equipotential area, and still deeper a sustained positive response. On the basis of differences between the two responses with respect to stimulus variables, especially wavelength, the existence of at least two potential origins in the octopus retina was suggested. Although there is evidence that in the squid retina the receptor cells act as a dipole, the assumption of only one dipole is not enough to account for the data from the octopus retina.

Studies of rod-process by polarization method.

Based upon differences in velocity of changes in electrical sensitivity of the eye after exposure to a flash of light, it is possible to isolate a rod-process from a mixture of cone- and rod-processes. By means of this method rod-responses to spectral lights were measured at 20° from the fovea as a function of wavelengths. The spectral distribution of rod-responses determined in this manner is found in satisfactory agreement with the scotopic visibility curve.Rod-responses to a flash of weak white light were measured at various parts of the retina. The spatial distribution of rod-responses so obtained is found to show close resemblance to the density distribution of rods in the retina, although the maximum of the former is displaced farther in the periphery beyond the maximum of the density as the intensity of the flash is reduced.