Electric response of visual center in fish, especially to colored light flash.

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The visual center responses to light flash, especially variable with respect to color, were recorded from the tectum opticum contralateral to the illuminated eye in two fresh water fishes, Carassius auratus (L.) and Anguilla japonica T. et S.1) The photopic response in Carassius to white light flash consisted of two components, a series of spike potential with positive electric sign which represent the potential changes caused by the synchronous volley of nerve impulses passing along the optic tract, and the slow long-lasting negative components (PSP 1, PSP2) which represent the post-synaptic potential. As the characteristics of the response in the dark-adapted fish, the ripple 5 was pronounced and was immediately followed by the sharp negative component, and the PSP 2 did not appear. The response of the photopic Anguilla to the same flash may consist of the PSP 2 only.2) The pattern of the response in Carassius differs according to the wavelength of the stimulating light but is independent of the intensity of the light, showing the selective appearance of the ripples followed by the post-synaptic components in response to the concerned colored light; whereas no characteristic differences among the responses to various colored lights were observed in Anguilla, revealing the PSP 2 only in response to any colored light.3) The pattern of the response from the middle part of the tectum in Carassius shows maximal amplitude and appears to be summation of the potential changes from both of inner and outer sides of the tectum of the dorsal aspect of the hemisphere. This was observed in the response to white light flash and also red.4) The retinal responses and the action potentials of the optic tract in response to white and various colored light flashes were recorded, and were considered with respect to the correlation to the central responses. 5) The possible correlation between the generation of the second surface negative component in the central response (PSP 2) and the abrupt inhibition of the afferent volley of optic nerve impulses was suggested.