Functional organization of the cyprinid fish retina as revealed by discriminative responses to spectral illumination.

1. The nature of Svaetichin's cone action potential was investigated on Cyprinus auratus by means of spectrum scanning method.2. Three types of spectral response were obtained, which might be designated as RG, RYB and L respectively, but the polarity of the present RG-type was opposite to that given by Svaetichin.3. Illumination given onto a retinal region at a distance from the recordingsite still produced response of considerable amplitude. The response could not be attributed to the effect of scattered light, since the response decreased to a great extent after making a cut to disconnect the recording and the illuminated regions.4. The spectral response pattern was found to be determined only by the position where recording was made and to be independent of which part of the retina was illuminated.5. It was confirmed that the site producing intraretinal action potential (fish EIRG) was second or higher neurone and not receptor itself.6. Based on the above result, a model of functional organization of the retina was presented and fully discussed.