Receptive field arrangement of color-opponent bipolar and amacrine cells in the carp retina.

Seven color-opponent bipolar and 50 color-opponent amacrine cells were identified in the carp retina and their spectral responses examined by using procion-dye-filled micropipets for staining and recording. Four of the bipolar cells had a +R-G-and three a +Y-B-type chromatic center. Six of the bipolar cells showed hyperpolarizing non-color-opponent surrounds, while one +R-G-type cell had a +Y-RB-type surround. This cell showed the greatest complexity of all bipolar cells identified so far, and its spectral property strongly suggests the existence of an intimate relation between it and +Y-RB-type horizontal cells. Examination and classification of the 50 amacrine cells revealed that 17 belonged to the +R-G, 16 to the -R+G, 6 to the +Y-B, and 11 to the -Y + B type. Most of these cells showed non-color-opponent surrounds. Yet, the similarity of the chromatic arrangement of their centers with that of the ganglion cells shows that the four basic types of color channels are already in existence in the amacrine cells where they seem to originate.