Spectral sensitivity of the feedback signal from horizontal cells to cones in goldfish retina.

The spectral sensitivity of cones in isolated goldfish retina was determined with whole-cell recording techniques. Three spectral classes of cones were found with maximal sensitivities around 620 nm, 540 nm, and 460 nm. UV-cones were not found because our stimulator did not allow effective stimulation in the UV range. The spectral sensitivity of the cones closely matched the cone photopigment absorption spectra at the long wavelength side of the spectrum, but deviated significantly at shorter wavelengths. Surround stimulation induced an inward current in cones due to feedback from horizontal cells. The spectral sensitivity of this feedback signal was determined in all three cone classes and found to be broader than the spectral sensitivity of the cones recorded from, and to be spectrally nonopponent. These data are consistent with a connectivity scheme between cones and horizontal cells in which the three horizontal cell systems feed back to all cone systems and in which all horizontal cell systems receive input from more than one cone system.