Color fundamentals deduced from carp ganglion cell responses.

Retinal ganglion cell responses were used to derive the action spectra (fundamentals) of the photopic color mechanisms in carp. Both silencing and chromatic adaptation techniques were used. The former proved to be more successful than the latter, because weak (even subthreshold) dynamic signals in one mechanism (mostly the red) caused strong effects on the other mechanisms. With chromatic adaptation these interacting signals were unavoidable, whereas with the silencing technique the modulation of the silenced mechanism was eliminated. The resultant pure action spectra agree well with the electrophysiological data of cone pedicles and horizontal cells. They differ, however, from the log-absorption specta found by microspectrophotometry. Apart from the differences in the slope of the long wavelength tails, the spectra also differ in the short wavelength region. The latter may indicate that in A-2 pigments, the beta-band absorption has a lower efficiency than the main-band absorption.