S-potential sources as excitation pools

Abstract

The dependence of the electrical responses of single elements of L- and RG-types on the excitation of different receptor types has been studied in several species of freshwater fishes. By colour matching and adaptation experiments the L-cells as well as RG-cells are shown to be always connected with two types of receptors having sensitivity maxima at 530 and 620 mμ. The amplitude of the L-response (taking into account only the stable potential deflection), is the sum of deflections corresponding to the excitation of each receptor type alone. Certain effects of red background observed on RG-cells, namely the polarity-reversal of response to the red test light, the rise of blue response and the shift of the neutral point, are also shown to follow from summation of signals from different receptors and selective suppression of the different receptors by coloured backgrounds. This conception of the summation of signals from different receptors in S-potential can also explain Tomita's (1963) observation of the increase of negative red response in the triphasic cell induced by a violet background, which produces a negative response as well.