Rod Cone Interaction In S Potentials From Cat Retina

Rod-cone interaction in cat S-potentials was studied by analyzing the effect of wavelength and intensity upon the form of dark-adapted responses. Flashes of white light and relatively monochromatic flashes produced responses that seemed to originate from the excitation of both receptor types. The rod response changed as a function of intensity, peaking at approx. 2.5 log above threshold and increasing in duration at approx. 3.0 log above threshold. The cone response seemed in some way to add to the changing rod response. V-Log I curves showed that the rod responses reached a ceiling (initial peak voltage) at approx. 3.5 log above threshold while the maintained voltage leveled off at a lower intensity. Both ceilings were obscured by the apparent addition of the cone contribution. Cone and rod responses to brief orange and blue lights of moderate intensity, separated in time, added together across a complete range of intervals. (Author).