Matching rod percepts with cone stimuli
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Updated: Aug 18, 2026

Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses
Published on: March 14, 2012
Dingcai Cao1, Joel Pokorny, Vivianne C Smith
1Department of Health Studies, University of Chicago, IL 60637, USA.
Abstract:
Traditional methods for studying the effects of rod activity on color vision make it hard to assess the underlying physiological mechanisms. In this study, rod-mediated changes in color appearance were assessed by matching them with cone-mediated color changes. A four-primary photostimulator allowed independent control of rod and cone stimulation and identification of the cone types that generate color sensations equivalent to rod color sensations. The results showed that increases in rod stimulation required matches with cone stimuli that excited M-cones more than L-cones for all conditions. Matches for low-luminance conditions also required some S-cone stimulation. A subsidiary experiment showed that increases in rod modulation of an inducing field produced chromatic contrast effects like those produced by the M-cone system. The data are consistent with a hypothesis of perceptual normalization of scotopic vision to the chromatic appearance of objects under photopic conditions.
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