Summary: Blue-Yellow Signals Are Enhanced by Spatiotemporal Luminance Contrast in
Gregory D. Horwitz,1,2
E. J. Chichilnisky,2
and Thomas D. Albright1,2
Howard Hughes Medical Institute, 2
Systems Neurobiology Laboratories, The Salk Institute for Biological Studies, La Jolla, California
Submitted 21 July 2004; accepted in final form 16 October 2004
Horwitz, Gregory, E. J. Chichilnisky, and Thomas D. Albright.
Blue-yellow signals are enhanced by spatiotemporal luminance
contrast in macaque V1. J Neurophysiol 93: 22632278, 2005;
doi:10.1152/jn.00743.2004. We measured the color tuning of a pop-
ulation of S-cone-driven V1 neurons in awake, fixating monkeys.
Analysis of randomly chosen color stimuli that were effective in
evoking action potentials showed that these neurons received opposite
sign input from the S cones and a combination of L and M cones.
Surprisingly, these cells also responded to LM cone contrast irrespec-
tive of polarity, a nonlinear sensitivity that was masked by conven-
tional linear analysis methods. Taken together, these observations can