Figure 9.
(A) Non-linearity index (a measure of response distortion; see text) for a sample of MC cells (n = 16, on- and off-center cells combined) as a function of direction of modulation in an M, L cone space at 3 frequencies. At 2.4 and 9.8 Hz, the index is minimal for luminance modulation but increases as the axis of modulation moves toward the silent substitution directions, and is maximal in the chromatic quadrant. At 26 Hz, most response distortions were associated with response rectification. (B) Response of a PC cell to 2.4 Hz modulation in L, M space. There is a response minimum to luminance modulation and maximum response to chromatic modulation.