Efficiency of color induction varies between the photoresponse of cones, output of cones, and optic nerve.

<p>(A) In the photoresponse of cones, the sensitivity ratio between UV and long wavelengths (580 nm/370 nm) under the Natural background (<i>R_N</i>) did not differ significantly from that under the LW adaptation background (<i>R_LW</i>), for both retina treated with saline (S + ASP) and retina treated with saline, aspartate and cobalt (S + ASP + Co). This suggests minimal efficiency of color induction in the photoresponse of cones, regardless of whether HC-cone feedback is inhibited or not. (B) In the output of cones and (C) optic nerve, the sensitivity ratio between UV and long wavelengths (640 nm/370 nm) under the Natural background was significantly smaller than under the LW adaptation background, for saline-treated retina (S) but not for retina treated with saline and cobalt (S + Co). This suggests relatively high efficiency of color induction in the output of cones and optic nerve. This efficiency, however, decreased with the application of cobalt and became insignificant. Note that the relationship between the sensitivity ratio under the Natural and LW adaptation conditions is in agreement with the estimation of the quantum catches of cone pigments. Filled symbols, mean of either <i>R_N</i> or <i>R_LW</i>; open symbols, individual <i>R_N</i> or <i>R_LW</i> values; error bars, ±1 SD; n.s., non-significant; asterisk, significant difference (<i>P</i><0.05). Sample size: cone photoresponse, S + ASP Natural = 4, S + ASP LW adaptation = 5, S + ASP + Co Natural = 4, S + ASP + Co LW adaptation = 5; cone output, S Natural = 5, S LW adaptation = 4, S + Co Natural = 4, S + Co LW adaptation = 5; optic nerve, S Natural = 5, S LW adaptation = 4, S + Co Natural = 5, S + Co LW adaptation = 5. See <i>Methods</i> for details of the choice of wavelengths used for the calculation of <i>R_N</i> and <i>R_LW</i>. Note that spectra missing sensitivity values at the wavelengths used for the calculation of <i>R_N</i> and <i>R_LW</i> (370 and 580 nm for cone photoresponse, and 370 and 640 nm for cone output and optic nerve) were omitted from analysis.