The S-cone contribution to luminance depends on the M- and L-cone adaptation levels: Silent surrounds?

Abstract

Under dim background conditions, the S-cones make little or no contribution to luminance (A. Eisner & D. I. MacLeod, 1980; W. Verdon & A. J. Adams, 1987), yet under conditions of intense long-wavelength adaptation, a small but robust contribution to luminance--as defined by heterochromatic flicker photometry (A. Stockman, D. I. MacLeod, & D. D. DePriest, 1987, 1991) or motion (J. Lee & C. F. Stromeyer, 1989)--can be found. Here, by using selective adaptation and/or tritanopic metamers to isolate the S-cone response, we investigate the dependence of the S-cone luminance input on changes in background wavelength and radiance. Interestingly, the S-cone luminance input disappears completely when no adapting background is present, even though the same S-cone stimulus makes a clear contribution to luminance when a background is present. The dependence of the S-cone luminance input on the wavelength and radiance of the adapting background is surprising. We find that the S-cone signal can be measured on fields of 491 nm and longer wavelengths that exceed a criterion background radiance. These criterion radiances roughly follow an L + M spectral sensitivity, which suggests that the S-cone luminance input is silent unless the L- and M-cones are excited above a certain level. We hypothesize that the L + M cone signals produced by the steady adapting backgrounds somehow "gate" the S-cone luminance signals, perhaps by being modulated by them.

Structure and function of skin in the pelagic sea snake, Hydrophis platurus

“…The epidermis of H. platurus exhibits distinct differences in its ultrastructural features from terrestrial snakes, and even semi-aquatic species described earlier (Landmann, 1979;Tu, Lillywhite, Menon, & Menon, 2002;Ripamonti, Alibardi, Falini, Fermani, & Gazzano, 2009). In stark contrast to the thick β-layer of these species, the pelagic sea snake H. platurus has a significantly thinner β-layer, bearing filamentous The epidermis appears to be innervated with elements that do not penetrate the cornified layers, but are likely to be spatially associated with filamentous sensillae.…”

Chromatic clocks: Color opponency in non-image-forming visual function

“…Determining color sensitivity is complicated by the fact that it may depend on the overall light intensity or adaptation state of other photoreceptors (e.g. S-OFF inputs to luminance in humans (Ripamonti et al, 2009), ‘concealed color opponency’ in primate RGCs (De Monasterio et al, 1975a)).…”

The Verriest Lecture: Short-wave-sensitive cone pathways across the life span

“…S cones are morphologically different from the M and L cones [10,11], but their isolated receptor response seems to not differ [12], suggesting that it is primarily their postreceptoral circuitry that endows them with their functionally distinct temporal properties [13]. Psychophysically, S-cone pathways are relatively less sensitive to spatial modulation [14,15] and make little contribution to border discrimination [16] and luminance [17], except under specific conditions that unveil a small subtractive signal [18,19]. Ganglion cells carrying S-cone ON signals are morphologically distinct [20] and project to separate laminae, the koniocellular layers, of the lateral geniculate nucleus (LGN) [21].…”