Previous research revealed significant individual variations in opsin genes and cone photopigments in several species of platyrrhine (New World) monkeys and showed that these in turn can yield significant variations in color vision. To extend the understanding of the nature of color vision in New World monkeys, electroretinogram flicker photometry was used to obtain spectral sensitivity measure...

Opsin proteins covalently bind to small molecular chromophores and each protein-chromophore complex is sensitive to particular wavelengths of light. Multiple opsins with different wavelength absorbance peaks are required for color vision. Comparing opsin responses is challenging at low light levels, explaining why color vision is often lost in nocturnal species. Here, we investigated opsin evol...

The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to ...

Deuteranomalous trichromacy, which affects medium-wavelength-sensitive cones, is more common than protanomalous trichromacy, which affects long-wavelength-sensitive cones. The aim of the present work was to test the extent to which these two kinds of anomalous trichromacy affect surface-color judgments in the natural world. Simulations of 18 natural scenes under different daylight illuminants w...

AIMS To determine whether the short wavelength sensitive (S) cone electroretinogram (ERG) is selectively altered in diabetic patients with and without retinopathy. METHODS Ganzfeld spectral flashes in the presence of bright white background illumination were used to elicit S cone ERGs is 15 non-retinopathic diabetics, 16 background retinopathic diabetics, and 16 age matched normal controls. ...

We compared the visual detection thresholds for cone-isolating stimuli of trichromats (those with normal color vision) with those of X-linked dichromats, who lack either the long-wavelength-sensitive (L) cones (protanopes) or middle-wavelength-sensitive (M) cones (deuteranopes). At low (1 Hz) temporal frequencies, dichromats have significantly higher (twofold) thresholds for all colored stimuli...

An important unanswered question in phototransduction is how visual pigments (VPs) regulate their wavelength of maximal absorption (lambda max). By constructing the evolutionary tree for 28 opsins with known lambda max values, we can identify the times and directions of lambda max shift of different VPs. A total of 55 amino acid changes are shown to correlate with the directions of lambda max s...

Spontaneous fluctuations in the electrical signals of the retina's photoreceptors impose a fundamental limit on visual sensitivity. While noise in the rods has been studied extensively, relatively little is known about the noise of cones. We show that the origin of the dark noise in salamander cones varies with cone type. Most of the noise in long wavelength-sensitive (L) cones arose from spont...

The relative numerosity of the long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cones and the red-green color appearance, as assessed by means of unique yellow, are stable from fovea to midperiphery (+/- 28 deg nasotemporal). As foveal tests decrease in size, unique yellow progressively shifts toward longer wavelengths, favoring a model of red-green opponency carried by cells w...