Stimulus size affects rod influence on tritan chromatic discrimination

Knight, Roger; Buck, Steven L.; Pereverzeva, Maria

doi:10.1002/1520-6378(2001)26:1+<::aid-col15>3.0.co;2-d

Cited by 9 publications

(7 citation statements)

References 10 publications

(10 reference statements)

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“…That rods impair discrimination along the tritan color axis for normal trichromats (Table 4) has been reported previously (Brown, 1951, Knight et al, 1998, Knight, Buck & Pereverzeva, 2001, Stabell & Stabell, 1977). In our experiments, the effect of the rod impairment is more or less the same for normal trichromats as for tritans, except that the effect of rod impairment starts at the highest level of luminance (92.3 Td) for tritans (c.f Hough, 1968…”

Section: Discussionsupporting

confidence: 83%

Substitution of isoleucine for threonine at position 190 of S-opsin causes S-cone-function abnormalities

et al. 2012

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Five mutations in the S-cone-opsin gene (OPN1SW) that give rise to different single amino-acid substitutions (L56P, G79R, S214P, P264S, R283Q) are known to be associated with tritan color-vision deficiency. Here we report a sixth OPN1SW mutation (T190I) and the associated color vision phenotype. S-opsin genotyping and clinical evaluation of color vision were performed on affected and unaffected family members and normal controls. Chromatic contrast was tested at different levels of retinal illuminance. Affected family members were heterozygous for a nucleotide change that substituted the amino acid isoleucine (I) in place of threonine (T) that is normally present at position 190 of the S-opsin. The mutation is in extracellular loop II (EII). The association between making tritan errors and having the T190I mutant S opsin was strong (p > 0.0001: Fisher's exact test). The performance of subjects with the T190I mutation was significantly different from that of normal trichromats along the tritan vector under all conditions tested (Mann-Whitney U: p < 0.05), but not along the protan or deutan vectors. Individuals with the T190I S-opsin mutation behaved as mild tritans at 12.3–92.3 Td, but as tritanopes at 1.2–9.2 Td, for both light-adapted and dark-adapted conditions. The results are consistent with the mutant opsin causing abnormal S-cone function.

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Section: Discussionsupporting

confidence: 83%

Substitution of isoleucine for threonine at position 190 of S-opsin causes S-cone-function abnormalities

et al. 2012

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“…This is difficult due to the common photophobia of such individuals when exposed to bright light 42 . However, several studies showed that rods impact aspects of color perception at scotopic and mesopic light levels in human trichromats 43 – 45 , dichromats 46 , and blue cone monochromats 47 (reviewed by Zele and Cao 48 ). This influence of rod signaling on color vision could be used to test for rod contribution to visual perception also under bright light conditions.…”

Section: Discussionmentioning

confidence: 99%

Rods progressively escape saturation to drive visual responses in daylight conditions

et al. 2017

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Rod and cone photoreceptors support vision across large light intensity ranges. Rods, active under dim illumination, are thought to saturate at higher (photopic) irradiances. The extent of rod saturation is not well defined; some studies report rod activity well into the photopic range. Using electrophysiological recordings from retina and dorsal lateral geniculate nucleus of cone-deficient and visually intact mice, we describe stimulus and physiological factors that influence photopic rod-driven responses. We find that rod contrast sensitivity is initially strongly reduced at high irradiances, but progressively recovers to allow responses to moderate contrast stimuli. Surprisingly, rods recover faster at higher light levels. A model of rod phototransduction suggests that phototransduction gain adjustments and bleaching adaptation underlie rod recovery. Consistently, exogenous chromophore reduces rod responses at bright background. Thus, bleaching adaptation renders mouse rods responsive to modest contrast at any irradiance. Paradoxically, raising irradiance across the photopic range increases the robustness of rod responses.

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“…In addition to affecting the perceived hue, brightness, and saturation, rod activity can alter cone-mediated chromatic discrimination ( Stabell and Stabell, 1977 ; Nagy and Doyal, 1993 ; Knight et al, 1998 , 2001 ; Cao et al, 2008b ; Shepherd and Wyatt, 2008 ; Volbrecht et al, 2011 ). In comparison to measurements under photopic illumination, chromatic sensitivity measured under mesopic illuminations is differentially altered in the areas of the protan, deutan, and tritan confusion lines, with the greatest sensitivity loss near the tritan axis, but in general, the magnitude of the rod intrusion is small when measured with luminance contrast masking techniques ( Walkey et al, 2001 ).…”

Section: Rod Contributions To Mesopic Color Visionmentioning

confidence: 99%

Vision under mesopic and scotopic illumination

2015

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Evidence has accumulated that rod activation under mesopic and scotopic light levels alters visual perception and performance. Here we review the most recent developments in the measurement of rod and cone contributions to mesopic color perception and temporal processing, with a focus on data measured using a four-primary photostimulator method that independently controls rod and cone excitations. We discuss the findings in the context of rod inputs to the three primary retinogeniculate pathways to understand rod contributions to mesopic vision. Additionally, we present evidence that hue perception is possible under scotopic, pure rod-mediated conditions that involves cortical mechanisms.

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Stimulus size affects rod influence on tritan chromatic discrimination

Cited by 9 publications

References 10 publications

Substitution of isoleucine for threonine at position 190 of S-opsin causes S-cone-function abnormalities

Substitution of isoleucine for threonine at position 190 of S-opsin causes S-cone-function abnormalities

Rods progressively escape saturation to drive visual responses in daylight conditions

Vision under mesopic and scotopic illumination

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