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S. L. Reinstein, G. Gingras, C. G. Broussard, G. K. Aguirre, D. H. Brainard, A. M. Komaromy; Behavioral Measurement of Photoreceptor-Directed Contrast Sensitivity in the Canine. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1063.
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© ARVO (1962-2015); The Authors (2016-present)
To measure behavioral contrast-detection performance for modulations designed to selectively stimulate canine rod, LM-cone, and S-cone photoreceptors.
A canine viewed three computer-controlled monitors. On each trial, a vertical sinusoidal grating flickering at 5 Hz was presented on one randomly chosen monitor. The canine received an automatic food reward for approaching the monitor with the grating. Gratings were presented at three contrast levels in each of three color directions; each direction was constructed to selectively stimulate one of the three canine photoreceptor classes (rods, LM cones, and S cones). A maximal-contrast luminance modulation was also included. All stimuli had an average luminance of ~60 cd/m2. Receptor directed modulations were produced using standard silent substitution methods with respect to estimates of the spectral sensitivities of dog photoreceptors [from the Govardovskii (Vis. Neurosci, 2000) photopigment nomogram; wavelengths of peak absorption (nm) taken as 555, 429, and 506 (Neitz et al. Vis. Neurosci., 1989; Parkes et al., IOVS, 1982)]. 1150 trials were collected.
Accuracy for high-contrast luminance modulation was ~100%. For the cone directed modulations, accuracy increased with contrast and reached ~70% correct at the highest displayable contrasts. As expected for rod-saturating luminance, performance for rod directed modulations was at chance.
Canine visual performance may be measured for stimuli detected by different photoreceptor classes. Above chance detection of rod modulations is predicted for luminance-attenuated stimuli in future studies. Receptor class-specific performance may be measured in congenital canine achromats before and after LM-cone gene therapy.
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