Purchase this article with an account.
Jenny M. Bosten, Gary Bargary, Patrick G. Goodbourn, Ruth E. Hogg, Adam J. Lawrance-Owen, John D. Mollon; Individual Differences Provide Psychophysical Evidence for Separate S-on and S-off Channels. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3907.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
There are two distinct populations of retinal ganglion cells that carry signals from the s-cones: those that receive excitatory input (S+) and those that receive inhibitory input (S-). The two cell populations are morphologically, anatomically and functionally distinct. We used individual differences in human visual performance as a method of determining whether the two pathways contribute separately to perceptual abilities.
We used a psychophysical test based on the Cambridge Colour Test, but in which detection thresholds for S-cone spatial increments and S-cone spatial decrements were measured separately. Thresholds for increment and decrement detection were estimated each as the average of two ZEST staircases, run in four separate blocks. 1062 participants aged 16-40 took part, as part of the PERGENIC test battery. 105 participants were tested on two different occasions, separated by at least a week, and data from these participants form the basis of our test-retest reliabilities.
Detection thresholds for S-cone increments and decrements each showed good test-retest reliability (ρ = 0.64, 0.67 respectively). The ratio of increment to decrement thresholds also showed significant test-retest reliability (ρ = 0.48). The correlation between thresholds for increments and thresholds for decrements was ρ = 0.65 (n = 1062).
Significant test-retest reliabilities show that stable individual differences in S-cone sensitivity can be measured psychophysically in a normal adult population aged 16-40. At least 40% of the variance in S-cone stimulus thresholds is shared between increments and decrements. However, a further portion of the variance (at least 20%) is stable across individuals, but unique to S-cone increments or decrements. Thus there is both a shared mechanism contributing to S-cone increment and decrement sensitivity, and mechanisms that are distinct for each type of stimulus.
This PDF is available to Subscribers Only