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Ambarish Pawar, Paul Laddis, Sergei Gepshtein, Thomas Albright; Measuring the spatiotemporal contrast sensitivity function in the macaque monkey. Journal of Vision 2013;13(9):366. doi: 10.1167/13.9.366.
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The spatiotemporal contrast sensitivity function is a large-scale characteristic of visual performance measured by estimating contrast thresholds across a broad range of spatial and temporal frequencies of luminance modulation (Kelly, 1979; Nakayama, 1985). Estimation of the sensitivity function is important for basic vision research and for evaluating the deficiencies that accompany visual pathology (e.g., Comerford, 1983). The human sensitivity function was previously found to have an invariant shape across tasks and subjects, as predicted by a theory of visual sensitivity (Gepshtein et al., 2007). Changes in statistics of stimulation caused a shift of the sensitivity function in the graph of spatial and temporal frequencies of luminance modulation, while preserving the shape of the function (Gepshtein et al., 2009). How is the large-scale change of sensitivity is mediated by cortical visual neurons, each of which is selective to a narrow range of spatiotemporal stimulation? To answer this question, one needs to evaluate both the behavioral sensitivity function and the sensitivity functions of individual neurons rapidly enough to capture the adaptive transformation of sensitivity. We measured the spatiotemporal contrast sensitivity function in two macaque monkeys, using intensive psychometric procedures that allowed us to estimate contrast thresholds using a fraction of trials required by the method of constant stimuli. In a direction discrimination task, stimulus contrasts were controlled by adaptive Bayesian procedures (Kontsevich and Tyler, 1999; Lesmes et al., 2010) such as to directly estimate parameters of the sensitivity function, rather than the sensitivities for individual stimuli, over a broad range of stimulus conditions (0.05-20 cycles/deg and 0.4-55 Hz). In both monkeys, the sensitivity functions had the same shapes as the human sensitivity function. We validated the results using the method of constant stimuli, indicating that the intensive psychometric procedures could be used to capture adaptive changes of behavioral and neuronal contrast sensitivities.
Meeting abstract presented at VSS 2013
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