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Abhishek De, Gregory D. Horwitz; Detection thresholds for lime-magenta and orange-cyan differ in eccentricity- and spatial frequency- dependence. Journal of Vision 2017;17(7):59. doi: https://doi.org/10.1167/17.7.59.
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© ARVO (1962-2015); The Authors (2016-present)
Isoluminant, in-phase modulation of S- and M- cone signals appear orange-cyan whereas isoluminant, in-phase modulation of S- and L- cone signals appear lime-magenta. The neural pathways that detect these modulations are not understood. To investigate the spatial selectivity of these pathways, we used a two-interval 2-AFC detection task. The stimulus was a static Gabor pattern that modulated either along the lime-magenta axis or along the orange-cyan axis at 0.5 cycles/deg or 3.0 cycles/deg. Thresholds at the fovea were lowest for the low spatial frequency lime-magenta stimulus. Thresholds at 5 deg were lowest for the high spatial frequency orange-cyan stimulus. This dependence of behavioral sensitivity on eccentricity and spatial frequency indicates that orange-cyan modulations are detected by neurons with smaller receptive fields than lime-magenta modulations. These results reconcile seemingly contradictory findings regarding the relative magnitude of BOLD responses to these modulations in the visual cortex.
Meeting abstract presented at the 2016 OSA Fall Vision Meeting
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