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Jeremy Wurbs, Ennio Mingolla, Arash Yazdanbakhsh; Modeling a space-variant cortical representation for motion under continuous and phi motion conditions. Journal of Vision 2012;12(9):762. doi: 10.1167/12.9.762.
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V1 receptive field sizes increase with eccentricity, as does temporal processing speed (Carrasco et al. 2003, Hartmann et al. 1979). The fovea is evidently specialized for slow, fine movements while the periphery is suited for fast, coarse movements. In either the fovea or periphery discrete flashes can produce motion percepts. Grossberg and Rudd (1989) used traveling Gaussian activity profiles to model such apparent motion percepts as beta, phi, gamma, and the Ternus effect. We use physiological data to constrain a related model of how signals from retinal ganglion cells to V1 affect the percept of motion as a function of eccentricity. Our model incorporates cortical magnification (Dow et al. 1981, Wässle et al. 1989), receptive field overlap (Braccini et al. 1982, Stone 1965) and scatter (Dow et al. 1981), and spatial (Dow et al. 1981, Wässle et al. 1989) and temporal response characteristics (Baker&Braddick 1985, Hartmann et al. 1979, Ogawa et al. 1966) of retinal ganglion cells for cortical processing of motion. Following Baker and Braddick (1985) in our model D-max and D-min increase linearly as a function of eccentricity. Baker and Braddick (1985) make qualitative predictions about the functional significance of both stimulus and visual system parameters that constrain motion perception, such as an increase in the range of detectable motions as a function of eccentricity, a decrease in D-max as a function of input discretization, and the likely role of higher visual processes in determining D-max. We generate analogous quantitative predictions for those functional dependencies on individual aspects of motion processing. Simulation results suggest involvement of extrastriate areas in determination of values for D-max, but not D-min, which can be fit using only parameters from the retina through V1. Additional simulations indicate that D-max increases as a function of the number of frames, saturating after a few frames.
Meeting abstract presented at VSS 2012
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