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Wolf Harmening, Azalea Lee, Thom Carney, Austin Roorda; Retinally stabilized stimulation reveals mismappings between retinal and perceived location. Journal of Vision 2012;12(9):1119. doi: https://doi.org/10.1167/12.9.1119.
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© ARVO (1962-2015); The Authors (2016-present)
In the human fovea, retinal wiring shows low or no neural convergence, such that the excitation of single photoreceptor cells is mapped to the receptive field of single ganglion cells. Outside the fovea, a one-to-one wiring is replaced by a less precise retinotopic mapping and increased convergence. As a result, mismappings between the exact retinal location and the corresponding receptive fields may exist. In normal viewing, however, the contribution of these mismappings might be obscured by a constantly moving and thus spatio-temporally averaged retinal image. We here employ an adaptive optics scanning laser ophthalmoscope (AOSLO) with real-time motion tracking to deliver visual stimuli at high levels of retinal contingency. In a vertical three-dot hyperacuity task, subjects had to adjust the position of the central dot (2 arcmin square) to be collinear with the two flanking dots. Under retinally stabilized viewing conditions we find local point of subjective equality (PSE) biases that differ depending on retinal location. As an example, along a 10 arcmin strip of retina, 0.6 deg from the fovea, PSE bias changes were as large as 30 arcsec, roughly equaling the diameter of a single cone at that retinal location. The results suggest that vernier alignment under retinal stabilization can be used as a tool to discover minute retinal mismappings, and help to characterize the discrete retinal wiring underlying extra-foveal vision. The AOSLO is also able to reliably position stimuli on target cones over many months such that it will be possible to track biases over time to see if they change as a result of visual experience.
Meeting abstract presented at VSS 2012
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