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Dawei Dong, Sergei Nikonov; Temporal differentiation by photoreceptors reduces spatiotemporal correlation of natural visual input on the retina. Journal of Vision 2015;15(12):1288. doi: https://doi.org/10.1167/15.12.1288.
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© ARVO (1962-2015); The Authors (2016-present)
On the retina, the illuminating intensities of natural visual input at different times and spatial positions are highly correlated. Such spatiotemporal correlation is utilized by photoreceptors to reduce noise through temporal integration and spatial coupling. However, the correlation on a longer temporal and spatial scale is a source of inefficiency for visual representation. To understand how photoreceptors deal with such inefficiency, we investigated the shape of the photocurrent impulse response functions and found that they were biphasic during natural stimulation and capable to reduce the spatiotemporal correlation of natural stimuli. This is in sharp contrast to the monophasic impulse response to short light flashes. In particular, we measured the membrane current of the outer segment of rods in retinal slices stimulated with light stimuli derived from awake cats watching natural movies with eye movements. We found that beyond the classic integration time window the photocurrent responded to the temporal difference of the illumination. Due to the fact that the natural time-varying images are dominated by optical flow, the temporal differentiation not only greatly reduced the temporal correlation beyond the integration time window, but also eliminated the spatial correlation beyond a certain scale. We conclude that the photocurrent of photoreceptors efficiently represent the natural visual input.
Meeting abstract presented at VSS 2015
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