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Jennifer Schei, Garrett Kenyon, John George; Contributions of microscopic eye movements to retinal encoding. Journal of Vision 2013;13(15):T15. doi: 10.1167/13.15.15.
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© ARVO (1962-2015); The Authors (2016-present)
Models of visual processing suggest that temporal dynamics of firing within a neuronal population can encode patterns and relationships within visual data beyond those inferred from the firing rates of individual neurons. Properties of neurons and of networks lead to oscillatory firing under some conditions, but it is not clear how synchronous or correlated responses are created. Involuntary microscopic eye movements during “fixed” gaze shift a visual image across a few photoreceptors in the retina at frequencies that are similar to neural population oscillations observed in the lateral geniculate nucleus and visual cortex. We hypothesize that microscopic, fixational eye movements temporally modulate a visual stimulus and aid in encoding spatial feature relationships through precisely timed, spatially coherent responses of neuronal populations. In order to explore the role of microscopic eye movements in visual processing, we measured electrophysiological responses from isolated retina. We used a 3-dimensional multi-electrode array to measure neuronal spiking from retinal ganglion cells and simulated microscopic eye movements by jittering a visual stimulus across the tissue. The jittering stimulus elicited increased firing rates and synchronized spike timing to the jitter frequency. In contrast, stationary stimuli had lower neuronal firing rates with random spiking times. These results suggest that microscopic, fixational eye movements introduce temporally modulated responses from populations of neurons that are correlated with eye movements. Previous physiological and perceptual studies suggest that such eye movements aid in the perception of fine spatial detail and that neural population dynamics may contribute to encoding spatial relationships between visual features.
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