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Saad Idrees, Thomas A. Muench; Retinal processing around saccades. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2583.
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© ARVO (1962-2015); The Authors (2016-present)
During natural viewing, image flow on the retina is determined primarily by the behavior of the observer. Eye movements during active visual exploration, such as saccades, are particularly dominating in this regard, especially because they incessantly occur 3-5 times per second. Despite this, retinal image processing has in the past often been studied with isolated stimuli, ignoring the highly dynamic aspects of natural viewing. We are therefore exploring the effects of eye-movement induced image motion on signal processing in the retina. We hypothesize that response of ganglion cells, to a stimulus following a saccade, is modulated as a function of time between the saccade and that stimulus.
We recorded activity of ganglion cells from isolated mouse and pig retina using multi-electrode arrays (MEA) while showing a visual stimulus paradigm mimicking saccades. The paradigm consisted of rapid saccade-like image shifts across the retina followed by a test stimulus at different intervals after the saccade.
We found that the retinal responses to these "test stimuli", when presented in the context of saccades, are strongly modulated in comparison to responses to the same stimuli presented in isolation. Saccades exude their modulatory effects for up to 1 second, suggesting a highly relevant role of eye-movement induced effects under natural conditions with short inter-saccadic fixations. Such saccade-related retinal modulation critically depends on (1) the delay between saccade and test stimulus; (2) the statistical properties of the background scene present during the saccade; (3) the ambient luminance level; (4) and the specific retinal cell type. For example, the responses of OFF ganglion cells, but not ON ganglion cells, can be positively modulated after saccades.
Our results confirm our hypothesis that the response of ganglion cells to a stimulus following a saccade gets modulated. The results also indicate that the different pathways within the retina are distinct with respect to the properties of saccade-associated modulation. Thus, the diversity of modulations known from higher visual areas might, at least in part, be caused by the diverse modulations seen in the retina.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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