Effects of saccade-like image shifts on retinal processing: Phenomena, mechanisms, and relation to visual processing in higher brain centers
Final Report Abstract
Visual sensitivity, probed through perceptual detectability of very brief visual stimuli, is strongly impaired around the time of rapid eye movements. This robust perceptual phenomenon, called saccadic suppression, has frequently been attributed to active suppressive signals that are directly derived from eye movement commands. We have instead shown here that visual-only mechanisms, activated by saccade-induced image shifts, can account for a wide range of perceptual properties of saccadic suppression. Such mechanisms start at, but are not exclusive to, the very first stage of visual processing in the brain, the retina. Neural suppression originating in the retina outlasts perceptual suppression around the time of saccades, suggesting that extra-retinal movement-related signals, rather than causing suppression, act to shorten it. Taken together, our results demonstrate a far-reaching contribution of visual processing mechanisms to perceptual saccadic suppression, starting in the retina, without the need to invoke explicit motor-based suppression commands. We investigated the mechanisms underlying the saccadic suppression observed in the retina using electrophysiology, 2-photon calcium imaging, computational modeling, and human psychophysics. We found a novel retinal processing motif underlying retinal saccadic suppression, “dynamic reversal suppression”, which is triggered by sequential stimuli containing contrast reversals. This motif does not involve inhibition but relies on nonlinear transformation of the inherently slow responses of cone photoreceptors by downstream retinal pathways. Two further components of suppression are present in ON ganglion cells and originate in the cells’ receptive field surround, highlighting a novel disparity between ON and OFF ganglion cells. Our results are relevant for any sequential stimulation encountered frequently in naturalistic scenarios.
Publications
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(2019) Evaluation of optogenetic treatments of blindness – development of in-vitro and in-vivo methods to evaluate the treatment success as well as the characterization of retinal target responses. Dissertation, University Tübingen. Supervision: Münch TA
Idrees S
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(2020) Dependence of perceptual saccadic suppression on peri-saccadic image flow properties and luminance contrast polarity
Baumann MP, Idrees S, Münch TA, Hafed ZM
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(2020) Perceptual saccadic suppression starts in the retina. Nat Commun. 2020 Apr 24;11(1):1977
Idrees S, Baumann MP, Franke F, Münch TA, Hafed ZM
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(2020) Suppression without inhibition: A novel mechanism in the retina accounts for saccadic suppression
Idrees S, Baumann MP, Korympidou MM, Schubert T, Kling A, Franke K, Hafed ZM, Franke F, Münch TA
