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Frédéric Chavane, Alexandre Reynaud, Quentin Montardy, Guillaume Masson; Cortical origin of contextual modulations in motion integration: linking V1 population response to the behavioral ocular following response. Journal of Vision 2012;12(9):758. doi: 10.1167/12.9.758.
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© ARVO (1962-2015); The Authors (2016-present)
In psychophysics and physiology, it is well established that the contrast gain control is context-dependent. In both human and monkey ocular following studies, it has been shown that modulations of the contrast response functions (CRF) induced by a peripheral stimulus are delayed relative to center-alone conditions. We investigated the role of cortico-cortical interactions on this delayed contextual modulations using recording of population activity with voltage sensitive dye imaging (VSDI) in area V1 of behaving monkeys and investigated how much it could account for the one observed at the ocular following responses (OFR) stage. Dynamics of contrast response functions to a local stimulus were found to be very similar in V1 cortical activity and the OFR. At both levels, contrast gains increase over time in response to a single grating motion, with a latency difference of 20-30 ms. To probe the cortical origin of the contextual modulation of the contrast response function, we manipulated the peripheral stimulus distance and the stimulus scale. Our results in VSDI shows that the contrast-response function and horizontal spread are scale independent. However, scale differences were observed for surround-induced suppression. Small-scale stimuli were suppressed through a propagating wave of horizontal activity that spread from surround towards central representation. In contrast, at intermediate scale, we observed that an additional fast suppressive component was present at the very beginning of V1 response and in the OFR responses. However, the effect of peripheral distance was much weaker in the OFR response than in V1. Hence, effect of lateral distance on surround suppression in V1 and in the OFR is scale-dependent. The observed behavior seems to be a byproduct of a strong interplay among multiple regions such as V1, MT and presumably MST that would be recruited and interact differentially as a function of stimulus scale.
Meeting abstract presented at VSS 2012
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