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Irem Yildirim, Keith A. Schneider; Cortical and subcortical dynamics during binocular rivalry. Journal of Vision 2020;20(11):789. doi: https://doi.org/10.1167/jov.20.11.789.
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© ARVO (1962-2015); The Authors (2016-present)
Binocular rivalry occurs when the two eyes are presented with conflicting stimuli. These stimuli compete for perception such that the observer can only perceive one stimulus at a time. We sought to measure the interplay among visual cortex and subcortical nuclei in humans during binocular rivalry to better understand the control mechanism driving our visual perception. We were particularly interested in the superior colliculus (SC) and the magno- (M) and parvocellular (P) segments of lateral geniculate nucleus (LGN). Four subjects participated in the study. The subjects wore circularly polarized 3D-glasses while viewing a visual stimulus presented by a ProPixx projector with a synchronized polarizing shutter, allowing dichoptic presentation. In two separate sessions, subjects were scanned with a 3T MRI scanner for ten five-minute runs, using a multiband EPI sequence with 1.5mm isotopic resolution for the whole brain, with a TR of 1.5s. The stimuli were two superimposed monochromatic sinusoidal gratings that rotated in opposite directions, with a period of 1s. Subjects held down a button to indicate which direction of rotation they perceived at the time. In a replay condition, the subjects’ responses from their previous rivalry block were used to mimic their perceptions, presenting a mixture when subjects reported piecemeal rivalry. In a third scanning session, we acquired 40 proton density weighted images with 1mm isotropic resolution covering the thalamus and midbrain, to aid in anatomical segmentation of the subcortical nuclei. V1 and medial temporal areas were significantly active in rivalry and replay conditions. Parietal lobe activation, however, was significantly stronger for rivalry than replay. SC was found to be differentially activated in rivalry and replay conditions but the activity in the M and P layers of LGN did not differ. These results indicate a role of attention as well as the involvement of transient and sustained visual processing.
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