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Lu Shen, Lihan Chen, Qi Chen; Neural correlates of spatio-temporal grouping in bistable apparent motion perception. Journal of Vision 2014;14(10):800. doi: 10.1167/14.10.800.
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© ARVO (1962-2015); The Authors (2016-present)
Upon viewing dynamic ambiguous visual stimuli, observers often experience spontaneous transitions between two competing percepts although the physical stimulation remains unchanged. This phenomenon is termed as "bistable perception", of which the perceptual groupings in space and time need to be implemented jointly. The Ternus display as one of the typical ambiguous apparent motion, depending on the interstimulus interval (ISI) between each frame of the motion sequence, can elicit two different percepts: explicit element motion (EM) percept (with shorter ISI, i.e., 50ms) or group motion (GM) percept (with longer ISI, i.e., 230ms) (i.e., the two filler conditions). More importantly, when the ISI reaches certain threshold (as measured by psychophysical method for each individual), the two percepts can be alternatively induced with equal possibilities with the bottom-up stimuli being constant (i.e., the bistable condition). By adopting fMRI in the present study, we aimed to investigate the neural mechanisms underlying the bistable apparent motion perception. As compared to the explicit EM percept (ISI=50 ms), the explicit GM percept (ISI=230 ms) significantly activated the bilateral middle occipital gyrus extending to bilateral lateral occipital cortex (LOC), suggesting that the explicit GM percept implicated the perceptual grouping process in the ventral visual areas. In the bistable condition, when the EM percept won the bistable percept competition, the left inferior parietal cortex showed not only increased neural activity, but also enhanced functional connectivity with premotor cortex, indicating the functional role of the dorsal parieto-premotor stream in subserving temporal grouping. In contrast, when the GM percept won the competition, the default-mode-network in medial prefrontal cortex (MPFC) showed reduced deactivation, indicating the functional role of MPFC in spatial grouping, rather than temporal grouping. Taken together, our results, for the first time, showed how parieto-premotor pathway and MPFC determine the outcome of bistable apparent motion.
Meeting abstract presented at VSS 2014
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