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Russell Epstein, Nicholas Hon, John Duncan; Neural signature of consciously-perceived visual events. Journal of Vision 2003;3(9):579. doi: 10.1167/3.9.579.
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© ARVO (1962-2015); The Authors (2016-present)
Which brain regions are necessary for the conscious perception of a visual stimulus? We examined this question by scanning subjects with fMRI while they viewed an array of four photographs which flickered on and off several times a second. Every few seconds, one of the four photographs was replaced by a new photograph. Subjects were required to attend to two of the four array locations whilst ignoring the other two. We compared the event-related fMRI response to the appearance of new stimuli in the attended locations to response to stimuli in the unattended locations. The presence of a constant stream of visual transients ensured that subjects rarely noticed the appearance of a new photograph in the unattended locations. A surprise memory test given at the completion of the scan verified that stimuli in the unattended locations were rarely encoded into memory. Greater response to attended events was observed in ventral stream visual areas such as fusiform gyrus, but not in frontal-parietal regions that have previously been implicated in conscious perception. We suggest that occipitotemporal regions are involved in conscious perception per se, while frontal-parietal regions may be involved in redirecting attention towards novel stimuli, storing them in working memory, and arranging responses to them.
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