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Mark Mills, Mohammed Alwatban, Benjamin Hage, Erin Barney, Edward Truemper, Gregory Bashford, Michael Dodd; Cerebral hemodynamics during scene viewing: Hemispheric lateralization predicts temporal gaze behavior associated with distinct modes of visual processing . Journal of Vision 2016;16(12):102. doi: 10.1167/16.12.102.
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© ARVO (1962-2015); The Authors (2016-present)
Studies of eye movements during scene viewing often observe an increase in fixation duration and decrease in saccade amplitude with viewing time. This temporal gaze behavior has been taken as evidence for a functional distinction between two modes of viewing behavior associated with specialized cortical processing: a global/ambient mode (characterized by short fixations and large amplitudes) thought to reflect activity in the dorsal visual pathway and thus involved with spatial analysis, and a local/focal mode (characterized by long fixations and small amplitudes) thought to reflect activity in the ventral pathway and thus involved with object analysis. Currently, however, there is little neuroscientific evidence indicating that these viewing modes are indeed linked to processing in distinct cortical regions. Here, we used functional transcranial Doppler ultrasound (fTCD)—which measures cerebral blood flow velocity in basilar cerebral arteries—to investigate neural correlates of these viewing modes, particularly, whether these modes show hemispheric lateralization. Though not used in this manner before, fTCD may be ideal for studying this issue given its high temporal resolution. Participants viewed 40 real-world scenes for 20 seconds each. Prior to each scene, participants were cued either to search or memorize the scene. Overall, early viewing (first 3-5 seconds) was right lateralized, whereas later viewing (last 15-17 seconds) was left lateralized. This pattern interacted with task: search was right lateralized early with bilateral activation later on, whereas memory showed bilateral activation early and left lateralization later. Importantly, changes in lateralization correlated strongly with changes in fixation duration and saccade amplitude (rs > .6). These findings are the first demonstration of a right hemisphere bias for oculomotor behavior thought to service spatial analysis and a left hemisphere bias for oculomotor behavior thought to service object analysis.
Meeting abstract presented at VSS 2016
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