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Yuko Yotsumoto; The role of awareness on visual perceptual learning of inhibition : a fMRI study.. Journal of Vision 2013;13(9):913. doi: 10.1167/13.9.913.
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© ARVO (1962-2015); The Authors (2016-present)
Visual Perceptual Learning (VPL) is defined as a performance enhancement induced by repetitive exposure to visual tasks and/or stimuli, and has been observed both on task-relevant and on task-irrelevant stimuli. While many VPL studies were conducted in a context of increased sensitivity to the target stimulus, inhibition of the task-irrelevant noise is also its important aspect. Reduced neural responses to the irrelevant stimuli have been reported in some studies, but the role of awareness on such inhibitory VPL is still unclear. In this study, the role of awareness on the inhibitory VPL was examined using coherent random dot motion. Thirty-four subjects were divided into two groups: Supra group and Sub group. For both groups, a target direction was presented with a to-be-ignored direction. Subjects in Supra group were instructed to ignore the to-be-ignored motion direction while detecting the target motion direction. Subjects in Sub group were instructed to detect the target motion direction without knowing there was to-be-ignored motion direction hidden in the moving stimuli. All subjects underwent five behavioral training sessions. Two fMRI sessions were conducted before and after the training sessions, and BOLD signals were measured while subjects observed each motion direction. Two groups differed in sensitivity changes of the to-be-ignored motion direction. Sub group showed significant threshold decrease both in the target and to-be-ignored directions, while Supra group did not show significant sensitivity changes in either direction. Changes in BOLD signals were consistent with the behavioral changes. In Sub group, BOLD signals in MT+ for both target and to-be-ignored directions increased after the learning, while BOLD signals in Supra group tended to decrease after the learning. The results suggest two important features of VLP and awareness. First, awareness is necessary for inhibitory learning. Second spatially overlapped inhibitory attention might suppress VPL in signal detection.
Meeting abstract presented at VSS 2013
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