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Stephanie Nelli, Sarah Fraley, John Serences; Post-stimulus alpha oscillations influence visual discrimination performance. Journal of Vision 2015;15(12):225. doi: 10.1167/15.12.225.
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Visual attention allows organisms to more efficiently process behaviorally relevant stimuli. Several studies indicate that pre-stimulus alpha oscillations adjust the state of visual (Van Dijk et al 2008, Busch et al 2009, Mathewson et al 2009) and somatosensory (Haegens et al 2011) systems through top down attentional control (Capotosto et al 2009). Specifically, alpha band activity is involved in the engagement and disengagement of specific regions according to anticipated processing needs (Thut et al 2006), perhaps via an anticipatory desynchronization that regulates inhibition. However, most previous paradigms investigated the role of alpha oscillations during pre-stimulus attentional orienting, and did not address whether alpha is involved in mediating processing during decision making. In the current study, subjects participated in a 2AFC task in which they were asked to report the orientation of a temporally unpredictable and briefly flashed (~8 ms) orientated grating. The contrast of this grating was determined before the experiment for each subject to fix accuracy at 65%. Importantly, subjects were not cued to the possible stimulus location. As reported previously in the literature, behavioral performance was slightly lower on trials with higher parieto-occipital alpha power in the 200 ms before stimulus onset. However, logistic regression revealed that alpha power had the largest modulatory impact on behavior 200-700 ms post-stimulus, with lower alpha power predicting correct responses. This result suggests that alpha oscillations are involved in mediating information processing at multiple stages of visual perception.
Meeting abstract presented at VSS 2015
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