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The effects of prestimulus alpha power on neural and behavioral responses to task stimuli

Poster Session A - Saturday, March 7, 2026, 3:00 – 5:00 pm PST, Fairview/Kitsilano Ballrooms

R. Blaine Mollot¹ (rmollot@elon.edu), Kristina Krasich¹, Kenneth C. Roberts², Vincent Sinfuego², Moon Sun Kang², Matthew D. Bachman³, Khoi D. Vo², Joseph A. Harris⁴, Leah C. Acker², Marty G. Woldorff²; ¹Elon University, ²Duke University, ³University of Toronto, ⁴Bradley University

Bilateral alpha-band oscillations (8-12 Hz) over occipitoparietal cortex are thought to reflect large-scale thalamocortical and corticocortical interactions that support neural inhibition and are inversely associated with general attentiveness and arousal. Theories debate whether modulations in bilateral posterior prestimulus alpha gate sensory processing through inhibition or disinhibition of visual cortex—analogous to the selectively modulatory effects of spatial attention—or instead reflect general cortical readiness to process input. This study evaluated these accounts by examining how prestimulus alpha-power fluctuations relate to stimulus-evoked event-related potentials (ERPs) and whether this relationship influences cognitive task performance. EEG data were analyzed from three paradigms differing in visual and cognitive demands: (1) a target-perception task with masked targets, (2) a visual-search task, and (3) a color-word Stroop task. Across paradigms, lower prestimulus alpha power predicted a more negative ERP wave starting at 150 ms. However, the ramifying behavioral effects were varied and task-specific. With target-perception, the ‘prestimulus-alpha-negative-ERP’ effect predicted poorer accuracy of reporting target presence, but a greater likelihood to report seeing a target regardless of actual target presence. With visual search, the ‘prestimulus-alpha-negative-ERP’ effect predicted overall faster behavioral responses. With the Stroop task, the ‘prestimulus-alpha-negative-ERP’ effect did not result in significant cascading effects on performance. These findings suggest that lower bilateral posterior prestimulus alpha power reflects a domain-general state of cortical excitability that enhances early sensory and behavioral responsiveness but does not necessarily confer—and could even reduce—sensory specificity. Overall, the results favor a general cortical state account over one of gated inhibition.

Topic Area: ATTENTION: Nonspatial