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Neural Correlates of Visual Awareness and Unconscious Visual Processing: A Concurrent TMS-EEG Study

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

Zhilin Zhang¹ (zzhang5@gradcenter.cuny.edu), Tony Ro¹; ¹The Graduate Center, City University of New York

Accurate discrimination of visual features (e.g., orientation) can occur even when awareness is suppressed by transcranial magnetic stimulation (TMS) of the early visual cortex, demonstrating unconscious visual processing without the phenomenal experience of perception. However, little is known about the neural dynamics underlying this TMS-induced blindsight, limiting the understanding of processes that give rise to the subjective and objective outcomes of visual perception. Our study examines the electrophysiological correlates of visual awareness and unconscious processing by measuring electroencephalography (EEG) activity during TMS-induced blindsight. On each trial, TMS is delivered to the early visual cortex to suppress awareness of an oriented stimulus. Participants report whether they saw the orientation and what the orientation was. We expect participants to respond with above-chance discrimination accuracy even when they report not seeing the orientation, as established in previous studies. Importantly, we will compare the early, middle, and late visual-evoked potentials between conscious correct and unconscious correct trials to examine the neural correlates of visual awareness, and between unconscious correct and unconscious incorrect trials for unconscious visual processing. The findings will reveal the temporal dynamics of neural activity associated with the formation of visual awareness and will also provide insights into how TMS disrupts neural activity in early visual cortex.

Topic Area: PERCEPTION & ACTION: Vision