Figure 1.

Experimental design. A, visual–tactile stimuli were presented on each trial. Brief changes in stimulus intensity occurred concurrently in both modalities, either in the same direction (“congruent”) or in different directions (“incongruent”). B, Each trial started with a central arrow that cued the left or right side reliably. After 1 s of central fixation, the visual–tactile stimulus was presented on the cued side. Participants were asked to maintain central fixation and report congruence of the presented stimulus. After response, participants received feedback. C, Multi-electrode tACS montage (black and white electrodes represent different polarities) and estimation of current density on cortical surface. Participants received either left or right hemispheric stimulation with two 4-in-1 montages over visual and somatosensory cortices. Color coding on cortical surface corresponds to the simulated maximum absolute field strength in V/m. D, On a given trial, electrical and sensory stimulation could be targeted at the same hemisphere (left) or at different hemispheres (right).