Fig. 3: Transcranial alternating current stimulation (tACS) protocol.

a.i alternating currents at 10 Hz were applied to the dorsolateral prefrontal cortex (dlPFC) and temporoparietal junction (TPJ) inphase with each other (red pads), which were antiphase with the return current at Cz (blue pad). tACS at PFC and TPJ has an amplitude of 1 mA (zero-to-peak), while the return current at Cz has an amplitude of 2 mA (zero-to-peak). (a.i–a.iii) show the simulated voltage distribution over the brain from three different views (left posterior, left, top) when currents at PFC and TPJ reach their positive peak. (a.iv) shows the topography of the simulated voltage distribution projected from the surface of the gray matter to the location of EEG electrodes. (b.i-b.iii) show the simulated electric field magnitude on the brain from three different views, and (b.iv) shows the projection of the electric field magnitude back to the level of EEG electrodes. (a.iv) and (b.iv) are shown here for direct visual comparisons with EEG results.