Fig. 3

Electrode placement and the distribution of the envelope electric field. A The red and blue circles represent the stimulation points for two alternating currents; red represents one channel of alternating current, while blue represents the other channel. B, C Illustrates the envelope electric field distribution on the cortical surface and coronal plane, respectively. The shades of red and blue denote different electric field intensities, with a stronger intensity being indicated by a shift toward the red color