Fig. 2

The magnitude and radial component of the electric field induced by tDCS. Analysis of tDCS-induced strength and radial component (normal to the cortical surface) of the electric field (EF) using a head model developed from magnetic resonance imaging (MNI152). Electrode montages targeting the left dorsolateral prefrontal cortex with anodal tDCS. Anodal (red rectangle; 5 × 7 cm) and cathodal (blue rectangle; 5 × 7 cm) electrodes were placed over the scalp (A and E). The magnitude of the EF is shown in panels (B–D) with hot colors (e.g., red) representing stronger EF and cold colors (e.g., blue) representing weaker EF. Panels (F–H) depict the radial EF, with red representing the electric current flowing into the cortex (i.e., inducing excitatory effects) and blue representing the electric current flowing out of the cortex (i.e., inducing inhibitory effects). Panels (D) show that the tDCS montage reached the target area with enough electric current magnitude to generate a neuromodulatory effect (blue circle roughly indicating the target location). Furthermore, as shown in panel (H), the target area was stimulated with the desired polarity (i.e., anodal current) to elicit excitatory effects in the target regions (blue circle roughly indicating the target areas).