Motor maps (contour plots and color code). X-axis: sagittal coordinates, Y-axis coronal coordinates, Z-axis: corticomotor responses recorded in the contralateral gastrocnemius muscle. So-called "hot spots" (red) are identified. Coordinates of stimulation are established using the stereotactic frame. Maximal responses set at 100% on each side. Left panels: basal, right panels: high-frequency and trains of tDCS.