Fig. 4

FMRI results. (a) Group level of the overlapped stimulated area of subjects from the HD-tDCS group, regions in red represent the area that all the subjects from the HDtDCS-group were stimulated. (b) Group level motor activation at Pre, Post, and 6-month Follow-up sessions. The activation maps were generated from the HDtDCS-group and Sham-group during grasping the paretic hand. (c) Violin plots with mean and standard deviation showing the comparison of laterality index for the HDtDCS-group and Sham-group at Pre, Post, and 6-month Follow-up. (d) The demonstration of the overlaps between activated and stimulated regions (red), and the activated regions that were not stimulated (green) at Pre, Post, and 6-month Follow-up sessions. Activations were focused on the stimulated regions and reduced in the non-stimulated regions after intervention, and continuously at 6-month follow-up for HDtDCS-group, indicating an enhanced Specificity of stimulation. (e) The violin plots with mean and standard deviation show the comparison of specificity in both groups at Pre, Post, and 6-month Follow-up. Abbreviation HDtDCS-group High-definition transcranial direct stimulation with EMG-driven robotic hand group; Sham-group sham stimulation with EMG-driven robotic hand group; contra contralesional hemisphere; ipsi ipsilesional hemisphere; Pre before training; Post immediately after the training; 6 m Follow-up six-month follow-up. *: P < 0.05. The yellow dot and black bars represent the mean and standard deviation of the corresponding group