tDCS A research staff supervised by a physician will apply the tDCS to the subject. Direct current will be transferred by a saline-soaked pair of surface sponge electrode (35cm2) and delivered by a battery-operated, constant current stimulator with a maximum output of 10mA, through a non-metallic conductor rubber electrode. Stimulation will be conducted at the intensity of 2 mA and last for 20 minutes. The anode will be placed over the affected primary motor cortex (M1) of cortical representation of the tibialis anterior muscle (TA), while the cathode will be used as reference electrode and placed over the forehead of the unaffected side.