Combine Mirror Therapy and tDCS on CPSP

a mirror box will be placed in front of the participants with the mirror reflection side toward the non-paretic limb. The paretic arm will be placed behind the mirror, and the mirror box will block the vision of the paretic limb. Through this method, the patients can only view the movement of the non-paretic limb and its mirror reflection from the mirror. The participants will be instructed to move or perform functional tasks with their non-paretic limb and look at the mirror reflection of the non-paretic limb and mentally imagine that it is the paretic arm moving. At the same time, the participants will be encouraged to move the paretic arm along with the mirror reflection of the non-paretic arm. Activities practice during MT will include gross motor movements, fine motor movements, and functional tasks.

The tDCS will be delivered by a DC-stimulator (Soterix Medical Inc, New York, USA) through 2 saline-soaked surface sponge electrodes (anodal electrode size: 25 cm2; cathode electrode size: 25 cm2). The anodal electrode will be placed over the ipsilesional M1 while the cathodal electrode will be placed over the contralesional M1. The stimulation intensity will be ramped up to 2mA in 15 seconds, and maintained at 2mA throughout the 20-minute stimulation for the MT+tDCS group.

For the sham MT (s-MT) condition, the same mirror box will be used except that the mirror side will be made blurred to view; thus, the participants will not be able to view the mirror reflection of the paretic limb. The participants will perform the same activities as the real MT condition.

For the sham tDCS group, the electrodes will be placed on the brain regions as the real tDCS group. The intensity will first be ramped up to 2mA within 15 seconds and then the stimulator will be turned off gradually within the next 30 seconds.