Inclusion Criteria- 18-80 years old with a first-ever ischemic stroke that occurred at least 6 months ago;
- Finished rehabilitation therapy(including inpatient or outpatient Physical Therapy (PT) / Occupational Therapy (OT) / Speech Therapy (SP)) at least one month ago;
- Unilateral limb weakness with Fugl Meyer-Upper Extremity Scale score less than 56 (out of 66);
- Motor Evoked Potentials (MEP) is inducible on abductor pollicis brevis (APB) muscle on the affected side by TMS.
Exclusion Criteria- Primary intracerebral hematoma, or subarachnoid hemorrhage,
- Bihemispheric ischemic strokes;
- History of prior stroke or old infarct demonstrated on the CT or MRI or documented in medical records;
- Other concomitant neurological disorders affecting upper extremity motor function;
- Documented history of dementia before or after stroke;
- Documented history of uncontrolled depression or psychiatric disorder either before or after stroke which could affect their ability to participate in the experiment;
- Uncontrolled hypertension despite treatment, specifically Systolic blood pressure (SBP)/ Diastolic Blood Pressure (DBP) >= 180/100 mmHg at baseline;
- Presence of any MRI/tDCS/TMS risk factors: a) an electrically, magnetically or mechanically activated metal or nonmetal implant including cardiac pacemaker, intracerebral vascular clips or any other electrically sensitive support system; b) non-fixed metal in any part of the body, including a previous metallic injury to eye; c) pregnancy, since the effect of tDCS on the fetus is unknown; d) history of seizure disorder or post-stroke seizure; e) preexisting scalp lesion, bone defect or hemicraniectomy.