This research study is to find out if brain stimulation at different dosage level combined with an efficacy-proven rehabilitation therapy can improve arm function. The stimulation technique is called transcranial direct current stimulation (tDCS). The treatment uses direct currents to stimulate specific parts of the brain affected by stroke. The adjunctive rehabilitation therapy is called "modified Constraint-Induced Movement Therapy" (mCIMT). During this therapy the subject will wear a mitt on the hand of the arm that was not affected by a stroke and force to use the weak arm. The study will test 3 different doses of brain stimulation in combination with mCIMT to find out the most promising one.

Each subject must meet all of the following criteria to participate in this study:

1. 18-80 years old; and
2. First-ever unihemispheric ischemic stroke radiologically verified and occurred within the past 30-180 days; and
3. >10° of active wrist extension, >10° of thumb abduction/extension, and > 10° of extension in at least 2 additional digits; and
4. Unilateral limb weakness with a Fugl-Meyer Upper Extremity score of ≤ 54 (out of 66) to avoid ceiling effects; and
5. An absolute difference of FM-UE scores between the two baseline assessments that is ≤ 2 points indicating stable motor impairment; if subject is not stable, then he/she will be invited for a reassessment after 7-14 days (but no more than 3 reassessments); and
6. Pre-stroke mRS ≤2; and
7. Signed informed consent by the subject or Legally Authorized Representative (LAR).

Each Subject who meets any of the following criteria will be excluded from the study:

1. Primary intracerebral hematoma, subarachnoid hemorrhage or bi-hemispheric or bilateral brainstem ischemic strokes;
2. Medication use at the time of study that may interfere with tDCS, including but not limited to carbamazepine, flunarizine, sulpiride, rivastigmine, dextromethorphan;
3. Other co-existent neuromuscular disorders (pre- or post-stroke) affecting upper extremity motor function;
4. Other neurological disorders (pre- or post-stroke) affecting subject's ability to participate in the study;
5. Moderate to severe cognitive impairment defined as Montreal Cognitive Assessment (MOCA) score < 18/30;
6. History of medically uncontrolled depression or other neuro-psychiatric disorders despite medications either before or after stroke that may affect subject's ability to participate in the study;
7. Uncontrolled hypertension despite medical treatment(s) at the time of randomization, defined as SBP≥185 mmHg or DBP≥110 mmHg (patient can be treated, reassessed and randomized later);
8. Presence of any MRI/tDCS/TMS risk factors including but not limited to: 8a) an electrically, magnetically or mechanically activated metallic or nonmetallic implant including cardiac pacemaker, intracerebral vascular clips or any other electrically sensitive support system; 8b) a non-fixed metallic part in any part of the body, including a previous metallic injury to eye; 8c) pregnancy (effects of MRI, TMS, and tDCS on the fetus are unknown); 8d) history of seizure disorder or post-stroke seizure; 8e) preexisting scalp lesion under the intended electrode placement or a bone defect or hemicraniectomy;
9. Planning to move from the local area within the next 6 months;
10. Life expectancy less than 6 months;
11. Has received Botulinum toxin injection to the affected upper extremity in the past 3 months prior to randomization or expectation that Botulinum will be given to the Upper Extremity prior to the completion of the last follow-up visit;
12. Concurrent enrollment in another investigational stroke recovery study;
13. Doesn't speak sufficient English to comply with study procedures;
14. Expectation that subject cannot comply with study procedures and visits.

We will follow the National Institute of Health Stroke Trial Network policy and procedure to share IPD. Please refer to https://nihstrokenet.org/ for detailed information.

Please refer to https://nihstrokenet.org/ for detailed information in term of time-frame of sharing such data

Please refer to https://nihstrokenet.org/ for detailed information in term of time-frame of sharing such data