Inclusion Criteria- first episode of unilateral stroke
- time since stroke less than 3 months, i.e., acute or subacute stage
- initial motor part of upper limb of FMA score ranging from 10 to 40, indicating severe to moderate movement impairment
- no serious cognitive impairment (i.e., Mini Mental State Exam score > 23)
Exclusion Criteria- pregnant or breastfeeding women
- aphasia that might interfere with understanding instructions
- major health problems or poor physical conditions that might limit participation
- currently participation in any other research. Potential participants will be also excluded if they have any contraindication to fMRI scanning including claustrophobia, seizures, the presence of pacemaker, mental elements (e.g., steel nails) inside the body or in the eyes, and excessive obesity.