Part Ⅰ: Validation of Treatment Efficacy of the New Digital MT System with Different MVF Conditions and Training Modes  Inclusion Criteria:  diagnosed with a unilateral stroke; at least 6 months after stroke onset; age between 20 and 80 years old; having a baseline score of Fugl-Meyer Assessment (FMA) in a range of 20 to 60; able to follow the study instructions; capable of participating in therapy and assessment sessions  Exclusion Criteria:  global or receptive aphasia; severe neglect measured by line bisection test; other major medical diseases or comorbidities that have influenced upper-limb usage or caused severe pain  Part II: Investigation of the Electrophysiological Mechanisms Underlying Different MVF Conditions by EEG  Inclusion Criteria:  diagnosed with a unilateral stroke; at least 2 weeks after stroke onset and medical stable; aged 20 to 80 years; having a baseline score of FMA ≥ 40 and wrist flexion ≥ 20 degrees in order to perform EEG motor tasks; both wrist flexion and extension scores of Modified Ashworth Scale ≤ 1; able to follow the study instructions  Exclusion Criteria:  global or receptive aphasia; severe neglect measured by line bisection test; other major medical diseases or comorbidities, such as neurological and psychiatric diseases, that have caused severe pain of upper-limb or interfered brain neural activities