Inclusion criteria for aged matched healthy group

• Male or female whose age range between 40 and 75
• no known neurological injuries

Exclusion criteria for aged matched healthy group

• have an orthopedic disorder involving upper limbs;
• have a history of any neurologic disease;
• have any history of epilepsy of the potential participants and/or their family members;
• are unable to consent;
• are pregnant.

Inclusion criteria for stroke group

• male or female hemiparetic chronic stroke survivors;
• age ranging between 40-75 year;
• with single unilateral ischemic or hemorrhagic middle cerebral artery stroke;
• neurologically stable for >6 months;
• have an expectation that current medication will be maintained without changes for at least 3 months. Stable use of anti-spasticity medication (e.g., baclofen, diazepam, tizanidine) is accepted;
• without severe spasticity (Modified Ashworth (MA) <4);
• have not received botulinum toxin on the impaired arm within 3 months.

Exclusion criteria for stroke group

• have an orthopedic disorder involving upper limbs;
• cognitive impairment sufficient to interfere with informed consent or successful completion of the protocol (Montreal Cognitive Assessment (MoCA) score < 26);
• a history of another neurologic disease;
• anesthesia of joint position sense in upper limbs;
• are pregnant or have a chance that they might be (self-reported);

History of severe allergic reactions to study medication Currently pregnant or breastfeeding Recent participation in another clinical trial within the last 30 days Presence of uncontrolled medical conditions that could affect safety