Project goal:   Neurological disorders such as stroke and spinal cord injury often cause spasticity and contracture in the arm muscles that lead to rigid elbow, wrist, and finger joints in a flexed position. This project aims to develop a rehabilitation device to alleviate the symptoms. The device will consist of an adjustable mechanical framework, a servo motor with transmission to elicit a quick stretch in the arm flexor muscles (by a quick extension of the elbow joint), a force transducer to measure the stretch response, and software to control the motor and to provide the feedback information of the stretch response to the patient in a rehabilitation protocol called the operant conditioning of spinal reflex. In addition to the device development, fundamental research will be conducted on whether the force information of stretch reflex can be reliably obtained, which aims at eventual academic dissemination.