Augmenting Rehabilitation Outcomes and Functional Neuroplasticity Using Epidural Stimulation of Cervical Spinal Cord

Inclusion Criteria: * All participants must provide a signed and dated informed consent form. * Stated willingness to comply with all study procedures and availability for the duration of the study. * Male or female aged 22 - 65 years old. * Must provide documentation from personal primary treating physician that reports stable medical condition. * Able to passively range bilateral upper extremities within normal mobility parameters including: * greater than 90 degrees of shoulder flexion and 20 degrees of shoulder extension; * greater than 120 degrees of elbow flexion and reach elbow extension of approximately 150 degrees; * neutral wrist position reaching a minimum of 70 degrees of movement (between flexion and extension; * ability to passively flex and extend fingers. * Maintain current oral anti-spasticity regimen/dosage as approved by study physician with no change in regular use that may affect study outcomes. * Six (6) months to 20 years post spinal cord injury. * Non-progressive spinal cord injury. * Chronic SCI with neurologic level of injury as defined by ISNCSCI AIS A, B, or C. * Neurological level of injury above T2. * Eligible for fMRI per safety questionnaire. * Women of childbearing potential must agree to the use of an effective means of avoiding pregnancy for the duration of the study. Exclusion Criteria: * Currently involved in another rehabilitation training study. * Lower motor neuron injury revealed in the upper limbs. * Stabilization hardware in the cervical spine, preventing implantation of ESS system. * Active pressure sores, wounds, unhealed bone fractures, peripheral neuropathies, or painful musculoskeletal dysfunction (including contractures in the upper and lower extremities). * Any ongoing medical condition which would preclude participant from regular physical activity (including but not limited to: ventilator dependence, cardiopulmonary disease, uncontrollable autonomic dysreflexia or orthostatic hypotension, active urinary tract infections, pregnant or nursing). * Intrathecal baclofen pump therapy for spasticity. * Must not have received Botox injections to primary lower extremity and trunk musculature within the past 3 months which would result in absence of muscle tone and thus preclude response to electrical stimulation therapy. * Current or history of neuromuscular conditions (including but not limited to: unhealed ligament of muscular tears in the upper or lower extremities, pain in weight bearing positions for upper and lower extremities). * Clinically significant depression, psychiatric disorders, or ongoing drug abuse. * Any reason the PI or treating physician may deem as harmful to the participant or inappropriate for the participant to enroll or continue in the study. * Body Mass Index (BMI) over 30. * Pregnancy.