Inclusion Criteria:  Inclusion criteria for SCI:  Male and female Veterans between 18-70 years Chronic SCI (1 year of injury)  Cervical injury at C8 or above - damage between cervical spinal segments will be confirmed using MRI [preliminary data (Benavides et al., 2020) and analysis of MRIs in ~100 participants with cervical SCI confirm that the investigators can meet our recruitment goals. Note that most SCI in humans damage several spinal cord segments  Verification of damage to cervical spinal segments will ensure that TESS electrodes will target the injured spinal cord (Benavides et al., 2020) Intact or impaired, but not absent, innervations in dermatomes C6, C7 and C8 during light touch and pin prick stimulus using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) sensory scores as tested before in our studies (Bunday and Perez, 2012; Bunday et al., 2018; Benavides et al., 2020; Jo and Perez, 2020) Able to produce a visible power grip with one hand  Can score a minimum of two (2) in the cylindrical grasp the "Prehension Ability" GRASSP  This criterion was selected to ensure that hand impairment will not interfere with the ability to perform training and the proposed tests  Inclusion criteria for controls:  Males and females (18-70 years) Right-handed Able to complete grasping  Exclusion Criteria:  Exclusion criteria for SCI and control subjects:  Uncontrolled medical problems including pulmonary, cardiovascular or orthopedic disease Any debilitating disease prior to the SCI that caused exercise intolerance Premorbid, ongoing major depression or psychosis, altered cognitive status History of head injury or stroke Pacemaker Metal plate in skull History of seizures Receiving drugs acting primarily on the central nervous system, which lower the seizure threshold, such as antipsychotic drugs (chlorpromazine, clozapine) or tricyclic antidepressants Pregnant females Ongoing cord compression, or a syrinx in the spinal cord, or one who suffers from a spinal cord disease such as spinal stenosis, spina bifida, or herniated cervical disk