While physical exercise remains the foundation for any rehabilitation therapy, the team seeks to improve the benefits of exercise by combining it with the concept of "Fire Together, Wire Together" - when brain stimulation is synchronized with spinal cord stimulation, nerve circuits in the spinal cord strengthen - a phenomenon termed "Spinal Cord Associative Plasticity", or SCAP.

This project will build on the team's promising preliminary findings. When one pulse of brain stimulation is synchronized with one pulse of cervical spinal stimulation, hand muscle responses are larger than with brain stimulation alone or unsynchronized stimulation. However, the team does not know the best ways to apply SCAP repetitively, especially in conjunction with exercise, to increase and extend improvements in clinical function. Do ideal intervention parameters vary across individuals, or do they need to be customized?

The team will take a systematic approach with people who have chronic cervical SCI to determine each person's best combination of SCAP with task-oriented hand exercise. Participants will undergo up to 53 intervention, verification, and follow-up sessions over a period of 6 to 10 months each. The team will measure clinical and physiological responses of hand and arm muscles to each intervention.

Regaining control over hand function represents the top priority for individuals with cervical SCI. Furthermore, this approach could be compatible with other future interventions, including medications and cell-based treatments.

See above.

Inclusion Criteria:

• Age between 18-85 years.
• Must have stable prescription medication for 30 days prior to screening
• Must be able to: abstain from alcohol, smoking and heavy caffeine consumption on the day of each experiment; abstain from recreational drugs for the entirety of the study; commit to study requirements (i.e., 53 visits); provide informed consent.
• Score of 1-4 (out of 5) on manual muscle testing of finger extension, finger flexion, or finger abduction in left or right hand.

Exclusion Criteria:

• Personal or extensive family history of seizures;
• Ventilator dependence or patent tracheostomy site;
• History of stroke, brain tumor, brain abscess, or multiple sclerosis;
• History of severe head trauma requiring neurosurgery;
• History of implanted brain/spine/nerve stimulators, aneurysm clips, ferromagnetic metallic implants in the head (except for inside mouth); cochlear implants; cardiac pacemaker/defibrillator; intracardiac lines; currently increased intracranial pressure; or other contraindications to brain or spine stimulation;
• Significant coronary artery or cardiac conduction disease; recent history of myocardial infarction and heart failure with an ejection fraction of less than 30% or with a New York Heart Association Functional Classification of Class III or IV;
• Recent history (within past 6 months) of recurrent autonomic dysreflexia, defined as a syndrome of sudden rise in systolic pressure greater than 20 mm Hg or diastolic pressure greater than 10 mm Hg, without rise in heart rate, accompanied by symptoms such as headache, facial flushing, sweating, nasal congestion, and blurry vision (this will be closely monitored during all screening and testing procedures);
• History of significant hearing problems;
• History of bipolar disorder;
• History of suicide attempt;
• Active psychosis;
• Recent history (>1 year) of chemical substance dependency or significant psychosocial disturbance;
• Heavy alcohol consumption (greater than equivalent of 5oz of liquor) within previous 48 hours;
• Open skin lesions over the face, neck, shoulders, or arms;
• Pregnancy; and
• Unsuitable for study participation as determined by study physician.