A repetitive, non-invasive brain stimulation technique referred to as theta burst stimulation can modulate corticomotor excitability and therefore has great rehabilitative potential for individuals with neurologic deficits, including individuals with spinal cord injury (SCI). In particular, intermittent theta burst stimulation (iTBS) can increase corticomotor excitability and may be a useful adjunct to physical rehabilitation to promote motor re-education after upper limb reconstruction in individuals with tetraplegia. Upper limb reconstruction involves surgical transfer of a non-paralyzed tendon or nerve with a redundant or less important function to perform a more critical function. Upper limb reconstruction is intended to help individuals achieve their goals related to activities of daily living and independence in the community. Outcomes after reconstruction are variable and depend largely on the efficacy of motor re-education of the transferred muscle to perform a new function. The long-term goal of our research is to determine whether iTBS combined with physical rehabilitation can improve motor re-education after reconstruction. As a first step, the purpose of this proposal is to determine the effect of iTBS on corticomotor excitability of proximal muscles in nonimpaired individuals and two groups of individuals with tetraplegia: individuals with and without upper limb reconstruction.

Inclusion Criteria for all subjects with tetraplegia:

• Injury to the lower cervical spinal cord at least one year prior to the date of participation
• Motor function classified according to the American Spinal Injury Association International Standards for Neurological Classification of Spinal Cord Injury at levels ranging from C5-C8

Inclusion criteria for the subjects with tetraplegia and upper limb reconstruction:

• At least one year post-operative from tendon or nerve transfer surgery of the upper limb

Exclusion criteria for all subjects with tetraplegia:

• Presence of concurrent severe medical illness, including unhealed decubiti, use of baclofen pumps, existing infection, cardiovascular disease, significant osteoporosis, or a history of pulmonary complications.
• Metal implant near head or neck
• Risk of seizure of history of seizures