Spinal Plasticity to Reduce Hand Impairment After Stroke

Stroke is a leading cause of serious long-term disability in the United States with 795,000
individuals suffering a new or recurrent stroke each year. In most cases, disability is
associated with incomplete motor recovery of the paretic limb. Even with intensive therapy,
full recovery is often not achieved. Thus, there is a need for mechanistic approaches that
drive the impaired neuronal targets of retraining to fully harness the corticospinal system's
adaptive capacity.

The goals of this study are to leverage principles of spike timing-dependent plasticity
(STDP) via non-invasive stimulation techniques to strengthen corticospinal transmission. Few
studies have targeted the cortex after stroke in humans, and none have targeted the
corticospinal-motoneuronal synapse in the spinal cord. This study, therefore, is a novel
approach to studying neuroplasticity after stroke. Previous work in humans with incomplete
spinal cord injury demonstrates that the resulting plasticity transiently enhances motor
output, indicating that there is also therapeutic potential.

This study will attempt to induce bi-directional STDP in corticospinal-motoneuronal synapses
serving an intrinsic hand muscle of the hemiparetic limb. Control experiments will be
completed to provide evidence of the neurophysiological mechanism(s) mediating the effect and
to examine behavioral effects.

Individuals who are at least 6 months post first-ever subcortical stroke and have at least
partial range of motion of the paretic index finger will be recruited to participate.

INCLUSION CRITERIA

Individuals who have had a stroke:

1. Diagnosis of first ever subcortical stroke

2. At least 6 months after stroke onset

3. Score of 1 or greater on MRC Scale for the FDI muscle

4. Subjects must show an understanding of the study goals and have the ability to follow
simple directions as judged by the investigators.

All individuals:

5. Between the ages of 18 and 75 years old

EXCLUSION CRITERIA

Individuals who have had a stroke:

1. Hemispatial neglect, aphasia, or cognitive impairment that would impact testing and
would interfere with the ability to follow simple instructions, as judged by the
investigators

2. Diagnosis of neurological disorder(s) other than stroke influence movement

All individuals:

3. History of seizure or epilepsy

4. Metallic brain implants

5. Implantable cardioverter defibrillators, insulin pumps, or ventriculoperitoneal shunts

6. Pregnant or expecting to become pregnant

7. Difficulty maintaining alertness and/or remaining still.