Nearly half of all stroke survivors in the US are left with chronic deficits in movement ability. These deficits often persist despite the continued application of therapeutic interventions. Recent animal models of chronic stroke have demonstrated enhancements in movement ability following the application of brain stimulation in combination with motor skill training. Based on these findings, ongoing studies in human stroke have been initiated that use surgical techniques to implant electrical stimulators within the brain. While the outcomes of this intervention appear promising, the surgical implantation procedure is highly invasive, relatively costly, and poses a significant level of risk to the patient. The goal of this proposal is to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS), a non-invasive technique to stimulate the motor cortex, to enhance hand function in chronic human stroke. In non-impaired individuals, rTMS has been shown to upregulate cortical plasticity and enhance motor skill acquisition. The first of two studies proposed in this application will evaluate the effect of a single session of combined rTMS and motor training on behavioral measures of hand and finger function in people with upper limb deficits following stroke. The results will be compared to control sessions involving sham rTMS and stimulation applied over alternative cortical locations. The second experiment will examine the potential neural mechanisms of rTMS-induced effects on hand function. In this study, electrophysiological techniques will be used to evaluate the nature and time-course of changes in intracortical and corticomotor excitability following the application of rTMS and motor training. The results of this proposal have the potential to identify a therapeutic intervention to improve hand function in chronic stroke that is less expensive and less invasive than current procedures. This will be applicable to a large population of US adults with deficits in hand function resulting from stroke. ? ? ?
