Combined Neural and Behavioral Therapies to Enhance Stroke Recovery

Limited recovery of upper extremity (UE) function post-stroke continues to be one of the greatest challenges faced in neurorehabilitation. There is an urgent unmet need to identify effective approaches to drive UE recovery in this population. In response to this challenge, the overall purpose of this proposed research plan is to develop rehabilitation interventions that restore UE motor recovery. Contemporary approaches to motor rehabilitation are based on evidence that behavioral experience drives cortical reorganization following neural injury. Although the rationale of driving the damaged motor cortex by focused training of the paretic UE appears straightforward, and has historically been the focus of rehabilitation, functional recovery remains limited. There remains a gap between this central neurobiological change and a meaningful behavioral change. There is a need, therefore, to augment or potentiate behavioral experience. This proposal will address this gap by examining two potential drivers of the lesioned hemisphere: 1) the non-lesioned hemisphere via engagement of the unaffected UE in behavioral training and 2) stimulation of the lesioned hemisphere via repetitive Transcranial Magnetic Stimulation (rTMS). This proposal builds on the foundation of the applicant's previous work which suggested that the contralesional, intact, hemisphere could be used to drive the lesioned hemisphere through bimanual movement. Additionally, it is possible to drive the lesioned hemisphere externally using rTMS to enhance cortical stimulation. Thus, pairing externally-driven enhancement of cortical excitability with internally-driven activation of the intact hemisphere during bilateral movements could combine to further increase excitability in the lesioned hemisphere and manifest improved movement capability of the paretic UE. The fundamental hypothesis guiding this proposal is that increased excitability of the lesioned cortex will improve behavioral function of the paretic UE post-stroke. To investigate the overall hypothesis the investigators will examine these drivers of cortical excitability and their role in UE recovery by addressing the following aims: Specific Aim 1. Determine the magnitude of difference in central and behavioral changes in individuals with post-stroke hemiparesis randomized to a bilateral versus unilateral UE motor training program. Specific Aim 2a. Determine the magnitude of difference in central and behavioral changes in individuals with post-stroke hemiparesis randomized to behavioral UE training compared to behavioral UE training + rTMS. Specific Aim 2b. Determine the differential effects of rTMS on bilateral behavioral training compared to unilateral behavioral training as measured both centrally and behaviorally in individuals with post-stroke hemiparesis Post-stroke upper limb paresis and resultant loss of functional ability continues to present a barrier to those post-stroke in returning to full societal participation. Interventions that directly target the mechanism of hemiparesis, including decreased excitability of the lesioned hemisphere, are most likely to promote true recovery as opposed to the oft observed functional compensation in these individuals.