Despite increased monies dedicated to post-stroke care persistent deficits in the ability to perform everyday tasks with the paretic limb are a significant contributor to continuing declines in the quality of life. Therefore, a greater understanding of the processes underlying motor learning and recovery post-stroke is needed to enhance existing therapist-guided and robot-assisted interventions. Current rehabilitation practices and research focus on establishing new neuromotor patterns in preserved tissue through repetitive use of the paretic limb but place less emphasis on how compensatory strategies influence this process. In particular, functions mediated by cognitive areas of the brain that are recruited in support of the compensatory strategies may shape the neural patterns that emerge. These compensatory neural patterns may enhance short-term performance at the expense of persistent longer-term recovery. Understanding the consequences of compensatory cognitive recruitment of neural substrates like dorsolateral prefrontal cortex is critical to the development of effective, targeted interventions for adults living with stroke-related hemiparesis. In the absence of such knowledge development of interventions to promote motor recovery may be successful but limited in efficacy. As such enhancing and re-establishing quality of life post-stroke will remain a challenge. Our central hypothesis is that enhanced recruitment of cognitive functions, localized to dorsolateral prefrontal cortex, in support of compensatory motor strategies serves to develop and consolidate sub-optimal patterns of neural reorganization within motor cortical areas that limit learning. The overall objective of the proposed study is to determine whether short-term suppression of dorsolateral prefrontal cortex will reduce constraints upon emerging neural patterns in motor cortical areas and lead to greater sustained improvements in motor ability post-stroke. At the completion of the proposed work, it is our expectation that we will have demonstrated that learning, and by extension recovery, post-stroke is enhanced by suppressing dorsolateral prefrontal cortex despite any potential short-term decreases in performance. Further, we hope that this work will identify preliminary predictors of who might benefit clinically from suppression of dorsolateral prefrontal cortex and that this work will act as a substrate for future clinical trials. Successful completion of the proposed research activities is an important step towards developing enhanced therapist guided and robot-assisted rehabilitation interventions that integrate adjunctive non-invasive brain stimulation of non-motor cortex targets. Continued development of our knowledge of learning post-stroke and how to implement such knowledge in the clinical setting will ultimately decrease the socioeconomic impact of hemiparesis and enhance quality of life post-stroke.
The proposed research is relevant to public health because it will enhance our knowledge about how different learning systems interact to determine the extent of recovery post-stroke and assess the efficacy of a novel brain stimulation protocol as an adjunct to stroke rehabilitation. The proposed research is an important step towards a higher quality of life post-stroke by enhancing functional independence.
