Evaluating cognitive impairment as a moderator of locomotor learning in older adults post-stroke

PROJECT SUMMARY Stroke is a leading cause of long-term disability around the world and disproportionately affects older adults. After a stroke, older adults commonly exhibit gait dysfunction (e.g., slow, unstable, asymmetric walking), which is the top patient-reported rehabilitation target. In addition to motor deficits, approximately 70% of people living with chronic stroke also have post-stroke cognitive impairment (PSCI). While post-stroke gait rehabilitation interventions effectively mitigate gait dysfunction in aging adults, there remains a significant degree of inter- individual variability in walking outcomes. We posit this is because current gait rehabilitation interventions are predominantly structured to leverage explicit versus implicit locomotor learning. Importantly, explicit motor learning is cognitively demanding. It occurs through intentional changes to a movement based on external feedback and relies primarily on the dorsolateral prefrontal cortex. Whereas, implicit motor learning is cerebellum-dependent and occurs more automatically in response to proprioceptive feedback. Despite evidence of shared neural resources between cognitive and motor processing, the impact of PSCI on the capacity for these forms of motor learning during walking remains largely unexplored. The overall goal of this proposal is to demonstrate that PSCI moderates explicit, but not implicit, locomotor learning in older adults with chronic stroke and identify the role of the dorsolateral prefrontal cortex in this relationship. Under this career development award, the PI (Leech) will develop skills in neuropsychology, structural neuroimaging, and advanced statistics. This training will promote the achievement of her long-term career goal: as an independent investigator, to develop effective, comprehensive, individualized interventions to reduce disability in older adults. This project has three research aims. Aim 1 will determine the impact of PSCI severity on explicit locomotor learning in older adults post-stroke. Aim 2 will test the impact of the PSCI severity the capacity for implicit locomotor learning in the same group of participants. Finally, Aim 3 will examine the role of dorsolateral prefrontal cortex structural integrity in explicit locomotor learning post-stroke. Older adults with chronic stroke who have a range of PSCI severity will complete the procedures necessary for all three aims over a total of 2 experimental sessions. We expect to show that PSCI severity limits an individual’s capacity to learn a more symmetric walking pattern through explicit, but not implicit, locomotor learning and that this relationship will be mediated by the structural integrity of the dorsolateral prefrontal cortex. This work will provide necessary scientific foundation for a program of research to develop an individualized gait rehabilitation intervention anchored to cognitive impairment and a comprehensive predictive model of locomotor learning in older adults post-stroke.