Musical rhythm synchronization as a mechanism to optimize gait in the real-world in persons with Parkinson disease

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PROJECT SUMMARY Parkinson disease (PD) is a progressive movement disorder characterized by substantial walking- related disability. Loss of dopaminergic neurons in the basal ganglia results in reduced gait automaticity, for which persons with PD appear to compensate by reallocating an abnormally large amount of attention to walking. The re-allocation of attention contributes to walking disability by reducing gait speed, increasing stride time variability and hindering distribution of attentional resources to real-world walking, such as navigating the environment. Improving walking has been identified as the greatest priority among persons with PD. Rhythmic Auditory Stimulation (RAS) is a rehabilitation intervention which, unlike pharmacologic treatment, has shown promise for improving walking in PD. RAS is an external cueing medium utilizing repetitive auditory beats to prime neurons in the motor cortex by way of direct connections between auditory and motor brain regions. RAS hypothetically enhances gait automaticity through a process of auditory-motor entrainment, in which the motor signal frequency locks to the frequency of the auditory stimulus. Although RAS has been shown to improve select gait parameters, most studies have been conducted in relatively static clinic settings and use a metronome or music to provide fixed-tempo auditory cues to which a person must entrain. This open loop approach fails to account for the vast heterogeneity in PD gait impairments, diminished entrainment ability of persons with PD, and real-world environments that demand adaptive walking behavior. Moreover, the impact of RAS on gait automaticity is poorly understood. To overcome these limitations and advance this field, our team has sought to examine a closed-loop, music-based digital therapeutic designed to automate yet individualize a progressive RAS gait training program for use in real-world environments. For this project, I will describe the relationships between auditory-motor entrainment, stride-time variability (gait automaticity), and gait speed in persons with PD engaged in RAS gait training in the community using our music-based digital therapeutic. More specifically, 24 persons with PD will complete a 4-week gait training program (5 days/week for 30 minutes; totaling 20 sessions) in the community. I will characterize entrainment ability during RAS with a music-based digital therapeutic in the community (Aim 1) and determine the relationship between entrainment precision and (a) gait automaticity (stride time variability) and (b) gait speed during cued and uncued walking (Aim 2). I hypothesize that this closed-loop music-based digital therapeutic will facilitate entrainment, require fewer attentional resources, restore gait automaticity and speed. This research project complements my development plan and serves as a catalyst towards my goal of becoming an independent investigator leading a research laboratory investigating the effectiveness of innovative, ecologically valid rehabilitation interventions and their underlying mechanisms with the goal of improving real-world walking outcomes in persons with neurological conditions.