Investigating the neural mechanisms underlying language recovery through rhythm therapy in Aphasia

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Every year, approximately 100,000 people are diagnosed with aphasia—a language disorder leading to substantial difficulties in their daily communication. Based on the observation that many people with aphasia can sing words that they otherwise cannot speak, melodic intonation therapy (MIT) was developed in the 1970s. Although recognized as a standard aphasia treatment, the neural mechanisms of MIT have been largely unexplored. Our first goal is to identify the active ingredient of this music-based intervention that leads to language recovery. Although rhythm has long been considered secondary to melody, recent evidence has challenged this notion by demonstrating that rhythm alone is sufficient enough to facilitate improvements in speech fluency for people with aphasia. To corroborate the faciliatory role of rhythm, we will train aphasic patients to leverage “rhythm” for sets of sentences/phrases delivered through a fun and engaging video gaming platform. This intervention emerges from the theoretical framework, built from neuroimaging data, that language processes heavily rely on neural resources within the sensorimotor and fronto-striatal circuits that subserve rhythm/timing processes. Our second goal is to characterize the neural plasticity associated with language recovery promoted by the novel rhythm-based therapy. We hypothesize that neuroplasticity will manifest itself as increased white matter tracts, presumably due to changes in myelination in either ipsilateral or contralateral (homologues) language areas. To effectively measure myelin white matter fraction (MWF) in candidate tracts, we will mainly use a patented Myelin-imaging technique. Additionally, we will measure resting-state functional connectivity using BOLD (Blood Oxygen- Level Dependent) fMRI. Lastly, we will attempt to record cortical activity using fNIRS (functional Near-Infrared Spectroscopy) during the pre-post behavioral assessments. Taken together, the proposed interdisciplinary research has theoretical, methodological, and clinical innovations and significance. This exploratory work will serve as a critical stepping stone toward unraveling the therapeutic component of music in neurological disorders and will provide evidence-based guidance to the clinicians and therapists.