Cerebellar stimulation for Aphasia Rehabilitation

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Project Abstract Aphasia is a devastating complication of stroke. Speech and language treatment (SLT) can be helpful in restoring language function, but not all individuals show improvement. Recent studies indicate that Transcranial Direct Current Stimulation (tDCS) is a promising adjuvant approach to enhance the effectiveness of SLT. tDCS is a noninvasive, non-painful, electrical stimulation of the brain. It is believed that tDCS boosts neural plasticity that underlies recovery with SLT. A majority of the tDCS studies of aphasia have stimulated the left hemisphere regions. However, left hemisphere lesions common in post-stroke aphasia affect the electrical field in unpredictable ways, potentially preventing stimulation from reaching perilesional tissue associated with optimal recovery. Our work addressed this problem by stimulating a novel region, the right cerebellum. The right cerebellum is connected to the left hemisphere and involved in a variety of cognitive and language functions, including naming, which is often impaired in people with aphasia. We show that cerebellar tDCS is safe, easily tolerated, and improved language skills in a number of stroke participants with aphasia. The proposed project will build on these findings by conducting a randomized, double-blind, sham-controlled, trial to determine the effectiveness of cathodal tDCS to the right cerebellum for the treatment of post-stroke aphasia. We will compare the effects of 15 sessions of cerebellar tDCS plus evidenced based naming treatment to 15 sessions of sham plus evidenced based naming treatment in patients with chronic (at least 6 months post stroke) aphasia. We will evaluate the effects of cerebellar tDCS on untrained picture naming as well as the effects on functional communication, content, efficiency, and word-retrieval of picture description, and quality of life. This project will also identify imaging and linguistic biomarkers to determine the characteristics of stroke patients that benefit from cerebellar tDCS. Individual response to tDCS treatment is highly variable, and little is known about how factors related to imaging and linguistic characteristics combine to induce treatment responsiveness. We will carry out resting state functional magnetic resonance imaging (rsfMRI), diffusion tensor imaging (DTI), high resolution structural imaging, and detailed linguistic testing before the start of treatment to determine whether these factors can predict response to cerebellar tDCS. The long-term aim of this study is to provide the basis for a Phase III randomized controlled trial of cerebellar tDCS vs sham with concurrent SLT for treatment of chronic aphasia.