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. The PI's prior work shows 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 combined with an evidenced-based anomia
treatment (semantic feature analysis, SFA) to 15 sessions of sham combined with SFA treatment in patients with
chronic (at least 6 months post stroke) aphasia. We will evaluate the effects of cerebellar tDCS on naming
untrained items 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 and SFA treatment. 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 and/or SFA. 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.