Transcranial direct current stimulation (tDCS) has been proposed as a method of enhancing treatment for aphasia but has mostly been tested on spared brain regions associated with language function. Although this approach has been largely successful, feasibility of providing tDCS to aphasia clients in a typical clinical setting is limited given the expense and unavailability of functional neuroimaging required to identify functional brain areas surrounding the lesion. We propose an alternative approach, which aims to target attention as a means to improve language learning. Studies have shown that anodal tDCS applied to dorsolateral prefrontal cortex (DLPFC) can improve attention after stroke. However, it remains unknown if tDCS administered to DLPFC will improve attention, language recovery, or language learning in persons with aphasia. The long-term objective of our proposed research is to is to increase the efficiency and efficacy of existing speech and language treatments for aphasia. The proposed project will be a first step toward achieving this objective, specifically investigating effects of tDCS-mediated language-specific attention training on measures of attention and language in persons with aphasia. This project will advance the NIDCD?s mission by advancing research for stroke and aphasia rehabilitation. For this clinical trial, we will pursue the following specific aim: Determine the impact of tDCS applied to DLPFC on (Aim 1a) domain-general attention skills, (Aim 1b) complex language comprehension, and (Aim 1c) artificial grammar rule learning. Participants will undergo 10 sessions of combined language-specific attention and artificial grammar training while active or sham tDCS is simultaneously administered to left DLPFC. We will measure performance at three time points (baseline, post- training, one-month follow-up) on two domain-general attention tasks, a sentence comprehension task, and two measures of artificial grammar learning. We will address our study aims by comparing performance on these tasks across active and sham tDCS conditions. At the conclusion of this clinical trial, we expect to provide evidence that active anodal tDCS to DLPFC can enhance attention ability, complex sentence comprehension, and artificial grammar learning. Successful completion of this project will provide essential preliminary data to enable subsequent large-scale studies investigating the effects of tDCS-mediated attention training on language recovery in persons with aphasia.
Language and communication are essential for almost every aspect of human life, but for people who have aphasia, a language processing disorder that can occur after stroke or brain injury, even simple conversations can become a formidable challenge. Speech and language therapy can help people recover their language ability, but often requires months or even years of therapy before a person is able to overcome these challenges. This research will investigate non-invasive brain stimulation as a way to enhance the effects of speech and language therapy, which may ultimately lead to better and faster recovery from stroke and aphasia.
