The purpose this study is to test the utility of pairing external neuromodulation with behavioral language treatment to boost therapy outcomes and to investigate the mechanisms associated with recovery. Because all PWA have word retrieval deficits, this project will test if greater language gains can be achieved by supplementing anomia intervention with excitatory brain stimulation to the left hemisphere and will evaluate associated functional brain changes to aid the optimization of neural reorganization to facilitate language processing.

Aphasia is a language impairment that commonly occurs following brain damage (e.g., stroke). While language rehabilitation can yield improved language functioning, treatment outcomes vary greatly across individuals. In chronic aphasia, language gains occur through the brain's inherent ability to reorganize (i.e., neuroplasticity).

While Speech-language therapy (SLT) can target various language skills and modalities, the most pervasive deficit across all persons with aphasia (PWA) is difficulty with word finding. Thus, aphasia treatment often includes some form of intervention focused on improving naming abilities. As with language function in general, naming abilities in PWA seems to be associated with left hemisphere recruitment, particularly with the viable tissue at the rim of the lesion (perilesional areas). This project investigates an innovative approach to improving current therapy by examining the benefits of using excitatory transcranial direct current stimulation (tDCS) stimulation/neuromodulation during anomia treatment (i.e. word-finding treatment).

This study investigates an innovative approach to improving current therapy by examining the benefits of using excitatory tDCS stimulation/neuromodulation during anomia treatment. This project will provide novel mechanistic understanding of changes in functional brain connectivity in persons with post-stroke aphasia and how connectivity relates to treatment outcomes.

The aims of this study are as follows:

Aim 1. To investigate the benefits of using broad transcranial direct current stimulation (tDCS) to improve word retrieval in persons with aphasia (PWA). Aim 2. To study functional brain changes related to this treatment. Aim 3. To examine behavioral and neural re-organization correlates related to treatment outcomes.

All participants will complete the following 3 components: (1) Baseline Assessment, (2) Interventions (i.e., SLT with active tDCS & sham tDCS , and (3) Outcome Testing (i.e., Behavioral & Brain Imaging). During the first week, each participant will complete all of the Neuropsychological Testing Battery and the first round of the outcome measures as pre-testing before starting SLT. Then the participant will complete 2 weeks of SLT accompanied with either active tDCS or sham tDCS. Once the SLT is completed, the participant will complete round 2 of outcome testing (i.e., post-testing for 1st SLT phase and pre-testing for 2nd SLT phase). Then, the participant will complete another 2 weeks of SLT but with the other tDCS condition. Once SLT is completed, the participant will complete round 3 of outcome testing (i.e., post-testing for 2nd SLT phase). Lastly, the participant will complete round 4 of outcome testing (i.e., follow-up)

Inclusion Criteria:

• Presence of post-stroke aphasia
• Single left hemisphere stroke etiology
• At least 6 months post-stroke
• Age range between 18 and 80 years old
• Speak English as a native language
• Adequate hearing and vision to complete the tasks

Exclusion Criteria:

• Severe auditory comprehension deficits (determined by pretest) (i.e., global aphasia, Wernicke's aphasia, transcortical sensory aphasia)
• Inability to provide informed consent
• Co-occurring history of neurological disease/disorder/injury (e.g., traumatic brain injury, right hemisphere stroke, dementia)
• Co-occurring history of a major mental illness (e.g., schizophrenia, drug addiction, bipolar)
• Clinical conditions contraindicated for MRI or tDCS (e.g., implanted electrical devices, claustrophobia, seizure disorder)
• Positive pregnancy test (for females)

Active tDCS versus sham tDCS will be masked to the participants