Transcranial Direct Current Stimulation (tDCS) With Verb Network Strengthening Treatment (VNeST) in Chronic Aphasia

General Study Design: Following screening, participants complete four behavioral assessments and four brain scans (magnetic resonance imaging; MRI). Two behavioral assessments and two brain scans occur in the month before tDCS and therapy (about 3 weeks apart). One behavioral assessment and one brain scan occur in the week following therapy. The last behavioral assessment and brain scan occur approximately 8 weeks after therapy. Participants cannot receive any other speech therapy while enrolled in this study (about 20 weeks or 5 months).

Screening: Participants are screened twice, once by phone or email and once in-person at the City University of New York (CUNY). Screenings address eligibility, including adequate hearing and vision, ability to perform all required tasks, and safety for tDCS and MRI (brain scans). The investigators also collect medical and demographic information to ensure study eligibility.

Behavioral Assessment: Language samples are elicited on 11 discourse tasks, including picture descriptions, general questions, and telling a story. The Western Aphasia Battery-Revised and Boston Naming Test are also administered. These procedures are video recorded for later review and transcription. Participants also complete a pre-tDCS safety screening questionnaire. Our primary outcome measure is performance on the discourse tasks, for which the investigators measure the number of correct information units (CIUs) produced. Words are counted as correct information units if they are novel, intelligible, informative, and appropriate to the task.

Brain Scans: Brain scans (MRI) are collected at the CUNY Advanced Science Research Center (85 St. Nicholas Terrace, New York, NY 10031). Each brain scan lasts about 45 minutes. There is one task of approximately 7 minutes that will require decision-making and responses by pressing a button with the left hand. For the rest of the time, the participant simply lies still while the MRI acquires images of the brain.

Therapy: Therapy is provided for two 1-hour sessions per week for 8 weeks at the CUNY Graduate Center (365 Fifth Avenue, New York, NY 10016). This is a typical behavioral aphasia therapy intended to improve language skills. The investigators use a therapy called Verb Network Strengthening Treatment (VNeST) that has demonstrated effectiveness in a small number of research studies. tDCS (see below) is administered for the first 20 minutes of each aphasia therapy session.