Using Non-invasive Brain Stimulation to Treat Word Finding Difficulty in Chronic Traumatic Brain Injury

Inclusion Criteria: * Age between 18 and 85 * Fluent in speaking and reading English * Able to provide informed consent * Has a TBI at least one year prior to enrollment and not related to military experience * Has a confirmation of verbal retrieval difficulties as measured by the Verbal Retrieval Difficulty Interview questions Exclusion Criteria: * Lifetime major or active neurologic conditions (e.g., stroke, epilepsy, brain tumor, dementia, seizure occurrence less than one year ago) * Lifetime major or active cardiovascular conditions (e.g., cardiac arrythmia, heart failure, heart attack) * Current substance use disorder * Lifetime major psychiatric disorders (e.g., schizophrenia, bipolar disorder) * Severe depression at the time of enrollment (BDI-II \>= 29) or psychiatric ER visits or hospitalization less than 6 months ago prior to enrollment * Current sensory (e.g., blind, deaf) or physical (e.g., severe motor weakness) impairment that interferes with testing * Contraindications for tDCS or MRI * The person cannot be left alone for 8+ hours. * Not verbally communicative. * Currently undergoing and not wishing to discontinue speech and cognitive therapy during study participation. * Incapable of understanding the consent or unable to consent for oneself. * Unable to travel to BIDMC's Berenson-Allen Center * Pregnancy