tACS to Enhance Language Abilities

Inclusion Criteria for Persons with Aphasia: 1. Presence of aphasia 2. Suffered a single, left hemisphere stroke 3. Stroke ≥6 months old (chronic) at the time of enrollment Inclusion Criteria for Healthy Controls: 1. Right-handedness 2. Must be able to understand the nature of the study, and give informed consent Exclusion criteria for Persons with Aphasia: 1. Inability to understand the nature of the study 2. Marked naming impairment 3. Impaired non-verbal, conceptual processing 4. History of significant medical or neurological disorder (other than stroke) 5. History of significant or poorly controlled psychiatric disorders 6. Current abuse of alcohol or drugs, prescription or otherwise 7. Nursing a child, pregnancy, or intent to become pregnant during the study 8. Clinically significant hearing loss 9. Contraindications to tACS 10. Contraindications to MRI Exclusion Criteria for Healthy Controls 1. Diagnosis of a neurodegenerative disease or clinically significant cognitive complaint 2. Any unrelated neurologic or physical condition that impairs communication ability 3. History of unrelated neurological conditions including but not limited to traumatic brain injury, stroke, or small vessel disease that has resulted in a neurologic deficit 4. Any additional neurological condition that would likely reduce the safety of study participation, including central nervous system (CNS) vasculitis, intracranial tumor, intracranial aneurysm, multiple sclerosis or arteriovenous malformations 5. A medically unstable cardiopulmonary or metabolic disorder 6. Terminal illness associated with survival \<12 months 7. Major active psychiatric illness that may interfere with required study procedures or treatments as determined by the enrolling physician 8. Current abuse of alcohol or drugs, prescription or otherwise 9. Contraindications to tACS 10. Contraindications to MRI