Vagus Nerve Stimulation (VNS) Electroencephalogram (EEG) Protocol Supplement

Inclusion Criteria: 1. Participants must be at least 18 years old. 2. Participants must be able to read, understand and have the capacity to provide written informed consent and Health Insurance Portability and Accountability Act (HIPAA) authorization. 3. Proficiency in English sufficient to complete questionnaire and follow instructions during fMRI assessments and iTBS interventions. 4. Willingness to comply with all study procedures and the ability to communicate with study personnel about adverse events and other clinically important information 5. Participant must be currently enrolled in the REVEAL study and implanted with a VNS device for the clinical indication of Major Depressive Disorder (MDD) a. Clinical Indication of MDD as defined: Participant has a diagnosis of chronic (≥ 2 years) or ≥ 4 recurrent depressive episodes as defined by DSM-5 criteria documented using the MINI criteria and psychiatric medical record review. 6. For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation. 7. Access to ongoing psychiatric care before and after completion of the study. 8. In good general health, as evidenced by medical history 9. Agreement to adhere to Lifestyle Considerations throughout study duration. Exclusion Criteria: 1. Participant is pregnant 2. Participant does not speak or read English 3. Any other clinical reasons deemed by the investigator of the study for which the participant would not be an appropriate candidate for the study. 4. Contraindication to MRI (ferromagnetic metal in their body) 5. Contraindication to EEG 6. Medication Contraindications