The purpose of this study is to better understand how ketamine may affect the brain’s ability to modify its connections or re-wire itself. As part of the study, you will first complete a screening visit with a study doctor to assess eligibility. If eligible, you will be asked to complete three scanning visits at the Martinos Center for Biomedical Imaging at the MGH Charlestown Navy Yard. These scanning visits will consist of undergoing an EEG battery task, followed by an MRI scan session. Participation should be completed in about 3-4 weeks. If you’re interested, ask your doctor about our study at your next regularly schedule ketamine infusion visit!