FMRI of Patients Receiving IV Ketamine for Treatment Resistant Bipolar Depression

This is a prospective open-label observational study of patients with treatment resistant bipolar depression referred for intravenous ketamine. All participants will receive an acute series of ketamine consisting of twice weekly infusions over three weeks. Non-responders will have their End of Study visits within 5 days of the last ketamine infusion. Responders (participants who achieve a greater than or equal to 50% decrease on their QIDS-SR-16 score from Baseline) will return for three weeks of continuation treatment (weekly ketamine) and then have their End of Study visit within 5 days of the last continuation treatment. All participants will undergo fMRI the prior to their first ketamine infusion, and after completion of their acute series.