Title: Safety and Feasibility of Individualized Low Amplitude Seizure Therapy (iLAST)

Background: Electroconvulsive therapy (ECT) is used to treat people with severe depression. During ECT, the brain is given electric pulses that cause a seizure. Although it is effective, it can cause side effects, including memory loss. Researchers want to study a new way to give ECT called iLAST. Objective: To see if iLAST is safe and feasible in treating depression. Eligibility: People ages 22 70 years old who have major depressive disorder and are eligible for ECT Design: Participants will be screened under protocol 01-M-0254. This includes: Medical and psychiatric history and exam Blood and urine tests Participants will be inpatients at the Clinical Center. They study has 3 phases and will last up to 20 weeks. Phase I will last 1 week. It includes: MRI: Participants will lie in a scanner that takes pictures of the body MEG: A cone over the participant s head will record brain activity. TMS: A wire coil placed on the participant s scalp will produce an electrical current to affect brain activity. SEP: An electrode on the participant s wrist will give a small electrical shock to test nerve function. Phase II will last 2 and a half weeks. It includes: Seven sessions of iLAST under general anesthesia. Participants may also get standard ECT. EEG: A small electrode placed on the participant s scalp will record brain waves. Interviews about mood, symptoms, and side effects. Participants facial expressions may be video recorded. TMS Phase III will last at least 1 week. It will include: MRI EEG TMS MEG Standard ECT if needed. Participants will have sessions every other day, 3 times a week.