Additional Study Information: Do you suffer from depression? Have standard treatments not been helpful? Researchers at Columbia University Irving Medical Center are conducting a study of an experimental antidepressant called ketamine, which can provide rapid relief of depressive symptoms in some patients. The study involves an inpatient stay, during which participants undergo brain imaging before and after ketamine treatment, and receive 4 intravenous infusions of ketamine over two weeks. Financial compensation of up to $600 is provided for time and effort, and outpatient psychiatric treatment is provided at no cost after ketamine treatment for a total of six months of psychiatric treatment. Please call Agrima at 551-239-2946 or email her at Agrima.Dutt@nyspi.columbia.edu if you are interested in participating or to learn more.