Behavioral and Electrophysiological Effects of Ketamine in Treatment-Resistant Depression

Major Depressive Disorder (MDD) participants with treatment-resistant depression (TRD) will be recruited from McLean's Ketamine clinic. Suitability for Ketamine treatment will be determined as typically done by the service - through evaluation by the clinicians on the staff of the Ketamine Service who perform psychiatric consultations and assessments for Ketamine suitability. Potential subjects will be informed about the study only after they have received a positive consultation at the clinic and have already agreed to receive the treatment. This study consists of a set of questionnaires, urine drug screen, and electroencephalogram (EEG) recordings.