Study to Treat Major Depressive Disorder With a New Medication

Inclusion Criteria: * Written informed consent obtained from subject and ability for subject to comply with the requirements of the study; * Men and women, age 18-65; * Participants must meet DSM-V criteria for current depressive disorder (major depressive disorder \[MDD\], persistent depressive disorder, other specified depressive disorder) as determined by a study psychiatrist and confirmed using the Structured Clinical Interview for DSM-V (SCID); * Clinically significant anhedonia as determined by a SHAPS score ≥ 20 at screening; * Current illness severity is at least moderate, defined as a score of ≥4 on the Clinical Global Impression-Severity (CGI-S) Scale; * If female of childbearing potential, must agree to use of a medically accepted form of contraception, or else agree to abstinence. Exclusion Criteria: * A primary psychiatric diagnosis other than a depressive disorder as defined by DSM-V \[co-morbid anxiety disorders (including agoraphobia, generalized anxiety disorder, social anxiety disorder and panic disorder) and Posttraumatic Stress Disorder (PTSD) are allowed\] or major cognitive disorder; * Meets criteria for a substance or alcohol use disorder in the past 6 months; * Female participants who are pregnant, breastfeeding, or may become pregnant, or unwilling to practice birth control during participation in the study; * Positive urine toxicology screen for drugs of abuse at the time of screening; * Any unstable medical illnesses including hepatic, renal, gastroenterologic, respiratory, cardiovascular (including ischemic heart disease), endocrinologic, neurologic, immunologic, or hematologic disease; * Clinically significant abnormalities of laboratory tests, physical examination, or ECG; * Prolonged QT Interval at screening, operationalized as a QTc of \> 480 ms; * A history of retinal abnormalities (i.e., pigment changes, retinal dystrophy) or findings of retinal pathology on ophthalmological exam at baseline; * Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data; * Use of any dis-allowed medication according to the study protocol; * Serious and imminent risk of self harm or violence as determined by the PI; * Extreme illness severity as defined by a GCI-S score \>6; * Any contraindication to MRI including claustrophobia, any trauma or surgery which may have left magnetic material in the body, magnetic implants or pacemakers, and inability to lie still for 1 hour or more; * History of non-response to electroconvulsive therapy in the current depressive episode * Exceptions: 1. Subjects with a positive urine drug screen for cannabinoids, barbiturates, opiates, amphetamines, or benzodiazepines may be allowed in the study provided that the drug was used for a documented, legitimate medical purpose and/or the use of such products may be discontinued (documented by a negative repeat test) prior to randomization; 2. Medically appropriate episodic use (up to 3 days) of narcotic analgesics for acute medical indications is allowed (Discussion with PI required) * Potential participants will not be discontinued from medication for the purposes of this study. If a patient is taking a protocol dis-allowed medication at the time of screening, the patient may discontinue the medication under the supervision of the treating physician in the case that the patient is not benefiting from the medication or otherwise wishes to discontinue the medication. In no case will a dis-allowed medication be discontinued for the purpose of study participation if the patient is receiving clinical benefit from the medication.