This study looks at how ketamine, a medicine, affects people with Major Depressive Disorder (MDD) in areas like feeling pleasure (anhedonia), making decisions, and handling emotions. Some people with MDD will get a low dose of ketamine. Researchers will use surveys, brain imaging (like taking pictures of the brain), and tasks to study the effects. People without MDD will also participate but will not receive any medication. They help researchers have a baseline to compare. Participants need to be 18-65 years old. MDD patients shouldn’t be on antidepressants for 8 weeks before joining. People with certain health problems or drug use are not eligible.

• Study Length and Visits: The study involves several visits, including imaging and behavioral tasks.
• Compensation: Participants may be compensated for their time and travel.
• Risks: There are specific health conditions and drug use that would exclude participation.

Participation involves a commitment to attending all required sessions and following study rules. Make sure you meet all eligibility criteria before considering joining the study.