Pharmaco-Neuroimaging Studies of Approach/Avoidance Behaviors and Post-Mortem Studies: Pharmacological Manipulation

This study is examining how people with major depression, anxiety disorders, or PTSD approach or avoid social situations, and how medications that target specific brain chemicals (like dopamine and serotonin) affect these behaviors. The study uses brain imaging and smartphone-based daily assessments. **You may be eligible if...** - You have a confirmed diagnosis of major depressive disorder (MDD), generalized anxiety disorder, social phobia, panic disorder, or PTSD - You have a baseline depression score of 16 or higher on the Hamilton Depression Rating Scale (for MDD participants) - You are right-handed - You have a smartphone (iPhone or Android) **You may NOT be eligible if...** - You have contraindications to MRI (such as metal implants) - You are currently taking medications that would interfere with study drugs - You are pregnant or planning to become pregnant during the study - You have a history of seizures or other neurological conditions affecting the brain Talk to your doctor to see if this trial is right for you.