Investigating the Neuropsychological Effects of 5-HT2a Antagonism

Serotonin is an important chemical in the brain that helps control mood, sleep, and appetite. Most antidepressant medications work by affecting serotonin to help improve symptoms. A serotonin receptor is like a "lock" on the surface of brain cells, and serotonin acts like a "key" that fits into these locks. When serotonin binds to the receptor, it sends a signal that helps control different functions in the brain, like mood and behavior. There are different types of serotonin receptors, and each one affects different parts of the brain. Pimavanserin is a medication licensed in the United States of America for the treatment of patients with Parkinson's Disease. It has a very specific effect on one type of serotonin receptor (the serotonin 2a receptor). In this study, the investigators will use pimavanserin to understand more about this serotonin receptor, which may help develop new treatments for depression in the future. More specifically, the study will focus on how pimavanserin impacts cognitive functions such as memory, how we process emotional information and how we make decisions, and will compare these effects to a placebo (a treatment that doesn't have active ingredients).