Neuroimaging of Pavlovian Fear Conditioning Processes in Patients With Pathological Anxiety

The purpose of this study is to use functional magnetic resonance imaging to investigate how the human brain learns to form associations between neutral and emotional stimuli. The study is based on the basic principles of Pavlovian conditioning. When someone learns that a neutral stimulus (such as the sound of a bell) predicts an unpleasant stimulus (such as a mild electrical shock), the neutral stimulus takes on the properties of an emotional stimulus. The investigators are interested in the neural processes involved in this learning in people with a clinical anxiety disorder and posttraumatic stress disorder (PTSD).