Our research uses neuroimaging and repetitive transcranial magnetic stimulation (rTMS) to understand and treat the brain circuit pathophysiology driving disorders of thinking, perception, communication, mood and emotion. rTMS is an FDA-approved treatment for depression, obsessive-compulsive disorder, and for smoking cessation. We use analyses of resting-state functional connectivity to study the brain networks that are affecting psychiatric disorders and identify relationships between brain and behavior. After identifying these brain-behavior relationships, we use rTMS to probe these relationships and establish causality - i.e., does rTMS-induced change in this circuitry lead to changes in behavior. Our research then aims to develop and test rTMS therapeutic interventions in clinical trials. Our particular areas of expertise are in substance use disorders and psychotic disorders, but our research methods are directly translatable to other psychiatric disorders and intellectual and developmental disabilities.