Research in the lab addresses the molecular basis of drug addiction. We focus on the functional organization and regulation of neurotransmitter signaling pathways mediated by G protein-coupled receptors (GPCRs). Emerging data indicate that the sub cellular localization of GPCRs is a critical determinant of their signaling. We have developed state-of-the-art fluorescence imaging approaches to precisely track the location and signaling of these GPCRs in real time in living neurons. Using these approaches, we study the fundamental cell biological mechanisms linking GPCR trafficking to signaling, and how these mechanisms are perturbed in addiction and neuropsychiatric disorders.