Overall Summary The ?University of Washington Center of Excellence in Opioid Addiction Research? is designed to provide shared resources that would enhance efficiency and facilitate collaborative research for the study of the effects of opioids on neural circuits with the goal of understanding opioid addiction mechanisms and developing novel treatments for drug addiction. Center participants from 16 UW laboratories are using optogenetic control of rodent behavior, in vivo neuroimaging of single cell calcium signals and other receptor signaling probes, viral gene expression and CRISPR/cas9 manipulations to deconstruct and study opioid self-administration. This group has a long-history of highly productive, collaborative, cutting-edge research and training that will be strengthened by the shared resources provided by this award. The proposed Center would be comprised of four components: The Administrative Core will coordinate resource utilization, organize monthly Research Progress Meetings, organize training and outreach efforts. The Imaging and Neural Circuits Core would develop shared resources for in vivo brain imaging in rats and mice using 1-Photon endoscopy, Inscopix imaging, 2-Photon confocal microscopy, Spatial Light Modulation, fiber photometry and operant behaviors. The Molecular Genetics Resource Core would provide DIO-AAV / CRISPR-cas9 / Canine Adeno Viral reagents, develop new activity actuators and sensors and provide advanced training in cell-specific genetic manipulation coupled with behavioral and computational analysis. A Pilot Project Core would enable participants and trainees to initiate new projects utilizing the Imaging and Genetic Cores and would foster training and collaborations within the Center laboratory groups and university community at large. The Center would become a national neuroscience resource by providing training to visiting scientists, reagents for genetic manipulation and novel actuators/sensors on request from investigators at other institutions. It will provide workshops and summer courses for training advanced undergraduate and graduate students in optogenetics, computational neuroscience, and viral design & construction techniques. All of these components would be focused on understanding the changes in neural circuitry responsible for opioid addiction and on the development of new therapeutic tools based on these insights.