Overall Project Summary The “University of Washington Center of Excellence in Opioid Addiction Research” is designed to provide shared resources that would continue to 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 27 University of Washington 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 addiction mechanisms. This group has a long history of highly productive, collaborative, cutting-edge research and training that will be strengthened by the continued sharing of resources provided by this award. The renewed NIDA-P30 Center would continue to be comprised of four components: The Administrative Core will coordinate resource utilization, organize weekly Research Progress Meetings, organize training, professional development of trainees, and URM outreach efforts. The Imaging and Neural Circuits Core would develop and maintain shared resources for in vivo brain imaging in rodents using 1-Photon endoscopy, Inscopix imaging, 2-Photon confocal microscopy, Spatial Light Modulation, fiber photometry, Neuropixels in vivo electrophysiology, and operant behaviors. The Molecular Genetics Resource Core would provide DIO-AAV / CRISPR-cas9 / Canine Adeno Viral reagents, develop new activity actuators and novel sensors, and would provide advanced training in cell-specific genetic manipulation coupled with behavioral and computational analysis. A Pilot Project Core would enable NIDA-P30 faculty participants and trainees to initiate new projects utilizing the Imaging and Genetic Cores and would foster training and collaborations within the NIDA-P30 Center laboratory groups and the university community at large. The NIDA-P30 Center would continue as 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. The NIDA-P30 Center will support the recruitment and professional development of early-stage investigators and URM/1st Gen trainees both at the University of Washington and through active collaborations with HBCU 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 for translation based on these insights.