Abstract Prescription opioid abuse is the fastest growing drug problem in the United States. Now, deaths from overdose of opioid pain relievers exceed those from all illegal drugs. Chronic opioid use induces opioid dependence, which is characterized by extremely unpleasant physiological and psychological symptoms after drug use is terminated. Opioid users learn to associate opioid intake with relief from negative physical and affective states. This maladaptive association might last long after withdrawal has terminated and underlie the drug cravings experience by many users after exposure to drug-associated cues or stressful life events. We have recently identified that the paraventricular nucleus of the thalamus (PVT) is a prominent neuronal substrate mediating the physical signs and negative emotion accompanied with opioid withdrawal, which provide a unique opportunity to directly examine the contribution of withdrawal states to opioid-associated memories. In this application, we propose to use pathway specific optogenetic and pharmacogenetic manipulation (1) to determining roles of the PVT output pathways in the formation and maintenance of opioid-associated memories; (2) to study morphine induced plasticity in each PVT pathway and impact of pathway silencing on this plasticity; (3) we will combine pathway specific manipulation in the PVT, c-Fos iDISCO+, and light sheet fluorescent microscopy to mapping brain-wide network activities underlying opioid-associated memories. Our work will inspire the development of novel strategy to treat opioid abuse. Ana Caro Del Castillo will conduct research to prepare for a career in the biomedical sciences. Research conduct may include laboratory experiments, data collection, data analysis, participation in lab meetings, manuscript preparation, and literature reviews. She will examine brain wide c-Fos expression from animals at different stages of morphine CPP training, 3D reconstruction c-Fos expression dataset and analysis these data with iDISCO map platform. She is expected to deliver a formal presentation on her research project at the end of the internship. She will receive an amount of $15.00 per hour for a maximum of $4,800 for eight (8) weeks.