Abstract Our multidisciplinary and highly collaborative consortium identifies gene variants associated with increased vulnerability to compulsive-like cocaine use by performing the first GWAS using an advanced model of chronic intravenous cocaine self-administration. We have also created the first preclinical cocaine biobank which enables researchers who do not have the resources to perform chronic intravenous self-administration or next-generation genome sequencing to perform advanced genetic, molecular, and cellular studies to further our understanding of the biological changes underlying addiction-like behaviors. We have obtained results suggesting that it is critical to add brain and blood samples to measure cocaine levels in rats, however, the rising costs of supplies and labor threaten the biobank's operations and the overall project. Indeed, our recent GWAS identified a gene, carboxyl esterase (ces1), encoding an enzyme that degrades cocaine in tissue, but not in blood, underscores the need for precise measurement of cocaine levels in both the brain and blood, which we did not plan to do in the parent grant. We identified several coding variants for ces1a, 1c, 1, 1e, and 1g that may alter the ability of the enzyme to metabolize cocaine. It is critical that we perform additional experiments to test the feasibility of measuring the pharmacokinetics of cocaine in the brain in vivo within subjects to know if it is possible to expand the Cocaine Biobank with brain and blood cocaine measurements. This dual measurement is crucial for understanding individual differences in vulnerability to cocaine addiction. Previous research that relied solely on blood cocaine levels would have missed significant insights into cocaine pharmacokinetics within the brain. Therefore, incorporating these measurements into our experimental design is essential to advancing our understanding of addiction mechanisms and individual vulnerabilities. The overall goal of the following two aims for this 12-month supplement is to demonstrate the feasibility of integrating brain and blood cocaine measurements to the biobank using DNA aptamer implanted in the brain and the jugular vein. In Specific Aim 1, we will gather preliminary data that will allow us to identify individual differences in cocaine pharmacokinetics between brain and blood in heterogeneous stock rats. In Specific Aim 2, we will ensure the continued viability and expansion of the Cocaine Biobank, which has become an invaluable resource for addiction research. This project will continue having a sustained and powerful impact on the field because it provides an exponential increase in the number of genetic loci identified; establishes the first high-throughput behavioral motifs analysis of addiction-like behaviors using parallel video-recording and automated machine learning analysis; identifies novel behavioral endophenotypes of vulnerability/resistance to addiction-like behaviors; and expands and improves the Co...