Abstract Cocaine abuse remains a major burden on public health with significant numbers of overdose deaths each year. The proposed work characterizes a neural circuit that underlies the increased drug consumption that takes place by some individuals following chronic drug use. This application leverages previous work demonstrating that corticotropin releasing factor (CRF), dynorphin and dopamine signaling can individually impact drug intake and that each of these systems changes with chronic cocaine use. Specifically, the proposed experiments ask how these three neuromodulatory systems interact with each other in the regulation drug consumption. The working hypothesis is that escalation of drug intake following chronic drug use, comes about through a serial pathway where elevated CRF levels causes an increase in dynorphin which consequently reduces dopamine release, producing escalation. However, the experiments are designed to systematically test the functional connections between each of these nodes in the regulation of cocaine intake and, in doing so, discern between eight competing models of the interactions. Therefore, regardless, of whether the results match the working hypothesis or not, the experiments will yield new insight into the interactions between these systems. This information will inform potential treatment targets for moderating intake in substance abusers and thereby reducing harm.