 Animals can learn to repeat behaviors to earn desired rewards through a process called reinforcement learning. This process involves the ascending dopaminergic projections to the basal ganglia, which have been previously linked to this type of learning. However, little is known about the role of the hippocampus in this process. In this study, researchers found that a specific population of hippocampal neurons and their dopaminergic innovation contribute to op-amp self-stimulation. These neurons are located in the dentate gyrus, receive dopaminergic projections from the locus coruleus, and express D1 dopamine receptors. When activated, these neurons cause mice to press a lever to earn optogenetic activation of these neurons, selectively activating the locus coruleus projections to the dentate gyrus or blocking them with D1 receptor antagonists produces similar effects. Additionally, calcium imaging of these neurons revealed significant activity at the time of action selection, but not during passive reward delivery. These findings suggest that the hippocampus plays a key role in. This article was authored by Elijah Apetta, Isabella P. Fallon, Ryan M. Hughes and others. We are article.tv, links in the description below.