A closed-loop optogenetic screen for neurons controlling feeding in Drosophila

Feeding is an essential part of animal life that is impacted greatly by the sense of taste. Although the characterization of taste-detection at the periphery is extensive, higher-order taste and feeding circuits are still being elucidated. Here, we use an automated closed-loop optogenetic activation screen for novel taste and feeding neurons in Drosophila melanogaster. Out of 122 Janelia FlyLight Project GAL4 lines preselected based on expression pattern, we identify six lines that acutely promote feeding and 35 lines that inhibit it. As proof of principle, we follow up on the R70C07-GAL4 neuron population, which strongly inhibits feeding. Using split-GAL4 lines to isolate subsets of the R70C07-GAL4 population, we find both appetitive and aversive neurons. We also show that R70C07-GAL4 labels a population of putative second-order taste interneurons that contact both sweet and bitter sensory neurons. These results serve as a resource for further functional dissection of fly feeding circuits.