A Subset of Brain Neurons Controls a Sexually Dimorphic Proboscis Holding Behavior in Adult Drosophilia Melanogaster

Abstract

Taste is essential for humans and animals alike to evaluate food quality and make important decisions about food choice and intake . How complex brains process sensory information to produce behavior is an essential question in the field of sensory neurobiology. Currently, little is known about taste circuits in the brain as compared to other sensory systems. Here, we used the common vinegar fly, Drosophila melanogaster, to explore the potential role of brain neurons labeled by a transgenic line (VT041723-GAL4) in producing "proboscis holding" behavior (extrusion of the mouthpart without withdrawal) . By utilizing the GAL4/UAS binary expression system, we expressed a heat-activated cation channel (UAS-dTrpA1) in these brain neurons and artificially activated them by elevation of temperature, subsequently examining behavior in the heat-activated proboscis extension reflex (PER) assay . We found that activation of these neurons induced proboscis holding . Interestingly, the proboscis holding phenotype was sexually dimorphic. Male flies rarely showed proboscis holding and those that did had shorter proboscis holding durations . On the other hand, both mated and virgin females showed significantly more proboscis holding and had longer proboscis holding durations than male flies. Overall, we identified a subset of brain neurons labeled by the VT041723-GAL4 line that controls a sexually dimorphic feeding response (proboscis holding) upon activation .