Title: Cross-compartmental modulation and plasticity in the Drosophila mushroom body
Description: The mushroom body (MB) is the site of odor association learning in Drosophila. In the canonical model, there are two types of reinforcing dopamine neurons (DANs): one set for rewarding unconditioned stimuli (US), and one responding to aversive US. When DANs are activated together with an odor (the conditioned stimulus, or CS), plasticity is induced in the downstream output neurons (MBONs). We have identified a DAN (V1) that surprisingly responds preferentially to odors, and responds weakly or not at all to various classical US. In order to explore the relationship between V1 odor responses and the established roles of the MB, I characterized the responses of DAN V1, and probed its relationship to odor-driven behavior, associative conditioning, and activity in other MB compartments. These data show that V1 receives recurrent input from identified MBONs, contributes to the activity of an MBON that enhances alerting behavior, and that its odor responses are modulated by conditioning. We therefore present the study of the alpha2 compartment, which V1 innervates, as the dissection of an atypical compartment of the MB, one that acts as a hub by which various information from other compartments and brain areas is integrated in order to alter a behavioral response to odor.

This work furthers our understanding of the MB not simply as an engine of classical learning, but as a system of diverse interconnected modules that allow coordinated fine control of behavior.