Neuromodulation Exerts Feedback and Feedforward Control of Action Selection

To be effective, behavioral choices must result in actions that are appropriate to an animals needs and environmental circumstances. In addition, the actions must be ones the animal can sustain until its needs are met. This aligning of goals, action, and motivation requires the coordinated activity of multiple brain circuits, but how such coordination is achieved is poorly understood. Here, we show how the insect hormone Bursicon coordinates the selection and sustains execution of a behavior in newly emerged adult Drosophila. Such flies must expand and harden their wings after metamorphosis, but they choose to delay expansion in confined conditions. We show that the decision to expand is mediated by an environmentally-sensitive, positive feedback loop in which Bursicon promotes its own sustained release. Released Bursicon then modulates motor neurons to promote wing expansion behavior. Bursicon thus exerts feedforward and feedback control to coordinately select and motivate a goal-directed action.