Selective control of course correction over long timescales in the Drosophila central complex

The insect central complex governs intricate navigational behaviors. One key region of the central complex, the fan-shaped body (FB), is where movement decisions are computed during goal-directed behaviors. However, our knowledge of when FB circuits are deployed is limited, and the FB has only been directly implicated in a few, narrowly defined behaviors. Here, we demonstrate that FB circuits affect course-correcting movements that, over long timescales, align the fly's heading with the perceived direction of optic flow. Silencing a major input neuronal population to the FB, the PFN_d neurons, abolishes this behavior while leaving certain reflexive turning behaviors intact. Further, introduction of a fictive error signal in either the PFN_d or PFN_a neurons via optogenetic activation reveals that they are sufficient to affect the forward movement of the fly while slightly biasing its heading direction. We propose a model whereby the fly recruits the circuitry of the central complex to selectively influence features of movement that emerge over long timescales.