Identifying behavioral circuits in Drosophila melanogaster: moving targets in a flying insect

Drosophila melanogaster has historically been the premier model system for understanding the molecular and genetic bases of complex behaviors. In the last decade technical advances, in the form of new genetic tools and electrophysiological and optical methods, have allowed investigators to begin to dissect the neuronal circuits that generate behavior in the adult. The blossoming of circuit analysis in this organism has also reinforced our appreciation of the inadequacy of wiring diagrams for specifying complex behavior. Neuromodulation and neuronal plasticity act to reconfigure circuits on both short and long time scales. These processes act on the connectome, providing context by integrating external and internal cues that are relevant for behavioral choices. New approaches in the fly are providing insight into these basic principles of circuit function.

► Behavioral mutants can be used to identify candidate circuit components. ► Binary expression systems allow precise manipulation of specific neurons. ► Drosophila has a wide variety of tools for manipulation of neuronal activity in behaving animals. ► Functional connectivity between circuit elements can be demonstrated with genetic tools. ► Modulation of connectivity in a circuit is a general feature of behavior.