Visually induced initiation of Drosophila innate courtship-like following pursuit is mediated by central excitatory state

The courtship ritual of male Drosophila represents an innate behaviour that is initiated by female-derived sensory stimuli. Here we report that moving light spots can induce courtship-like following pursuit in tethered wild-type male flies provided the fly is primed by optogenetic stimulation of specific dsx-expressing neuronal clusters in the lateral protocerebrum (LPR). Namely, stimulation of the pC1 neuronal cluster initiates unilateral wing extension and vibration of both sides, whereas stimulation of the pC2l cluster initiates only contralateral wing displays. In addition, stimulation of pC2l but not pC1 neurons induced abdominal bending and proboscis extension. Ca2+ imaging of the pC1 cluster revealed periodic Ca2+ rises, each corresponding to a turn of the male fly during courtship. In contrast, group-reared fru mutant males exhibit light spot-induced courtship pursuit without optogenetic priming. Ca2+ imaging revealed enhanced responses of LPR neurons to visual stimuli in the mutants, suggesting a neural correlate of the light spot-induced courtship behaviour.