Activation of Central Brain Neurons in Female Drosophila melanogaster Promotes a Persistent Internal State that Increases Courtship Receptivity and Aggression

Abstract

Across species, decisions are driven by internal states, personal experience, and sensory input. Acoustic communication between animals represents one medium through which one animal can influence another’s behavior. This relationship can be studied through the multisensory cues involved in Drosophila melanogaster courtship and their influences on the female to mate. While the factors that motivate and modulate the male’s production of courtship song have been widely studied, the neuronal circuitry underlying the female’s processing and response to song (such as receptivity to courtship) remain poorly understood. Using the extensive genetic toolkit available for Drosophila melanogaster, we have investigated the role of two neuronal clusters of the Drosophila protocerebrum (pC1, pCd) in the dynamic sensorimotor transformations of the female fly. We have found that while persistent inactivation of either pC1 or pCd decreases copulation success by about half, optogenetically-stimulating pC1 (but not pCd) in the female brain prior to courtship significantly promotes mating, as measured by shorter times to copulation and increased copulation rates. Furthermore, by introducing a delay of several minutes between optogenetic activation and courtship, we have established that pC1 activation promotes a persistent internal state, as similar increases in courtship receptivity are still observed. Interestingly, we have also found that their activation also promotes aggressive behaviors towards the courting male, suggesting some shared circuits for courtship and aggression in the fly brain. By analyzing the relationship between aggression and courtship song, we have begun to elucidate how the neuronal circuitry underlying aggression and courtship receptivity are related. Our observations will add to the understanding of how both internal states and ongoing sensory stimuli drive animal behavior on different timescales, ranging from seconds to minutes.