A circuit logic for sexually shared and dimorphic aggressive behaviors in Drosophila

Aggression involves both sexually monomorphic and dimorphic actions. How the brain implements these two types of actions is poorly understood. We have identified three cell types that regulate aggression in Drosophila: one type is sexually shared, and the other two are sex specific. Shared common aggression-promoting (CAP) neurons mediate aggressive approach in both sexes, whereas functionally downstream dimorphic but homologous cell types, called male-specific aggression-promoting (MAP) neurons in males and fpC1 in females, control dimorphic attack. These symmetric circuits underlie the divergence of male and female aggressive behaviors, from their monomorphic appetitive/motivational to their dimorphic consummatory phases. The strength of the monomorphic → dimorphic functional connection is increased by social isolation in both sexes, suggesting that it may be a locus for isolation-dependent enhancement of aggression. Together, these findings reveal a circuit logic for the neural control of behaviors that include both sexually monomorphic and dimorphic actions, which may generalize to other organisms. [Display omitted] •Sexually dimorphic attack is controlled by sexually dimorphic neurons in Drosophila•Shared cells that control aggressive approach activate the dimorphic attack neurons•The transition from approach to attack occurs at a higher threshold than approach•Isolation enhances shared → dimorphic functional connectivity to promote aggression Chiu et al. uncover how a sexually dimorphic behavior is wired in the brains of male and female flies. Looking for neuronal components controlling aggressive behaviors, they find a single type of neuron that controls aggressive approach in both sexes connected hierarchically to different neurons in males versus females that control dimorphic attack responses (lunge versus headbutt, respectively). They then show that social isolation, known to augment aggressive behaviors in both sexes, strengthens the connections between the monomorphic and dimorphic neurons.