A neural network for intermale aggression to establish social hierarchy.

Intermale aggression is used to establish social rank. Several neuronal populations have been implicated in aggression, but the circuit mechanisms that shape this innate behavior and coordinate its different components (including attack execution and reward) remain elusive. We show that dopamine transporter-expressing neurons in the hypothalamic ventral premammillary nucleus (PMv neurons) organize goal-oriented aggression in male mice. Activation of PMv neurons triggers attack behavior; silencing these neurons interrupts attacks. Regenerative PMv membrane conductances interacting with recurrent and reciprocal excitation explain how a brief trigger can elicit a long-lasting response (hysteresis). PMv projections to the ventrolateral part of the ventromedial hypothalamic and the supramammillary nuclei control attack execution and aggression reward, respectively. Brief manipulation of PMv activity switched the dominance relationship between males, an effect persisting for weeks. These results identify a network structure anchored in PMv neurons that organizes aggressive behavior and, as a consequence, determines intermale hierarchy.