Urocortin-3 neurons in the mouse perifornical area promote infant-directed neglect and aggression.

While recent studies have uncovered dedicated neural pathways mediating the positive control of parenting, the regulation of infant-directed aggression and how it relates to adult-adult aggression is poorly understood. Here we show that urocortin-3 (Ucn3)-expressing neurons in the hypothalamic perifornical area (PeFAUcn3) are activated during infant-directed attacks in males and females, but not other behaviors. Functional manipulations of PeFAUcn3 neurons demonstrate the role of this population in the negative control of parenting in both sexes. PeFAUcn3 neurons receive input from areas associated with vomeronasal sensing, stress, and parenting, and send projections to hypothalamic and limbic areas. Optogenetic activation of PeFAUcn3 axon terminals in these regions triggers various aspects of infant-directed agonistic responses, such as neglect, repulsion, and aggression. Thus, PeFAUcn3 neurons emerge as a dedicated circuit component controlling infant-directed neglect and aggression, providing a new framework to understand the positive and negative regulation of parenting in health and disease.

Charting a Path toward Aggression.

Hypothalamic stimulation can elicit complex behaviors such as aggression, but how discrete motor components of such behaviors are organized at the circuit level remains largely unknown. In this issue of Neuron, Falkner et al. (2020) find that complex neural representations get transformed into a simplified action signal along a hypothalamic-midbrain pathway.

Neuroscience: Plasticity Matters for Mating.

It remains unclear how hormonally mediated internal states affect specific brain circuits to modify behaviour. A new study reveals that a hypothalamic projection pathway critical for female sexual receptivity is extensively remodelled during the estrous cycle.