This research identifies a specific neural pathway that controls maternal aggression in mice, specifically the circuit connecting the posterior amygdala (PA) to the ventromedial hypothalamus (VMHvl). The study demonstrates that PA cells expressing estrogen receptor alpha are essential for driving protective attacks against intruders, showing significantly higher activity and synaptic strength during the lactation period compared to the virgin state. Scientists found that the hormone oxytocin acts as a key modulator, boosting the output of this circuit to increase aggression when pups are present. Furthermore, the intrinsic excitability of specialized neurons in the hypothalamus increases after birth, making the mother more responsive to social threats. When the offspring are removed, a decline in oxytocin levels causes a corresponding drop in aggressive behavior, highlighting a plastic neural mechanism that adapts to the mother's immediate needs. Overall, the sources reveal how hormonal shifts and structural brain changes collectively implement the rise and fall of maternal protective instincts.

References:

• Yamaguchi T, Yan R, Khan M, et al. The neural mechanisms supporting the rise and fall of maternal aggression[J]. Nature, 2026: 1-11.