In many species, including mice, female animals show markedly different pup-directed behaviours based on their reproductive state^1,2. Naive wild female mice often kill pups, while lactating female mice are dedicated to pup caring^3,4. The neural mechanisms that mediate infanticide and its switch to maternal behaviours during motherhood remain unclear. Here, on the basis of the hypothesis that maternal and infanticidal behaviours are supported by distinct and competing neural circuits^5,6, we use the medial preoptic area (MPOA), a key site for maternal behaviours^7,8,9,10,11, as a starting point and identify three MPOA-connected brain regions that drive differential negative pup-directed behaviours. Functional manipulation and in vivo recording reveal that oestrogen receptor α (ESR1)-expressing cells in the principal nucleus of the bed nucleus of stria terminalis (BNSTpr^ESR1) are necessary, sufficient and naturally activated during infanticide in female mice. MPOA^ESR1 and BNSTpr^ESR1 neurons form reciprocal inhibition to control the balance between positive and negative infant-directed behaviours. During motherhood, MPOA^ESR1 and BNSTpr^ESR1 cells change their excitability in opposite directions, supporting a marked switch of female behaviours towards the young.

在包括小鼠在内的许多物种中，雌性动物根据其繁殖状态表现出明显不同的针对幼崽的行为^1,2。天真的野生雌性小鼠经常杀死幼崽，而哺乳期的雌性小鼠则致力于照顾幼崽^3,4。介导杀婴及其在母性期间向母性行为转变的神经机制仍不清楚。在这里，基于母亲和婴儿杀婴行为由不同且竞争的神经回路支持的假设^5,6，我们使用内侧视前区 (MPOA)，这是母亲行为的关键部位^7,8,9,10,11，作为起点，确定三个与 MPOA 连接的大脑区域，这些区域驱动不同的负面小狗导向行为。功能操作和体内记录表明，终纹床核主核中表达雌激素受体α（ESR1）的细胞（BNSTpr ^ESR1）在雌性小鼠杀婴过程中是必要的、充分的和自然激活的。MPOA ^ESR1和 BNSTpr ^ESR1神经元形成相互抑制，以控制积极和消极的婴儿导向行为之间的平衡。在母性期间，MPOA ^ESR1和 BNSTpr ^ESR1细胞向相反方向改变其兴奋性，支持女性行为向年轻人的显着转变。