Mating and aggression are innate social behaviours that are controlled by subcortical circuits in the extended amygdala and hypothalamus^1,2,3,4. The bed nucleus of the stria terminalis (BNSTpr) is a node that receives input encoding sex-specific olfactory cues from the medial amygdala^5,6, and which in turn projects to hypothalamic nuclei that control mating^7,8,9 (medial preoptic area (MPOA)) and aggression^{9,10,11,12,13,14} (ventromedial hypothalamus, ventrolateral subdivision (VMHvl)), respectively¹⁵. Previous studies have demonstrated that male aromatase-positive BNSTpr neurons are required for mounting and attack, and may identify conspecific sex according to their overall level of activity¹⁶. However, neural representations in BNSTpr, their function and their transformations in the hypothalamus have not been characterized. Here we performed calcium imaging^17,18 of male BNSTpr^Esr1 neurons during social behaviours. We identify distinct populations of female- versus male-tuned neurons in BNSTpr, with the former outnumbering the latter by around two to one, similar to the medial amygdala and MPOA but opposite to VMHvl, in which male-tuned neurons predominate^6,9,19. Chemogenetic silencing of BNSTpr^Esr1 neurons while imaging MPOA^Esr1 or VMHvl^Esr1 neurons in behaving animals showed, unexpectedly, that the male-dominant sex-tuning bias in VMHvl was inverted to female-dominant whereas a switch from sniff- to mount-selective neurons during mating was attenuated in MPOA. Our data also indicate that BNSTpr^Esr1 neurons are not essential for conspecific sex identification. Rather, they control the transition from appetitive to consummatory phases of male social behaviours by shaping sex- and behaviour-specific neural representations in the hypothalamus.

^{交配和攻击性是先天的社会行为，由扩展的杏仁核和下丘脑1,2,3,4 的}皮层下回路控制。终纹床核 (BNSTpr) 是一个节点，它从内侧杏仁核^5,6接收输入编码的性别特异性嗅觉线索，然后投射到控制交配的下丘脑核^7,8,9（内侧视前区(MPOA)) 和攻击性^{9,10,11,12,13,14}（腹内侧下丘脑、腹外侧区 (VMHvl)），分别为¹⁵。先前的研究表明，雄性芳香化酶阳性 BNSTpr 神经元是安装和攻击所必需的，并且可以根据它们的总体活动水平来识别同种性别¹⁶. 然而，BNSTpr 中的神经表征、它们的功能和它们在下丘脑中的转换尚未被表征。在这里，我们在社交行为期间对雄性 BNSTpr ^{Esr1神经元进行了钙成像17,18}。我们在 BNSTpr 中识别出不同的女性调谐神经元和男性调谐神经元群体，前者的数量比后者大约二比一，类似于内侧杏仁核和 MPOA，但与 VMHvl 相反，其中男性调谐神经元占主导地位 6,9 ^{， 19} . 成像 MPOA ^Esr1或 VMHvl ^Esr1时BNSTpr ^{Esr1神经元的化学遗传学沉默}行为动物中的神经元出乎意料地表明，VMHvl 中雄性主导的性别调节偏差被反转为雌性主导，而在 MPOA 中，交配期间从嗅觉选择性神经元到坐骑选择性神经元的转换减弱了。我们的数据还表明 BNSTpr ^Esr1神经元对于同种性别识别不是必需的。相反，它们通过在下丘脑中塑造特定于性别和行为的神经表征来控制男性社会行为从欲望阶段到完成阶段的转变。