Oxytocin (OT) is a great facilitator of social life but, although its effects on socially relevant brain regions have been extensively studied, OT neuron activity during actual social interactions remains unexplored. Most OT neurons are magnocellular neurons, which simultaneously project to the pituitary and forebrain regions involved in social behaviors. In the present study, we show that a much smaller population of OT neurons, parvocellular neurons that do not project to the pituitary but synapse onto magnocellular neurons, is preferentially activated by somatosensory stimuli. This activation is transmitted to the larger population of magnocellular neurons, which consequently show coordinated increases in their activity during social interactions between virgin female rats. Selectively activating these parvocellular neurons promotes social motivation, whereas inhibiting them reduces social interactions. Thus, parvocellular OT neurons receive particular inputs to control social behavior by coordinating the responses of the much larger population of magnocellular OT neurons.

催产素（OT）是社交生活的重要促进者，但是，尽管它对与社会相关的大脑区域的影响已得到广泛研究，但在实际的社交互动过程中，OT神经元的活性仍未得到开发。多数OT神经元是巨细胞神经元，它们同时投射到参与社会行为的垂体和前脑区域。在本研究中，我们表明，体感刺激会优先激活较小的OT神经元，即不突出到垂体而是突触到大细胞神经元上的细小细胞神经元。这种激活被传递给较大的大细胞神经元群体，因此，在处女雌性大鼠之间的社交互动过程中，它们的活动显示出协调一致的增加。选择性激活这些小细胞神经元可以促进社交动机，而抑制它们会减少社交互动。因此，小细胞OT神经元通过协调更大数量的OT细胞神经元的响应来接受特定输入，以控制社会行为。