Infant signals, including infant sounds and facial expressions, play a critical role in eliciting parental proximity and care. Processing of infant signals in the adulthood brain is likely to recruit emotional empathy neural circuits, including the inferior frontal gyrus (IFG). Here, we used transcranial magnetic stimulation (TMS) to test the role of right IFG (rIFG) in behavioral responses to infant signals. Specifically, a group of nulliparous women were asked to perform a handgrip dynamometer task and an Approach-Avoidance Task (AAT) after receiving TMS over the right IFG or over a control site (vertex). Suppressing activity in the rIFG affected the modulation of handgrip force in response to infant crying. Moreover, the AAT showed that participants tend to avoid the sad infant face after Vertex stimulation, and this bias was counteracted by rIFG stimulation. Our results suggest a causal role of rIFG in sensitive responding towards sad infants and point to the rIFG as a critical node in the neural network underlying the innate releasing mechanism for feelings of love, affection and caring of sad infants.

婴儿的信号，包括婴儿的声音和面部表情，在引起父母亲和监护方面起着至关重要的作用。在成年大脑中处理婴儿信号很可能会招募情感共情神经回路，包括额下回（IFG）。在这里，我们使用经颅磁刺激（TMS）来测试右IFG（rIFG）在对婴儿信号的行为反应中的作用。具体而言，在未通过正确的IFG或在对照部位（顶点）接受TMS后，要求一组未产妇进行握力计测功和避免进路测功（AAT）。rIFG中的抑制活性影响了响应婴儿哭泣的握力的调节。此外，AAT显示，参与者在顶点刺激后倾向于避免悲伤的婴儿脸，rIFG刺激抵消了这种偏见。我们的研究结果表明，rIFG在对悲伤婴儿的敏感反应中起因果作用，并指出rIFG是神经网络中关爱先天释放机制的关键节点，以释放对悲伤婴儿的感情，情感和关怀。