The correct identification of facial expressions is critical for understanding the intention of others during social communication in the daily life of all primates. Here we used ultra-high-field fMRI at 9.4 T to investigate the neural network activated by facial expressions in awake New World common marmosets from both male and female sex, and to determine the effect of facial motions on this network. We further explored how the face-patch network is involved in the processing of facial expressions. Our results show that dynamic and static facial expressions activate face patches in temporal and frontal areas (O, PV, PD, MD, AD, and PL) as well as in the amygdala, with stronger responses for negative faces, also associated with an increase of the respiration rates of the monkey. Processing of dynamic facial expressions involves an extended network recruiting additional regions not known to be part of the face-processing network, suggesting that face motions may facilitate the recognition of facial expressions. We report for the first time in New World marmosets that the perception and identification of changeable facial expressions, vital for social communication, recruit face-selective brain patches also involved in face detection processing and are associated with an increase of arousal.

SIGNIFICANCE STATEMENT Recent research in humans and nonhuman primates has highlighted the importance to correctly recognize and process facial expressions to understand others' emotions in social interactions. The current study focuses on the fMRI responses of emotional facial expressions in the common marmoset (Callithrix jacchus), a New World primate species sharing several similarities of social behavior with humans. Our results reveal that temporal and frontal face patches are involved in both basic face detection and facial expression processing. The specific recruitment of these patches for negative faces associated with an increase of the arousal level show that marmosets process facial expressions of their congener, vital for social communication.

在所有灵长类动物的日常生活中，面部表情的正确识别对于理解他人的意图至关重要。在这里，我们使用 9.4 T 的超高场功能磁共振成像来研究清醒的雄性和雌性新世界普通狨猴中面部表情激活的神经网络，并确定面部运动对该网络的影响。我们进一步探讨了面部补丁网络如何参与面部表情的处理。我们的结果表明，动态和静态面部表情会激活颞叶和额叶区域（O、PV、PD、MD、AD 和 PL）以及杏仁核的面部斑块，对负面面部的反应更强，也与增加猴子的呼吸频率。动态面部表情的处理涉及一个扩展网络，该网络招募了不属于面部处理网络一部分的额外区域，这表明面部运动可能有助于面部表情的识别。我们首次在新大陆狨猴中报告，对多变的面部表情的感知和识别对于社交交流至关重要，它招募了面部选择性脑块，也参与了面部检测处理，并且与觉醒的增加有关。

意义声明最近对人类和非人类灵长类动物的研究强调了正确识别和处理面部表情以理解社交互动中他人情绪的重要性。目前的研究重点是普通狨猴（Callithrix jacchus）情绪面部表情的功能磁共振成像反应，狨猴是一种新大陆灵长类动物，在社会行为方面与人类有一些相似之处。我们的结果表明，颞部和额部面部斑块参与基本的面部检测和面部表情处理。这些与唤醒水平增加相关的负面面孔的斑块的具体募集表明，狨猴处理其同类的面部表情，这对于社交沟通至关重要。