Department of Anthropology, USA.
Department of Psychiatry and Behavioral Science, USA.
Behav Brain Res. 2023 Feb 2;437:114144. doi: 10.1016/j.bbr.2022.114144. Epub 2022 Oct 7.
Accurate perception of genuine vs. posed smiles is crucial for successful social navigation in humans. While people vary in their ability to assess the authenticity of smiles, little is known about the specific biological mechanisms underlying this variation. We investigated the neural substrates of smile authenticity judgments using functional magnetic resonance imaging (fMRI). We also tested a preliminary hypothesis that a common polymorphism in the oxytocin receptor gene (OXTR) rs53576 would modulate the behavioral and neural indices of accurate smile authenticity judgments. A total of 185 healthy adult participants (Neuroimaging arm: N = 44, Behavioral arm: N = 141) determined the authenticity of dynamic facial expressions of genuine and posed smiles either with or without fMRI scanning. Correctly identified genuine vs. posed smiles activated brain areas involved with reward processing, facial mimicry, and mentalizing. Activation within the inferior frontal gyrus and dorsomedial prefrontal cortex correlated with individual differences in sensitivity (d') and response criterion (C), respectively. Our exploratory genetic analysis revealed that rs53576 G homozygotes in the neuroimaging arm had a stronger tendency to judge posed smiles as genuine than did A allele carriers and showed decreased activation in the medial prefrontal cortex when viewing genuine vs. posed smiles. Yet, OXTR rs53576 did not modulate task performance in the behavioral arm, which calls for further studies to evaluate the legitimacy of this result. Our findings extend previous literature on the biological foundations of smile authenticity judgments, particularly emphasizing the involvement of brain regions implicated in reward, facial mimicry, and mentalizing.
准确感知真实微笑和虚假微笑对于人类在社交中取得成功至关重要。尽管人们在评估微笑真实性的能力上存在差异，但对于这种差异背后的具体生物学机制却知之甚少。我们使用功能磁共振成像（fMRI）技术研究了微笑真实性判断的神经基础。我们还测试了一个初步假设，即催产素受体基因（OXTR）rs53576 的一个常见多态性会调节准确微笑真实性判断的行为和神经指标。共有 185 名健康成年参与者（神经影像学组：N=44，行为学组：N=141）参与了这项研究，他们在进行 fMRI 扫描或不进行 fMRI 扫描的情况下，判断动态真实微笑和虚假微笑表情的真实性。正确识别真实微笑和虚假微笑会激活涉及奖励处理、面部模仿和心理理论的大脑区域。下额前回和背内侧前额叶皮层的激活与敏感性（d'）和反应标准（C）的个体差异相关。我们的探索性遗传分析表明，神经影像学组中的 rs53576 G 纯合子比 A 等位基因携带者更倾向于将虚假微笑判断为真实微笑，并且在观看真实微笑和虚假微笑时，内侧前额叶皮层的激活减少。然而，OXTR rs53576 并未调节行为学组中的任务表现，这需要进一步的研究来评估这一结果的合法性。我们的研究结果扩展了关于微笑真实性判断生物学基础的先前文献，特别是强调了涉及奖励、面部模仿和心理理论的大脑区域的参与。
