Although facial muscles are heavily involved in emotional expressions, there is still a lack of evidence about the role of face primary motor cortex (face M1) in the processing of facial recognition and expression. This work investigated the effects of the passive viewing of different facial expressions on face M1 and compared data with those obtained from the hand M1. Thirty healthy subjects were randomly assigned to two groups undergoing transcranial magnetic stimulation (TMS) of face or hand M1. In both groups, short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) were probed in the depressor anguli oris (DAO) and first dorsal interosseous (FDI) muscles 300 ms after presentation of a picture of a face that expressed happy, sad or neutral emotions. Statistical analysis of SICI showed a non-significant effect of muscle (F1,28 = 1.903, p = 0.179), but a significant effect of emotion (F2,56 = 6.860, p = 0.004) and a significant interaction between muscle and emotion (F2,56 = 5.072, p = 0.015). Post hoc analysis showed that there was a significant reduction of SICI in the DAO muscle after presentation of a face with a happy expression compared with a neutral face (p < 0.001). In the FDI, a significant difference was observed between neutral and sad expressions (p = 0.010) No clear differences in ICF were detected. The different responses of face and hand muscles to emotional stimuli may be due to their functional roles in emotional expression versus protection of the body.

中文翻译：

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快乐的面孔有选择地增加了神经神经元的兴奋性，神经神经元支配着嘴里皱着的肌肉。

尽管面部肌肉大量参与情绪表达，但仍缺乏有关面部初级运动皮层（面部M1）在面部识别和表情处理中的作用的证据。这项工作研究了被动观察面部M1上不同面部表情的影响，并将数据与从手M1获得的数据进行了比较。30名健康受试者被随机分为两组，分别接受经脸部或手部M1的经颅磁刺激（TMS）。在这两组中，在呈现出一张表示高兴的脸部图片后300毫秒，分别在压迫性安吉利斯（DAO）和第一背骨间（FDI）肌肉中探查了短时皮质内抑制（SICI）和皮质内促进（ICF），悲伤或中性的情绪。SICI的统计分析显示，肌肉无显着影响（F1,28 = 1.903，p = 0.179），但情感有显着影响（F2,56 = 6.860，p = 0.004），肌肉与情感之间有显着相互作用（ F 2，56 ＝ 5.072，p ＝ 0.015）。事后分析表明，与中性脸相比，表现出满意表情的脸在DAO肌肉中的SICI显着降低（p <0.001）。在FDI中，观察到中性和悲伤表达之间存在显着差异（p = 0.010），未检测到ICF的明显差异。面部和手部肌肉对情绪刺激的不同反应可能是由于它们在情绪表达与保护身体方面的功能作用。004）和肌肉与情感之间的显着相互作用（F2,56 = 5.072，p = 0.015）。事后分析表明，与中性脸相比，表现出满意表情的脸在DAO肌肉中的SICI显着降低（p <0.001）。在FDI中，观察到中性和悲伤表达之间存在显着差异（p = 0.010），未检测到ICF的明显差异。面部和手部肌肉对情绪刺激的不同反应可能是由于它们在情绪表达与保护身体方面的功能作用。004）和肌肉与情感之间的显着相互作用（F2,56 = 5.072，p = 0.015）。事后分析表明，与中性脸相比，表现出满意表情的脸在DAO肌肉中的SICI显着降低（p <0.001）。在FDI中，观察到中性和悲伤表达之间存在显着差异（p = 0.010），未检测到ICF的明显差异。面部和手部肌肉对情绪刺激的不同反应可能是由于它们在情绪表达与保护身体方面的功能作用。在中性和悲伤表达之间观察到显着差异（p = 0.010）在ICF中未检测到明显差异。面部和手部肌肉对情绪刺激的不同反应可能是由于它们在情绪表达与保护身体方面的功能作用。在中性和悲伤表达之间观察到显着差异（p = 0.010）在ICF中未检测到明显差异。面部和手部肌肉对情绪刺激的不同反应可能是由于它们在情绪表达与保护身体方面的功能作用。