Meier Isabell M, Bos Peter A, Hamilton Katie, Stein Dan J, van Honk Jack, Malcolm-Smith Susan
Department of Experimental Psychology, Utrecht University, Utrecht, The Netherlands.
Department of Experimental Psychology, Utrecht University, Utrecht, The Netherlands.
Psychoneuroendocrinology. 2016 Dec;74:65-68. doi: 10.1016/j.psyneuen.2016.08.022. Epub 2016 Aug 23.
Positive social cues, like happy facial expressions, activate the brain's reward system and indicate interest in social affiliation. Facial mimicry of emotions, which is the predominantly automatic and unconscious imitation of another person's facial expression, has been shown to promote social affiliation. It has been demonstrated repeatedly that the opioid system is vital to social affiliation in rodents, but there is less evidence in humans. We investigated whether a 50mg administration of naltrexone, an opioid antagonist with highest affinity for the mu-opioid system, modulates emotional mimicry. A passive viewing task with dynamic facial expressions was used in a randomized placebo controlled between-subjects design. Mimicry was measured with electromyography (EMG) on three facial muscles, the corrugator supercilii and the depressor jaw muscle, associated with negatively-valenced emotions, and the zygomaticus major, which is activated during smiling. The results demonstrate an increase of negatively-valenced facial responses (corrugator and depressor) to happy facial expressions after naltrexone compared to placebo, consistent with lowered interest in social interaction or affiliation. Our findings provide evidence for a role of the opioid system in modulating automatic behavioral responses to cues of reward and social interaction, and translate to rodent models of the mu-opioid system and social affiliation.
积极的社交线索，如快乐的面部表情，会激活大脑的奖励系统，并表明对社交联系的兴趣。情绪的面部模仿，即对他人面部表情的主要自动且无意识的模仿，已被证明能促进社交联系。反复的研究表明，阿片系统对啮齿动物的社交联系至关重要，但在人类中的证据较少。我们研究了50毫克纳曲酮（一种对μ-阿片系统具有最高亲和力的阿片拮抗剂）的给药是否会调节情绪模仿。在一项随机安慰剂对照的受试者间设计中，使用了带有动态面部表情的被动观看任务。通过肌电图（EMG）测量三块面部肌肉的模仿情况，皱眉肌和降颌肌与负性情绪相关，而颧大肌在微笑时被激活。结果表明，与安慰剂相比，纳曲酮给药后对快乐的面部表情的负性面部反应（皱眉肌和降颌肌）增加，这与对社交互动或联系的兴趣降低一致。我们的研究结果为阿片系统在调节对奖励和社交互动线索的自动行为反应中的作用提供了证据，并转化为μ-阿片系统和社交联系的啮齿动物模型。
