Ardizzi Martina, Umiltà Maria Alessandra, Evangelista Valentina, Di Liscia Alessandra, Ravera Roberto, Gallese Vittorio
Department of Neuroscience, University of Parma, Parma, Italy.
Ravera Children Rehabilitation Centre (RCRC), Lakka, Freetown, Sierra Leone.
PLoS One. 2016 Sep 29;11(9):e0163853. doi: 10.1371/journal.pone.0163853. eCollection 2016.
Facial mimicry and vagal regulation represent two crucial physiological responses to others' facial expressions of emotions. Facial mimicry, defined as the automatic, rapid and congruent electromyographic activation to others' facial expressions, is implicated in empathy, emotional reciprocity and emotions recognition. Vagal regulation, quantified by the computation of Respiratory Sinus Arrhythmia (RSA), exemplifies the autonomic adaptation to contingent social cues. Although it has been demonstrated that childhood maltreatment induces alterations in the processing of the facial expression of emotions, both at an explicit and implicit level, the effects of maltreatment on children's facial mimicry and vagal regulation in response to facial expressions of emotions remain unknown. The purpose of the present study was to fill this gap, involving 24 street-children (maltreated group) and 20 age-matched controls (control group). We recorded their spontaneous facial electromyographic activations of corrugator and zygomaticus muscles and RSA responses during the visualization of the facial expressions of anger, fear, joy and sadness. Results demonstrated a different impact of childhood maltreatment on facial mimicry and vagal regulation. Maltreated children did not show the typical positive-negative modulation of corrugator mimicry. Furthermore, when only negative facial expressions were considered, maltreated children demonstrated lower corrugator mimicry than controls. With respect to vagal regulation, whereas maltreated children manifested the expected and functional inverse correlation between RSA value at rest and RSA response to angry facial expressions, controls did not. These results describe an early and divergent functional adaptation to hostile environment of the two investigated physiological mechanisms. On the one side, maltreatment leads to the suppression of the spontaneous facial mimicry normally concurring to empathic understanding of others' emotions. On the other side, maltreatment forces the precocious development of the functional synchronization between vagal regulation and threatening social cues facilitating the recruitment of fight-or-flight defensive behavioral strategies.
面部模仿和迷走神经调节是对他人面部情绪表达的两种关键生理反应。面部模仿被定义为对他人面部表情的自动、快速且一致的肌电图激活，与同理心、情感互惠和情绪识别有关。迷走神经调节通过呼吸性窦性心律不齐（RSA）的计算来量化，体现了自主神经系统对偶然社交线索的适应性。尽管已经证明童年期虐待会在显性和隐性层面上引起情绪面部表情处理的改变，但虐待对儿童在面对情绪面部表情时的面部模仿和迷走神经调节的影响仍然未知。本研究的目的是填补这一空白，研究对象包括24名流浪儿童（受虐待组）和20名年龄匹配的对照组儿童（对照组）。我们记录了他们在观看愤怒、恐惧、喜悦和悲伤的面部表情时皱眉肌和颧大肌的自发面部肌电图激活以及RSA反应。结果表明童年期虐待对面部模仿和迷走神经调节有不同的影响。受虐待儿童没有表现出典型的皱眉肌模仿的正负调制。此外，仅考虑负面面部表情时，受虐待儿童的皱眉肌模仿低于对照组。关于迷走神经调节，受虐待儿童在静息时的RSA值与对愤怒面部表情的RSA反应之间表现出预期的功能性负相关，而对照组则没有。这些结果描述了两种被研究的生理机制对恶劣环境的早期且不同的功能适应。一方面，虐待导致通常有助于对他人情绪产生同理心理解的自发面部模仿受到抑制。另一方面，虐待促使迷走神经调节与威胁性社交线索之间的功能同步早熟发展，从而促进战斗或逃跑防御行为策略的调用。
