Portnova Galina V, Proskurnina Elena V, Sokolova Svetlana V, Skorokhodov Ivan V, Varlamov Anton A
Institute of Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, 5A Butlerova St, Moscow, 117485, Russia.
Pushkin State Russian Language Institute, Moscow, Russia.
Exp Brain Res. 2020 Oct;238(10):2257-2268. doi: 10.1007/s00221-020-05891-y. Epub 2020 Jul 27.
Affective touch plays an important role in human social bonding, affiliative behavior, and in general emotional well-being. A system of unmyelinated low-threshold mechanosensitive C-type afferents innervating hairy skin (C-tactile or CT system) is postulated to provide the neurophysiological background of affective touch perception. C-tactile afferents respond optimally to soft and slow strokes, and this response correlates positively with pleasure ratings of tactile stimuli. As gentle touch is consistently associated with oxytocin release further promoting prosocial behavior, it has been suggested that this effect is mediated by the response of C-tactile afferents. This study assesses a possible link between CT-optimal touch, its subjective pleasantness, EEG indices of cortical arousal, and peripheral oxytocin response. EEG was recorded in 28 healthy volunteers during resting state and tactile stimulation[gentle slow brush strokes on forearm (CT-targeted touch) and palm (non-CT-targeted touch)]. Saliva samples were collected before and after the touch stimulation. Oxytocin concentration increase was significantly associated with greater subjective ratings of CT-targeted touch but not of non-CT-targeted touch, and with lower peak alpha frequency values indicating decreased cortical arousal. The findings suggest that CT-targeted stimulation triggers oxytocin release but only when the touch is perceived at an individual level as having clearly positive affective salience. This corresponds to previous studies reporting that oxytocin response to touch can be related to different personality factors, and bears important implications for planning touch-based interventions in social and medical care.
情感触摸在人类社会联结、亲和行为以及总体情绪健康中发挥着重要作用。一种由无髓鞘低阈值机械敏感C型传入神经组成的系统支配着多毛皮肤（C触觉或CT系统），据推测该系统为情感触摸感知提供了神经生理学背景。C触觉传入神经对轻柔缓慢的抚摸反应最佳，且这种反应与触觉刺激的愉悦评分呈正相关。由于轻柔触摸一直与催产素释放相关联，进而进一步促进亲社会行为，有人认为这种效应是由C触觉传入神经的反应介导的。本研究评估了CT最佳触摸、其主观愉悦感、皮层唤醒的脑电图指标以及外周催产素反应之间的可能联系。在静息状态和触觉刺激[在前臂（CT靶向触摸）和手掌（非CT靶向触摸）上进行轻柔缓慢的刷动]期间，对28名健康志愿者进行了脑电图记录。在触摸刺激前后收集唾液样本。催产素浓度的增加与CT靶向触摸而非非CT靶向触摸的更高主观评分显著相关，且与较低的α波峰值频率值相关，表明皮层唤醒降低。研究结果表明，CT靶向刺激会触发催产素释放，但前提是这种触摸在个体层面被感知为具有明显积极的情感显著性。这与之前的研究结果一致，即催产素对触摸的反应可能与不同的人格因素有关，并且对规划社会和医疗护理中基于触摸的干预措施具有重要意义。
