Yu Jiabin, Yang Jiajia, Yu Yinghua, Wu Qiong, Takahashi Satoshi, Ejima Yoshimichi, Wu Jinglong
Cognitive Neuroscience Laboratory, Graduate School of Natural Science and Technology, Okayama University, Okayama, 7008530, Japan.
Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University, Okayama, 7008530, Japan.
Heliyon. 2019 Aug 12;5(8):e02141. doi: 10.1016/j.heliyon.2019.e02141. eCollection 2019 Aug.
Human unmyelinated tactile afferents (CT afferents) in hairy skin are thought to be involved in the transmission of affective aspects of touch. How the perception of affective touch differs across human skin has made substantial progress; however, the majority of previous studies have mainly focused on the relationship between stroking velocities and pleasantness ratings. Here, we investigate how stroking hardness affects the perception of affective touch. Affective tactile stimulation was given with four different hardness of brushes at three different forces, which were presented to either palm or forearm. To quantify the physical factors of the stimuli (brush hardness), ten naïve, healthy participants assessed brush hardness using a seven-point scale. Based on these ten participants, five more participants were added to rate the hedonic value of brush stroking using a visual analogue scale (VAS). We found that pleasantness ratings over the skin resulted in a preference for light, soft stroking, which was rated as more pleasant when compared to heavy, hard stroking. Our results show that the hairy skin of the forearm is more susceptible to stroking hardness than the glabrous of the palm in terms of the perception of pleasantness. These findings of the current study extend the growing literature related to the effect of stroking characteristics on pleasantness ratings.
人体有毛皮肤中的无髓鞘触觉传入神经（CT传入神经）被认为参与了触觉情感方面的传递。关于情感触觉的感知在人体不同皮肤部位如何存在差异已经取得了实质性进展；然而，先前的大多数研究主要集中在抚摸速度与愉悦度评分之间的关系上。在这里，我们研究抚摸硬度如何影响情感触觉的感知。使用四种不同硬度的刷子在三种不同力度下对手掌或前臂进行情感触觉刺激。为了量化刺激的物理因素（刷子硬度），十名未接触过实验的健康参与者使用七点量表评估刷子硬度。基于这十名参与者，又增加了五名参与者，使用视觉模拟量表（VAS）对刷子抚摸的享乐价值进行评分。我们发现，对皮肤进行愉悦度评分时，人们更偏好轻柔的抚摸，与沉重、坚硬的抚摸相比，轻柔的抚摸被评为更愉悦。我们的结果表明，在前臂的有毛皮肤对抚摸硬度的感知方面，比手掌的无毛皮肤更敏感。当前研究的这些发现扩展了与抚摸特征对愉悦度评分影响相关的不断增加的文献。
