Department of Clinical Neurophysiology, Blå stråket 7, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden.
Brain. 2011 Apr;134(Pt 4):1116-26. doi: 10.1093/brain/awr011. Epub 2011 Mar 4.
We examined patients with a heritable disorder associated with a mutation affecting the nerve growth factor beta gene. Their condition has been classified as hereditary sensory and autonomic neuropathy type V. Carriers of the mutation show a reduction in density of thin and unmyelinated nerve fibres, including C afferents. A distinct type of unmyelinated, low-threshold mechanoreceptive C fibre, the C-tactile afferent, is present in hairy but not glabrous skin of humans and other mammals. They have been implicated in the coding of pleasant, hedonic touch of the kind that occurs in affiliative social interactions. We addressed the relationship between C fibre function and pleasant touch perception in 10 individuals from a unique population of mutation carriers in Sweden. We also investigated the effect of reduced C-fibre density on patients' evaluation of observed interpersonal touch (empathy). Results showed that patients perceived gentle, slow arm stroking, optimal for eliciting C-tactile afferent responses (1-10 cm/s), as less pleasant than did matched controls and also differed in their rating patterns across stimulation velocities. Further, patients' blood-oxygen-level-dependent responses in posterior insular cortex--a target for C afferents--were not modulated by stimulation optimal for activating C-tactile afferents. Hence, perception of the hedonic aspect of dynamic touch likely depends on C-tactile afferent density. Closely similar patterns between individuals' ratings of felt and seen touch suggest that appraisal of others' touch is anchored in one's own perceptual experience, whether typical or atypical.
我们研究了患有遗传性疾病的患者，这些患者的疾病与影响神经生长因子β基因的突变有关。他们的病情已被归类为遗传性感觉自主神经病 V 型。突变携带者的神经纤维密度降低，包括 C 传入纤维。一种独特的无髓、低阈值机械性 C 纤维，即 C 触觉传入纤维，存在于人类和其他哺乳动物的有毛皮肤上，但不存在于无毛皮肤上。它们与亲和性社会互动中发生的愉快、愉悦性触觉的编码有关。我们在瑞典一个独特的突变携带者群体中研究了 10 名个体的 C 纤维功能与愉快触摸感知之间的关系。我们还研究了 C 纤维密度降低对患者对观察到的人际触摸（同理心）的评估的影响。结果表明，患者感知到轻柔、缓慢的手臂抚摸，这是最适合引起 C 触觉传入反应的速度（1-10cm/s），比匹配的对照组感觉不那么愉快，并且在不同的刺激速度下，他们的评分模式也不同。此外，患者后岛叶皮层的血氧水平依赖反应——C 传入纤维的靶点——在刺激最佳刺激 C 触觉传入纤维时没有被调节。因此，动态触摸的愉悦方面的感知可能取决于 C 触觉传入纤维的密度。个体对感觉和看到的触摸的评分之间非常相似的模式表明，对他人触摸的评估是以自己的感知体验为基础的，无论是典型的还是非典型的。
