Liljencrantz Jaquette, Olausson Håkan
Institute of Neuroscience and Physiology, Gothenburg University Gothenburg, Sweden ; Department of Clinical Neurophysiology, Sahlgrenska University Hospital Gothenburg, Sweden.
Front Behav Neurosci. 2014 Mar 6;8:37. doi: 10.3389/fnbeh.2014.00037. eCollection 2014.
In humans converging evidence indicates that affective aspects of touch are signaled by low threshold mechanoreceptive C tactile (CT) afferents. Analyses of electrophysiological recordings, psychophysical studies in denervated subjects, and functional brain imaging, all indicate that CT primary afferents contribute to pleasant touch and provide an important sensory underpinning of social behavior. Considering both these pleasant and social aspects of gentle skin-to-skin contact, we have put forward a framework within which to consider CT afferent coding properties and pathways-the CT affective touch hypothesis. Recent evidence from studies in mice suggests that CTs, when activated, may have analgesic or anxiolytic effects. However, in neuropathic pain conditions, light touch can elicit unpleasant sensations, so called tactile allodynia. In humans, tactile allodynia is associated with reduced CT mediated hedonic touch processing suggesting loss of the normally analgesic effect of CT signaling. We thus propose that the contribution of CT afferents to tactile allodynia is mainly through a loss of their normally pain inhibiting role.
在人类中，越来越多的证据表明，触觉的情感方面是由低阈值机械感受性C触觉（CT）传入神经传递的。对电生理记录的分析、对去神经受试者的心理物理学研究以及功能性脑成像均表明，CT初级传入神经对愉悦触觉有贡献，并为社会行为提供了重要的感觉基础。考虑到轻柔的皮肤接触所具有的这些愉悦和社交方面，我们提出了一个框架，用以考量CT传入神经的编码特性和通路——CT情感触觉假说。来自小鼠研究的最新证据表明，CT被激活时可能具有镇痛或抗焦虑作用。然而，在神经性疼痛状态下，轻触可引发不愉快的感觉，即所谓的触觉异常性疼痛。在人类中，触觉异常性疼痛与CT介导的享乐性触觉处理减少有关，这表明CT信号的正常镇痛作用丧失。因此，我们提出CT传入神经对触觉异常性疼痛的作用主要是由于其正常的疼痛抑制作用丧失。
