中国科学院心理研究所机构知识库

过去曾认为,人类触觉信息特异地由大直径有髓(Aβ)神经纤维传导。然而最近的研究表明,哺乳动物皮肤的机械感受器不仅有Aβ纤维分布,还有大量低阈值、低传导速度的小直径无髓(C)神经纤维分布,后者对轻微的非伤害性皮肤变形反应敏感,而对快速的皮肤运动反应微弱。初级传入C纤维投射至脊髓浅层,并与脊髓板层II内的次级感觉神经元形成突触联系,再通过脊髓丘脑束投射至岛叶。功能磁共振(fMRI)研究发现,缓慢移动的触觉刺激可以明显地激活岛叶并引起愉悦感,同时还可以激活眶额叶内与愉悦味觉和嗅觉激活区域邻近的部位。这些反应的性质和所激活的部位说明,C纤维触觉主要与边缘系统的功能有关,编码触觉的情绪成分。

It has been accepted that human tactile sensation is mediated exclusively by large myelinated (Aβ) fibres. Nevertheless, recent studies indicated a dual mechanoceptive innervation of the skin in various mammals. Besides the known A fibers, the skin is also innervated by slow-conducting, low-threshold, small unmyelinated (C) afferents. These unmyelinated fibers respond vigorously to innocuous skin deformation, but poorly to rapid skin movement. They project to outer lamina II of spinal cord, and form synapse...