Treviño D L
Fed Proc. 1978 Jul;37(9):2234-6.
There is a growing body of evidence supporting the concept of pain as a specific sense. There are afferent fibers from the skin that respond only to noxious stimuli, the nociceptors. Some nociceptor afferents have small myelinated axons (Adelta) while the rest have unmyelinated axons (C). Among the neurons in the superficial layers of the spinal cord (laminae I, II and III) in the cat is a population that responds exclusively to noxious cutaneous stimuli. This input arrives over the nociceptor afferents. Another population responds best to mild temperature changes, reflecting an input from the thermoreceptive afferents. Many units in these two populations of spinal neurons have been shown to project to the brainstem. Therefore, they comprise a relay to the brain for nociceptive and thermal information. Another population of superficial neurons in the spinal cord responds to gentle mechanical stimuli, particularly to slow movement. They reflect an input from the C mechanoreceptor. This population is characterized by spatal and modality convergence. They do not project to the brain and their functional role is still unknown.
越来越多的证据支持疼痛是一种特殊感觉的概念。有来自皮肤的仅对伤害性刺激有反应的传入纤维，即伤害感受器。一些伤害感受器传入纤维有小的有髓轴突（Aδ），其余的有无髓轴突（C）。在猫脊髓浅层（I、II和III层）的神经元中，有一群神经元仅对伤害性皮肤刺激有反应。这种输入通过伤害感受器传入纤维到达。另一群神经元对温和的温度变化反应最佳，反映了来自温度感受传入纤维的输入。已证明这两类脊髓神经元中的许多单位投射到脑干。因此，它们构成了向大脑传递伤害性和热信息的中继。脊髓中的另一群浅层神经元对轻柔的机械刺激有反应，特别是对缓慢运动有反应。它们反映了来自C类机械感受器的输入。这群神经元的特点是空间和模式汇聚。它们不投射到大脑，其功能作用仍不清楚。
