Shea V K, Perl E R
J Neurophysiol. 1985 Sep;54(3):491-501. doi: 10.1152/jn.1985.54.3.491.
The cutaneous receptive properties of unmyelinated (C) fibers of the rabbit's great auricular nerve were determined by single-unit recordings. The majority of C-fiber units could be excited by cutaneous stimulation, and such sensory units fell into three major categories on the basis of responses to mechanical and thermal stimulation of their cutaneous receptive fields: low-threshold mechanoreceptors, nociceptors, or specific thermoreceptors. The majority of afferent elements were nociceptive, and all nociceptors responded to strong mechanical stimulation. Three types of nociceptors could be distinguished by their responses to thermal stimuli. Polymodal nociceptors responded to heat with thresholds of 40-55 degrees C and typically displayed enhanced responses or sensitization after noxious heating of their receptive fields. High-threshold mechanoreceptors failed to respond promptly to heat before noxious cutaneous stimulation which, however, elicited subsequent back-ground activity or sensitivity to heat. A third type of nociceptor responded to cold but not to heat. Low-threshold mechanoreceptors were identified by their brisk responses to very gentle, slowly moving mechanical stimulation of their receptive fields, and were readily distinguished from any element classified as nociceptive by their lower mechanical thresholds. Rapid innocuous warming or cooling excited some of the low-threshold mechanoreceptors. Specific thermoreceptors, both warming and cooling types, were rare, insensitive to mechanical stimulation, and responded to very slight changes in temperature. In contrast to the sensitization to heat, which was characteristic of most nociceptors, specific warming receptors displayed depressed thermal responses after noxious heating of their receptive fields. These results provide further evidence of the similarity of C-fiber receptors innervating hairy skin of different species. Some differences from past reports and additional features are described.
通过单单位记录法测定了家兔耳大神经无髓鞘（C）纤维的皮肤感受特性。大多数C纤维单位可被皮肤刺激所兴奋，根据其皮肤感受野对机械和热刺激的反应，这类感觉单位可分为三大类：低阈值机械感受器、伤害感受器或特定温度感受器。大多数传入成分是伤害性的，所有伤害感受器都对强机械刺激有反应。根据它们对热刺激的反应可区分出三种类型的伤害感受器。多模式伤害感受器对热的反应阈值为40 - 55摄氏度，其感受野受到有害加热后通常会表现出反应增强或敏感化。高阈值机械感受器在有害皮肤刺激之前对热没有迅速反应，但有害皮肤刺激会引发随后的背景活动或对热的敏感性。第三种类型的伤害感受器对冷有反应但对热无反应。低阈值机械感受器通过其对感受野非常轻柔、缓慢移动的机械刺激的轻快反应得以识别，并且因其较低的机械阈值很容易与任何被归类为伤害性的成分区分开来。快速的无害升温或降温会使一些低阈值机械感受器兴奋。特定温度感受器，包括升温型和降温型，都很罕见，对机械刺激不敏感，并且对温度的非常微小变化有反应。与大多数伤害感受器所具有的热敏感化特征相反，特定升温感受器在其感受野受到有害加热后会表现出热反应降低。这些结果进一步证明了支配不同物种有毛皮肤的C纤维感受器具有相似性。文中描述了与以往报道的一些差异以及其他特征。
