Torebjörk H E, Hallin R G
J Neurol Neurosurg Psychiatry. 1974 Jun;37(6):653-64. doi: 10.1136/jnnp.37.6.653.
The responses of A and C fibres to electrical intradermal stimulation were recorded with microelectrodes inserted percutaneously into intact human skin nerves. Unitary discharges deriving from A fibres were often encountered and sometimes even single C unit deflections were identified. When several C fibres responded to the stimulation, a compact time presentation of the filtered and dot-converted spikes improved the discrimination of individual spikes time-locked to the stimulation, so that unitary C elements could often be identified in the treated records even if the signal-to-noise ratio of the original signals was low. Increases in latency or blockings were traced in both A and C unit responses to repeated excitation, but the influence of repeated activation was more pronounced in thin nerve fibres even at low stimulation frequencies. The decreased excitability of thin nerve endings on repetitive stimulation suggests that not only central factors but also excitation failure in peripheral thin nerve fibres might be responsible for the decrease in pain perception experienced during local intense electrical intradermal stimulation at high frequencies.
将微电极经皮插入完整的人体皮肤神经，记录A纤维和C纤维对皮内电刺激的反应。经常能遇到源自A纤维的单一放电，有时甚至能识别出单个C单位的偏转。当几根C纤维对刺激产生反应时，对滤波后的尖峰进行点转换并紧凑呈现时间，有助于更好地区分与刺激时间锁定的单个尖峰，这样即使原始信号的信噪比很低，在处理后的记录中也常常能识别出单一的C纤维成分。在A纤维和C纤维对重复刺激的反应中，均能观察到潜伏期延长或阻滞现象，但即使在低刺激频率下，重复激活对细神经纤维的影响更为明显。重复刺激时细神经末梢兴奋性降低，这表明在高频局部强烈皮内电刺激过程中，疼痛感知降低不仅可能与中枢因素有关，外周细神经纤维的兴奋衰竭也可能起到了作用。
