C- and A delta-fiber components of heat-evoked cerebral potentials in healthy human subjects.
C- and A delta-fiber components of heat-evoked cerebral potentials in healthy human subjects.
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发表时间：
1999
期刊：
影响因子：
7.4
通讯作者：
W. Magerl;Z. Ali;J. Ellrich;R. Meyer;R. Treede
中科院分区：
文献类型：
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作者：
W. Magerl;Z. Ali;J. Ellrich;R. Meyer;R. Treede
用反馈控制激光热刺激手背和前臂的多毛皮肤，记录中线（Fz，Cz，Pz）和颞侧（T3，T4）头皮位置的热诱发脑电位。基于来自初级传入电生理学的数据，选择刺激水平（40 ℃），其高于C纤维热阈值，但明显低于A δ伤害感受器热阈值，以便选择性地激发C纤维而不伴随A δ纤维的激发。反馈控制的步进热刺激到40摄氏度引起ultralate激光诱发电位（LEPs）在顶点的实验比例很高（90%）。估计传导速度计算的手和前臂之间的潜伏期变化的ultralate LEPs（2.4米/秒）和反应时间（2.8米/秒）证实调解ultralate电位的无髓鞘神经纤维（伤害感受器和/或温暖的纤维）。超晚期LEP可通过其头皮地形与伴随性负变（CNV）的消退相鉴别，CNV是一种与预期和反应准备相关的内源性电位。48摄氏度的强热刺激，这是阈上的大多数A δ-和C-纤维伤害感受器，引起了众所周知的晚期LEPs介导的伤害性Adelta纤维证实以前的研究。强热刺激的LEP波形也包含了一个ultralate组件，让人想起一个ultralate LEP后，晚LEP。超晚期和晚期LEP具有相同的头皮地形图。总之，温度控制的激光热刺激的方法允许选择性和可靠的检查A δ和C纤维介导的传入通路和相关的皮质处理，而不分离A纤维神经阻滞的并发症。
Feedback-controlled laser heat was used to stimulate the hairy skin of the hand dorsum and forearm, and heat-evoked cerebral potentials were recorded at midline (Fz, Cz, Pz) and temporal (T3, T4) scalp positions. Based on data from primary afferent electrophysiology a stimulus level (40 degrees C) was chosen, which is above C-fiber heat threshold, but clearly below A delta-nociceptor heat threshold in order to excite selectively C-fibers without concomitant excitation of A delta-fibers. Feedback-controlled stepped heat stimuli to 40 degrees C elicited ultralate laser evoked potentials (LEPs) at the vertex in a high proportion of experiments (90%). Estimates of conduction velocity calculated from latency shifts between the hand and forearm sites of ultralate LEPs (2.4 m/s) and of reaction times (2.8 m/s) confirmed mediation of ultralate potentials by unmyelinated nerve fibers (nociceptors and/or warm fibers). The ultralate LEP could be differentiated from resolution of contingent negative variation (CNV), an endogenous potential related to expectation and response preparation, by its scalp topography. Strong heat stimuli of 48 degrees C, which is suprathreshold for most A delta- and C-fiber nociceptors, elicited the well-known late LEPs mediated by nociceptive Adelta-fibers confirming previous studies. The LEP waveform to strong heat stimuli also contained an ultralate component reminiscent of an ultralate LEP following the late LEP. Ultralate and late LEP had identical scalp topography. In conclusion, the method of temperature-controlled laser heat stimuli allows the selective and reliable examination of A delta- and C-fiber-mediated afferent pathways and the related cortical processing without the complication of dissociating A-fiber nerve blocks.