Nickerson Aidan P, Newton Graeme W T, O'Sullivan James H, Martinez-Perez Manuel, Sales Anna C, Williams Gethin, Pickering Anthony E, Dunham James P
Anaesthesia, Pain, and Critical Care Sciences, School of Physiology, Pharmacology, & Neuroscience, University of Bristol; Eli Lilly and Company.
Anaesthesia, Pain, and Critical Care Sciences, School of Physiology, Pharmacology, & Neuroscience, University of Bristol.
J Vis Exp. 2023 Apr 21(194). doi: 10.3791/64898.
Nociceptors are a class of primary afferent neurons that signal potentially harmful noxious stimuli. An increase in nociceptor excitability occurs in acute and chronic pain conditions. This produces abnormal ongoing activity or reduced activation thresholds to noxious stimuli. Identifying the cause of this increased excitability is required for the development and validation of mechanism-based treatments. Single-neuron electrical threshold tracking can quantify nociceptor excitability. Therefore, we have developed an application to allow such measurements and demonstrate its use in humans and rodents. APTrack provides real-time data visualization and action potential identification using a temporal raster plot. Algorithms detect action potentials by threshold crossing and monitor their latency after electrical stimulation. The plugin then modulates the electrical stimulation amplitude using an up-down method to estimate the electrical threshold of the nociceptors. The software was built upon the Open Ephys system (V0.54) and coded in C++ using the JUCE framework. It runs on Windows, Linux, and Mac operating systems. The open-source code is available (https://github.com/Microneurography/APTrack). The electrophysiological recordings were taken from nociceptors in both a mouse skin-nerve preparation using the teased fiber method in the saphenous nerve and in healthy human volunteers using microneurography in the superficial peroneal nerve. Nociceptors were classified by their response to thermal and mechanical stimuli, as well as by monitoring the activity-dependent slowing of the conduction velocity. The software facilitated the experiment by simplifying the action potential identification through the temporal raster plot. We demonstrate real-time closed-loop electrical threshold tracking of single-neuron action potentials during in vivo human microneurography, for the first time, and during ex vivo mouse electrophysiological recordings of C-fibers and Aδ-fibers. We establish proof of principle by showing that the electrical threshold of a human heat-sensitive C-fiber nociceptor is reduced by heating the receptive field. This plugin enables the electrical threshold tracking of single-neuron action potentials and allows the quantification of changes in nociceptor excitability.
伤害感受器是一类初级传入神经元，可对潜在有害的伤害性刺激发出信号。在急性和慢性疼痛状态下，伤害感受器的兴奋性会增加。这会产生异常的持续活动或降低对伤害性刺激的激活阈值。确定这种兴奋性增加的原因是基于机制的治疗方法开发和验证所必需的。单神经元电阈值追踪可以量化伤害感受器的兴奋性。因此，我们开发了一种应用程序来进行此类测量，并展示其在人类和啮齿动物中的应用。APTrack 使用时间光栅图提供实时数据可视化和动作电位识别。算法通过阈值穿越检测动作电位，并监测电刺激后的潜伏期。然后，该插件使用上下方法调节电刺激幅度，以估计伤害感受器的电阈值。该软件基于 Open Ephys 系统（V0.54）构建，并使用 JUCE 框架用 C++ 编码。它可在 Windows、Linux 和 Mac 操作系统上运行。开源代码可获取（https://github.com/Microneurography/APTrack）。电生理记录取自使用隐神经的分离纤维法的小鼠皮肤 - 神经标本中的伤害感受器，以及使用腓浅神经的微神经ography 技术的健康人类志愿者。伤害感受器根据其对热和机械刺激的反应以及通过监测传导速度的活动依赖性减慢进行分类。该软件通过时间光栅图简化动作电位识别，从而促进了实验。我们首次展示了在体内人类微神经ography 期间以及在体外小鼠 C 纤维和 Aδ 纤维的电生理记录期间对单神经元动作电位的实时闭环电阈值追踪。我们通过证明加热感受野会降低人类热敏感 C 纤维伤害感受器的电阈值来建立原理证明。此插件能够对单神经元动作电位进行电阈值追踪，并允许量化伤害感受器兴奋性的变化。
