Cluster of Excellence "Hearing4all," Department of Neuroscience, Faculty 6, University of Oldenburg, 26129 Oldenburg, Germany.
Cluster of Excellence "Hearing4all," Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany.
eNeuro. 2018 Sep 7;5(4). doi: 10.1523/ENEURO.0112-18.2018. eCollection 2018 Jul-Aug.
Modeling is a useful tool for investigating various biophysical characteristics of neurons. Recent simulation studies of propagating action potentials (spike conduction) along axons include the investigation of neuronal activity evoked by electrical stimulation from implantable prosthetic devices. In contrast to point-neuron simulations, where a large variety of models are readily available, Hodgkin-Huxley-type conductance-based models have been almost the only option for simulating axonal spike conduction, as simpler models cannot faithfully replicate the waveforms of propagating spikes. Since the amount of available physiological data, especially in humans, is usually limited, calibration, and justification of the large number of parameters of a complex model is generally difficult. In addition, not all simulation studies of axons require detailed descriptions of nonlinear ionic dynamics. In this study, we construct a simple model of spike generation and conduction based on the exponential integrate-and-fire model, which can simulate the rapid growth of the membrane potential at spike initiation. In terms of the number of parameters and equations, this model is much more compact than conventional models, but can still reliably simulate spike conduction along myelinated and unmyelinated axons that are stimulated intracellularly or extracellularly. Our simulations of auditory nerve fibers with this new model suggest that, because of the difference in intrinsic membrane properties, the axonal spike conduction of high-frequency nerve fibers is faster than that of low-frequency fibers. The simple model developed in this study can serve as a computationally efficient alternative to more complex models for future studies, including simulations of neuroprosthetic devices.
建模是研究神经元各种生物物理特性的有用工具。最近对轴突中传播动作电位（脉冲传导）的模拟研究包括对来自植入式假肢设备的电刺激引起的神经元活动的研究。与点神经元模拟不同，那里有大量各种模型可供选择，基于 Hodgkin-Huxley 型电导率的模型几乎是模拟轴突尖峰传导的唯一选择，因为更简单的模型不能忠实地复制传播尖峰的波形。由于可用的生理数据量通常有限，尤其是在人类中，因此对复杂模型的大量参数进行校准和证明是困难的。此外，并非所有轴突的模拟研究都需要详细描述非线性离子动力学。在这项研究中，我们基于指数积分和放电模型构建了一个简单的尖峰生成和传导模型，该模型可以模拟尖峰起始时膜电位的快速增长。就参数和方程的数量而言，该模型比传统模型紧凑得多，但仍可可靠地模拟髓鞘和非髓鞘轴突的尖峰传导，无论是通过细胞内还是细胞外刺激。我们使用这个新模型对听觉神经纤维的模拟表明，由于固有膜特性的差异，高频神经纤维的轴突尖峰传导速度比低频纤维快。本研究中开发的简单模型可以作为未来研究的更复杂模型的计算效率替代方案，包括神经假肢设备的模拟。
