Zeng Shangyou, Jung Peter
Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Jul;70(1 Pt 1):011903. doi: 10.1103/PhysRevE.70.011903. Epub 2004 Jul 7.
Neuronal action potentials are generated by clusters of ion channels between the Hillock and the first segment. If the clusters comprise a large number of sodium and potassium channels, action potentials are generated if the membrane potential exceeds a threshold of about -55 mV. Such behavior is well described by an excitable model such as, for example, the Hodgkin-Huxley equations. In this paper we show through stochastic modeling that if the size of the generating ion channel cluster is small, action potentials are generated regardless of whether the membrane potential is below or above the excitation threshold. Action potential generation is then determined by single-channel kinetics. We further show that this switch in generation mechanism manifests itself in peculiar statistical properties of the generated spike trains at small cluster sizes.
神经元动作电位由轴丘和第一段之间的离子通道簇产生。如果这些簇包含大量的钠通道和钾通道，当膜电位超过约 -55 mV 的阈值时就会产生动作电位。这种行为可以用一个可兴奋模型很好地描述，例如霍奇金 - 赫胥黎方程。在本文中，我们通过随机建模表明，如果产生动作电位的离子通道簇的尺寸较小，那么无论膜电位是低于还是高于兴奋阈值，都会产生动作电位。动作电位的产生随后由单通道动力学决定。我们进一步表明，这种产生机制的转变在小簇尺寸下所产生的脉冲序列的特殊统计特性中表现出来。
