Theoretical relation between axon initial segment geometry and excitability
Theoretical relation between axon initial segment geometry and excitability
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DOI：
10.7554/elife.53432
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发表时间：
2020-03-30
期刊：
影响因子：
7.7
通讯作者：
Brette, Romain
中科院分区：
文献类型：
--
作者：
Goethals, Sarah;Brette, Romain
在大多数脊椎动物神经元中，动作电位是在轴突起始段(AIS)的远端触发的。AIS的位置和长度在不同类型的神经元和不同类型的神经元中都不同，其活动、发育和病理情况也不同。AIS几何结构对兴奋性有什么影响？由于存在许多潜在的混杂因素，直接的经验评估被证明是困难的。在这里，我们进行了原则性的理论分析来回答这个问题。我们提供了一个简单的公式，将AIS几何形状和钠电导密度与体细胞电压阈值联系起来。AIS的远端移位通常会导致兴奋性(适度)增加，但我们解释了如果AIS存在超极化电流，由于与胞体的阻性耦合，这种模式如何逆转。这项工作为评估结构AIS塑性对电功能的意义提供了理论工具。
In most vertebrate neurons, action potentials are triggered at the distal end of the axon initial segment (AIS). Both position and length of the AIS vary across and within neuron types, with activity, development and pathology. What is the impact of AIS geometry on excitability? Direct empirical assessment has proven difficult because of the many potential confounding factors. Here, we carried a principled theoretical analysis to answer this question. We provide a simple formula relating AIS geometry and sodium conductance density to the somatic voltage threshold. A distal shift of the AIS normally produces a (modest) increase in excitability, but we explain how this pattern can reverse if a hyperpolarizing current is present at the AIS, due to resistive coupling with the soma. This work provides a theoretical tool to assess the significance of structural AIS plasticity for electrical function.