THE DETERMINANTS OF THE ONSET DYNAMICS OF ACTION POTENTIALS IN A COMPUTATIONAL MODEL
THE DETERMINANTS OF THE ONSET DYNAMICS OF ACTION POTENTIALS IN A COMPUTATIONAL MODEL
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DOI：
10.1016/j.neuroscience.2010.02.072
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发表时间：
2010-06-02
期刊：
影响因子：
3.3
通讯作者：
Volgushev, M.
中科院分区：
文献类型：
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作者：
Baranauskas, G.;Mukovskiy, A.;Volgushev, M.
中枢神经元索马内的动作电位（AP）具有明显的阶跃式起始动力学，这有利于将微弱但快速变化的输入信号编码为动作电位序列。解释AP快速发作动力学的一种可能性是假设钠通道的协同激活。然而，没有直接的证据表明，在中枢哺乳动物神经元的电压门控钠通道的协同性。皮层神经元中的AP起始于轴突并反向传播到索马，这一事实促使对躯体AP的突然发生提出了另一种解释。在入侵的情况下，AP的发病是顺利的轴突起始段的起始位点，但目前侵入索马体细胞钠通道被激活之前，产生一个急剧发病的体细胞AP。在这里，我们使用多隔室神经元模型，以确定范围内的主动和被动的细胞特性，是必要的，以重现尖锐的AP发病的入侵情况。我们的模拟结果表明，在轴突中的AP启动是一个必要的，但不是一个充分的条件，体AP的急剧发病：对于广泛的参数范围，模型可以重现远端AP启动和反向传播，但未能定量再现发病动态观察皮层神经元体AP。为了再现体细胞AP的急剧发作，入侵场景需要主动和被动细胞特性的特定组合。轴突初始段所需的属性显着不同，从目前接受的和实验估计值。我们的结论是，额外的因素的入侵有助于急剧AP发病和进一步的实验需要解释的AP发病动力学在皮层神经元。(C)2010年IBRO。由爱思唯尔有限公司出版。保留所有权利。
Action potentials (APs) in the soma of central neurons exhibit a sharp, step-like onset dynamics, which facilitates the encoding of weak but rapidly changing input signals into trains of action potentials. One possibility to explain the rapid AP onset dynamics is to assume cooperative activation of sodium channels. However, there is no direct evidence for cooperativity of voltage gated sodium channels in central mammalian neurons. The fact that APs in cortical neurons are initiated in the axon and backpropagate into the soma, prompted an alternative explanation of the sharp onset of somatic APs. In the invasion scenario, the AP onset is smooth at the initiation site in the axon initial segment, but the current invading the soma before somatic sodium channels are activated produces a sharp onset of somatic APs. Here we used multicompartment neuron models to identify ranges of active and passive cell properties that are necessary to reproduce the sharp AP onset in the invasion scenario. Results of our simulations show that AP initiation in the axon is a necessary but not a sufficient condition for the sharp onset of somatic AP: for a broad range of parameters, models could reproduce distal AP initiation and backpropagation but failed to quantitatively reproduce the onset dynamics of somatic APs observed in cortical neurons. To reproduce sharp onset of somatic APs, the invasion scenario required specific combinations of active and passive cell properties. The required properties of the axon initial segment differ significantly from the currently accepted and experimentally estimated values. We conclude that factors additional to the invasion contribute to the sharp AP onset and further experiments are needed to explain the AP onset dynamics in cortical neurons. (C) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.