Dynamic compensation mechanism gives rise to period and duty-cycle level sets in oscillatory neuronal models.
Dynamic compensation mechanism gives rise to period and duty-cycle level sets in oscillatory neuronal models.
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动态补偿机制在振荡神经元模型中产生周期和占空比水平集。
DOI：
10.1152/jn.00357.2016
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发表时间：
2016
影响因子：
2.5
通讯作者：
Golowasch,Jorge
中科院分区：
文献类型：
--
作者：
Rotstein,HoracioG;Olarinre,Motolani;Golowasch,Jorge
神经元的节律振荡可以通过振荡周期和占空比等多种属性来表征。这些特征的值取决于参与离子电流的振幅，这可以通过它们的最大电导值来表征。最近的实验和理论工作表明，对于两个或多个不同电导的离子电流的不同组合，这些属性的值可以保持恒定，从而定义了所谓的电导空间中的水平集。在二维电导空间中，水平集是一条曲线，通常是一条直线，沿着这条曲线，一个特定的振荡属性值是守恒的。在这项工作中，我们使用建模、动力系统工具（相空间分析）和数值模拟来研究在简化（线性化和FitzHugh-Nagumo）和基于电导的（Morris-Lecar）神经元振荡模型中产生周期和占空比水平集的可能动态机制。一个简单的假设是，具有相同或相反有效符号的离子电流之间的张力平衡足以产生水平集。根据这一假设，在给定的周期内，每个离子电流的动态可以通过一些常量（例如，最大电导）很好地捕获，并且对于这些最大电导的不同组合，相平面图是相同的或几乎相同的（例如，具有相同最大值和最小值的立方状零线）。相反，我们表明这些机制是动态的，并且涉及非线性电压依赖关系和离子电流动态变量运行的有效时间尺度之间的复杂相互作用。
Rhythmic oscillation in neurons can be characterized by various attributes, such as the oscillation period and duty cycle. The values of these features depend on the amplitudes of the participating ionic currents, which can be characterized by their maximum conductance values. Recent experimental and theoretical work has shown that the values of these attributes can be maintained constant for different combinations of two or more ionic currents of varying conductances, defining what is known as level sets in conductance space. In two-dimensional conductance spaces, a level set is a curve, often a line, along which a particular oscillation attribute value is conserved. In this work, we use modeling, dynamical systems tools (phase-space analysis), and numerical simulations to investigate the possible dynamic mechanisms responsible for the generation of period and duty-cycle levels sets in simplified (linearized and FitzHugh-Nagumo) and conductance-based (Morris-Lecar) models of neuronal oscillations. A simplistic hypothesis would be that the tonic balance between ionic currents with the same or opposite effective signs is sufficient to create level sets. According to this hypothesis, the dynamics of each ionic current during a given cycle are well captured by some constant quantity (e.g., maximal conductances), and the phase-plane diagrams are identical or are almost identical (e.g., cubic-like nullclines with the same maxima and minima) for different combinations of these maximal conductances. In contrast, we show that these mechanisms are dynamic and involve the complex interaction between the nonlinear voltage dependencies and the effective time scales at which the ionic current's dynamical variables operate.