The roles potassium currents play in regulating the electrical activity of ventral cochlear nucleus neurons
The roles potassium currents play in regulating the electrical activity of ventral cochlear nucleus neurons
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DOI：
10.1152/jn.00127.2002
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发表时间：
2003-06-01
影响因子：
2.5
通讯作者：
Manis, PB
中科院分区：
文献类型：
--
作者：
Rothman, JS;Manis, PB
使用动力学数据从三个不同的K+电流在急性分离的神经元，一个单一的电室代表腹侧耳蜗核（VCN）神经元的索马。K+电流包括快速瞬态电流（I-A）、缓慢失活低阈值电流（I-LT）和非失活高阈值电流（I-HT）。该模型还包括快速失活Na+电流，超极化激活的阳离子电流（I-h）和1-50个听觉神经突触。利用该模型，探讨了I-A、I-LT和I-HT在VCN细胞放电模式形成中的作用。模拟结果表明，I-HT主要作用是在动作电位过程中恢复细胞膜，而I-A主要作用是调节重复放电的频率。I-LT被认为是负责在II型细胞（bushy细胞）中观察到的阶段性放电模式。然而，通过调节I-LT的强度，观察到阶段性和规则的放电模式，表明临界水平的I-LT是产生II型反应所必需的。模拟的II型细胞与I型细胞（星状细胞）相比具有显著更快的膜时间常数，并且因此通过充当精确的符合检测器并且具有短的不应期而更适合于在其听觉神经输入中保存时间信息。最后，我们表明，调制I-H，改变静息膜电位，是一种更有效的手段，调制I-LT的激活水平比简单地调制I-LT本身。这一结果可以解释为什么I-LT和I-h经常在整个神经系统中共表达。
Using kinetic data from three different K+ currents in acutely isolated neurons, a single electrical compartment representing the soma of a ventral cochlear nucleus (VCN) neuron was created. The K+ currents include a fast transient current (I-A), a slow-inactivating low-threshold current (I-LT), and a noninactivating high-threshold current (I-HT). The model also includes a fast-inactivating Na+ current, a hyperpolarization-activated cation current (I-h), and 1-50 auditory nerve synapses. With this model, the role I-A, I-LT, and I-HT play in shaping the discharge patterns of VCN cells is explored. Simulation results indicate that I-HT mainly functions to repolarize the membrane during an action potential, and I-A functions to modulate the rate of repetitive firing. I-LT is found to be responsible for the phasic discharge pattern observed in Type II cells (bushy cells). However, by adjusting the strength of I-LT, both phasic and regular discharge patterns are observed, demonstrating that a critical level of I-LT is necessary to produce the Type II response. Simulated Type II cells have a significantly faster membrane time constant in comparison to Type I cells (stellate cells) and are therefore better suited to preserve temporal information in their auditory nerve inputs by acting as precise coincidence detectors and having a short refractory period. Finally, we demonstrate that modulation of I-h, which changes the resting membrane potential, is a more effective means of modulating the activation level of I-LT than simply modulating I-LT itself. This result may explain why I-LT and I-h are often coexpressed throughout the nervous system.