EXTRACELLULAR POTASSIUM DYNAMICS AND EPILEPTOGENESIS
EXTRACELLULAR POTASSIUM DYNAMICS AND EPILEPTOGENESIS
复制标题
DOI：
10.1016/b978-012373649-9.50029-6
复制
发表时间：
2008-01-01
期刊：
影响因子：
--
通讯作者：
Bazhenov, Maxim
中科院分区：
文献类型：
--
作者：
Froehlich, Flavio;Timofeev, Igor;Bazhenov, Maxim
细胞外离子浓度作为神经元活动的函数而变化，并且代表影响神经元群体的动态状态的重要因素。特别是，细胞外钾浓度（[K+]（o））的相对较小的变化介导神经元兴奋性和内在放电模式的实质性变化。虽然实验方法是有限的，在他们的能力来阐明离子浓度和神经活动之间的动态反馈相互作用，计算模型和动态系统理论提供了强大的工具来研究细胞外离子浓度动态介导的内在兴奋性的活动依赖性调制。在这一章中，我们讨论了细胞外钾浓度动态在新皮层网络癫痫样活动的产生中的潜在作用。详细的模型锥体细胞的分叉分析揭示了两个不同的放电模式（紧张性放电和缓慢爆发）之间的滞后与轻度升高[K+]（o）的双稳态。在新皮层网络模型中，这种双稳态引起了先前无法解释的快速运行和缓慢爆发的缓慢交替时期，如在猫和Lennox-Gastaut综合征患者的新皮层电图癫痫发作期间在体内记录的。我们的结论是，细胞外钾浓度动态可能发挥了重要作用，在癫痫发作的产生。
Extracellular ion concentrations change as a function of neuronal activity and represent important factors influencing the dynamic state of a population of neurons. In particular, relatively small changes in extracellular potassium concentration ([K+](o)) mediate substantial changes in neuronal excitability and intrinsic firing patterns. While experimental approaches are limited in their ability to shed light on the dynamic feedback interaction between ion concentration and neural activity, computational models and dynamic system theory provide powerful tools to study activity-dependent modulation of intrinsic excitability mediated by extracellular ion concentration dynamics. In this chapter, we discuss the potential role of extracellular potassium concentration dynamics in the generation of epileptiform activity in neocortical networks. Detailed bifurcation analysis of a model pyramidal cell revealed a bistability with hysteresis between two distinct firing modes (tonic firing and slow bursting) for mildly elevated [K+](o). In neocortical network models, this bistability gives rise to previously unexplained slow alternating epochs of fast runs and slow bursting as recorded in vivo during neocortical electrographic seizures in cats and in human patients with the Lennox-Gastaut syndrome. We conclude that extracellular potassium concentration dynamics may play an important role in the generation of seizures.