González Oscar C., Timofeev Igor, Bazhenov Maxim
The regulation of transmembrane ion flux is crucial for maintaining physiological neuronal activity and preventing the occurrence of epileptic seizures. The net effect (e.g., depolarization or hyperpolarization) of the transmembrane ion flux is determined by the relative ion concentration gradients established across the cellular membrane. Because of the tight regulation of neuronal excitability and dynamics by changes in the ion concentrations, the brain has evolved multiple mechanisms to precisely regulate and maintain these concentration gradients. It has been demonstrated that the breakdown in the maintenance of ion gradients may lead to development of seizure discharges and may underly various forms of pathological neuronal activity. It is now well established that during a seizure discharge, the extracellular potassium concentration substantially increases, while the concentrations of extracellular sodium and calcium decrease. More recently, experimental recordings and computational models have demonstrated preictal increases in the intracellular chloride concentration in pyramidal neurons. This chapter discusses the effects of the ion concentration dynamics on seizure initiation, progression, and termination with the goal of providing novel insights into the underlying biophysical mechanisms of epileptic seizures.
跨膜离子通量的调节对于维持生理性神经元活动和预防癫痫发作至关重要。跨膜离子通量的净效应（例如去极化或超极化）由跨细胞膜建立的相对离子浓度梯度决定。由于离子浓度变化对神经元兴奋性和动力学的严格调节，大脑进化出了多种机制来精确调节和维持这些浓度梯度。已经证明，离子梯度维持的破坏可能导致癫痫放电的发生，并可能是各种形式病理性神经元活动的基础。目前已经明确，在癫痫放电期间，细胞外钾浓度会大幅增加，而细胞外钠和钙的浓度会降低。最近，实验记录和计算模型表明，发作前锥体神经元细胞内氯化物浓度会升高。本章将讨论离子浓度动态对癫痫发作起始、进展和终止的影响，旨在为癫痫发作的潜在生物物理机制提供新的见解。
