Ullah Ghanim, Cressman John R, Barreto Ernest, Schiff Steven J
Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, 212 Earth Engineering Science Building, University Park, PA 16802, USA.
J Comput Neurosci. 2009 Apr;26(2):171-83. doi: 10.1007/s10827-008-0130-6. Epub 2008 Dec 13.
In these companion papers, we study how the interrelated dynamics of sodium and potassium affect the excitability of neurons, the occurrence of seizures, and the stability of persistent states of activity. We seek to study these dynamics with respect to the following compartments: neurons, glia, and extracellular space. We are particularly interested in the slower time-scale dynamics that determine overall excitability, and set the stage for transient episodes of persistent oscillations, working memory, or seizures. In this second of two companion papers, we present an ionic current network model composed of populations of Hodgkin-Huxley type excitatory and inhibitory neurons embedded within extracellular space and glia, in order to investigate the role of micro-environmental ionic dynamics on the stability of persistent activity. We show that these networks reproduce seizure-like activity if glial cells fail to maintain the proper micro-environmental conditions surrounding neurons, and produce several experimentally testable predictions. Our work suggests that the stability of persistent states to perturbation is set by glial activity, and that how the response to such perturbations decays or grows may be a critical factor in a variety of disparate transient phenomena such as working memory, burst firing in neonatal brain or spinal cord, up states, seizures, and cortical oscillations.
在这些配套论文中，我们研究了钠和钾的相互关联动态如何影响神经元的兴奋性、癫痫发作的发生以及持续活动状态的稳定性。我们试图针对以下区室研究这些动态：神经元、神经胶质细胞和细胞外空间。我们特别关注决定整体兴奋性并为持续振荡、工作记忆或癫痫发作的短暂事件奠定基础的较慢时间尺度动态。在这两篇配套论文的第二篇中，我们提出了一个离子电流网络模型，该模型由嵌入细胞外空间和神经胶质细胞内的霍奇金-赫胥黎型兴奋性和抑制性神经元群体组成，以研究微环境离子动态对持续活动稳定性的作用。我们表明，如果神经胶质细胞未能维持神经元周围适当的微环境条件，则这些网络会重现癫痫样活动，并产生几个可通过实验验证的预测。我们的工作表明，持续状态对扰动的稳定性由神经胶质活动设定，并且对这种扰动的反应如何衰减或增强可能是各种不同的短暂现象（如工作记忆、新生儿脑或脊髓中的爆发式放电、上行状态、癫痫发作和皮层振荡）中的关键因素。
