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The influence of sodium and potassium dynamics on excitability,seizures, and the stability of persistent states: I. Single neuron dynamics 总被引:1,自引:1,他引:0
John R. CressmanJr. Ghanim Ullah Jokubas Ziburkus Steven J. Schiff Ernest Barreto 《Journal of computational neuroscience》2009,26(2):159-170
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. In this first paper, we construct a mathematical
model consisting of a single conductance-based neuron together with intra- and extracellular ion concentration dynamics. We
formulate a reduction of this model that permits a detailed bifurcation analysis, and show that the reduced model is a reasonable
approximation of the full model. We find that competition between intrinsic neuronal currents, sodium-potassium pumps, glia,
and diffusion can produce very slow and large-amplitude oscillations in ion concentrations similar to what is seen physiologically
in seizures. Using the reduced model, we identify the dynamical mechanisms that give rise to these phenomena. These models
reveal several experimentally testable predictions. Our work emphasizes the critical role of ion concentration homeostasis
in the proper functioning of neurons, and points to important fundamental processes that may underlie pathological states
such as epilepsy.
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John R. Cressman Jr.Email: |
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Robert Bouzerar Issyan Tekaya Roger Bouzerar Olivier Balédent 《Journal of biological physics》2012,38(2):251-266
As brain ventricles lose their ability to regulate the cerebrospinal fluid (CSF) pressure, serious brain conditions collectively
named hydrocephalus can appear. By modelling ventricular dynamics with the laws of physics, dynamical instabilities are evidenced,
caused by either CSF transport dysregulations or abnormal properties of the elasticity of the ependyma. We show that these
instabilities would lead, in most cases, to dilation of the ventricles, establishing a close connection to hydrocephalus,
or in some other cases to a ventricular contraction as observed in the slit ventricle syndrome. Signs seem to indicate the
possibility of phase transitions occurring as a result of these instabilities, which might have important clinical consequences,
such as the inability to recover a healthy state. Even so, our dynamical approach could allow the development of a unified
view of these complex intracranial conditions along with a classification that might be clinically relevant. 相似文献
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