Journal of Computational Neuroscience

, Volume 22, Issue 2, pp 105–128 | Cite as

Seizure-like afterdischarges simulated in a model neuron

Article

Abstract

To explore non-synaptic mechanisms in paroxysmal discharges, we used a computer model of a simplified hippocampal pyramidal cell, surrounded by interstitial space and a “glial-endothelial” buffer system. Ion channels for Na+, K+, Ca2+ and Cl , ion antiport 3Na/Ca, and “active” ion pumps were represented in the neuron membrane. The glia had “leak” conductances and an ion pump. Fluxes, concentration changes and cell swelling were computed. The neuron was stimulated by injecting current. Afterdischarge (AD) followed stimulation if depolarization due to rising interstitial K+ concentration ([K+]o) activated persistent Na+ current (I Na,P). AD was either simple or self-regenerating; either regular (tonic) or burst-type (clonic); and always self-limiting. Self-regenerating AD required sufficient I Na,P to ensure re-excitation. Burst firing depended on activation of dendritic Ca2+ currents and Ca-dependent K+ current. Varying glial buffer function influenced [K+]o accumulation and afterdischarge duration. Variations in Na+ and K+ currents influenced the threshold and the duration of AD. The data show that high [K+]o and intrinsic membrane currents can produce the feedback of self-regenerating afterdischarges without synaptic input. The simulated discharge resembles neuron behavior during paroxysmal firing in living brain tissue.

Keywords

Epilepsy Ion channels Persistent current Ion distribution Potassium concentration Firing pattern 

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Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  1. 1.SILS-Center for NeuroScienceUniversity of AmsterdamAmsterdamThe Netherlands
  2. 2.Department of Cell BiologyDuke University Medical CenterDurhamUSA

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