Seizure-like afterdischarges simulated in a model neuron.

Published

Journal Article

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 (INa.P). AD was either simple or self-regenerating; either regular (tonic) or burst-type (clonic); and always self-limiting. Self-regenerating AD required sufficient INa.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.

Full Text

Duke Authors

Cited Authors

  • Kager, H; Wadman, WJ; Somjen, GG

Published Date

  • April 2007

Published In

Volume / Issue

  • 22 / 2

Start / End Page

  • 105 - 128

PubMed ID

  • 17053996

Pubmed Central ID

  • 17053996

International Standard Serial Number (ISSN)

  • 0929-5313

Digital Object Identifier (DOI)

  • 10.1007/s10827-006-0001-y

Language

  • eng

Conference Location

  • United States