Neuronal Activity and Ion Homeostasis in the Hypoxic Brain

Recent experiments in rats have shown the occurrence of a high amplitude slow brain wavein the EEG approximately 1 minute after decapitation, with a duration of 5-15 s (van Rijn et al, PLoSOne 6, e16514, 2011) that was presumed to signify the death of brain neurons. We present a compu-tational model of a single neuron and its intraand extracellular ion concentrations, which shows thephysiological mechanism for this observation. The wave is caused by membrane potential oscillations,that occur after the cessation of activity of the sodium-potassium pumps has led to an excess of extracel-lular potassium. These oscillations can be described by the Hodgkin-Huxley equations for the sodiumand potassium channels, and result in a sudden change in mean membrane voltage. In combination witha high-pass filter, this sudden depolarization leads to a wave in the EEG. We discuss that this process isnot necessarily irreversible. ∗Published as: BJ Zandt, B ten Haken, JG van Dijk, MJAM van Putten (2011) Neural Dynamicsduring Anoxia and the Wave of Death. PLoS ONE 6(7): e22127. doi:10.1371/journal.pone.0022127