Essential role of a fast persistent inward current in action potential initiation and control of rhythmic firing

R. H. Lee*, C. J. Heckman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

In spinal motoneurons in an in vivo preparation, we investigated the relationship between a fast persistent inward current located in or near the soma and the capacity of these cells to fire rhythmically. The fast persistent current could be markedly reduced by prolonged depolarization. Modest reductions resulted in profound changes in the slope of the frequency-current relationship. At greater reduction levels, rhythmic firing failed and could not be restored by increasing injected current. However, fully formed spikes still occurred in a slow, uncoordinated fashion, suggesting that the fast inactivating Na+ currents that generate the spike itself remained unchanged. Consequently, the fast persistent inward current, which may be primarily generated by persistent Na+ channels, appears to be essential for initiation of spikes during rhythmic firing. Additionally, it appears that the fast persistent current plays a major role in setting the frequency-current gain.

Original languageEnglish (US)
Pages (from-to)472-475
Number of pages4
JournalJournal of neurophysiology
Volume85
Issue number1
DOIs
StatePublished - 2001

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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