Midcervical neuronal discharge patterns during and following hypoxia

M. S. Sandhu, D. M. Baekey, N. G. Maling, Justin C. Sanchez, P. J. Reier, D. D. Fuller

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Anatomical evidence indicates that midcervical interneurons can be synaptically coupled with phrenic motoneurons. Accordingly, we hypothesized that interneurons in the C3-C4 spinal cord can display discharge patterns temporally linked with inspiratory phrenic motor output. Anesthetized adult rats were studied before, during, and after a 4-min bout of moderate hypoxia. Neuronal discharge in C3-C4 lamina I-IX was monitored using a multielectrode array while phrenic nerve activity was extracellularly recorded. For the majority of cells, spike-triggered averaging (STA) of ipsilateral inspiratory phrenic nerve activity based on neuronal discharge provided no evidence of discharge synchrony. However, a distinct STA phrenic peak with a 6.83 ± 1.1 ms lag was present for 5% of neurons, a result that indicates a monosynaptic connection with phrenic motoneurons. The majority (93%) of neurons changed discharge rate during hypoxia, and the diverse responses included both increased and decreased firing. Hypoxia did not change the incidence of STA peaks in the phrenic nerve signal. Following hypoxia, 40% of neurons continued to discharge at rates above prehypoxia values (i.e., short-term potentiation, STP), and cells with initially low discharge rates were more likely to show STP (P < 0.001). We conclude that a population of nonphrenic C3-C4 neurons in the rat spinal cord is synaptically coupled to the phrenic motoneuron pool, and these cells can modulate inspiratory phrenic output. In addition, the C3-C4 propriospinal network shows a robust and complex pattern of activation both during and following an acute bout of hypoxia.

Original languageEnglish (US)
Pages (from-to)2091-2101
Number of pages11
JournalJournal of Neurophysiology
Volume113
Issue number7
DOIs
StatePublished - Apr 1 2015

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Diaphragm
Phrenic Nerve
Motor Neurons
Neurons
Interneurons
Spinal Cord
Hypoxia
Incidence
Population

Keywords

  • cervical interneurons
  • hypoxia
  • phrenic
  • plasticity
  • short-term potentiation

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

Cite this

Sandhu, M. S., Baekey, D. M., Maling, N. G., Sanchez, J. C., Reier, P. J., & Fuller, D. D. (2015). Midcervical neuronal discharge patterns during and following hypoxia. Journal of Neurophysiology, 113(7), 2091-2101. https://doi.org/10.1152/jn.00834.2014

Midcervical neuronal discharge patterns during and following hypoxia. / Sandhu, M. S.; Baekey, D. M.; Maling, N. G.; Sanchez, Justin C.; Reier, P. J.; Fuller, D. D.

In: Journal of Neurophysiology, Vol. 113, No. 7, 01.04.2015, p. 2091-2101.

Research output: Contribution to journalArticle

Sandhu, MS, Baekey, DM, Maling, NG, Sanchez, JC, Reier, PJ & Fuller, DD 2015, 'Midcervical neuronal discharge patterns during and following hypoxia', Journal of Neurophysiology, vol. 113, no. 7, pp. 2091-2101. https://doi.org/10.1152/jn.00834.2014
Sandhu MS, Baekey DM, Maling NG, Sanchez JC, Reier PJ, Fuller DD. Midcervical neuronal discharge patterns during and following hypoxia. Journal of Neurophysiology. 2015 Apr 1;113(7):2091-2101. https://doi.org/10.1152/jn.00834.2014
Sandhu, M. S. ; Baekey, D. M. ; Maling, N. G. ; Sanchez, Justin C. ; Reier, P. J. ; Fuller, D. D. / Midcervical neuronal discharge patterns during and following hypoxia. In: Journal of Neurophysiology. 2015 ; Vol. 113, No. 7. pp. 2091-2101.
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