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Fast rhythms in phrenic motoneuron and nerve discharges
C N Christakos1, M I Cohen, R Barnhardt
1Department of Physiology and Biophysics, Albert Einstein College of Medicine, New York, New York 10461.
Journal of Neurophysiology
|September 1, 1991
Summary
This study investigated fast rhythms in phrenic (PHR) motoneuron discharges. Medium-frequency oscillations originate from individual motoneuron firing, while high-frequency oscillations suggest population synchrony.
Area of Science:
- Neuroscience
- Respiratory Physiology
Background:
- Phrenic (PHR) motoneurons control breathing.
- PHR nerve and motoneuron activity exhibit fast rhythms (20-100 Hz).
Purpose of the Study:
- To determine the origin of medium-frequency oscillations (MFO) and high-frequency oscillations (HFO) in PHR motoneuron and nerve activity.
- To differentiate between unitary and population-based rhythms.
Main Methods:
- Spectral and interval analyses of single PHR motoneuron discharges.
- Coherence analysis comparing motoneuron activity to whole-PHR nerve discharge.
- Recordings from paralyzed, artificially ventilated cats.
Main Results:
- MFOs in PHR motoneuron discharges correlate with individual motoneuron firing rates and contribute to the overall nerve MFO rhythm.
- Coherence between motoneuron MFOs and nerve MFOs was low, indicating limited population synchrony for MFOs.
- HFOs were observed in about half of PHR motoneurons and showed substantial coherence with nerve HFOs, suggesting population synchrony for HFOs.
Conclusions:
- Medium-frequency oscillations in PHR nerve activity arise from the superposition of individual motoneuron discharges.
- High-frequency oscillations in PHR nerve activity reflect synchronized firing among a subpopulation of PHR motoneurons.