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Excitatory interactions between phrenic motoneurons: intracellular study in the cat
M Khatib1, G Hilaire, R Monteau
1Département de Physiologie et Neurophysiologie (UA 205), Faculté des Sciences et Techniques Saint-Jérôme, Marseille, France.
Experimental Brain Research
|January 1, 1989
Summary
This study investigated recurrent responses in phrenic motoneurons. Findings suggest interconnections and coupling within the phrenic motor pool, indicating re-excitation beyond central synchronization.
Area of Science:
- Neuroscience
- Motor Control
- Respiratory Physiology
Background:
- Recurrent responses (RR) in phrenic motoneurons (PM) axons are known but their somatic origin is unclear.
- Previous research indicated RR can be evoked without antidromic activation.
Purpose of the Study:
- To investigate somatic events related to recurrent responses in phrenic motoneurons.
- To determine if recurrent excitation occurs at the soma level within the phrenic motor pool.
Main Methods:
- Intracellular recordings from 220 phrenic motoneurons in deafferented cats.
- Stimulation of phrenic nerve and specific phrenic nerve strands.
- Averaging techniques to detect small synaptic events.
Main Results:
- Failed to observe somatic events corresponding to axonal RR after antidromic activation.
- Sporadic RR-like somatic events were observed in a small percentage of PMs under specific stimulation conditions.
- Short latency depolarizations resembling recurrent EPSPs were detected in a significant portion of PMs.
Conclusions:
- Confirms interconnections and coupling within the phrenic motoneuron pool.
- Suggests re-excitation occurs at the somatic level, contributing to phrenic motor output.
- Highlights a mechanism for phrenic motor synchronization beyond central commands.