Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1982;327:137–155. doi: 10.1113/jphysiol.1982.sp014224

The spatial distribution of synchronization of intercostal motoneurones in the cat

P A Kirkwood 1, T A Sears 1, D Stagg 1,*, R H Westgaard 1,†
PMCID: PMC1225101  PMID: 7120135

Abstract

1. The three different types of synchronization of intercostal motoneurones which were described in the preceding paper (Kirkwood, Sears, Tuck & Westgaard, 1982) were studied for motoneurones of the same segment or for different segmental separations (up to five segments) and for motoneurones on opposite sides of the same segment.

2. The strength of synchronization declined with segmental separation for all three categories, although the rate of decline was more variable for broad-peak synchronization than for the two other types. Short-term synchronization was undetectable for separations greater than three or four segments but clear peaks were still visible in the cross correlation histograms for high-frequency oscillation (h.f.o.) or broad-peak synchronization at a segmental separation of five. Synchronization between motoneurones on opposite sides of the cord was generally weak although less so for broad-peak or h.f.o. components.

3. The decline in strength of short-term synchronization with segmental separation could not be explained by temporal dispersion of impulses in presynaptic axons.

4. A time shift was observed in the position of the cross-correlation histogram peak which was dependent on segmental separation and equivalent to a mean descending conduction velocity of 28 m/s in the assumed common input. This figure is similar to the mean conduction velocity of bulbospinal respiratory neurones derived from published values.

5. We conclude that the short-term synchronization in these preparations is generated by the bulbospinal respiratory neurones and that the majority of their axons do not branch to make strong synaptic connexions to motoneurones over more than three to four segments.

6. Interpretations of the different distributions of the other types of synchronization are discussed.

Full text

PDF
137

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Aminoff M. J., Sears T. A. Spinal integration of segmental, cortical and breathing inputs to thoracic respiratory motoneurones. J Physiol. 1971 Jun;215(2):557–575. doi: 10.1113/jphysiol.1971.sp009485. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Arnett D. W. Correlation analysis of units recorded in the cat dorsal lateral geniculate nucleus. Exp Brain Res. 1975 Dec 22;24(2):111–130. doi: 10.1007/BF00234058. [DOI] [PubMed] [Google Scholar]
  3. Arnett D., Spraker T. E. Cross-correlation analysis of the maintained discharge of rabbit retinal ganglion cells. J Physiol. 1981 Aug;317:29–47. doi: 10.1113/jphysiol.1981.sp013812. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Berger A. J. Dorsal respiratory group neurons in the medulla of cat: spinal projections, responses to lung inflation and superior laryngeal nerve stimulation. Brain Res. 1977 Oct 28;135(2):231–254. doi: 10.1016/0006-8993(77)91028-9. [DOI] [PubMed] [Google Scholar]
  5. Cohen M. I., Piercey M. F., Gootman P. M., Wolotsky P. Synaptic connections between medullary inspiratory neurons and phrenic motoneurons as revealed by cross-correlation. Brain Res. 1974 Dec 6;81(2):319–324. doi: 10.1016/0006-8993(74)90946-9. [DOI] [PubMed] [Google Scholar]
  6. DOWNMAN C. B. Skeletal muscle reflexes of splanchnic and intercostal nerve origin in acute spinal and decerebrate cats. J Neurophysiol. 1955 May;18(3):217–235. doi: 10.1152/jn.1955.18.3.217. [DOI] [PubMed] [Google Scholar]
  7. Duron B. Postural and ventilatory functions of intercostal muscles. Acta Neurobiol Exp (Wars) 1973;33(1):355–380. [PubMed] [Google Scholar]
  8. Feldman J. L., Sommer D., Cohen M. I. Short time scale correlations between discharges of medullary respiratory neurons. J Neurophysiol. 1980 May;43(5):1284–1295. doi: 10.1152/jn.1980.43.5.1284. [DOI] [PubMed] [Google Scholar]
  9. Hilaire G., Monteau R. Connexions entre les neurones inspiratoires bulbaires et les motoneurones phréniques et intercostaux. J Physiol (Paris) 1976;72(8):987–1000. [PubMed] [Google Scholar]
  10. Kirkwood P. A., Sears T. A. Excitatory post-synaptic potentials from single muscle spindle afferents in external intercostal motoneurones of the cat. J Physiol. 1982 Jan;322:287–314. doi: 10.1113/jphysiol.1982.sp014038. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Kirkwood P. A., Sears T. A., Stagg D. Proceedings: Synchronized firing of respiratory motoneurones during spontaneous breathing in the anaesthetized cat. J Physiol. 1974 May;239(1):11P–13P. [PubMed] [Google Scholar]
  12. Kirkwood P. A., Sears T. A. The effects of single afferent impulses on the probability of firing of external intercostal motoneurones in the cat. J Physiol. 1982 Jan;322:315–336. doi: 10.1113/jphysiol.1982.sp014039. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kirkwood P. A., Sears T. A. The synaptic connexions to intercostal motoneurones as revealed by the average common excitation potential. J Physiol. 1978 Feb;275:103–134. doi: 10.1113/jphysiol.1978.sp012180. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Kirkwood P. A., Sears T. A., Tuck D. L., Westgaard R. H. Variations in the time course of the synchronization of intercostal motoneurones in the cat. J Physiol. 1982 Jun;327:105–135. doi: 10.1113/jphysiol.1982.sp014223. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kirkwood P. A., Sears T. A., Westgaard R. H. Recurrent inhibition of intercostal motoneurones in the cat. J Physiol. 1981;319:111–130. doi: 10.1113/jphysiol.1981.sp013895. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Noda H., Adey W. R. Firing of neuron pairs in cat association cortex during sleep and wakefulness. J Neurophysiol. 1970 Sep;33(5):672–684. doi: 10.1152/jn.1970.33.5.672. [DOI] [PubMed] [Google Scholar]
  17. Richter D. W., Heyde F., Gabriel M. Intracellular recordings from different types of medullary respiratory neurons of the cat. J Neurophysiol. 1975 Sep;38(5):1162–1171. doi: 10.1152/jn.1975.38.5.1162. [DOI] [PubMed] [Google Scholar]
  18. SEARS T. A. INVESTIGATIONS ON RESPIRATORY MOTONEURONES OF THE THORACIC SPINAL CORD. Prog Brain Res. 1964;12:259–273. doi: 10.1016/s0079-6123(08)60627-5. [DOI] [PubMed] [Google Scholar]
  19. Sears T. A., Stagg D. Short-term synchronization of intercostal motoneurone activity. J Physiol. 1976 Dec;263(3):357–381. doi: 10.1113/jphysiol.1976.sp011635. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Vachon B. R., Duffin J. Cross-correlation of medullary respiratory neurons in the cat. Exp Neurol. 1978 Aug;61(1):15–30. doi: 10.1016/0014-4886(78)90178-4. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES