Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1972 Jul;224(2):271–286. doi: 10.1113/jphysiol.1972.sp009894

Facilitation of monosynaptic excitatory synaptic potentials in spinal motoneurones evoked by internuncial impulses

M Kuno, J N Weakly
PMCID: PMC1331489  PMID: 4341934

Abstract

1. Descending tracts and primary afferent fibres were chronically degenerated in the lumbosacral cord of the cat, and attempts were made to evoke monosynaptic e.p.s.p.s in motoneurones by stimulation of interneurones with a pair of fine electrodes inserted into the cord.

2. The reversal potential of monosynaptic e.p.s.p.s so produced was more negative than that measured for monosynaptic e.p.s.p.s produced by afferent impulses.

3. Monosynaptic e.p.s.p.s evoked in motoneurones by internuncial impulses showed a significantly greater facilitation than those produced by afferent impulses.

4. Monosynaptic e.p.s.p.s in a motoneurone produced by supramaximal intraspinal stimuli often revealed a fluctuation in amplitude. In such cases, when two successive stimuli were applied at a short interval, the mean amplitude of the second e.p.s.p.s was greater than that of the first e.p.s.p.s. This facilitation was associated with a decrease in the coefficient of variation of the e.p.s.p. amplitude fluctuation.

5. The degree of facilitation of monosynaptic e.p.s.p.s evoked by internuncial impulses was not related to the amount of transmitter released by the preceding impulses.

6. It is concluded that facilitation of monosynaptic e.p.s.p.s evoked by both afferent and internuncial impulses is based on the same mechanism and that the degree of facilitation of e.p.s.p.s is entirely determined by the nature of presynaptic elements.

Full text

PDF
271

Selected References

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

  1. Atwood H. L., Bittner G. D. Matching of excitatory and inhibitory inputs to crustacean muscle fibers. J Neurophysiol. 1971 Jan;34(1):157–170. doi: 10.1152/jn.1971.34.1.157. [DOI] [PubMed] [Google Scholar]
  2. BROCK L. G., COOMBS J. S., ECCLES J. C. The recording of potentials from motoneurones with an intracellular electrode. J Physiol. 1952 Aug;117(4):431–460. doi: 10.1113/jphysiol.1952.sp004759. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bennett M. V. Analysis of parallel excitatory and inhibitory synaptic channels. J Neurophysiol. 1971 Jan;34(1):69–75. doi: 10.1152/jn.1971.34.1.69. [DOI] [PubMed] [Google Scholar]
  4. Bittner G. D. Differentiation of nerve terminals in the crayfish opener muscle and its functional significance. J Gen Physiol. 1968 Jun;51(6):731–758. doi: 10.1085/jgp.51.6.731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. COOMBS J. S., ECCLES J. C., FATT P. Excitatory synaptic action in motoneurones. J Physiol. 1955 Nov 28;130(2):374–395. doi: 10.1113/jphysiol.1955.sp005413. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. CURTIS D. R., ECCLES J. C. Synaptic action during and after repetitive stimulation. J Physiol. 1960 Feb;150:374–398. doi: 10.1113/jphysiol.1960.sp006393. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Calvin W. H. Dendritic synapses and reversal potentials: theoretical implications of the view from the soma. Exp Neurol. 1969 Jun;24(2):248–264. doi: 10.1016/0014-4886(69)90018-1. [DOI] [PubMed] [Google Scholar]
  8. DEL CASTILLO J., KATZ B. Quantal components of the end-plate potential. J Physiol. 1954 Jun 28;124(3):560–573. doi: 10.1113/jphysiol.1954.sp005129. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. DEL CASTILLO J., KATZ B. Statistical factors involved in neuromuscular facilitation and depression. J Physiol. 1954 Jun 28;124(3):574–585. doi: 10.1113/jphysiol.1954.sp005130. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. DUDEL J., KUFFLER S. W. Mechanism of facilitation at the crayfish neuromuscular junction. J Physiol. 1961 Mar;155:530–542. doi: 10.1113/jphysiol.1961.sp006645. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. ECCLES J. C., FATT P., LANDGREN S. Central pathway for direct inhibitory action of impulses in largest afferent nerve fibres to muscle. J Neurophysiol. 1956 Jan;19(1):75–98. doi: 10.1152/jn.1956.19.1.75. [DOI] [PubMed] [Google Scholar]
  12. ECCLES J. C., HUBBARD J. I., OSCARSSON O. Intracellular recording from cells of the ventral spinocerebellar tract. J Physiol. 1961 Oct;158:486–516. doi: 10.1113/jphysiol.1961.sp006782. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. EIDE E., LUNDBERG A., VOORHOEVE P. Monosynaptically evoked inhibitory post-synaptic potentials in motoneurones. Acta Physiol Scand. 1961 Oct;53:185–195. doi: 10.1111/j.1748-1716.1961.tb02276.x. [DOI] [PubMed] [Google Scholar]
  14. FADIGA E., BROOKHART J. M. Monosynaptic activation of different portions of the motor neuron membrane. Am J Physiol. 1960 Apr;198:693–703. doi: 10.1152/ajplegacy.1960.198.4.693. [DOI] [PubMed] [Google Scholar]
  15. FRANK K., FUORTES M. G. Stimulation of spinal motoneurones with intracellular electrodes. J Physiol. 1956 Nov 28;134(2):451–470. doi: 10.1113/jphysiol.1956.sp005657. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. FRANK K., FUORTES M. G. Unitary activity of spinal interneurones of cats. J Physiol. 1956 Feb 28;131(2):424–435. doi: 10.1113/jphysiol.1956.sp005472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. FRANK K., SPRAGUE J. M. Direct contralateral inhibition in the lower sacral spinal cord. Exp Neurol. 1959 Apr;1(1):28–43. doi: 10.1016/0014-4886(59)90011-1. [DOI] [PubMed] [Google Scholar]
  18. HUBBARD J. I. REPETITIVE STIMULATION AT THE MAMMALIAN NEUROMUSCULAR JUNCTION, AND THE MOBILIZATION OF TRANSMITTER. J Physiol. 1963 Dec;169:641–662. doi: 10.1113/jphysiol.1963.sp007286. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. HUNT C. C., KUNO M. Properties of spinal interneurones. J Physiol. 1959 Sep 2;147:346–363. doi: 10.1113/jphysiol.1959.sp006248. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Ito M., Oshima T. Electrical behaviour of the motoneurone membrane during intracellularly applied current steps. J Physiol. 1965 Oct;180(3):607–635. doi: 10.1113/jphysiol.1965.sp007720. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. KUNO M. MECHANSIM OF FACILITATION AND DEPRESSION OF THE EXCITATORY SYNAPTIC POTENTIAL IN SPINAL MOTONEURONES. J Physiol. 1964 Dec;175:100–112. doi: 10.1113/jphysiol.1964.sp007505. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. KUNO M. QUANTAL COMPONENTS OF EXCITATORY SYNAPTIC POTENTIALS IN SPINAL MOTONEURONES. J Physiol. 1964 Dec;175:81–99. doi: 10.1113/jphysiol.1964.sp007504. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Klee M. R., Wagner A., Brooks B. A. Differences between monosynaptic and polysynaptic excitatory post-synaptic potentials of cat motoneurons during current injection. Brain Res. 1967 Jan 20;3(4):387–391. doi: 10.1016/0006-8993(67)90102-3. [DOI] [PubMed] [Google Scholar]
  24. Kuno M., Llinás R. Alterations of synaptic action in chromatolysed motoneurones of the cat. J Physiol. 1970 Nov;210(4):823–838. doi: 10.1113/jphysiol.1970.sp009244. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Kuno M., Weakly J. N. Quantal components of the inhibitory synaptic potential in spinal mononeurones of the cat. J Physiol. 1972 Jul;224(2):287–303. doi: 10.1113/jphysiol.1972.sp009895. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Nelson P. G., Frank K. Anomalous rectification in cat spinal motoneurons and effect of polarizing currents on excitatory postsynaptic potential. J Neurophysiol. 1967 Sep;30(5):1097–1113. doi: 10.1152/jn.1967.30.5.1097. [DOI] [PubMed] [Google Scholar]
  27. Porter R. Early facilitation at corticomotoneuronal synapses. J Physiol. 1970 May;207(3):733–745. doi: 10.1113/jphysiol.1970.sp009091. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Porter R., Hore J. Time course of minimal corticomotoneuronal excitatory postsynaptic potentials in lumbar motoneurons of the monkey. J Neurophysiol. 1969 May;32(3):443–451. doi: 10.1152/jn.1969.32.3.443. [DOI] [PubMed] [Google Scholar]
  29. Rall W. Distinguishing theoretical synaptic potentials computed for different soma-dendritic distributions of synaptic input. J Neurophysiol. 1967 Sep;30(5):1138–1168. doi: 10.1152/jn.1967.30.5.1138. [DOI] [PubMed] [Google Scholar]
  30. SUDA I., KOIZUMI K., BROOKS C. M. Reticular formation influences on neurons of spinal reflex pathway. J Neurophysiol. 1958 Mar;21(2):113–123. doi: 10.1152/jn.1958.21.2.113. [DOI] [PubMed] [Google Scholar]
  31. Toyama K., Tsukahara N., Kosaka K., Matsunami K. Synaptic excitation of red nucleus neurones by fibres from interpositus nucleus. Exp Brain Res. 1970;11(2):187–198. doi: 10.1007/BF00234322. [DOI] [PubMed] [Google Scholar]
  32. Tsukahara N., Kosaka K. The mode of cerebral excitation of red nucleus neurons. Exp Brain Res. 1968;5(2):102–117. doi: 10.1007/BF00238700. [DOI] [PubMed] [Google Scholar]
  33. WALL P. D. Repetitive discharge of neurons. J Neurophysiol. 1959 May;22(3):305–320. doi: 10.1152/jn.1959.22.3.305. [DOI] [PubMed] [Google Scholar]
  34. Wachtel H., Kandel E. R. Conversion of synaptic excitation to inhibition at a dual chemical synapse. J Neurophysiol. 1971 Jan;34(1):56–68. doi: 10.1152/jn.1971.34.1.56. [DOI] [PubMed] [Google Scholar]

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

RESOURCES