Skip to main content
NCBI home page
The Journal of General Physiology logoLink to The Journal of General Physiology
. 1969 Feb 1;53(2):211–237. doi: 10.1085/jgp.53.2.211

A Rectifying Electrotonic Synapse in the Central Nervous System of a Vertebrate

A A Auerbach 1, M V L Bennett 1
PMCID: PMC2202903  PMID: 4303657

Abstract

The adductor muscles of the pectoral fins of the hatchetfish Gasteropelecus are innervated by bilateral pools of about 40 motoneurons which lie primarily in the first spinal segment. A pair of giant fibers on each side of the medulla send processes ventroposteriorly to the motoneuron pools. Electrophysiological evidence indicates that giant fibers are presynaptic to ipsilateral motoneurons, but not to contralateral ones. Transmission across the giant fiber, motoneuron synapse is electrically mediated as is indicated by direct measurement of electrotonic spread in either direction across the synapse, and by the extremely short latency of the giant fiber postsynaptic potentials (PSP's) in the motoneuron. The coupling resistance across the synapse was calculated from measurements of input and transfer resistance. The coupling resistance rectifies in such a way as to facilitate spread of depolarization from giant fiber to motoneuron, and to oppose transmission in the opposite direction. As a consequence of rectification, the giant fiber PSP in a motoneuron is augmented by hyperpolarization of the motoneuron. The coupling resistance calculated on the basis of this effect is in good agreement with calculations from input and transfer resistance data. Rectification at the electrotonic synapses may permit the motoneurons to act in small swimming movements as well as to fire synchronously in an extremely fast escape reflex mediated by Mauthner and giant fibers.

Full Text

The Full Text of this article is available as a PDF (1.7 MB).

Selected References

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

  1. Auerbach A. A., Bennett M. V. Chemically mediated transmission at a giant fiber synapse in the central nervous system of a vertebrate. J Gen Physiol. 1969 Feb;53(2):183–210. doi: 10.1085/jgp.53.2.183. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bennett M. V., Nakajima Y., Pappas G. D. Physiology and ultrastructure of electrotonic junctions. 3. Giant electromotor neurons of Malapterurus electricus. J Neurophysiol. 1967 Mar;30(2):209–235. doi: 10.1152/jn.1967.30.2.209. [DOI] [PubMed] [Google Scholar]
  3. Bennett M. V., Nakajima Y., Pappas G. D. Physiology and ultrastructure of electrotonic junctions. I. Supramedullary neurons. J Neurophysiol. 1967 Mar;30(2):161–179. doi: 10.1152/jn.1967.30.2.161. [DOI] [PubMed] [Google Scholar]
  4. Bennett M. V., Pappas G. D., Giménez M., Nakajima Y. Physiology and ultrastructure of electrotonic junctions. IV. Medullary electromotor nuclei in gymnotid fish. J Neurophysiol. 1967 Mar;30(2):236–300. doi: 10.1152/jn.1967.30.2.236. [DOI] [PubMed] [Google Scholar]
  5. Bennett M. V. Physiology of electrotonic junctions. Ann N Y Acad Sci. 1966 Jul 14;137(2):509–539. doi: 10.1111/j.1749-6632.1966.tb50178.x. [DOI] [PubMed] [Google Scholar]
  6. COOMBS J. S., CURTIS D. R., ECCLES J. C. The interpretation of spike potentials of motoneurones. J Physiol. 1957 Dec 3;139(2):198–231. doi: 10.1113/jphysiol.1957.sp005887. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. 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]
  8. FUORTES M. G., FRANK K., BECKER M. C. Steps in the production of motoneuron spikes. J Gen Physiol. 1957 May 20;40(5):735–752. doi: 10.1085/jgp.40.5.735. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. FURSHPAN E. J., POTTER D. D. Transmission at the giant motor synapses of the crayfish. J Physiol. 1959 Mar 3;145(2):289–325. doi: 10.1113/jphysiol.1959.sp006143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Katz B., Miledi R. The effect of temperature on the synaptic delay at the neuromuscular junction. J Physiol. 1965 Dec;181(3):656–670. doi: 10.1113/jphysiol.1965.sp007790. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Pappas G. D., Bennett M. V. Specialized junctions involved in electrical transmission between neurons. Ann N Y Acad Sci. 1966 Jul 14;137(2):495–508. doi: 10.1111/j.1749-6632.1966.tb50177.x. [DOI] [PubMed] [Google Scholar]
  12. RALL W. Membrane potential transients and membrane time constant of motoneurons. Exp Neurol. 1960 Oct;2:503–532. doi: 10.1016/0014-4886(60)90029-7. [DOI] [PubMed] [Google Scholar]
  13. SMITH T. G., BAUMANN F., FUORTES M. G. ELECTRICAL CONNECTIONS BETWEEN VISUAL CELLS IN THE OMMATIDIUM OF LIMULUS. Science. 1965 Mar 19;147(3664):1446–1448. doi: 10.1126/science.147.3664.1446. [DOI] [PubMed] [Google Scholar]
  14. WATANABE A., GRUNDFEST H. Impulse propagation at the septal and commissural junctions of crayfish lateral giant axons. J Gen Physiol. 1961 Nov;45:267–308. doi: 10.1085/jgp.45.2.267. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of General Physiology are provided here courtesy of The Rockefeller University Press

RESOURCES