For more than 70 years, biologists and biophysicists have been trying to unravel the mystery surrounding the saltatory conduction of so-called myelinated neurons. This conduction is indeed very different and faster than for fibres “without” myelin. Many theories have been developed. Albert Einstein used the metaphor of the train to explain the theory of relativity. It is also possible to use a similar metaphor to better understand this transient functioning of the neuron: the transmission of the action potential in myelinated fibres. By studying the various theories that have been put forward and confronting them with physics, mathematics and microscopic anatomical observations, it is possible to refute or confirm certain hypotheses. It is easy and simple, then, to demonstrate unequivocally that the action potential cannot, in any way, jump from node of Ranvier (noR) to node of Ranvier as has been assumed and taught until now. It is possible to describe that the neuron uses an elegant and very simple method to increase the speed of transmission of the neuronal message. It is also important to conclude that this increase in speed, contrary to common belief, has an energetic cost that is greater than expected and that is proportional to the speed and in perfect agreement with the laws of thermodynamics.
Cite this paper
Delalande, B. , Tamagawa, H. and Matveev, V. (2021). Another Train Paradox: May the Myelin Be with You!. Open Access Library Journal, 8, e7379. doi: http://dx.doi.org/10.4236/oalib.1107379.
Hodgkin, A.L. (1937) Evidence for Electrical Transmission in Nerve: Part I. The Journal of Physiology, 90, 183-210. https://doi.org/10.1113/jphysiol.1937.sp003507
Hodgkin, A.L. (1937) Evidence for Electrical Transmission in Nerve: Part II. The Journal of Physiology, 90, 211-232. https://doi.org/10.1113/jphysiol.1937.sp003508
Heimburg, T. and Jackson, A.D. (2005) On Soliton Propagation in Biomembranes and Nerves. Proceedings of the National Academy of Sciences of the United States of America, 102, 9790-9795. https://doi.org/10.1073/pnas.0503823102
Akaishi, T. (2018) Saltatory Conduction as an Electrostatic Compressional Wave in the Axoplasm. The Tohoku Journal of Experimental Medicine, 244, 151-161.
https://doi.org/10.1620/tjem.244.151
Jacak, J.E. and Jacak, W.A. (2020) New Wave-Type Mechanism of Salutatory Conduction in Myelinated Axons and Micro-Salutatory Conduction in C Fibres. European Biophysics Journal, 49, 343-360. https://doi.org/10.1007/s00249-020-01442-z
Pannese, E. (1994) Neurocytology: Fine Structure of Neurons, Nerve Processes, and Neuroglial Cells. G. Thieme Verlag, Stuttgart; Thieme Medical Publishers, New York.
Bear, R.S., Schmitt, F.O. and Young, J.Z. (1937) The Sheath Components of the Giant Nerve Fibres of the Squid. Proceedings of the Royal Society of London. Series B, Biological Sciences, 123, 496-504. https://doi.org/10.1098/rspb.1937.0065
Brown, E.R. and Abbott, N.J. (1993) Ultrastructure and Permeability of the Schwann Cell Layer Surrounding the Giant Axon of the Squid. Journal of Neurocytology, 22, 283-298. https://doi.org/10.1007/BF01187127
Martin, R. (1965) On the Structure and Embryonic Development of the Giant Fibre System of the Squid Loligo vulgaris. Zeitschrift für Zellforschung und Mikroskopische Anatomie, 67, 77-85. https://doi.org/10.1007/BF00339277
Fitzhugh, R. (1962) Computation of Impulse Initiation and Saltatory Conduction in a Myelinated Nerve Fiber. Biophysical Journal, 2, 11-21.
https://doi.org/10.1016/S0006-3495(62)86837-4
Giuliodori, M.J. and DiCarlo, S.E. (2004) Myelinated vs. Unmyelinated Nerve Conduction: A Novel Way of Understanding the Mechanisms. Advances in Physiology Education, 28, 80-81. https://doi.org/10.1152/advan.00045.2003
Laporte, Y. (1951) Continuous Conduction of Impulses in Peripheral Myelinated Nerve Fibers. The Journal of General Physiology, 35, 343-360.
https://doi.org/10.1085/jgp.35.2.343
Rasminsky, M. and Sears, T.A. (1972) Internodal Conduction in Undissected Demyelinated Nerve Fibres. The Journal of Physiology, 227, 323-350.
https://doi.org/10.1113/jphysiol.1972.sp010035
Huxley, A.F. and Stampfli, R. (1951) Effect of Potassium and Sodium on Resting and Action Potentials of Single Myelinated Nerve Fibers. The Journal of Physiology, 112, 496-508. https://doi.org/10.1113/jphysiol.1951.sp004546
Huxley, A.F. and St?mpfli, R. (1949) Evidence for Saltatory Conduction in Peripheral Myelinated Nerve Fibres. The Journal of Physiology, 108, 315-339.
https://doi.org/10.1113/jphysiol.1949.sp004335
Foust, A., Popovic, M., Zecevic, D. and McCormick, D.A. (2010) Action Potentials Initiate in the Axon Initial Segment and Propagate through Axon Collaterals Reliably in Cerebellar Purkinje Neurons. Journal of Neuroscience, 30, 6891-6902.
https://doi.org/10.1523/JNEUROSCI.0552-10.2010
Foust, A.J., Yu, Y., Popovic, M., Zecevic, D. and McCormick, D.A. (2011) Somatic Membrane Potential and Kv1 Channels Control Spike Repolarization in Cortical Axon Collaterals and Presynaptic Boutons. Journal of Neuroscience, 31, 15490- 15498. https://doi.org/10.1523/JNEUROSCI.2752-11.2011
Goodman, B.E. and Waller, S.B. (2002) Propagation of Action Potentials in Myelinated vs. Unmyelinated Neurons. Advances in Physiology Education, 26, 223.
https://doi.org/10.1152/advan.00023.2002
Debanne, D., Campanac, E., Bialowas, A., Carlier, E. and Alcaraz, G. (2011) Axon Physiology. Physiological Reviews, 91, 555-602.
https://doi.org/10.1152/physrev.00048.2009
Baraban, M., Mensch, S. and Lyons, D.A. (2016) Adaptive Myelination from Fish to Man. Brain Research, 1641, 149-161. https://doi.org/10.1016/j.brainres.2015.10.026
Fern, R. and Harrison, P.J. (1994) The Relationship between Ischaemic Conduction Failure and Conduction Velocity in Cat Myelinated Axons. Experimental Physiology, 79, 571-581. https://doi.org/10.1113/expphysiol.1994.sp003790
Ffrench-Constant, C., Colognato, H. and Franklin, R.J.M. (2004) Neuroscience. The Mysteries of Myelin Unwrapped. Science, 304, 688-689.
https://doi.org/10.1126/science.1097851
Grandis, M., Leandri, M., Vigo, T., Cilli, M., Sereda, M.W., Gherardi, G., et al. (2004) Early Abnormalities in Sciatic Nerve Function and Structure in a Rat Model of Charcot-Marie-Tooth Type 1A Disease. Experimental Neurology, 190, 213-223.
https://doi.org/10.1016/j.expneurol.2004.07.008
Padrón, R. and Mateu, L. (1982) Repetitive Propagation of Action Potentials Destabilizes the Structure of the Myelin Sheath. A Dynamic X-Ray Diffraction Study. Biophysical Journal, 39, 183-188. https://doi.org/10.1016/S0006-3495(82)84506-2
Williams, A. C. and Brophy, P.J. (2002) The Function of the Periaxin Gene during Nerve Repair in a Model of CMT4F. Journal of Anatomy, 200, 323-330.
https://doi.org/10.1046/j.1469-7580.2002.00038.x