echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Active Ingredient News > Study of Nervous System > Cell . . . Rewrite the understanding! There is a jump conduction in the axon-side clearance.

    Cell . . . Rewrite the understanding! There is a jump conduction in the axon-side clearance.

    • Last Update: 2020-07-23
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com
    The axons of vertebrates are surrounded by many dense myelin membranes, which are the anatomical basis for the rapid and jumping conduction of currents in the peripheral and central nervous system.however, the myelin sheath does not cover the entire axon, and there is a gap in the covering area, which is called the Langfei's node.the action potential "jumps" from one node to another along the axon, which is called jumping conduction.the action potential of frog sciatic nerve in college physics textbook is a classic model of jumping conduction.in recent years, many important research progresses have been made on the cellular and molecular mechanisms of myelination, including the interaction between neurons and glial cells to regulate myelination.on December 26, 2019, the Maarten H.P. KOLE research team of the Institute of neuroscience of the Royal Dutch Academy of Sciences published an article in the journal Cell, saltatory conduction along myeliminated axons involves a periodnal nanocircuit, which revealed the existence of jumping conduction in the axonal space.similar to the equivalent circuit diagram in physics, axon and myelin form a membrane closely combined with each other, without intermediate conduction path, which is called "single cable" (SC).corresponding to it is the "double cable" (DC). In addition to the "cable" between axon and myelin sheath, there is also a "cable" between the fluid filled paraaxonal space and the paralymphatic space to conduct current conduction.the researchers built "single cable" and "double cable" models by computer, and used bipolar electrodes to simultaneously record the voltage of cell body and axon (the distance between them is at least 830 μ m) to evaluate the sensitivity of the models.by continuously optimizing the parameters of resistance and capacitance in the model, it is found that the "double cable" mode can better reflect the characteristics of transient voltage conduction on axons.they further observed the ultrastructure of myelin sheath with electron microscope. The results showed that the number of lamellar myelin sheath layers on axons was 5-19, which was positively correlated with axon diameter. In other words, the larger the axon diameter, the more lamellar myelin sheath layers.can the "single cable" and "double cable" models predict the thickness of myelin sheath, the number of lamellar layers, and the resistance and capacitance of myelin membrane? The average number of myelin lamellar layers predicted by the "double cable" model was 14, which was consistent with the electron microscope results, while the "single cable" model predicted that the number of myelin lamellar layers was only 4.these results show that the "double cable" model is more consistent with the real neuronal current loop.in addition, the average width of the paraaxonal space is 12.3 nm, and the average resistance is 53.7 Ω cm, while the resistance of liquid flowing through the gap is 550 Ω cm.the ultrastructural and axial resistivity data of myelin sheath showed that the conductivity of the axon gap at nanometer level (12 nm) was 3 times higher than that of the axon, and this conduction was limited by the paralymphatic space.by measuring the action potential, they found that the resistance produced by the axon gap had jump conduction.in order to further confirm that the gap between axons can generate voltage independently. the researchers used voltage sensitive dye (VSD) to record the action potential. The current generated by the stimulated node was faster than that of the upstream node and downstream node (the distance between the nodes was 5 μ m), and the time interval between them was less than 200 μ s, while in the "double cable" model, the interval time was not 400 μ s. These results reveal that the time resolution between axons is higher than that of the upstream node and downstream node The characteristics of gap jump conduction. What are the characteristics of space? The researchers recorded the action potentials between several nodes with a total length of 250 μ m at a lower frequency. It was found that the hopping propagation mode was reliably repeated in the first three nodes. Although the voltage rise time was slow, it still reached about – 30 mV at the intermediate node. surprisingly, the "double cable" model can produce jump conduction with similar spatial and temporal resolution. in general, this paper reveals that there is jump conduction in the paraaxonal gap, which has been neglected for a long time, by means of mathematical model combined with electron microscopy and voltage recording technology. this discovery is of great significance, making up for the previous vacancy and becoming the second longitudinal action potential conduction pathway. original link: plate maker: Ke
    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.