Scurfield Abby, Latimer David C
Department of Physics, University of Puget Sound, Tacoma, Washington, United States of America.
PLoS One. 2018 Jan 12;13(1):e0191106. doi: 10.1371/journal.pone.0191106. eCollection 2018.
Age-related decreases in the conduction velocity (CV) of action potentials along myelinated axons have been linked to morphological changes in the myelin sheath. In particular, evidence suggests the presence of segmental demyelination and remyelination of axons. In remyelinated segments, the distance between adjacent nodes of Ranvier is typically shorter, and myelin sheaths are thinner. Both experimental and computational evidence indicates that shortened internodes slows CV. In this computational study, we determine the impact of progressive segmental demyelination and remyelination, modeled by shorter internodes with thinner myelin sheaths interspersed with normal ones, upon the CV. We find that CV progressively decreases as the number of remyelinated segments increases, but this decrease is greater than one would expect from an estimate of the CV based merely upon the number of short and long internodes. We trace the additional suppression of the CV to transitions between long and short internodes. Our study presents an important consideration for the precise modeling of neural circuits with remyelinated neurons.
随着年龄增长，动作电位沿有髓轴突的传导速度（CV）下降，这与髓鞘的形态变化有关。特别是，有证据表明轴突存在节段性脱髓鞘和再髓鞘化。在再髓鞘化的节段中，相邻郎飞结之间的距离通常较短，髓鞘也较薄。实验和计算证据均表明，节间缩短会减慢传导速度。在这项计算研究中，我们通过将节间缩短且髓鞘变薄的节段与正常节段相间排列来模拟进行性节段性脱髓鞘和再髓鞘化，从而确定其对传导速度的影响。我们发现，随着再髓鞘化节段数量的增加，传导速度逐渐降低，但这种降低幅度大于仅根据短节间和长节间数量对传导速度进行估计时的预期。我们将传导速度的额外抑制归因于长节间和短节间之间的过渡。我们的研究为精确模拟有再髓鞘化神经元的神经回路提供了重要考虑因素。
