Discipline of Biomedical Engineering, National University of Ireland, Galway, Ireland.
School of Mathematics, Statistics and Ap, NUI, Galway, Ireland.
Int J Numer Method Biomed Eng. 2018 Sep;34(9):e3118. doi: 10.1002/cnm.3118. Epub 2018 Jul 10.
We confirm that alteration of a neuron structure can induce abnormalities in signal propagation for nervous systems, as observed in brain damage. Here, we investigate the effects of geometrical changes and damage of a neuron structure in 2 scaled nerve bundle models, made of myelinated nerve fibers or unmyelinated nerve fibers.
We propose a 3D finite element model of nerve bundles, combining a real-time full electromechanical coupling, a modulated threshold for spiking activation, and independent alteration of the electrical properties for each fiber. With the inclusion of plasticity, we then simulate mechanical compression and tension to induce damage at the membrane of a nerve bundle made of 4 fibers. We examine the resulting changes in strain and neural activity by considering in turn the cases of intact and traumatized nerve membranes.
Our results show lower strain and lower electrophysiological impairments in unmyelinated fibers than in myelinated fibers, higher deformation levels in larger bundles, and higher electrophysiological impairments in smaller bundles.
We conclude that the insulation sheath of myelin constricts the membrane deformation and scatters plastic strains within the bundle, that larger bundles deform more than small bundles, and that small fibers tolerate a higher level of elongation before mechanical failure.
我们证实神经元结构的改变会导致神经系统信号传递异常，就像在脑损伤中观察到的那样。在这里，我们研究了由有髓神经纤维或无髓神经纤维组成的 2 个缩放神经束模型中神经元结构的几何形状改变和损伤的影响。
我们提出了一个神经束的三维有限元模型，结合实时全电-机械耦合、尖峰激活的调制阈值以及每个纤维独立的电特性改变。通过包含可塑性，我们模拟机械压缩和拉伸，以在由 4 根纤维组成的神经束的膜上诱导损伤。我们通过依次考虑完整和受伤的神经膜的情况来检查应变和神经活动的变化。
我们的结果表明，无髓神经纤维的应变和电生理损伤比有髓神经纤维低，较大束的变形水平较高，较小束的电生理损伤较高。
我们的结论是，髓鞘的绝缘鞘限制了膜的变形，并在束内分散了塑性应变，较大的束比小的束变形更多，小纤维在机械失效之前能承受更高的伸长水平。
