Damage Analysis of a Multilayered Myelin Sheath Under High Strain Rate Loading: A Molecular Simulation Study
摘要
The proper functionality of the brain depends on the ability of neurons to receive and transmit signals. Glial cells aid in signal transmission process by keeping the cells in healthy states. Additionally, in the event of any trauma, the glial cells impart support to the brain cells by isolating injured cells and keeping brain’s functionality active. Among the glial cells, the oligodendrocytes establish a direct connection with the neuron by encapsulating it with a fat-driven layer, termed a myelin sheath. This bubble of fat and protein provides insulation to the axons and assists in delivering electrical responses at an accelerated speed. Myelin sheath degeneration may occur due to sudden impact at the cellular level during brain trauma, which, may affect brain functionality due to impaired signal transmission along the axons. Here, using molecular dynamics simulations, we study the role of high strain rate mechanical loadings (108 and 109 s−1) on the damage threshold of myelin sheath. The molecular model was simulated using LAMMPS, an openly available molecular solver. The potentials for the associated system components were defined using OPLS force field. We have observed that upon mechanical loading, a multilayer myelin model can withstand up to 5–18% apparent tensile strain to failure, depending on loading sites and conditions. The separation of the protein from the lipid layers is considered to be the most likely failure mode of the myelin system.