Simulation of Neural Signals' Spectrum and Transmission from the Perspective of Impedance-Matching Effect of the Ranvier Node.

Addressing the current issues of the uncertain primary frequency bands and the difficulty in directly measuring the spectral characteristics of neural electromagnetic signals transmitted within nerve fibers, this study investigates the spectral and time-domain properties of the neural electromagnetic signals through finite element simulations, using the influence of the node of Ranvier on nerve conduction velocity as a breakthrough point, and develops a coaxial transmission line impedance transformation model. The research results demonstrate that the primary signals capable of effective transmission within nerve fibers may reside in the terahertz (THz) band. They also show that the node of Ranvier essentially functions by regulating its geometric length to achieve impedance matching between the node and the myelin sheath, thereby reaching the optimal efficiency for signal coupling. The above finding not only explains the mechanism underlying the non-monotonic variation in neural conduction velocity with the length of the node of Ranvier, but also provides the latest perspective for understanding the relationship and differences between transmembrane action potentials that accompany the generation of neural signals and information transmission carriers-electromagnetic signals. It may also provide a theoretical supplement to the understanding of signal frequency-timing issues in neural encoding.