Study On Neural Signal Transmission Mechanism Based On Soft Material Waveguide

China has increasingly attached importance to research related to brain science.In the "Outline of the Strategic Plan for Expanding Domestic Demand(2022-2035)",it is clear that China will implement a number of forward-looking and strategic national major science and technology projects in cutting-edge fields such as artificial intelligence and brain science.As a fundamental issue in brain science research,although cellular neuroscience has been explored for many years,the mechanisms of neural signal generation and transmission still need to be further clarified.Since the 1950s,many mathematical physics models describing the generation and transmission mechanism of neural signals have been proposed,such as cable model,electromechanical soliton model,quantum communication model,neural soft matter waveguide model,etc.In 2012,the neural soft material waveguide model proposed that there is a soft material waveguide structure in the nerve,which is a sandwich structure with a uniform dielectric layer sandwiched between conductive liquids on both sides.The neural electromagnetic signal is reflected and advanced at the interface between the organic dielectric layer and the electrolyte solution on both sides.The neural soft material waveguide model clarifies the transmission pathway of neural electromagnetic signals,namely the organic dielectric layer between conductive liquids on both sides,and is suitable for the transmission of neural signals in unmyelinated and myelinated nerves.In recent years,the neural soft matter waveguide model has been used by many researchers to analyze the generation and transmission of neural signals because it is suitable for both unmyelinated nerves and myelinated nerves to explain the Saltatory conduction of myelinated nerves.However,there is still a lack of systematic research and verification of neural soft material waveguide transmission models.In the preliminary research,our research group discovered the spectral characteristics of neural electromagnetic signals(105-106 Hz)through the biomimetic Na+ channel established by COMSOL,and clarified the linear relationship between the electromagnetic transmission characteristics of neural soft material waveguides and the transmission speed of neural signals,providing a feasible solution for the validation of neural soft material waveguide models.In this study,we will focus on the transmission characteristics of neural electromagnetic signals in neural soft material waveguides.Firstly,we will conduct simulation research on the electromagnetic characteristics of soft material waveguides.Based on this,we will establish a neural soft material waveguide simulation model that mimics myelinated nerve fibers,comprehensively analyze the transmission mechanism of neural signals in myelinated nerves,and conduct confirmatory research on it.In order to clarify the electromagnetic characteristics of soft material waveguides,we established a centimeter level neural like structure soft material waveguide model in HFSS,and set wave ports on both sides of the dielectric layer to explore the transmission characteristics of electromagnetic signals in soft material waveguides.The simulation results show that the neural like soft material waveguide has low-pass characteristics,but the near-field effect can cause the soft material waveguide model to exhibit high pass phenomenon at short transmission distances.Afterwards,we investigated the influence of structural and electrical parameters of soft material waveguides on their transmission characteristics to understand the impact of neural structures on neural signal transmission.The research results found that:(1)the thickness of the dielectric layer can improve the transmission efficiency of electromagnetic signals in soft material waveguides,but the amplitude of its improvement will decrease with the increase of the thickness of the dielectric layer,and the change curve of transmission efficiency will eventually tend to be flat;(2)The concentration of electrolyte solutions inside and outside the soft material waveguide can significantly improve the efficiency of electromagnetic signal transmssion in it;(3)The curvature of a soft material waveguide has little effect on the transmission of electromagnetic signals in the soft material waveguide model.Finally,we further miniaturized the size of the soft material waveguide model to simulate the transmission characteristics of neural electromagnetic signals in myelinated and unmyelinated nerve fibers.We found that the transmission efficiency of electromagnetic signals in myelinated nerves is much better than that in unmyelinated nerves,which indirectly proves the feasibility of the soft material waveguide model in exploring neural signal transmission mechanisms,It also laid the foundation for further building a simulation model of myelinated nerves.After obtaining the simulation results of the soft material waveguide,we customized materials to build an experimental model of the soft material waveguide,and used a vector network measurement instrument to obtain the S21 parameters of the experimental model.The variation trend of the S21 parameters of the low-frequency signal is generally consistent with the simulation results,while the S21 parameters of the high-frequency signal vary more complex and are easily affected by noise,Especially for experimental models with smaller structural parameter values,the S21 parameter waveform is more significantly affected by noise,while the S21 parameter waveform under other parameters is roughly the same.After proving that soft material waveguides can be used to explore the transmission mechanism of neural signals in myelinated nerves,we refer to the structure of myelinated nerves and add a node of Ranvier structure on the basis of the previous simple myelinated nerve simulation model.We replace the excitation source with the current port at the node of Ranvier,introducing the axon inner diameter d,myelin sheath thickness M,length of node of Ranvier l,and ion channel density p Wait for four physical quantities to analyze the impact of these structures on the transmission of neural signals.Through simulation and parameter fitting,we obtained the following results:(1)The effective transmission distance s of neural signals is related to the inner diameter d of axons,the thickness M of myelin sheaths,the length l of node of Ranvier,and the ion channel density,respectively p The unary fitting function of.This is consistent with the trend of the influence of axon diameter d and myelin sheath thickness M on nerve signal transmission in the previous biological nerve experiment,which proves the correctness and applicability of the neural soft matter waveguide model;(2)The binary fitting function between the effective transmission distance s of neural signals and the inner diameter d of axons and the thickness M of myelin sheaths.We used the functional form of the binary fitting function obtained in this study to fit the data in the research literature,and achieved good fitting results,indicating that the fitting function we obtained is in line with the impact of neural structure on neural signal transmission in actual biological nerves.(3)The effective transmission distance s of neural signals is a ternary fitting function of axon inner diameter d,myelin sheath thickness M,and length of node of Ranvier 1.This comprehensively summarizes the impact of various structures of myelinated nerves on neural signal transmission,providing strong support for exploring neural signal transmission mechanisms at the simulation level,and also serving as the theoretical basis for our subsequent biological experiments.The two simulation models established in this study were used to analyze the electromagnetic characteristics of the soft material waveguide model and the transmission mechanism of neural signals in myelinated nerves.The neural structure parameters and electrical parameters that affect the transmission effect of neural signals were deeply explored,and these factors were fitted.Although these two models currently have some shortcomings due to limitations in simulation software,such as unreal liquid environment and single excitation source settings,the comprehensive research results are consistent with biological experimental phenomena,strongly supporting the neural signal transmission mechanism based on the neural soft material waveguide model.This provides a new physical theoretical model for the research fields of neural information encoding mechanisms,brain information processing principles,and memory access in brain science research.