Investigation of Electro-mechanical Coupling in Neuronal Membrane - Towards an Electro-mechanical Model of Nerve Pulse Propagation

拟议的项目与神经退行性疾病的基础研究和分别涉及植入物和电极的治疗有关。这一结果将有助于更好地了解神经元的功能。随着人类神经系统并发症的增加，电刺激植入物的使用也越来越多。然而，神经脉冲传导下的基本现象还不是很清楚。除了Hodgkin-Huxley关于神经脉冲产生和传播的假设和模型外，2005年Heimburg和Jackson提出了基于热力学的假设和模型。其中，脂质相变和与之相关的脂质基质的机电变化被归因于神经信号的传递。脂质基质在神经信号产生和传播中的作用不容忽视，需要从理论和实验两方面进行研究。20世纪60年代的一些实验发现已经显著地表明了脂膜的机电特性的耦合。然而，脂质-脂链转变的固有性质影响着神经的机电性质，并可能负责神经脉冲的产生和传播。从理论和实验上研究这种多参数依赖关系是非常重要的。因此，本项目的目的是通过理论方法研究脂膜的机电耦合，为神经脉冲的产生和传播提供一个机电模型。为此，人们发展了生理条件下具有空间变介电常数的脂质双分子层的静电模型。因此，神经信号传递的多物理模型可以用于神经植入研究，如耳蜗学和脑深部刺激模型。主要目标是：1.建立神经脉冲传播的多物理现象模型，包括热力学、力学和电学现象；2.数值求解这一耦合问题；3.为了更好地了解神经元的功能。

The proposed project is connected to the basic research of neurodegenerative disorders and respective treatments involving implants and electrodes. The results would be more beneficial for a better understanding of neuronal function. With growing number of neurological complications in human population, the usage of electrically stimulating implants is growing. However, the basic phenomena under the nerve pulse transmission are not clearly understood. Besides the Hodgkin-Huxley hypothesis and model about nerve pulse generation and propagation, in 2005 Heimburg and Jackson have proposed a thermodynamics-based hypothesis and model. Therein the lipid phase transition and the associated electro-mechanical changes in the lipid matrix are attributed for the nerve signal transmission. The role of the lipid matrix in the nerve signal generation and propagation cannot be ignored and needs to be investigated both theoretically and experimentally. There are number of experimental findings in 1960s that have significantly shown the coupling of electro-mechanical properties of lipid membranes. However, the intrinsic property of lipid-lipid chain transition affects the electro-mechanical properties and can be responsible for nerve pulse generation and propagation. It is indeed important to investigate this multi-parametric dependence both theoretically and experimentally. Therefore, the aim of this project is to investigate the electro-mechanical coupling of lipid membranes through theoretical procedures and to provide an electro-mechanical model for nerve pulse generation and propagation. To this end, electrostatic models for lipid bilayers in physiological conditions, with space varying permittivity have been developed. Thus the multi-physics model for nerve signal transmission can be used in neurological implant studies like Cochlea and Deep Brain Stimulation models. The key objectives are 1. to model the multi-physics phenomena of nerve pulse propagation including thermodynamics, mechanical and electrical phenomena 2. to solve this coupled problem numerically 3. for gaining better understanding of neuronal function