经颅磁刺激感应外电场作用下最小神经元模型放电起始动态机理分析

经颅磁刺激(TMS)是一种采用电磁线圈在大脑指定区域产生磁场的刺激方式. TMS的治疗原理是通过电磁感应产生作用于神经元的外加电场进而影响神经元编码. 然而目前TMS感应外电场改变神经元编码的内在机理尚不清楚.研究表明, 神经元编码由神经元的放电起始动态机理决定. 本文建立了TMS感应外电场作用下的最小神经元模型, 采用相平面分析和分岔分析方法, 研究了外电场作用下神经元放电起始动态的动力学机理, 并从阈下电位的不同动力学特性离子电流竞争角度揭示了TMS感应外电 场作用下神经元放电起始动态的生理学机理.

Action potential initial dynamical mechanism analysis in a minimum neuron model exposure to TMS induced electric field

Transcranial magnetic stimulation (TMS) is a kind of brain stimulation method of producing magnetic field at the designated area of brain employing electromagnetic coils. The principle of TMS is to apply an electric field which is generated through the electromagnetic induction to neuron, thereby influencing the excitability of neuron. Though it has been used for decades, its underlying mechanism, i.e., how TMS induction electric field changes neuronal excitability, is still unknown. To address this problem, we establish a minimum neuron model under action of TMS induced electric field, analyze the mechanism from the viewpoint of action potential initial dynamical mechanism which has been proved to be the decision factor of neural coding in previous studies. Through phase plane and bifurcation analysis, we reveal the dynamical mechanism of different firing patterns of neuron. Finally, we find that the physiological basis of different excitabilities under action of TMS induced electric field, which is the different outcomes of competition between ion currents of neuron with different kinetic behaviors in sub-threshold potential.