利用单电极不对称双向脉冲刺激实现哺乳动物有髓神经纤维选择性兴奋的仿真研究

Modeling Study on Selective Activation of Small Mammalian Nerve Fibers Using Asymmetric Biphasic Pulses with a Monopolar Point Electrode

本研究的目的是要从理论上探讨利用单电极双向脉冲刺激实现哺乳动物神经纤维选择性刺激 ,(即当刺激一束神经时 ,不兴奋粗神经而兴奋细神经 )的可能性 .双向脉冲刺激可以降低刺激脉冲对神经纤维产生的电化学损伤 .为研究哺乳动物有髓神经纤维的电特性 ,建立了一个基于简单的无穷大、各向同性的容积导体模型的仿真系统 .利用该仿真系统 ,采用“不对称但电荷平衡”的双向脉冲刺激 ,计算了神经纤维的兴奋和阻断阈值与纤维直径、纤维 电极间距离的关系 .结果表明

The aim of this study is to investigate theoretically the possibility for activation of small mammalian myelinated nerve fibers without activating larger ones when stimulating a fiber bundle with a monopolar point electrode using biphasic pulses, which can reduce the electrochemical damage resulted from stimulation pulses to nerve fibers. A simulation system for studying the electrical properties of mammalian myelinated nerve fibers was built based on a simple infinite and homogeneous volume conductor model. By use of an asymmetric but charge-balanced stimulation waveform, the sensitivity of excitation and blocking threshold of nerve fibers to fiber diameter, electrode-fiber distance was calculated. The results show that selective activation of small mammalian myelinated fibers may be possible in a region at some distance from the electrode using biphasic pulses.