摘要
目的刺入式电极激活视神经纤维是发展视神经假体的新思路。以MATLAB为平台建立仿真系统来研究其作用机制，并通过改变刺激参数来探讨刺激效果。方法首先建立视神经的容积导体模型和视神经纤维模型，然后计算在刺入式电极刺激下不同深度纤维的兴奋阈值，并用激活函数和组织激活区来表征外加刺激的作用效果；随后改变纤维的直径、刺激脉冲脉宽来探讨不同参数对刺激效果的影响。结果兴奋阈值随着电极一纤维距离的增加增大，此时视神经内能同时被激活的纤维数量增多；增大纤维直径，同一深度纤维兴奋阈值会减小，电极一纤维距离越大，阈值减小程度也越大；增加单相矩形波脉宽，兴奋阈值减小，脉宽大于0．5ms时，同一深度纤维兴奋阈值几乎不再随脉宽增加而变化。结论刺入式电极可以实现对视神经的有效刺激，不同的刺激参数能产生不同的激活效应。所得结论对实验具有一定的指导意义。
Objective Optic nerve stimulation with penetrating electrode is a new method for developing visual prosthesis. A simulation system was developed with computer software MATLAB to investigate its mechanism. Methods Volume conductor model of optic nerve and optic nerve fiber model were developed. With the stimulation of monopolar penetrating electrode, the excitation thresholds of fibers at different depth were calculated. The activating function and activation region were employed to characterize the external stimulation effect. The impact of different parameters on stimulation effects were explored by changing the fiber diameter and the stimulation pulse width. Results Excitation thresholds increased as well as the percentage of activated fibers with the increase of electrode-fiber distance. Excitation threshold of the same depth fiber decreased as the fiber diameter increased, and the longer the electrode-fiber distance was, the more significant the drop was. Excitation threshold of the same depth fiber decreased as the pulse width of monophasic rectangle wave increased. The excitation threshold of the fiber at the same depth hardly changed for pulse durations greater than 0.5 ms. Conclusion The simulation results indicates that optical nerve stimulation can be realized with penetrating electrode, and different stimulation parameters can produce different activation effects. The present results provide theoretical guidance for the design of experiments.
出处
《国际生物医学工程杂志》
CAS
2012年第1期24-28,共5页
International Journal of Biomedical Engineering
基金
基金项目：国家自然科学基金资助项目（30870649）
科技部973项目（2005CB724302）
关键词
刺入式电极
视神经
兴奋阈值
激活函数
Penetrating electrode
Optic nerve
Excitation threshold
Activation function
