外部电场作用下的视神经纤维兴奋性的仿真研究

doi:10.3969/j.issn.0258-8021. 2014. 05.08

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摘要基于刺入式电极的视神经视觉假体,为盲人的视觉修复提供了新的可能性。为了对该视神经假体的电刺激策略和微电极设计提供理论支持，基于真实的电极结构，在COMSOL软件中建立刺入式微电极的外部电场仿真模型，并将其与利用NEURNO软件实现的神经纤维双层电缆模型结合，系统地研究电极与视神经纤维的相对位置、电刺激脉冲宽度以及电极几何结构的改变对视神经纤维兴奋阈值的影响。不同电极位置、刺激脉宽刺激下阈值变化规律的仿真结果，与以往报道的动物实验和仿真实验结果相符，证明了所建模型的有效性。
根据仿真结果，对刺入式视神经假体中刺激脉宽的选择和电极几何结构的设计，建议如下：窄脉宽刺激有利于降低能量消耗；电极锥度的设计要在满足电极力学特性及易于植入视神经的基础上，尽可能地减小，以降低纤维兴奋的阈值；电极的暴露面积越小，纤维兴奋所需的电流阈值越低，但电荷密度阈值越高；较低的电流阈值有利于减少能量消耗，但过高的电荷密度阈值却容易造成组织损伤，因此电极暴露面积的设计需要在耗能与安全性之间进行综合考虑。电极绝缘层厚度的改变对视神经纤维的兴奋阈值没有明显的影响，但从电极插入的难易考虑，应尽可能减小绝缘层厚度。以上结果对人体其他部位神经纤维的电刺激同样具有参考价值

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	郭红¹隋晓红¹ 李孟辉²李丽明^1*

关键词 ：视觉假体, 微电极的电场仿真模型, 视神经纤维, 双层电缆多室模型, 刺激阈值

Abstract：A visual prosthesis based on penetrating electrode stimulation within the optic nerve (ON) is a potential way to restore partial functional vision for the blind patients. In order to provide theoretical basis for electrical stimulation strategies and the electrode design of abovementioned visual prosthesis, a finiteelement model of the electric field generated by an actual penetrating microelectrode was constructed in COMSOL, and then coupled to the multicompartment cable model of the optic nerve fiber implemented using NEURON. With this method, we evaluated the effects of stimulating electrode location, pulse duration of electrical stimulus and electrode structure on the excitation thresholds of optic nerve fibers. Simulation results showed that the impact of the former two factors on the fiber thresholds agreed with that reported in previous animal and simulation studies, which demonstrated the effectiveness of our models. The following suggestions about the design of stimulus pulse duration and electrode structure of the penetrative ON prosthesis were also obtained according to our simulation work. Stimulus with narrow pulse width helps reduce energy consumption. The electrode taper should be designed as small as possible to lower the threshold but should not disturb the electrode insertion. Decreasing the electrode exposed area helps lower the current threshold and therefore reduces the power consumption, but it also increases the charge density threshold, which eases to result in electrochemical damage to ON. Thus, the electrode exposed area should be designed appropriately to avoid excessive power consumption and tissue damage. Changing the coating thickness of the electrode has no significant effect on the fiber threshold, but a electrode with thin coating is recommended to decrease the insertion difficulty. These results are also of valuable reference to the electrical stimulation of other nerve fibers of human body.

Key words： visual prosthesis FEM model of the electric field optic nerve fiber multicompartment double cable model stimulation threshold

基金资助:国家重点基础研究发展计划（973计划）（2011CB7075002/5，2011CB013304）；国家自然科学基金（61171174）

引用本文:

郭红¹隋晓红¹ 李孟辉²李丽明^1*. 外部电场作用下的视神经纤维兴奋性的仿真研究[J]. 中国生物医学工程学报, 2014, 33(5): 574-584.
GUO Hong¹ SUI Xiao Hong¹ LI Meng Hui² LI Li Ming^1*. Effects of the Extracellular Electrical Stimulation on the Excitability of Optic Nerve Fibers by Mathematical Modeling. journal1, 2014, 33(5): 574-584.

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http://cjbme.csbme.org/CN/ 10.3969/j.issn.0258-8021. 2014. 05.08 或 http://cjbme.csbme.org/CN/Y2014/V33/I5/574

［1］Maynard EM. Visual prostheses ［J］. Annu Rev Biomed Eng, 2001, 3(1): 145-168.
［2］Veraart C, Raftopoulos C, Mortimer JT, et al. Visual sensations produced by optic nerve stimulation using an implanted selfsizing spiral cuff electrode ［J］. Brain Res, 1998, 813(1): 181-186.
［3］Veraart C, WanetDefalque MC, Gérard B, et al. Pattern recognition with the optic nerve visual prosthesis ［J］. Artif Organs, 2003, 27(11): 996-1004.
［4］Duret F, Brelén ME, Lambert V, et al. Object localization, discrimination, and grasping with the optic nerve visual prosthesis ［J］. Restor Neurol Neurosci, 2006, 24(1): 31-40.
［5］Chai Xinyu, Li Liming, Wu Kaijie, et al. CSight visual prostheses for the blind ［J］. IEEE Eng Med Biol Mag, 2008, 27（5): 20-28.
［6］Li Liming, Cao Pengjia, Sun Mingjie, et al. Intraorbital optic nerve stimulation with penetrating electrodes: in vivo electrophysiology study in rabbits ［J］. Graefes Arch Clin Exp Ophthalmol, 2009, 247(3): 349-361.
［7］Sun Jingjing, Lu Yiliang, Cao Pengjia, et al. Spatiotemporal properties of multipeaked electrically evoked potentials elicited by penetrative optic nerve stimulation in rabbits ［J］. Invest Ophth Vis Sci, 2011, 52(1): 146-154.
［8］Lu Yiliang, Yan Yan, Chai Xinyu, et al. Electrical stimulation with a penetrating optic nerve electrode array elicits visuotopic cortical responses in cats ［J］. J Neural Eng, 2013, 10(3): 036022.
［9］Choi CTM, Hsu CH. Conditions for generating virtual channels in cochlear prosthesis systems ［J］. Ann Biomed Eng, 2009, 37(3): 614-624.
［10］Rattay F, Resatz S. Effective electrode configuration for selective stimulation with inner eye prostheses ［J］. IEEE Trans Biomed Eng, 2004, 51(9): 1659-1664.［11］Kasi H, Hasenkamp W, Cosendai G, et al. Simulation of epiretinal prosthesesevaluation of geometrical factors affecting stimulation thresholds ［J］. J Neuroeng Rehabil, 2011, 8(1): 44-53.
［12］Butson CR, McIntyre CC. Role of electrode design on the volume of tissue activated during deep brain stimulation ［J］. J Neural Eng, 2006, 3(1): 1-8.
［13］Parrini S, Delbeke J, Legat V, et al. Modelling analysis of human optic nerve fibre excitation based on experimental data ［J］. Med Biol Eng Comput, 2000, 38(4): 454-464.［14］Oozeer M, Veraart C, Legat V, et al. Simulation of intraorbital optic nerve electrical stimulation ［J］. Med Biol Eng Comput, 2005, 43(5): 608-617.
［15］Oozeer M, Veraart C, Legat V, et al. A model of the mammalian optic nerve fibre based on experimental data ［J］. Vis Res, 2006, 46(16): 2513-2524.
［16］McIntyre CC, Richardson AG, Grill WM. Modeling the excitability of mammalian nerve fibers: influence of afterpotentials on the recovery cycle ［J］. J Neurophysiol, 2002, 87(2): 995-1006.
［17］Li Menghui, Yan Yan, Wang Qixin, et al. A simulation of current focusing and steering with penetrating optic nerve electrodes［J］. J Neural Eng, 2013, 10(6): 066007.
［18］Manola L, Roelofsen BH, Holsheimer J, et al. Modelling motor cortex stimulation for chronic pain control: electrical potential field, activating functions and responses of simple nerve fibre models ［J］. Med Biol Eng Comput, 2005, 43(3): 335-343.
［19］[JP3]Killer HE, Laeng HR, Flammer J, et al. Architecture of arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve: anatomy and clinical considerations ［J］. Br J Ophthalmol, 2003, 87(6): 777-781.[JP]
［20］Struijk JJ, Holsheimer J, Barolat G, et al. Paresthesia thresholds in spinal cord stimulation: a comparison of theoretical results with clinical data ［J］. IEEE Trans Rehab Eng, 1993, 1(2): 101-108.
［21］Jonas JB, Schmidt AM, MüllerBergh JA, et al. Human optic nerve fiber count and optic disc size ［J］. Invest Ophth Vis Sci, 1992, 33(6): 2012-2018.
［22］Devaux J, Gola M, Jacquet G, et al. Effects of K+ channel blockers on developing rat myelinated CNS axons: identification of four types of K+ channels ［J］. J Neurophysiol, 2002, 87(3): 1376-1385.
［23］Stys PK, Sontheimer H, Ransom BR, et al. Noninactivating, tetrodotoxinsensitive Na+ conductance in rat optic nerve axons ［J］. P Natl Acad Sci USA, 1993, 90(15): 6976-6980.
［24］Berthold CH, Nilsson I, Rydmark M. Axon diameter and myelin sheath thickness in nerve fibres of the ventral spinal root of the seventh lumbar nerve of the adult and developing cat ［J］. J Anat, 1983, 136(3): 483-508.
［25］Brummer SB, Turner MJ. Electrical stimulation with Pt electrodes: IIestimation of maximum surface redox (theoretical nongassing) limits ［J］. IEEE Trans Biomed Eng, 1977, 5(1): 440-443.
［26］Grill WM, Mortimer JT. Stimulus waveforms for selective neural stimulation ［J］. IEEE Eng Med Biol, 1995, 14(4): 375-385.
［27］Jensen RJ, Ziv O R, Rizzo JF. Thresholds for activation of rabbit retinal ganglion cells with relatively large, extracellular microelectrodes ［J］. Invest Ophth Vis Sci, 2005, 46(4): 1486-1496.
［28］Warman EN, Grill WM, Durand D. Modeling the effects of electric fields on nerve fibers: determination of excitation thresholds ［J］. IEEE Trans Biomed Eng, 1992, 39(12): 1244-1254.