A novel electrode array for diameter-dependent control of axonal excitability: A simulation study
A novel electrode array for diameter-dependent control of axonal excitability: A simulation study
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DOI：
10.1109/tbme.2004.827347
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发表时间：
2004-07-01
影响因子：
4.6
通讯作者：
Durand, DM
中科院分区：
文献类型：
--
作者：
Lertmanorat, Z;Durand, DM
周围神经的细胞外电刺激会先激活大直径的运动纤维，然后再激活小直径的运动纤维，这一招募顺序与随意肌肉收缩期间有髓运动纤维的生理招募相反。目前解决这一问题的方法需要长时间的刺激脉冲，这可能会导致电极腐蚀和神经损伤。通过在两种不同体积的导体中进行计算机模拟，验证了这样一种假设，即通过使用多个电极重塑沿轴突的细胞外电位轮廓，可以抑制特定直径纤维的兴奋性。在9触点电极阵列的均匀介质中的模拟表明，在200微米的轴突-电极距离和10微米的刺激脉冲下，大直径轴突(13-17微米)(0.6-3.0毫安)的电流激发阈值(I-th)高于小直径轴突(2-7微米)(0.4-0.7毫安)的电流激发阈值。该电极阵列还在狗(S3的前根)模型的三维有限元模型中进行了测试。单个阴极在激活小轴突之前先激活大直径轴突。然而，九电极阵列激活50%的小轴突，而只招募10%的大轴突，激活90%的小轴突，而只招募50%的大轴突。模拟结果表明，电极阵列可以实现近生理的募集顺序。电极阵列的直径选择性可以通过电极间距来控制，并且该方法与脉冲宽度无关。
Electrical extracellular stimulation of peripheral nerve activates the large-diameter motor fibers before the small ones, a recruitment order opposite the physiological recruitment of myelinated motor fibers during voluntary muscle contraction. Current methods to solve this problem require a long-duration stimulus pulse which could lead to electrode corrosion and nerve damage. The hypothesis that the excitability of specific diameter fibers can be suppressed by reshaping the profile of extracellular potential along the axon using multiple electrodes is tested using computer simulations in two different volume conductors. Simulations in a homogenous medium with a nine-contact electrode array show that the current excitation threshold (I-th) of large diameter axons (13-17 mum) (0.6-3.0 mA) is higher than that of small-diameter axons (2-7 mum) (0.4-0.7 mA) with 200-mum axon-electrode distance and 10-mus stimulus pulse. The electrode array is also tested in a three-dimensional finite-element model of the sacral root model of dog (ventral root of S3). A single cathode activates large-diameter axons before activating small axons. However, a nine-electrode array activates 50% of small axons while recruiting only 10% of large ones and activates 90% of small axons while recruiting only 50% of large ones. The simulations suggest that the near-physiological recruitment order can be achieved with an electrode array. The diameter selectivity of the electrode array can be controlled by the electrode separation and the method is independent of pulse width.