SELECTIVE ACTIVATION OF SMALL MOTOR AXONS BY QUASITRAPEZOIDAL CURRENT PULSES
SELECTIVE ACTIVATION OF SMALL MOTOR AXONS BY QUASITRAPEZOIDAL CURRENT PULSES
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DOI：
10.1109/10.76383
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发表时间：
1991-02-01
影响因子：
4.6
通讯作者：
MORTIMER, JT
中科院分区：
文献类型：
--
作者：
FANG, ZP;MORTIMER, JT
我们已经发现了一种方法，可以电激活较小的神经纤维，而不会激活同一神经干中的较大纤维。 该方法利用了这样一个事实，即在较大的纤维中比在较小的纤维中具有更少的膜超极化来阻断动作电位。 在我们的神经刺激系统中，通过三极袖状电极传递准梯形电流脉冲，以通过膜超极化实现差异阻滞。 具有方形前沿、350 μ s平台和指数拖尾相位的准梯形脉冲确保了传播动作电位的阻断，并防止了阳极断裂激发的发生。 三极袖带电极设计限制了袖带内的电流流动，因此消除了由于“虚拟阴极”造成的不必要的神经刺激。“实验在13只猫身上进行。 将袖带电极放置在腓肠肌内侧神经上。 复合和单纤维动作电位记录从L7腹根细丝。 结果表明，较大的α运动轴突可以在较低的电流水平下比较小的α运动轴突被阻断，并且所有的α纤维可以在较低的电流水平下比γ纤维被阻断。 统计学分析表明，阻滞阈值与轴突传导速度或纤维直径相关。 该方法可用于生理学实验和神经假体，以实现运动或感觉系统中从小到大的募集顺序。
We have found a method to activate electrically smaller nerve fibers without activating larger fibers in the same nerve trunk. The method takes advantage of the fact that action potentials are blocked with less membrane hyperpolarization in larger fibers than in smaller fibers. In our nerve stimulation system, quasitrapezoidal-shaped current pulses were delivered through a tripolar cuff electrode to effect differential block by membrane hyperpolarization. The quasitrapezoidal-shaped pulses with a square leading edge, a 350-mu-s plateau, and an exponential trailing phase ensured the block of propagating action potentials and prevented the occurrence of anodal break excitation. The tripolar cuff electrode design restricted current flow inside the cuff and thus eliminated the undersired nerve stimulation due to a "virtual cathode." Experiments were performed on 13 cats. The cuff electrode was placed on the medial gastrocnemius nerve. Both compound and single fiber action potentials were recorded from L7 ventral root filaments. The results demonstrated that larger alpha motor axons could be blocked at lower current levels than smaller alpha motor axons, and that all alpha fibers could be blocked at lower current levels than gamma fibers. A statistical analysis indicated that the blocking threshold was correlated with the axonal conduction velocity or fiber diameter. This method could be used in physiological experiments and neural prostheses to achieve a small-to-large recruitment order in motor or sensory systems.