A computational model for estimating recruitment of primary afferent fibers by intraneural stimulation in the dorsal root ganglia.
A computational model for estimating recruitment of primary afferent fibers by intraneural stimulation in the dorsal root ganglia.
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DOI：
10.1088/1741-2560/8/5/056009
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发表时间：
2011-10
影响因子：
4
通讯作者：
Weber DJ
中科院分区：
文献类型：
--
作者：
Bourbeau DJ;Hokanson JA;Rubin JE;Weber DJ
初级传入微刺激已被提出作为用于激活皮肤和肌肉传入纤维以在肢体丧失或周围神经病变后恢复触觉和本体感觉反馈的方法。通过在背根神经节（DRG）植入微电极阵列，可以直接进入大量的初级传入纤维，这为刺激不同的感觉纤维群提供了紧凑而稳定的靶点。为了深入了解影响激活的初级传入神经的数量和类型的因素，我们开发了一个计算模型，模拟猫L7背根神经节中纤维的募集。该模型由两部分组成。第一部分是单纤维模型，用于描述电流-距离关系，并基于McIntyre-Richardson-Grill（MRG）模型的兴奋性。第二部分使用单纤维模型的结果和纤维尺寸分布的公布数据，预测招募给定数量的纤维作为刺激强度的函数的概率。准确招募一条纤维的强度范围约为0.5 - 5 μA（每相0.1 - 1 nC）;准确招募一条纤维的概率最大的刺激强度为2.3 μA。然而，在2.3 μA时，也可以招募多达三根纤维，尽管概率较低。用群体模型测试了高达6 μA的刺激幅度，结果表明，随着幅度的增加，招募的纤维数量呈指数增加。由该模型预测的阈值振幅的分布是类似于以前报道的在体内实验。最后，该模型表明，中等直径的纤维（7.3 - 11.5 μm）可能比大直径的纤维（12.8 - 16 μm）更有可能被招募。该模型可用于有效地测试一系列刺激参数和神经形态，以补充电生理学实验的结果，并有助于设计用于神经接口的微电极阵列。
Primary afferent microstimulation has been proposed as a method for activating cutaneous and muscle afferent fibers to restore tactile and proprioceptive feedback after limb loss or peripheral neuropathy. Large populations of primary afferent fibers can be accessed directly by implanting microelectrode arrays in the dorsal root ganglia (DRG), which provide a compact and stable target for stimulating a diverse group of sensory fibers. To gain insight into factors affecting the number and types of primary afferents activated, we developed a computational model that simulates recruitment of fibers in the feline L7 DRG. The model comprises two parts. The first part is a single-fiber model used to describe the current-distance relation and was based on the McIntyre-Richardson-Grill (MRG) model for excitability. The second part uses the results of the singe-fiber model and published data on fiber size distributions, to predict the probability of recruiting a given number of fibers as a function of stimulus intensity. The range of intensities over which exactly one fiber was recruited was approximately 0.5 – 5 μA (0.1 – 1 nC per phase); the stimulus intensity at which the probability of recruiting exactly one fiber was maximized was 2.3 μA. However, at 2.3 μA, it was also possible to recruit up to three fibers, albeit with a lower probability. Stimulation amplitudes up to 6 μA were tested with the population model, which showed that as the amplitude increased, the number of fibers recruited increased exponentially. The distribution of threshold amplitudes predicted by the model was similar to that previously reported by in vivo experimentation. Finally, the model suggested that medium-diameter fibers (7.3 – 11.5 μm) may be recruited with much greater probability than large-diameter fibers (12.8 – 16 μm). This model may be used to efficiently test a range of stimulation parameters and nerve morphologies to complement results from electrophysiology experiments and to aid in the design of microelectrode arrays for neural interfaces.