Takahashi Hirokazu, Nakao Masayuki, Kaga Kimitaka
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
IEEE Trans Biomed Eng. 2007 Mar;54(3):563-9. doi: 10.1109/TBME.2006.890509.
Neural prostheses for restoring lost functions can benefit from selective activation of nerves with limited number and density of electrodes. Here, we show by simulations and animal experiments that multipoint simultaneous stimulation with a surface electrode array can selectively activate nerves in a bundle at a desired location in between the array or at a desired depth, which are referred to as lateral or depth-wise gating stimulation, respectively. The stimulation broadly generates action potentials with cathodic source electrodes, and simultaneously blocks unnecessary propagation with downstream anodic gate electrodes. In general, stimulation with a small diameter electrode can affect a nearly hemispherical region, while a large electrode is effective at a more vertically compressed region, i.e., a surface of nerve bundle. The gating stimulation takes advantage of the size effects by utilizing an asymmetrical electrode array. The array of the lateral gating stimulation is designed to have four electrodes; a pair of large source electrodes and a pair of small gate electrodes. The depth-wise gating stimulation array consists of two electrodes; a large gate and small source electrodes. The simulation first demonstrated that appropriate combination of currents at the source and gate electrodes can change recruitment patterns of nerves with lateral or depth-wise selectivity as desired. We then applied the lateral gating stimulation on the rat spinal cords and obtained a preliminary support for the feasibility.
用于恢复丧失功能的神经假体可以受益于使用电极数量和密度有限的情况下对神经进行选择性激活。在此，我们通过模拟和动物实验表明，使用表面电极阵列进行多点同步刺激可以在阵列之间的期望位置或期望深度选择性激活一束神经，分别称为横向或深度门控刺激。刺激通过阴极源电极广泛产生动作电位，同时用下游阳极门控电极阻断不必要的传播。一般来说，使用小直径电极进行刺激可以影响近半球形区域，而大电极在更垂直压缩的区域（即神经束表面）有效。门控刺激通过利用不对称电极阵列利用了尺寸效应。横向门控刺激阵列设计有四个电极；一对大的源电极和一对小的门控电极。深度门控刺激阵列由两个电极组成；一个大的门控电极和小的源电极。模拟首先表明，源电极和门控电极处电流的适当组合可以根据需要改变具有横向或深度选择性的神经募集模式。然后我们在大鼠脊髓上应用了横向门控刺激，并获得了对其可行性的初步支持。
