Electric stimulation parameters for an epi-retinal prosthesis
Electric stimulation parameters for an epi-retinal prosthesis
复制标题
视网膜前假体的电刺激参数
DOI：
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
A. Grumet
中科院分区：
文献类型：
--
作者：
A. Grumet
这项工作的目的是促进视网膜外假体的开发，有朝一日可以使因视网膜色素变性等外视网膜变性失明的患者恢复视力。通过刺激视网膜表面数十或数百个不同区域的存活细胞，假体可以以与计算机屏幕上呈现图像相同的方式传达视觉场景。然而，视网膜神经元的解剖和功能排列对这种方法的成功构成了潜在的障碍。对神经节细胞轴突的刺激（位于刺激电极与其预期目标之间的视神经纤维层中，并且源自相对分散的外围区域）可能会传达外围模糊的感觉，从而降低图像的实用性。受大脑和周围神经刺激相关研究结果的启发，在离体兔子视网膜上进行了实验，以确定是否可以通过将刺激电场垂直于轴突路径来提高神经节细胞轴突的兴奋阈值。使用定制设计的设备，通过微型制造的圆盘电极阵列测量刺激的轴突（可能还有树突）阈值，每个圆盘电极的直径为十微米。电极单独驱动，相对于远距离返回（单极刺激）和成对驱动（双极刺激），沿纤维（纵向）或跨纤维（横向）定向。测量双极电极对的两个极之间的一系列纤维位移的横向阈值，并在每种情况下与较近的极的单极阈值进行比较。当其中一个极直接位于光纤上方时，横向/单极阈值比率接近一致，但随着双极对中心的改善而迅速上升。在相同的位移范围内，纵向/单极阈值比率接近一致。与其他人之前的工作一样，垂直刺激场的阈值最高。这一结果的实际应用将需要最大限度地减少纵向边缘场的电极设计。论文导师：John L. Wyatt, Jr. 职称：电气工程教授
This work was undertaken to contribute to the development of an epi-retinal prosthesis which may someday restore vision to patients blinded by outer retinal degenerations like retinitis pigmentosa. By stimulating surviving cells in tens or hundreds of distinct regions across the retinal surface, the prosthesis might convey the visual scene in the same way that images are represented on a computer screen. The anatomical and functional arrangement of retinal neurons, however, poses a potential obstacle to the success of this approach. Stimulation of ganglion cell axons—which lie in the optic nerve fiber layer between stimulating electrodes and their intended targets, and which originate from a relatively diffuse peripheral region—would probably convey the perception of a peripheral blur, detracting from the usefulness of the imagery. Inspired by related findings in brain and peripheral nerve stimulation, experiments were performed in the isolated rabbit retina to determine if excitation thresholds for ganglion cell axons could be raised by orienting the stimulating electric field perpendicularly to the axons’ path. Using a custom-designed apparatus, axon (and possibly dendrite) thresholds were measured for stimulation through a micro-fabricated array of disk electrodes each having a diameter of ten microns. The electrodes were driven singly versus a distant return (monopolar stimulation) and in pairs (bipolar stimulation) oriented along fibers (longitudinal orientation) or across fibers (transverse orientation). Transverse thresholds were measured for a range of fiber displacements between the two poles of the bipolar electrode pair, and compared in each case with the monopolar threshold for the closer pole. Transverse/monopolar threshold ratios were near unity when one of the poles was directly over the fiber, but rose rapidly with improved centering of the bipolar pair. Longitudinal/monopolar threshold ratios were near unity over the same range of displacements. As in previous work by others, thresholds were highest for perpendicular stimulating fields. Practical application of this result will require electrode designs which minimize longitudinal fringing fields. Thesis Supervisor: John L. Wyatt, Jr. Title: Professor of Electrical Engineering
影响因子：
--
作者：
STONE, JL;BARLOW, WE;MILAM, AH
通讯作者：
MILAM, AH
影响因子：
1.8
作者：
Zrenner, E;Stett, A;Haemmerle, H
通讯作者：
Haemmerle, H
用焦点电极对神经进行细胞外电刺激的分析理论。
影响因子：
3.4
作者：
Rubinstein,JT;Spelman,FA
通讯作者：
Spelman,FA