Neurosciences PhD Program, Stanford University, Stanford, CA, United States of America.
School of Medicine, Stanford University, Stanford, CA, United States of America.
J Neural Eng. 2022 Dec 19;19(6). doi: 10.1088/1741-2552/aca5b5.
. Vision restoration with retinal implants is limited by indiscriminate simultaneous activation of many cells and cell types, which is incompatible with reproducing the neural code of the retina. Recent work has shown that primate retinal ganglion cells (RGCs), which transmit visual information to the brain, can be directly electrically activated with single-cell, single-spike, cell-type precision - however, this possibility has never been tested in the human retina. In this study we aim to characterize, for the first time, direct in situ extracellular electrical stimulation of individual human RGCs.. Extracellular electrical stimulation of individual human RGCs was conducted in three human retinas ex vivo using a custom large-scale, multi-electrode array capable of simultaneous recording and stimulation. Measured activation properties were compared directly to extensive results from macaque.. Precise activation was in many cases possible without activating overlying axon bundles, at low stimulation current levels similar to those used in macaque. The major RGC types could be identified and targeted based on their distinctive electrical signatures. The measured electrical activation properties of RGCs, combined with a dynamic stimulation algorithm, was sufficient to produce an evoked visual signal that was nearly optimal given the constraints of the interface.. These results suggest the possibility of high-fidelity vision restoration in humans using bi-directional epiretinal implants.
视网膜植入物的视力恢复受到同时激活许多细胞和细胞类型的限制，这与重现视网膜的神经编码不兼容。最近的工作表明，传递视觉信息到大脑的灵长类动物视网膜神经节细胞 (RGC) 可以通过单细胞、单尖峰、细胞类型精度进行直接电激活 - 然而，这种可能性从未在人类视网膜中进行过测试。在这项研究中，我们旨在首次对个体人类 RGC 进行直接原位细胞外电刺激。
在三个离体人视网膜中使用定制的大规模多电极阵列进行了个体人类 RGC 的细胞外电刺激，该阵列能够同时进行记录和刺激。测量的激活特性与猕猴的广泛结果进行了直接比较。
在不激活覆盖的轴突束的情况下，在类似于猕猴中使用的低刺激电流水平下，可以在许多情况下进行精确的激活。可以根据其独特的电签名来识别和靶向主要的 RGC 类型。RGC 的测量电激活特性，结合动态刺激算法，足以产生几乎最佳的诱发视觉信号，考虑到接口的限制。
这些结果表明，使用双向视网膜上植入物有可能实现人类的高保真视力恢复。
