ABSTRACT This review evaluates the potential of optogenetic methods for the stimulation of the auditory nerve and assesses the feasability of optogenetic cochlear implants (CIs). It provides an overview of all critical steps like opsin targeting strategies, how opsins work, how their function can be modeled and included in neuronal models and the properties of light sources available for optical stimulation. From these foundations, quantitative estimates for the number of independent stimulation channels and the temporal precision of optogenetic stimulation of the auditory nerve are derived and compared with state-of-the-art electrical CIs. We conclude that optogenetic CIs have the potential to increase the number of independent stimulation channels by up to one order of magnitude to about 100, but only if light sources are able to deliver confined illumination patterns independently and parallelly. Already now, opsin variants like ChETA and Chronos enable driving of the auditory nerve up to rates of 200 spikes/s, close to the physiological value of their maximum sustained firing rate. Apart from requiring 10 times more energy than electrical stimulation, optical CIs still face major hurdles concerning the safety of gene transfection and optrode array implantation, for example, before becoming an option to replace electrical CIs.

中文翻译：

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耳蜗的光遗传学刺激——机制、测量和第一个模型的回顾

摘要 本综述评估了光遗传学方法刺激听神经的潜力，并评估了光遗传学人工耳蜗 (CI) 的可行性。它概述了所有关键步骤，如视蛋白靶向策略、视蛋白的工作原理、其功能如何建模并包含在神经元模型中，以及可用于光刺激的光源的特性。从这些基础上，推导出独立刺激通道数量的定量估计和听觉神经光遗传学刺激的时间精度，并与最先进的电 CI 进行比较。我们得出结论，光遗传学 CI 有可能将独立刺激通道的数量增加一个数量级，达到约 100 个，但前提是光源能够独立和并行地提供有限的照明模式。现在，ChETA 和 Chronos 等视蛋白变体已经能够以高达 200 脉冲/秒的速率驱动听觉神经，接近其最大持续放电率的生理值。除了需要比电刺激多 10 倍的能量外，光学 CI 在成为替代电 CI 的选择之前，仍然面临有关基因转染和光电极阵列植入安全性的主要障碍。