Automatic Identification of Axon Bundle Activation for Epiretinal Prosthesis.
Automatic Identification of Axon Bundle Activation for Epiretinal Prosthesis.
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DOI：
10.1109/tnsre.2021.3128486
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Mitra S
中科院分区：
文献类型：
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作者：
Tandon P;Bhaskhar N;Shah N;Madugula S;Grosberg L;Fan VH;Hottowy P;Sher A;Litke AM;Chichilnisky EJ;Mitra S
视网膜假体必须能够以选择性的方式激活细胞，才能恢复高保真视力。然而，通过电刺激轴突束而无意中激活遥远的视网膜神经节细胞(RGC)会产生不规则和控制不良的感觉，限制了人工视觉。在这项工作中，我们旨在为双向视网膜前假体检测轴突束激活的问题提供一种算法解决方案。该算法利用电记录来确定刺激电流的幅度，超过这个幅度就会发生轴突束激活。束激活被定义为对具有未知胞体和感受野位置的视网膜节细胞的轴突刺激，通常超出电极阵列。该方法利用电诱发棘波的时空特性来克服检测小轴突棘波的挑战。通过在猕猴视网膜上进行大规模、单电极和短脉冲的体外刺激和记录实验，通过比较算法和手动识别的束激活阈值，验证了该算法的有效性。对于88%的被分析电极，算法识别的阈值与人工识别的阈值在±10%以内，相关系数为0.95。这项工作提出了一种简单、准确和有效的算法来检测视网膜前假体中轴突束的激活。该算法可以在未来的视网膜前假体中以闭环的方式使用，以减少与束激活相关的控制不良的视觉感知。通过轴突刺激激活远端细胞可能会发生在其他类型的视网膜植入物和皮质植入物中，因此该方法可能会广泛适用。
Retinal prostheses must be able to activate cells in a selective way in order to restore high-fidelity vision. However, inadvertent activation of far-away retinal ganglion cells (RGCs) through electrical stimulation of axon bundles can produce irregular and poorly controlled percepts, limiting artificial vision. In this work, we aim to provide an algorithmic solution to the problem of detecting axon bundle activation with a bi-directional epiretinal prostheses. The algorithm utilizes electrical recordings to determine the stimulation current amplitudes above which axon bundle activation occurs. Bundle activation is defined as the axonal stimulation of RGCs with unknown soma and receptive field locations, typically beyond the electrode array. The method exploits spatiotemporal characteristics of electrically-evoked spikes to overcome the challenge of detecting small axonal spikes. The algorithm was validated using large-scale, single-electrode and short pulse, ex vivo stimulation and recording experiments in macaque retina, by comparing algorithmically and manually identified bundle activation thresholds. For 88% of the electrodes analyzed, the threshold identified by the algorithm was within ±10% of the manually identified threshold, with a correlation coefficient of 0.95. This works presents a simple, accurate and efficient algorithm to detect axon bundle activation in epiretinal prostheses. The algorithm could be used in a closed-loop manner by a future epiretinal prosthesis to reduce poorly controlled visual percepts associated with bundle activation. Activation of distant cells via axonal stimulation will likely occur in other types of retinal implants and cortical implants, and the method may therefore be broadly applicable.