The effect of waveform asymmetry on perception with epiretinal prostheses.
The effect of waveform asymmetry on perception with epiretinal prostheses.
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波形不对称的影响对视网膜假体感知的影响。
DOI：
10.1088/1741-2552/aba07e
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发表时间：
2020-07-24
影响因子：
4
通讯作者：
Weiland JD
中科院分区：
文献类型：
--
作者：
Haji Ghaffari D;Finn KE;Jeganathan VSE;Patel U;Wuyyuru V;Roy A;Weiland JD
视网膜假体植入物有助于改善因光感受器变性而失明的患者的视力。视网膜植入用户报告称，光感知和执行视觉任务有所改善，但由于视网膜激活的精度较低，他们感知形状和字母的能力受到限制，而轴突刺激和高感知阈值又加剧了这种情况。我们实验室之前的一项体外研究使用钙成像来测量小鼠视网膜神经节细胞 (RGC) 对电刺激的反应的空间活动。基于这项研究，对称阳极优先 (SA) 刺激有效避免了轴突激活，而非对称阳极优先刺激 (AA) 的持续时间比（阳极与阴极阶段的比率）大于 10，显着降低了 RGC 激活阈值。在临床中应用这些新颖的刺激策略可以提高感知精度并改善患者的整体治疗结果。我们结合人体测试和计算模型，进一步研究 SA 和 AA 刺激对 RGC 视网膜前刺激的感知形状和阈值的影响。三名 Argus II 参与者的阈值测量表明，与标准对称阴极优先 (SC) 脉冲相比，AA 刺激可以增加感知概率，并且可以通过添加相间间隙 (IPG) 来增强这种效果。与 SC 脉冲相比，我们的计算机 RGC 模型预测 AA 和不对称阴极优先 (AC) 刺激的阈值较低。这种效应在较短的脉冲宽度下更为明显。短脉冲持续时间 (≤ 0.12 ms) 降低阈值最有效的脉冲是小持续时间比 (≤ 5) 和长 IPG (≥ 2 ms) 的 AA 刺激。对于 0.5 ms 脉冲持续时间，使用长于 0.5 ms 的 IPG 进行 SC 刺激或具有较大持续时间比 (≥ 20) 的不对称刺激对于降低阈值最为有效。光幻视形状分析并未揭示 SA 刺激感知伸长的显着变化。然而，与标准脉冲相比，一名参与者在 AA 刺激下的感知大小显着增加 (P < 0.01)。包括不对称波形功能将为视网膜植入物的优化和个性化适配提供更灵活的选择。
Retinal prosthetic implants have helped improve vision in patients blinded by photoreceptor degeneration. Retinal implant users report improvements in light perception and performing visual tasks, but their ability to perceive shapes and letters is limited due to the low precision of retinal activation, which is exacerbated by axonal stimulation and high perceptual thresholds. A previous in vitro study in our lab used calcium imaging to measure the spatial activity of mouse retinal ganglion cells (RGCs) in response to electrical stimulation. Based on this study, symmetric anodic-first (SA) stimulation effectively avoided axonal activation and asymmetric anodic-first stimulation (AA) with duration ratios (ratio of the anodic to cathodic phase) greater than 10 reduced RGC activation thresholds significantly. Applying these novel stimulation strategies in clinic may increase perception precision and improve the overall patient outcomes. We combined human subject testing and computational modeling to further examine the effect of SA and AA stimuli on perception shapes and thresholds for epiretinal stimulation of RGCs. Threshold measurement in three Argus II participants indicated that AA stimulation could increase perception probabilities compared to a standard symmetric cathodic-first (SC) pulse, and this effect can be intensified by addition of an interphae gap (IPG). Our in silico RGC model predicts lower thresholds with AA and asymmetric cathodic-first (AC) stimuli compared to a SC pulse. This effect was more pronounced at shorter pulse widths. The most effective pulse for threshold reduction with short pulse durations (≤ 0.12 ms) was AA stimulation with small duration ratios (≤ 5) and long IPGs (≥ 2 ms). For the 0.5 ms pulse duration, SC stimulation with IPGs longer than 0.5 ms, or asymmetric stimuli with large duration ratios (≥ 20) were most effective in threshold reduction. Phosphene shape analysis did not reveal a significant change in percept elongation with SA stimulation. However, there was a significant increase in percept size (P < 0.01) with AA stimulation compared to the standard pulse in one participant. Including asymmetric waveform capability will provide more flexible options for optimization and personalized fitting of retinal implants.
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影响因子：
2.8
作者：
McKay, CM;Henshall, KR
通讯作者：
Henshall, KR
DOI：
10.4196/kjpp.2015.19.2.167
发表时间：
2015-03
期刊：
The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology
影响因子：
--
作者：
Ahn KN;Ahn JY;Kim JH;Cho K;Koo KI;Senok SS;Goo YS
通讯作者：
Goo YS
DOI：
10.1109/tnsre.2006.870488
发表时间：
2006-03-01
影响因子：
4.9
作者：
Schiefer, MA;Grill, WM
通讯作者：
Grill, WM
影响因子：
4.4
作者：
Nanduri, Devyani;Fine, Ione;Weiland, James D.
通讯作者：
Weiland, James D.
影响因子：
4.4
作者：
Jensen, RJ;Ziv, OR;Rizzo, JF
通讯作者：
Rizzo, JF