Hadjinicolaou Alex E, Werginz Paul, Lee Jae-Ik, Fried Shelley I
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3529-3532. doi: 10.1109/EMBC44109.2020.9175276.
Retinal microprostheses strive to evoke a sense of vision in individuals blinded by outer retinal degenerative diseases, by electrically stimulating the surviving retina. It is widely suspected that a stimulation strategy that can selectively activate different retinal ganglion cell types will improve the quality of evoked phosphenes. Previous efforts towards this goal demonstrated the potential for selective ON and OFF brisk-transient cell activation using high-rate (2000 pulses per second, PPS) stimulation. Here, we build upon this earlier work by testing an additional rate of stimulation and additional cell populations. We find considerable variability in responses both within and across individual cell types, but show that the sensitivity of a ganglion cell to repetitive stimulation is highly correlated to its single-pulse threshold. Consistent with this, we found thresholds for both stimuli to be correlated to soma size, and thus likely mediated by the properties of the axon initial segment. The ultimate efficacy of high-rate stimulation will likely depend on several factors, chief among which are (a) the residual ganglion types, and (b) the stimulation frequency.
视网膜微假体致力于通过电刺激存活的视网膜，使因外层视网膜退行性疾病而失明的个体产生视觉感受。人们普遍怀疑，一种能够选择性激活不同视网膜神经节细胞类型的刺激策略将提高诱发光幻视的质量。此前为实现这一目标所做的努力表明，使用高速率（每秒2000脉冲，PPS）刺激有选择性地激活ON和OFF快速瞬态细胞的潜力。在此，我们在这项早期工作的基础上，测试了额外的刺激速率和其他细胞群体。我们发现，在单个细胞类型内部和之间的反应存在相当大的变异性，但表明神经节细胞对重复刺激的敏感性与其单脉冲阈值高度相关。与此一致的是，我们发现两种刺激的阈值都与胞体大小相关，因此可能由轴突起始段的特性介导。高速率刺激的最终效果可能取决于几个因素，其中主要的因素是（a）残留的神经节细胞类型，以及（b）刺激频率。
