Center for Innovative Visual Rehabilitation, Boston VA Healthcare System, 150 South Huntington Ave, Boston, MA 02130, USA.
J Neural Eng. 2011 Jun;8(3):035005. doi: 10.1088/1741-2560/8/3/035005. Epub 2011 May 18.
Retinal prostheses aim to restore functional vision to those blinded by outer retinal diseases using electric stimulation of surviving retinal neurons. The ability to replicate the spatiotemporal pattern of ganglion cell spike trains present under normal viewing conditions is presumably an important factor for restoring high-quality vision. In order to replicate such activity with a retinal prosthesis, it is important to consider both how visual information is encoded in ganglion cell spike trains, and how retinal neurons respond to electric stimulation. The goal of the current review is to bring together these two concepts in order to guide the development of more effective stimulation strategies. We review the experiments to date that have studied how retinal neurons respond to electric stimulation and discuss these findings in the context of known retinal signaling strategies. The results from such in vitro studies reveal the advantages and disadvantages of activating the ganglion cell directly with the electric stimulus (direct activation) as compared to activation of neurons that are presynaptic to the ganglion cell (indirect activation). While direct activation allows high temporal but low spatial resolution, indirect activation yields improved spatial resolution but poor temporal resolution. Finally, we use knowledge gained from in vitro experiments to infer the patterns of elicited activity in ongoing human trials, providing insights into some of the factors limiting the quality of prosthetic vision.
视网膜假体旨在通过对存活的视网膜神经元进行电刺激，为那些因外视网膜疾病而失明的人恢复功能性视力。复制正常视觉条件下神经节细胞尖峰活动的时空模式的能力，大概是恢复高质量视力的一个重要因素。为了用视网膜假体复制这种活动，重要的是要考虑视觉信息是如何在神经节细胞尖峰活动中编码的，以及视网膜神经元对电刺激的反应如何。本综述的目的是将这两个概念结合起来，以指导更有效的刺激策略的发展。我们回顾了迄今为止研究视网膜神经元对电刺激反应的实验，并在已知的视网膜信号传递策略的背景下讨论了这些发现。这些体外研究的结果揭示了用电刺激直接激活神经节细胞（直接激活）与激活神经节细胞的前突触神经元（间接激活）相比的优缺点。虽然直接激活允许高时间分辨率但低空间分辨率，但间接激活则提高了空间分辨率但降低了时间分辨率。最后，我们利用从体外实验中获得的知识来推断正在进行的人类试验中诱发电活动的模式，为理解限制假体视力质量的一些因素提供了线索。
