Patterned optical activation of Channelrhodopsin II expressing retinal ganglion cells

Neuroprosthetic retinal interfaces depend upon the ability to bypass the damaged photoreceptor layer and directly activate populations of retinal ganglion cells (RGCs). Current approaches to this task largely rely on electrode array implants. We are pursuing an alternative, light-based approach towards direct activation of the RGCs, by artificially causing them to express Channelrhodopsin II (ChR2), a light-gated cation channel. In addition to being non-contact, optical techniques lend themselves relatively easily to a variety of technologies for achieving patterned stimulation with high temporal and spatial resolution. In early studies, we are using viral vectors to obtain wide spread expression of ChR2 in rat retinas, and have developed a system capable of controlled large-scale, flexible stimulation of the retinal tissue with high temporal accuracy through adaptations of video projection technology. Finally, we demonstrate a PC-based wearable system that can perform the image processing transformations required for optical retinal neuroprosthetic interfaces in real time.