In conventional electrical visual prostheses, current spread produces diffuse patches of response, whereas optical stimulation of gold nanorods bound to genetically modified photoreceptors has recently shown great promise. Here we demonstrate that Retinal Ganglion Cells (RGCs) can be optically stimulated directly via gold nanorods without the need for genetic modification. Single-cell responses from explanted rat retinae exposed to gold nanorods were recorded by patch clamping. Near infrared laser pulses of 100 and 500 µs evoked robust stimulation, whilst longer 200 ms pulses were biased towards OFF-type inhibition. Differential modulation of ON- and OFF-type RGCs is essential for future high-acuity prostheses.

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James M. Begeng, Wei Tong, Blanca del Rosal, Michael Ibbotson, Tatiana Kameneva, and Paul R. Stoddart, "Nanoparticle-enhanced infrared neural stimulation and inhibition of ganglion cells in the rat retina," Proc. SPIE PC12366, Optogenetics and Optical Manipulation 2023, PC1236607 (Presented at SPIE BiOS: January 29, 2023; Published: 17 March 2023); https://doi.org/10.1117/12.2657688.6321586815112.