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Wun-Ting Li; Asynchronous Electrical Stimulation Improves Spatial Resolution with Subretinal Electrodes. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3231.
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Electrical stimulation using retinal prosthesis has been a promising strategy for helping patients with retinal degenerative diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). However, multiple electrodes applying stimulation simultaneously in retinal prosthesis decreases spatial resolution, which is one of the major challenges. In this study, we recorded the spiking response of retinal ganglion cells (RGCs) under two neighboring stimulating electrodes either applying electrical stimulations synchronously or asynchronously to assess the crosstalk effect.
The retinas dissected from adult C57BL/6J mice were placed onto a microelectrode array (MEA) with the photoreceptor (bottom) side down. Whole-cell current clamp recordings were used to record the spiking responses of RGCs. An anodic-biphasic voltage pulse from 0.1 V to 2.4 V was delivered from one electrode or two neighboring electrodes synchronously or asynchronously.
When the dominated stimulating electrode (under the recorded cell) and the subordinated stimulating electrode (the neighbor electrode) stimulated the RGC synchronously, the threshold voltage required to activate the RGC was lowered comparing to the dominated stimulating electrode alone. In the dominated stimulating electrode leading experiment, the spikes resulting from the subordinated stimulating electrode were significantly less than the one from the subordinated electrode alone. In the subordinated stimulating electrode leading experiment, the spikes resulting from the dominated stimulating electrode decreased as the delay time of the dominated stimulating electrode increased. By separating these recorded RGCs into two groups based on their membrane potential (MP) changes, the cells with hyperpolarized MP had less spiking responses than the cells with depolarized MP after stimulation.
Although both neighboring electrodes stimulating the RGC synchronously can decrease the threshold voltage, nearby cells were also stimulated by the neighboring electrodes, which reducing the spatial resolution . In this study, we demonstrate that two neighboring electrodes stimulated the RGC asynchronously can effectively prevent cells from generating unwanted spikes. Among these RGCs, cells that exhibit long-term hyperpolarization after stimulation were more difficult to generate the second spike by the neighbor electrode.
This is a 2021 ARVO Annual Meeting abstract.
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