PROJECT TITLE :

Optimizing the Electrical Stimulation of Retinal Ganglion Cells

ABSTRACT:

Epiretinal prostheses aim to restore visual perception in the blind through electrical stimulation of surviving retinal ganglion cells (RGCs). Whereas the effects of many waveform parameters (e.g., part length) on stimulation efficacy have been described, their relative influence remains unclear. Additional, morphological variations between RGC categories represent a key supply of variability that has not been accounted for in previous studies. Here we tend to investigate the result of electrical stimulus waveform parameters on activation of an anatomically homogenous RGC population and describe a technique for identifying optimal stimulus parameters to attenuate the specified stimulus charge. Responses of rat A2-sort RGCs to a broad array of biphasic stimulation parameters, delivered via an epiretinal stimulating electrode (two hundred$,times,$ 200 $mu$ m) were recorded using whole-cell current clamp techniques. The information demonstrate that for rectangular charge-balanced stimuli, phase period and polarity have the largest effect on threshold current amplitude—cells were most attentive to cathodic-initial pulses of short section duration. Waveform asymmetry and increases in interphase interval any reduced thresholds. Using optimal waveform parameters, we observed a drop in stimulus efficacy with increasing stimulation frequency. This was a lot of pronounced for massive cells. Our results demonstrate that careful choice of electrical waveform parameters can considerably improve the efficacy of electrical stimulation and therefore the efficacy of implantable neurostimulators for the retina.