Effect of anodic-first asymmetric pulse stimulation in retinal prostheses

Abstract

To find out more effective parameter of electrical stimulation, we examined the effect of an asymmetric pulse in retinal prostheses electrophysiologically. An anodic-first biphasic current pulse, with both symmetric and asymmetric pulses, was applied to the rat's eye using a stimulating electrode. The symmetric pulse had a duration of 0.5 ms and a stimulation current amplitude of 0.1 mA. The pulse duration of the anodal phase was modified to create an asymmetric pulse, and the charge balance was adjusted by changing the amplitude of the electrical current. Evoked potentials were recorded from the superior colliculus. All rats, the pulse duration of the anodal phase was shorter, and as the current amplitude increased, the amplitude of evoked potential increased significantly. The results suggest that the asymmetric pulse with a shorter pulse duration of the anodal phase and a higher current amplitude induces a greater response than the symmetric pulse.