Abstract
We recently developed an electrical stimulation method for retinal prosthesis named Suprachoroidal-Transretinal Stimulation (STS, Kanda et al., IOVS 2004). It was shown that a monophasic pulse of STS focally applied between an anode on the sclera and an intravitreal cathode (inward STS) evokes well-localized field potentials in the superior colliculus (SC) of both normal and retinal dystrophic rats. When the outward STS was delivered by reversing the stimulus polarity, the threshold was much higher than that of the inward STS. To avoid the electrochemical retinal damage due to charge imbalances, a biphasic pulse must be used in the STS-based artificial retina. Thus, we examined the SC response to biphasic STS comparing with that to the monophasic STS. In normal rats, Electrically-Evoked Potentials (EEP) to the single biphasic or monophasic STS were recorded from the SC contralateral to the stimulated eye. In response to the biphasic STS the late oscillatory components of EEP were greatly suppressed, although the early component of EEP was smaller in amplitude than that to the monophasic inward STS. Thus, biphasic STS may be beneficial for generating artificial perception with high temporal resolution, as well as being harmless. [J Physiol Sci. 2006;56 Suppl:S175]
