Abstract
As a method of retinal prosthesis we newly developed suprachoroidal-transretinal stimulation (STS), in which electrical current passed between scleral electrode and vitreous electrode (Kanda et al. '04). Previously we reported the spatial properties of STS (Kanda et al., PSJ meeting '05), however the recorded neurons with the receptive fields close to the scleral electrode were few. Here, we enlarged the sampling especially within 2° from the scleral electrode and investigated whether STS can activate neurons in the localized retinal area. 105 unit activities of relay cells in the lateral geniculate nucleus were recorded from 12 adult cats. The response probability to STS of various current intensities between 50-500 μA was examined for each unit, and its relationship with the distance from the electrode was analyzed. It was confirmed that the response probability depended on the distance from the electrode. As the intensity decreased, the units with high response probability limited near the electrode. For example, at 100 μA of STS, the units with the probability over 80% were within 2.5° from the electrode. The median of the probability of the units within 1° was the highest among those with further distance when STS of 150 μA or 200 μA was applied. These results suggested that the retinal activation by STS can be localized near the electrode with adequate current intensity. [J Physiol Sci. 2006;56 Suppl:S175]
