Retinal prostheses are being developed to restore vision for the blind with
retinal diseases such as
retinitis pigmentosa (RP) or
age-related macular degeneration (AMD). Among the many issues for
prosthesis development, stimulation encoding strategy is one of the most essential electrophysiological issues. The more we understand the
retinal circuitry how it encodes and processes visual information, the greater it could help decide stimulation encoding strategy for
retinal prosthesis. Therefore, we examined how retinal ganglion cells (RGCs) in in-vitro
retinal preparation act together to encode a visual scene with multielectrode array (MEA). Simultaneous recording of many RGCs with MEA showed that nearby neurons often fired synchronously, with spike delays mostly within 1 ms range. This synchronized firing - narrow correlation - was blocked by gap junction blocker,
heptanol, but not by glutamatergic synapse blocker,
kynurenic acid. By tracking down all the RGC pairs which showed narrow correlation, we could harvest 40 functional connectivity maps of RGCs which showed the cell cluster firing together. We suggest that finding functional connectivity map would be useful in stimulation encoding strategy for the
retinal prosthesis since stimulating the cluster of RGCs would be more efficient than separately stimulating each individual RGC.