As efforts to optimize artificial stimulation of the retina have proceeded, a number of practical impediments have been identified. Notable among these is the observation by human patients implanted with retinal prostheses that the visual percepts (phosphenes) evoked by an electrical pulse may fade with repeated stimulation. For a retinal implant to provide optimal visual percepts, it is important that this limited temporal resolution be increased. Serendipitously, recent in vitro animal experiments have demonstrated that ganglion cell spiking responses to electrical stimulation also decrease under repetitive stimulation in a frequency-dependent manner. Because these retinal ganglion cells (RGCs) are the only neurons that carry visual information from the retina to the brain, it is suspected that this ‘desensitization’ effect may underlie the perceptual fading reported by human patients. Accordingly, we have undertaken experiments to investigate the spatiotemporal properties of ganglion cell desensitization in order to guide retinal prosthesis optimization through reduced perceptual fading.

Results

1. Hosseinzadeh Z, Jalligampala A, Zrenner E, Rathbun DL.  “The spatial extent of epiretinal electrical stimulation in the healthy mouse retina.”  Neurosignals.  2017 Jul 26;25(1):15-25.
2. Jalligampala A, Zrenner E, Rathbun DL.  “Electrical stimulation alters light responses of mouse retinal ganglion cells.”  7th International IEEE/EMBS Conference on Neural Engineering, Montpellier France, April 2015