title: Direct activation and temporal response properties of rabbit retinal ganglion cells following subretinal stimulation.
abstract: In the last decade several groups have been developing vision prostheses to restore visual perception to the profoundly blind. Despite some promising results from human trials, further understanding of the neural mechanisms involved is crucial for improving the efficacy of these devices. One of the techniques involves placing stimulating electrodes in the subretinal space between the photoreceptor layer and the pigment epithelium to evoke neural responses in the degenerative retina. This study used cell-attached and whole cell current-clamp recordings to investigate the responses of rabbit retinal ganglion cells (RGCs) following subretinal stimulation with 25-mum-diameter electrodes. We found that direct RGC responses with short latency (</=2 ms using 0.1-ms pulses) could be reliably elicited. The thresholds for these responses were reported for on, off, and on-off RGCs over pulse widths 0.1-5.0 ms. During repetitive stimulation these direct activation responses were more readily elicited than responses arising from stimulation of the retinal network. The temporal spiking characteristics of RGCs were characterized as a function of stimulus configurations. We found that the response profiles could be generalized into four classes with distinctive properties. Our results suggest that for subretinal vision prostheses short pulses are preferable for efficacy and safety considerations, and that direct activation of RGCs will be necessary for reliable activation during high-frequency stimulation.
authors.affiliation: Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2125, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Tsai
authors.forename: John W
authors.initials: JW
authors.lastname: Morley
authors.forename: Gregg J
authors.initials: GJ
authors.lastname: Suaning
authors.forename: Nigel H
authors.initials: NH
authors.lastname: Lovell
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D055592:Biophysical Phenomena / Q000187:drug effects / Q000502:physiology; D019256:Cadmium Chloride / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D066298:In Vitro Techniques; D018408:Patch-Clamp Techniques / Q000379:methods; D010775:Photic Stimulation / Q000379:methods; D011336:Probability; D011817:Rabbits; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology
chemical_list: D019256:Cadmium Chloride