title: Neural responses elicited by electrical stimulation of the retina.
abstract: OBJECTIVE
  To study electrically elicited responses (EERs) that are produced by epiretinal stimulation of normal and degenerated retina.
  
  
  METHODS
  Three biological models of retinal degeneration are compared: normal and rd1 mouse, normal and RCD1 dog, and human with retinitis pigmentosa. In mouse, epiretinal stimulation was accomplished by means of a wire inserted in the vitreous cavity, and single-unit activity was recorded in visual cortex. In dog and human, an implantable retinal stimulator was used to stimulate the retina, and evoked potentials were recorded from the cortical surface (dog) or scalp (human).
  
  
  RESULTS
  Analysis of EERs revealed distinct early (less than 10 ms) and late (greater than 50 ms) responses. Synaptic blockers abolished the late response but not the early response. For eliciting the early response in normal and rd mice, a square pulse stimulus was more efficient than the sine wave or pulse train. In normal and degenerate canine retina, electrically elicited responses also exhibited early and late phases. EERs in a retinal prosthesis test subject (with retinitis pigmentosa) showed latency similar to the canine, but no evidence of an early response, possibly due to the lack of sensitivity in scalp (human) vs cortical surface (canine) electrode placement.
  
  
  CONCLUSIONS
  EERs could be elicited from both normal and degenerated retina. Mouse, dog, and human EERs showed common characteristics.
authors.affiliation: Wilmer Ophthalmological Institute at Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Chen
authors.forename: Manjunatha
authors.initials: M
authors.lastname: Mahadevappa
authors.forename: Roberto
authors.initials: R
authors.lastname: Roizenblatt
authors.forename: James
authors.initials: J
authors.lastname: Weiland
authors.forename: Mark
authors.initials: M
authors.lastname: Humayun
mesh_terms: D000368:Aged; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology*; D012162:Retinal Degeneration / Q000235:genetics / Q000503:physiopathology* / Q000662:veterinary; D012174:Retinitis Pigmentosa / Q000235:genetics / Q000503:physiopathology; D014793:Visual Cortex / Q000502:physiology*