Neural responses elicited by electrical stimulation of the retina.
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.
Chen
Shih-Jen
SJ
Wilmer Ophthalmological Institute at Johns Hopkins University, Baltimore, Maryland, USA.
Mahadevappa
Manjunatha
M
Roizenblatt
Roberto
R
Weiland
James
J
Humayun
Mark
M
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*