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Inner retinal mechanisms engaged by retinal electrical stimulation.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Margalit, Eyal Thoreson, Wallace B. |
| Copyright Year | 2006 |
| Abstract | PURPOSE Retinal prosthetic devices are being developed to bypass degenerated retinal photoreceptors by directly activating retinal neurons with electrical stimulation. However, little is known about retinal activity during such stimulation. METHODS Whole cell patch-clamp recordings were obtained from ganglion and bipolar cells in the salamander retinal slice preparation. A stimulating electrode was positioned at the vitreal surface of the slice. RESULTS Brief pulses of cathodic current evoked transient inward currents in ganglion cells arising from action potentials. Longer pulses (>5 milliseconds) also evoked sustained inward currents in ganglion cells that appeared synaptic in origin because, unlike transient currents, sustained currents were blocked by inhibiting synaptic transmission with Cd2+. These synaptic currents reversed around ECl and were blocked by picrotoxin, strychnine, or both, suggesting they were mediated by GABAa/c and glycine receptors. Synaptic currents were also blocked by the NMDA antagonist MK801 and the KA/AMPA antagonist NBQX, suggesting that epiretinal stimulation evoked glutamate release from bipolar cells, which in turn stimulated the release of GABA and glycine from amacrine cells. Sustained currents were also evoked by epiretinal stimulation in bipolar cells. These currents reversed near ECl and were blocked by picrotoxin, suggesting they arose from GABAa/c receptors. CONCLUSIONS Pulse duration is an important parameter for effective activation of the inner retina by epiretinal stimulation. Brief pulses evoke action potentials only in ganglion cells. However, longer pulses also evoke sustained synaptic currents by stimulating glutamate release from bipolar cell terminals, which, in turn, evokes the release of GABA and glycine from amacrine cells. |
| Starting Page | 1 |
| Ending Page | 5 |
| Page Count | 5 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://iovs.arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/932938/z7g00606002606.pdf |
| PubMed reference number | 16723477v1 |
| Volume Number | 47 |
| Issue Number | 6 |
| Journal | Investigative ophthalmology & visual science |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Abnormal degeneration Action Potentials CCL21 wt Allele Dizocilpine Maleate Electric stimulation technique Ganglia Ganglion cell Glutamic Acid Glycine Receptors Inhibition N-Methylaspartate Photoreceptors Picrotoxin Population Parameter Prosthesis Retina Retinal Neurons Stimulation (motivation) Strychnine Synaptic Transmission bypass gamma-Aminobutyric Acid |
| Content Type | Text |
| Resource Type | Article |
