title: Interphase gap decreases electrical stimulation threshold of retinal ganglion cells.
abstract: The most common electrical stimulation pulse used in retinal implants is a symmetric biphasic current pulse. Prior electrophysiological studies in peripheral nerve have shown that adding an interphase gap (IPG) between the two phases makes stimulation more efficient. We investigated the effect of IPG duration on retinal ganglion cell (RGC) electrical threshold. We used calcium imaging to measure the activity of RGCs in isolated retina in response to electrical stimulation. By varying IPG duration, we were able to examine the effect of duration on threshold. We further studied this effect by simulating RGC behavior with a Hodgkin-Huxley-type model. Our results indicate that the threshold for electrical activation of RGCs can be reduced by increasing the length of the IPG.
authors.affiliation: Biomedical Engineering Department, University of Southern California, Los Angeles, CA 90033, USA. aweitz@usc.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Weitz
authors.forename: M R
authors.initials: MR
authors.lastname: Behrend
authors.forename: M S
authors.initials: MS
authors.lastname: Humayun
authors.forename: R H
authors.initials: RH
authors.lastname: Chow
authors.forename: J D
authors.initials: JD
authors.lastname: Weiland
mesh_terms: D000557:Ambystoma; D000818:Animals; D001369:Axons / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D003198:Computer Simulation; D004558:Electric Stimulation / Q000379:methods*; D004566:Electrodes; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D008839:Microelectrodes; D008856:Microscopy, Fluorescence / Q000379:methods; D023421:Models, Animal; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000166:cytology*; D012174:Retinitis Pigmentosa / Q000628:therapy
chemical_list: D002118:Calcium