Responses of rabbit retinal ganglion cells to electrical stimulation with an epiretinal electrode

Abstract

Rational selection of electrical stimulus parameters for an electronic retinal prosthesis requires knowledge of the electrophysiological responses of retinal neurons to electrical stimuli. In this study, we examined the effects of cathodal and anodal current pulses on the extracellularly recorded responses of OFF and ON rabbit retinal ganglion cells (RGCs) in an in vitro preparation. Current pulses (1 msec duration), delivered by a 125 microm electrode placed on the inner retinal surface within the receptive field of a RGC, produced both short-latency (< or =5 msec) and long-latency (8-60 msec) responses. The long-latency responses, but not the short-latency responses, were abolished upon application of the glutamate receptor antagonists CNQX and NBQX, thus indicating that the long-latency responses of RGCs are due to activation of presynaptic neurons in the retina. The latency of the long-latency response depended upon the polarity of the stimulus. For OFF RGCs, the average latency was 11 msec for a cathodal stimulus and 24 msec for an anodal stimulus. For ON RGCs, the average latency was 25 msec for a cathodal stimulus and 16 msec for an anodal stimulus. The threshold current also depended upon the polarity of the stimulus, at least for OFF RGCs. The average threshold current for evoking a long-latency response in OFF RGCs was 10 microA for a cathodal stimulus and 21 microA for an anodal stimulus. In ON RGCs, the average threshold current was 13 microA for a cathodal stimulus and 15 microA for an anodal stimulus.

Response variability to high rates of electric stimulation in retinal ganglion cells

“…5). The amplitude and kinetics of the first type of response were identical to that of light-elicited action potentials, consistent with much previous work that found that short-duration pulses elicit single action potentials (Fried et al 2006;Jensen et al 2005;Sekirnjak et al 2006). The amplitude of the second type of response was considerably smaller than the standard spike (Fig.…”

“…The variability in responsiveness to pulse trains most likely arises from differences in the spike-generating machinery of each type. Almost certainly, the responses in the present study arose through direct activation of the ganglion cell: previous studies consistently indicate that pulse durations comparable to those used in our study activate ganglion cells directly without simultaneously activating presynaptic neurons (Fried et al 2006;Sekirnjak et al 2006), and also, the bursts of spiking that are characteristic of presynaptic activation (Fried et al 2006;Jensen et al 2005) were not observed in these experiments. Within the ganglion cell it is likely that spikes were initiated within the dense band of sodium channels within the axon initial segment (AIS): this region is known to have the highest sensitivity to extracellular electric stimulation (Behrend et al 2009;Fried et al 2009;Sekirnjak et al 2008), and the stimulating electrode was consistently positioned directly over its center.…”

Electrically-evoked Neural Activities of rd1 Mice Retinal Ganglion Cells by Repetitive Pulse Stimulation

“…However, the number of spikes increased most noticeably within about 100 ms post-stimulus. Two types of evoked RGC spikes were observed as previously reported (Jensen et al, 2005). Long-latency spikes were evoked approximately 20∼100 ms after stimulation, and could be clearly identified without contamination from a stimulation artifact.…”

“…Long-latency spikes were evoked approximately 20∼100 ms after stimulation, and could be clearly identified without contamination from a stimulation artifact. These spikes are regarded as resulting from indirect stimulation of RGCs through the retinal neural network (Jensen et al, 2005). The spike waveforms in Fig.…”

The Effect of the Electrical Stimulation on Temperature Rise in the Retinal Tissue for Visual Prostheses

“…Degenerative retinal diseases that result in the most prevalent blindness are Retinitis Pigmentosa (RP) and Age Related Macular Degeneration (AMD) [2]. Degenerative retinal diseases that lead to the most prevalent blindness are AMD and RP throughout the world and unfortunately there is no effective treatment method ranging from rebirth of photoreceptors from stem cells to neuro-protective therapy [3], [4]. Retinal Pigment Epithelium (RPE) layer of the retina are damaged by AMD.…”