Effect of Stimulus Waveform of Biphasic Current Pulse on Retinal Ganglion Cell Responses in Retinal Degeneration (rd1) mice

Abstract

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an 8×8 multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than 10 µA and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to 500 µs (30 µA), changing the intensities (or duration) from 2 to 60 µA (60 to 1000 µs). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

Synchrony of Spontaneous Burst Firing between Retinal Ganglion Cells Across Species

“…Four retinas at postnatal year two and higher were used. The detailed procedures for the preparation of the ex-vivo retinal patch were described in previous studies [ 20 , 21 ]. Briefly, the eyeball was enucleated, and then the retina was isolated from the sclera and the retinal pigment epithelium (RPE) and cut into a 2×2 mm 2 patch.…”

The advantage of topographic prominence-adopted filter for the detection of short-latency spikes of retinal ganglion cells

“…All experimental methods and animal care procedures were approved by the institutional animal care committee of Chungbuk National University (approval number: CBNURA-042-0902-1). Details of the method of retinal patch preparation and stimulation used in our laboratory may be found in [ 9 ]. After eliciting short- and long-latency RGC spikes by electrical stimulation, the long-latency spikes (which are network mediated through synaptic transmission), were blocked by application of a Ca 2+ -channel blocker, cadmium chloride (CdCl 2 ; 20 µM).…”

“…Electrical stimulation elicits two kinds of RGC spikes, short- and long-latency RGC spikes. Short-latency spikes which are also known as directly-evoked spikes are the result of direct stimulation of RGCs by retinal prosthesis, while long-latency spikes are originated from network mediated stimulation of RGCs through BCs [ 9 , 10 11 12 13 14 15 ].…”

New Features of Receptive Fields in Mouse Retina through Spike-triggered Covariance

“…The mice were anesthetized with an intramuscular injection of 30 mg/kg tiletamine-zolazepam hydroxide (Zoletil 50; Virbac, Sao Paulo, Brazil), 10 mg/kg of zylazine hydrochloride (Rumpun; Bayer Korea, Seoul, South Korea), and 5,000 IU of heparin sodium (heparin; JW Pharmaceutical Corp., Seoul, South Korea). The detailed procedures for the preparation of ex vivo retinal patches were described in a previous study [43]. Briefly, the eye was enucleated and then the retina was isolated from the sclera and the retinal pigment epithelium (RPE) and cut into a 2×2 mm 2 patch.…”