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Artificial Vision 2013

The International Symposium on Visual Prosthetics

08.11. - 09.11.2013, Aachen

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What is the optimal electrical stimulus for most RGCs?

Meeting Abstract

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  • Archana Jalligampala - Institute for Ophthalmic Research, Center for Integrative Neuroscience, Tuebingen, Germany; Graduate Training Centre of Neuroscience, Tuebingen, Germany
  • D.L. Rathbun - Institute for Ophthalmic Research, Center for Integrative Neuroscience, Tuebingen, Germany
  • E. Zrenner - Institute for Ophthalmic Research, Center for Integrative Neuroscience, Tuebingen, Germany

Artificial Vision 2013. Aachen, 08.-09.11.2013. Düsseldorf: German Medical Science GMS Publishing House; 2014. Doc13artvis05

doi: 10.3205/13artvis05, urn:nbn:de:0183-13artvis054

Published: February 13, 2014

© 2014 Jalligampala et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Objective: To determine optimal stimuli for wild type (wt) and rd10 retinas.

Material and Methods: Retinal ganglion cell (RGC) spiking responses were recorded in vitro from patches of wt (C3H & C57BL/6) and degenerated (rd10) retina, using a planar multi-electrode array (MEA, 60 electrodes, 200µm interelectrode distance, 30µm diameter, MCS, GmbH). Epiretinal stimuli were delivered via one of the 60 electrodes while the other electrodes recorded electrically-evoked responses. Stimuli consisted of square-wave, monophasic voltage pulses in incremental blocks (0.1V-2.5V) with randomized pulse durations. Responses were processed & analyzed offline using spike sorting software (Offline Sorter & NeuroExplorer, Plexon Inc, TX) and custom Matlab scripts (The Mathworks, Natick, MA) to generate rastergrams, peri-stimulus time histograms, and response surfaces over the 2D stimulus space.

Results: Electrical responsiveness of RGCs is a nonlinear function of both voltage and duration. By sampling a complete response surface for each RGC, we were able to determine the fraction of the recorded population that would respond to each unique stimulus at a rate both above threshold and below saturation. This allowed us to identify a small number of optimal stimuli that can be used in future studies to activate the majority of RGCs.

Discussion: Our findings present one of the first examinations of electrical stimulation in rd10 retina. Based on these findings, we propose tentative stimulation parameters appropriate for activation of rd10 and wt retina in our continued development of more efficient stimuli for the Tübingen retinal prosthesis.

Acknowledgements: Kerstan Stiftung; Neuro-Ophthalmologische Gesellschaft; Pro-Retina; BMBF, FKZ: 01GQ1002; DFG, EXC307