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Computational Modeling of Retinal Neurons for Visual Prosthesis Research - Fundamental Approaches
Published on: June 21, 2022
An in vitro model of a retinal prosthesis
Ashish K Ahuja1, Matthew R Behrend, Masako Kuroda
1Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089-2654, USA. aahuja@2-sight.com
IEEE Transactions on Bio-Medical Engineering
|August 22, 2008
Summary
Custom microelectrodes for epiretinal prostheses can effectively stimulate retinal cells. Shorter pulses and electrode design influence neural excitation and dynamic range for vision restoration.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Ophthalmology
Background:
- Epiretinal prostheses aim to restore vision by stimulating surviving retinal neurons.
- Degeneration of the photoreceptor layer necessitates bypassing these cells to activate inner retinal neurons.
Purpose of the Study:
- To investigate the efficacy of custom microelectrode arrays for stimulating retinal ganglion cells.
- To analyze the impact of electrode size and stimulation parameters on neural response and charge density.
Main Methods:
- Utilized custom microfabricated multielectrode arrays (200-microm stimulating, 10-microm recording) in isolated tiger salamander retina.
- Employed pharmacological agents to isolate direct ganglion cell excitation.
- Conducted strength-duration testing and electrostatic finite-element modeling.
Main Results:
- Shorter pulse durations (200 micros) offer a larger dynamic range for brightness coding compared to longer pulses (1 ms).
- Electrode-electrode interactions increase stimulation thresholds between electrodes (29.4 nC) versus monopolar stimulation (13.3 nC).
- Smaller electrodes (10-microm) require lower threshold charge densities (7.66 nC/cm2) for presynaptic stimulation.
Conclusions:
- Custom microelectrode arrays show promise for retinal prostheses.
- Optimizing electrode design and stimulation parameters is crucial for effective vision restoration.
- Understanding electrode interactions and charge density is key for developing advanced visual prosthetics.
