Mediating Retinal Ganglion Cell Spike Rates Using High-Frequency Electrical Stimulation

Area of Science:

• Neuroscience
• Biophysics
• Biomedical Engineering

Background:

• Recent retinal studies focus on high-frequency electrical stimulation (>1.0 kHz) for retinal prosthetics.
• Retinal ganglion cell (RGC) type-specific responses to HFS offer potential for targeted neural stimulation.
• Ionic mechanisms influencing RGC responses to HFS are not fully understood.

Purpose of the Study:

• Investigate the ionic mechanisms underlying RGC responses to HFS.
• Understand how these mechanisms affect RGCs during high-frequency electrical stimulation.
• Explore the possibility of focally targeting retinal neurons for visual prosthetics.

Main Methods:

• Developed and utilized an in silico model of RGCs.
• Calibrated and validated the RGC model using in vitro retinal preparations.
• Employed a biophysically accurate RGC model with realistic cell morphology.

Main Results:

• The model successfully replicated stimulus-strength-dependent suppression of RGC action potentials observed experimentally.
• HFS-induced spike inhibition is attributed to local membrane hyperpolarization from outward currents.
• Inward sodium current properties significantly alter HFS-induced inhibition.
• Stimulus-strength-dependent suppression is tunable across various frequencies and electrode placements.

Conclusions:

• HFS-induced spike inhibition in RGCs is primarily driven by membrane hyperpolarization and influenced by sodium current dynamics.
• Computational modeling validated by in vitro experiments provides insights into HFS effects on RGCs.
• This approach can advance understanding of novel stimulation strategies for retinal prosthetics.