Multichannel optogenetic stimulation of the auditory pathway using microfabricated LED cochlear implants in rodents.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Ophthalmology

Background:

• Electrical cochlear implants (eCIs) restore hearing but suffer from poor spectral selectivity due to wide current spread.
• Optical cochlear implants (oCIs) offer a potential solution by enabling spatially confined stimulation of auditory neurons.

Purpose of the Study:

• To develop and evaluate a multichannel optical cochlear implant system based on light-emitting diodes (LEDs) for hearing restoration.
• To assess the spectral selectivity and efficacy of optogenetic stimulation of spiral ganglion neurons (SGNs).

Main Methods:

• Fabrication of power-efficient, thin-film multichannel oCIs using blue LED arrays on polyimide carriers.
• In vitro characterization of oCI optoelectronic, thermal, and mechanical properties, demonstrating stability.
• In vivo implantation in channelrhodopsin (ChR)-expressing rodents (rats and gerbils) for electrophysiological and behavioral assessments.

Main Results:

• Demonstrated multichannel optogenetic stimulation of SGNs with improved spectral selectivity, confirmed by auditory midbrain recordings.
• Verified specificity of optogenetic stimulation in long-term studies with deafened animals.
• Observed auditory percepts in behavioral studies using a wireless oCI sound processor.

Conclusions:

• The developed LED-based multichannel oCI system successfully restores hearing with enhanced spectral selectivity.
• Optical stimulation offers a promising alternative to electrical stimulation for cochlear implants.