To lighten the burdens of hearing loss, bioengineering researchers are working with a new generation of hearing devices that use light instead of electricity to trigger an auditory response. Surpassing the performance of cochlear implants, proponents of this technology believe light-based approaches could be a major step forward in hearing prosthetics.
Optical stimulation may be the breakthrough to increase the frequency resolution of cochlear implants and make them a more universal solution. There are two primary approaches being taken for optical cochlear implant engineering. One method combines the gene reprogramming technique known as optogenetics with a fibre-optic-based device that carries light pulses into the cochlea from a remote light source while the other major approach involves the use of near-infrared laser beams to recreate the sound experience by manipulating fluid within the cochlea.
Tobias Moser, an auditory neuroscience expert at the University Medical Center Goettingen, Germany and his group is one of the few adapting optogenetics to the correction of deafness. The group has even reported success with optogenetics to achieve spatially and temporally precise, cell-specific stimulation of cochlear neurons in deaf gerbils. The work builds on earlier studies with mice and rats that first proved the principle of optical cochlear implants.
The gerbil’s cochlea is somewhat closer in size to a human’s and its hearing range extends to the low-frequency ranges perceived by the human ear and hence is a superior model for hearing research. The team measured stable optical auditory responses in the test animals’ brains over a period of weeks through a battery of electrophysiological and behavioural tests. Moser wants to expand the current study from a single-channel device to a multichannel system based on waveguide arrays or LEDs. This will help determine the optimal number of stimulation channels future optical cochlear implants should possess.
Keep watching this space to know about the second method of optical stimulation for hearing-impaired humans.