Scientists have developed cochlear implant, which optogenetics stimulates the auditory nerve of rats. In the result, deaf animals can hear the sound — light stimulation resulted in excitation of the auditory centers of the brainstem and behavioral responses. Spatial and frequency resolution of the optical implant is higher than that of conventional electrode. Article published in the journal Science Translational Medicine.
About five percent of the world’s population lives with hearing impairment. The cause of the most common forms of sensorineural hearing loss — eliminate have not yet learned, so the hundreds of thousands of people in the cochlea of the inner ear set of cochlear implants.
The sensory part of the cochlea is a membrane that is rolled in a spiral; different areas of the membrane resonate when vibrations of different frequencies and transmit a signal to the auditory nerve (it runs parallel to the membrane), and that — in the brain. The basis of cochlear implants — electrode chain, which is implanted along the membrane of the cochlea. The electrodes stimulate different parts of the auditory nerve, depending on the frequency of the sound and allow people with hearing loss to perceive speech in silence.
The lack of modern implants — low spatial (and hence frequency) resolution. One electrode stimulates a wide area of the auditory nerve, and the whole set from 12 to 24 electrodes by the corresponding number of segments divided by the entire audible frequency range. Analogue can be optogenetics stimulation: instead of electrodes, it is possible to use LEDs, if in the membrane of nerve fibers, to insert light-sensitive channels. Thus to encourage smaller portions of the auditory nerve and signal the brain about a narrow range of frequencies.
Researchers from Germany under the leadership of Patrick Router (Patrick Ruther) from the University of Freiburg and Tobias Moser (Tobias Moser) from göttingen University developed an optical cochlear implant for rodents — polyimide tape with 10 svetodiody at the end. A led strip was placed in the snail transgenic rats, neurons which expressed a light-sensitive channels.
The inclusion of LEDs for four seconds causing the activation of the auditory centers of the brain stem, similar to the excitation in response to the clicking sound. Signal amplitude increased with increasing light intensity and duration of the stimulus and decreased with increasing frequency of stimulation.