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      Developing a new hearing implant based on light stimulation

      This work could, ultimately, lead to the development of a new type of hearing implant, for those who cannot benefit from a cochlear implant.

      This is a PhD studentship being carried out by Aimee Bias in the laboratory of Dr Shuzo Sakata at the University of Strathclyde. Aimee started work in October 2016 and will finish in September 2019.

      Background

      A cochlear implant restores someone's hearing by converting sound into electrical signals that are transferred to electrical contacts implanted in the inner ear. The hearing nerve then carries these signals to the brain.

      Although cochlear implants have been revolutionary in enabling deaf people to hear, a significant number of people can't benefit, because their auditory nerve is damaged (so the signals can't travel from the ear to the brain).

      Over the last 20 years, some alternative devices have been developed. Called auditory brainstem implants and auditory midbrain implants, these devices stimulate the auditory system at a point further along the normal pathway of sound information to the brain, beyond the auditory nerve. Unfortunately, their capabilities are still limited, compared to the cochlear implant.

      A new technology, called optogenetics, uses light to control cells, such as nerve cells, that have been genetically altered to produce proteins which are sensitive to light. Researchers are now able to turn nerve cells on or off with extraordinary precision, so they can study their structure and functions. These optogenetic tools also hold clinical promise: they have the potential to control the activity of brain networks involved in hearing.

      Project aims

      Aimee is using this new optogenetic technology to develop a better auditory midbrain implant to restore hearing. She's using an innovative microLED array, a tiny, needle-like probe with many small LEDs (similar in thickness to a human hair) to activate nerve cells that have been specially modified to produce light-sensitive proteins. By using this she'll be able to test, on mice, whether a light-based auditory midbrain implant works.

      Expected impact

      We believe that Aimee's study will help in the development of an optogenetic midbrain implant for people whose hearing loss is caused by damage to the auditory nerve, who can't benefit from cochlear implants.