Optical stimulation technology to improve the precision of bionic devices

Background

Cochlear implants electrically stimulate neurons in the cochlea enabling people with a profound hearing loss to communicate. The 12-22 electrodes or “channels” placed along the length of the tonotopically-organised cochlea help recipients to distinguish low-pitched and high-pitched sounds but with low resolution. Speech understanding in even moderately challenging environments (such as a noisy restaurant) requires effort and compromise, and music perception is poor.

A fundamental limitation of contemporary cochlear implants is the spread of electrical current that causes considerable channel overlap, significantly affecting the ability to resolve different frequencies and therefore understand speech.

Our research

An innovative solution: optical/electrical co-stimulation

New technology is needed to break the bottleneck in improvements of clinical outcomes with cochlear implants. Recently developed methods of activating neurons with light via optogenetics are promising to overcome this limitation. Optogenetics refers to the use of genetic engineering or gene therapy to introduce light sensitive ion channels (opsins) into neural membranes to make them responsive to low-power light. Optical stimulation can be focused onto a target and is not limited by the same conductive spread as electrical current. Our research is exploiting the potential of optical stimulation to advance precision in neural stimulation and expand the range of health conditions that can be treated via bionic devices.

Our aim

The aim of this project is to improve precision of neural stimulation in bionic devices for the treatment of human health conditions. The project will use the established field of auditory stimulation (cochlear implants) to assess the benefit and feasibility of innovative optical/electrical co-stimulation technology. The study outcomes will enable the development of platform technology that can be applied to numerous bionic applications where precise neural stimulation is required such as a retinal prosthesis or deep brain stimulation.

This research involves:

  1. Developing suitable implantable optical arrays with associated hardware
  2. Establishing a safe method for achieving opsin expression in mature neurons
  3. Determining the spatial and/or temporal precision of optical stimulation
  4. Ensuring clinical safety and long-term benefit.

Our preclinical research uses a number of multidisciplinary techniques including gene therapy, optogenetics, electrophysiology, behavioural studies, neurobiology, histology and molecular biology.

Research team

Program leader: A/Prof Rachael Richardson

Team membersA/Prof Andrew Wise, A/Prof James Fallon, Dr Alex Thompson, and Prof Stephen O’Leary (University of Melbourne), Dr Karina Needham (University of Melbourne), and Prof Paul Stoddart (Swinburne University).

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