Repurposing sugically implanted cochlear implants to measure EEG (electroenephalography)

Summary

Cochlear implants (CIs) are perhaps the most advanced current implantable neuroprostheses, and are truly transformative for deaf adults and children. Their primary function is to stimulate the hearing nerve electrically. 

A major problem with CIs implantation of very young deaf children is that we can only rely on various observational measures and simple auditory nerve recordings to program implants for optimal hearing. This is difficult, and not accurate. It would be very helpful to know how much sound actually reaches the auditory brain cortex.

One way to to this is to use the implant itself to record EEG. Eventually this could be made into a “closed loop” system where the implant adjusts itself based on its cortical recordings.  
The basic electrical potential recording hardware is already in the implant, and is used to record auditory nerve responses (eCAPS).  

However, many technical problems need to be overcome to record cortical EEG: CI electrodes are several cm away from the cortex, as opposed to a few mm for eCAPS. The cortical potentials are much smaller than the electrical stimulation artefact . The cortical signal duration is 100s of milliseconds compared to <2ms for eCAPs. This then requires stitching together multiple recording windows and averaging to retrieve the signal. 

Project aims

A series of work packages will move from bench measurements to cadavers to human subjects. The deliverable is a functioning recording system, including comparative data to the gold standard EP machine. Documentation will inform development of a clinical recording system.

Contact details

Manohar Bance - mlb59@cam.ac.uk

Opportunities

This project is open to applicants who want to do a:

• PhD