The electrically evoked auditory change complex: preliminary results from nucleus cochlear implant users.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Auditory Electrophysiology

Background:

• Cochlear implants (CIs) restore hearing in deafened individuals.
• Understanding neural responses to CI stimulation is crucial for optimizing device performance.
• The electrically evoked auditory change complex (EACC) reflects neural processing of auditory stimuli.

Purpose of the Study:

• To investigate if altering stimulating electrode position in Nucleus cochlear implant users can elicit the EACC.
• To determine the relationship between electrode separation and EACC amplitude.

Main Methods:

• Nine postlingually deafened adults with Nucleus CI24 implants participated.
• The CI speech processor was bypassed for direct control of stimulation.
• A change in stimulating electrode position was introduced during a pulse train to elicit the EACC, recorded via surface electrodes.

Main Results:

• A clear onset response and a subsequent EACC were recorded in all participants.
• The EACC exhibited morphological similarities to the onset response.
• Increased separation between stimulating electrodes led to a trend of increased EACC amplitudes.

Conclusions:

• The study demonstrates the feasibility of eliciting the EACC by changing stimulating electrode position in cochlear implant users.
• EACC amplitude is positively correlated with the spatial separation of stimulating electrodes.
• This technique offers a potential method for assessing CI function at an individual level.