Free-Field Cortical Steady-State Evoked Potentials in Cochlear Implant Users

Area of Science:

• Auditory Neuroscience
• Neurophysiology
• Biomedical Engineering

Background:

• Auditory steady-state evoked potentials (SS-EPs) are objective neural measures of auditory processing.
• SS-EPs are valuable for hearing threshold assessment and are increasingly considered for cochlear implant (CI) fitting.
• Feasibility of SS-EP recording in CI users requires investigation due to potential stimulation artifacts.

Purpose of the Study:

• To assess the feasibility of recording free-field SS-EPs in adult CI users.
• To compare SS-EP characteristics between CI users and normal-hearing controls.
• To evaluate the utility of SS-EPs in understanding auditory processing in CI recipients.

Main Methods:

• Utilized a dual-frequency tagging method to record subcortical and cortical SS-EPs.
• Employed Independent Component Analysis (ICA) for artifact removal from CI stimulation.
• Compared SS-EP amplitudes and brain topographies between CI users and controls.

Main Results:

• Reliable SS-EPs were obtained in controls, but subcortical responses in CI users were often artifact-contaminated.
• Cortical SS-EPs were significantly larger in controls compared to CI users.
• Brain topographies and response characteristics of cortical SS-EPs were similar across groups.

Conclusions:

• Cortical SS-EPs are feasible to record in CI users, though amplitudes may be reduced, potentially indicating altered neural synchrony.
• Artifacts remain a challenge for subcortical SS-EP recording in CI users, necessitating advanced denoising techniques.
• Despite amplitude differences, the neural origin and topography of cortical SS-EPs are confirmed in CI recipients.