AUTHOR=Min Shiyao , Lu Tianhao , Chen Min , Mao Jiabao , Hu Xuerui , Li Shufeng 

TITLE=Forward Electric Stimulation-Induced Interference in Intracochlear Electrocochleography of Acoustic Stimulation in the Cochlea of Guinea Pigs

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 16 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2022.853275

DOI=10.3389/fnins.2022.853275

ISSN=1662-453X

ABSTRACT=Electric-acoustic stimulation (EAS) uses amplified sound by hearing aid to stimulate an apical low-frequency region of the cochlea and electrical current from a cochlear implant (CI) to stimulate the basal high-frequency region. EAS recipients had significantly improved speech perception, music appreciation and hearing function in noise than compared to those relying on CI electrical stimulation alone. However, the interaction between basal electrical stimulation (ES) and apical acoustic stimulation (AS) in the cochlea potentially affects EAS advantages. To investigate ES-AS interaction, we designed a system that recorded the electrically-evoked compound action potential (ECAP) and the auditory evoked potential (AEP). We used an intracochlear electrode array to deliver electrical stimulation at the basal cochlea and detect intracochlear electrocochleography (iECochG) generated from apical acoustic stimulation. Within iECochG, 3 dB or 6 dB (double or quadruple intensity of ECAP threshold) electric stimulation, 1ms-forward ES significantly increased CAP amplitudes of 4 kHz/20 dB AS compared to 0dB ES. One ms-forward 3 dB ES significantly increased CAP amplitudes of 4 kHz/20 dB AS while 3 ms- or 5 ms-forward ES did not change the CAP amplitudes. The elevation in CAP amplitude of 40 dB/4 kHz AS induced by 1ms-forward 3 dB ES was significantly lower than that in 20 dB/4 kHz AS. With 1ms-forward 3 dB ES, AS frequency and stimulating-electrode location has no significant impact on relative CAP amplitudes of 20 dB AS. These results suggest that the basal forward ES and the following apical AS could produce a cumulative effect on the auditory nerve response.