The effect of development on cortical auditory evoked potentials in normal hearing listeners and cochlear implant users

When a baby is born deaf, a cochlear implant is often recommended as a medical habilitation tool to the parents. A cochlear implant is designed to bypass a damaged cochlea and stimulates auditory nerve directly, from where signals are sent all the way to the auditory cortex where sounds are perceived. We expect that a deaf child can detect and discriminate speech sounds with this device. With continuous auditory experiences, we hope that the auditory cortex of the deaf child can be developed as children with normal hearing do. Can a cochlear implant facilitate the development of the auditory brain? This study attempts to answer this question, exploring developmental effects on evoked potentials measured at the cortical level. Early-implanted, pre-lingually deafened cochlear implant users showed similar developmental patterns of cortical auditory evoked potentials to those of normal hearing listeners. However, the responses, related to sound discrimination, were affected by noise more in cochlear implant users. This may be related to perceptual abilities of cochlear implant users in harder listening conditions. The findings indicate that cortical auditory evoked potentials, related to both detection and discrimination, can be used to document the long developmental trajectory of the central auditory system in both normal hearing listeners and cochlear implant users. This study suggests that these responses can be used as a tool for estimating behavioral performance in cochlear implant users.