Auditory development in the absence of hearing in infancy.

The auditory brainstem pathways require stimulation to mature, but do they develop in the absence of auditory input? To answer this, peaks of the electrically evoked auditory nerve (wave eN1) and brainstem response (eII, eIII, and eV) were measured in 117 children with early-onset deafness who had received cochlear implants. Data were collected at cochlear implant activation. In the absence of significant input, the interpeak latency eN1-eIII decreased over the first year of life but remained constant thereafter. Chronic cochlear implant stimulation was required to promote significant reduction in eIII-eV interpeak latency. Thus, activity-independent changes occurring in infancy are concentrated in the caudal auditory brainstem and likely involve the auditory nerve. Changes requiring input are most prevalent in rostral brainstem.