Development of Brainstem-Evoked Responses in Congenital Auditory Deprivation

Abstract

To compare the development of the auditory system in hearing and completely acoustically deprived animals, naive congenitally deaf white cats (CDCs) and hearing controls (HCs) were investigated at different developmental stages from birth till adulthood. The CDCs had no hearing experience before the acute experiment. In both groups of animals, responses to cochlear implant stimulation were acutely assessed. Electrically evoked auditory brainstem responses (E-ABRs) were recorded with monopolar stimulation at different current levels. CDCs demonstrated extensive development of E-ABRs, from first signs of responses at postnatal (p.n.) day 3 through appearance of all waves of brainstem response at day 8 p.n. to mature responses around day 90 p.n.. Wave I of E-ABRs could not be distinguished from the artifact in majority of CDCs, whereas in HCs, it was clearly separated from the stimulus artifact. Waves II, III, and IV demonstrated higher thresholds in CDCs, whereas this difference was not found for wave V. Amplitudes of wave III were significantly higher in HCs, whereas wave V amplitudes were significantly higher in CDCs. No differences in latencies were observed between the animal groups. These data demonstrate significant postnatal subcortical development in absence of hearing, and also divergent effects of deafness on early waves II–IV and wave V of the E-ABR.

Hearing and Age-Related Changes in the Gray Mouse Lemur

“…Consequently, the number of components is likely to be dependent on stimulus level (relative to hearing threshold) and neuronal synchrony. Given the fact that consecutive components can merge (Boettcher 2002;Tillein et al, 2012), the present results are consistent with previous findings and indicate similar generators, including the auditory nerve, the cochlear nucleus, and the superior olivary complex (Biacabe et al 2001;Boettcher 2002;.…”

“…However, when a highly synchronized stimulus (electrical pulse applied through a cochlear implant) was used in cats, a break-up of some components in up to three subcomponents with increasing current level was observed (Tillein et al 2012). Consequently, the number of components is likely to be dependent on stimulus level (relative to hearing threshold) and neuronal synchrony.…”

Musical training heightens auditory brainstem function during sensitive periods in development

“…We speculate that many of the same general developmental principles hold for the auditory brainstem and auditory cortex, while at the same time acknowledging potential differences between brainstem and cortical development. For example, based on their work with inborn deaf populations, Tillein et al (2012) have argued that there is no sensitive period in auditory brainstem development (Tillein et al, 2012). In deaf populations, the auditory brainstem (unlike the auditory cortex) remains in a state of arrested development until input is provided after which auditory brainstem development proceeds along a similar trajectory relative to hearing populations no matter when implantation occurs, with the developmental trajectory being driven by “age in sound” instead of biological age (Gordon et al, 2011; Tillein et al, 2012).…”

Neurocognitive factors in sensory restoration of early deafness: a connectome model

“…6,7,31 Development of the afferent auditory pathway starts before cochlear function is established and continues afterwards. 32 Since the human cochlea is functional from weeks 24–26 after conception, some processes affected by the environment might start in utero. Even before the onset of auditory function, loss of cochlear cells might result in death of subsequent auditory neurons in the brainstem.…”