Postnatal development of human brainstem potentials during the first year of life.

Average brainstem potentials evoked by auditory stimuli were recorded from the scalp's surface of human newborns and infants, 6 weeks, 3 months, 6 months and 1 year of age as well as from normal adults. The auditory processes related to peripheral transmission (PT) and central transmission (CT) were shown to mature at differential rates during the first year of life. By the 6th week PT had reached the adult latency. In contrast, CT through the brainstem did not match that of the adult until approximately 1 year of age. In addition, the waveform of the brainstem evoked potential (BEP) displayed an independent time course for development. The adult configuration replaced the infantile response by 3--6 months. Despite considerable inter-subject variability in the BEP amplitude during the neonatal period, a general wave-form pattern could easily be delineated. Preliminary results revealed the BEP to be quite resistant to habituation following continuous stimulus presentation. Longitudinal follow-ups on several babies paralleled the transverse data.