Maturation of cortical sound processing as indexed by event-related potentials.

Abstract

Children's auditory event-related potentials (ERPs) are dominated by the P1 and N2 peaks, while the N1 wave emerges between 3 and 4 years of age. The neural substrates and the behavioral correlates of the protracted N1 maturation, as well as of the 10-year long predominance of the N2 are unclear. The present study utilized high-resolution electroencephalography to study the maturation of auditory ERPs from age 4 to adulthood and to compare the sources of the N1 and the N2 peaks in 9-year-old children and adults. Three partial harmonic tones were delivered with short (700 ms) and long (mean of 5s) stimulus onset asynchrony (SOA), with only 700 ms SOA used with 4-year-olds. With a short SOA, 4- and 9-year-old children displayed P1 and N2 peaks, whereas adults showed P1, N1, P2, and N2 waves. With a long SOA, 9-year-olds also displayed an N1 peak, which was frontal in scalp distribution to that in adults who showed P1, N1, and P2 peaks. After filtering out the slow N2 activity, the N1 wave was also revealed in the short-SOA data in 9-year-old but not in 4-year-old children. In adults and in 9-year-olds, the neural sources of the N2 and N1 mapped onto the superior aspects of the temporal lobes, the sources of the N2 being anterior to those of the N1. The results indicated that children's N1 is composed of differently weighted components as that in adults, and that in both children and adults the N1 and N2 are generated by anatomically distinct generators. A protracted ontogeny of the N1 could be linked with that of auditory sensitivity and orienting, whereas the P1 and N2 peaks are suggested to reflect auditory sensory processes.