P296 Source localization of middle- and long-latency auditory evoked potentials using realistic head models

Abstract

BAEP has been found to be useful for assessment of subcortical maturation. However, the precise maturational changes of the peripheral and central transmission in normal human subjects are still open to controversy. We obtained a total of 200 BAEPs from 165 normal human subjects ranging from infants to young adults. Electrodes were placed at both mastoids and the reference at the vertex. 85 dB SL click stimuli were presented binaurally at a rate of 13/sec and 2,048 responses were summated on line with an averager. Investigation of the maturation of the transmission time indicated that the peripheral auditory apparatus attains functional maturity during the first 2 months of life, whereas the central transmission time shortens up to the age of 5 to 8 years. III-II and V-IV interpeak latencies (IPLs) showed maturational changes similar to those of V-I IPLs, in contrast II-I and IV-III showed little changes. A clear increase of the amplitude of peak V up to 4 years of age and a subsequent decreasing tendency was observed. The V-I IPLs of males were longer than those of females in each age group. Females also displayed larger BAEPs for wave V than males after 2 years of age. These data indicate that it is worthwhile to have separate latency and amplitude norms for males and females from infants to adults for attaching diagnostic significance to BAEP measures.