Age-related changes in the brainstem auditory evoked potentials of the marmoset

Changes in brain-stem auditory evoked potentials (BAEPs) with age were reco rded in common marmosets (Callithrix jacchus) at the age of 1-2, 6-8 and 10 -12 years. The auditory function was assessed by thresholds, latencies and amplitudes of BAEPs evoked by use of tone burst stimulations with audible f requencies ranging from 1 to 99 kHz. Prolongation of the latencies of later waves was observed in the animals at the age of 6-8 and 10-12 years at hig h frequencies, suggesting that aging in marmosets, as reported previously i n humans and other animals, may cause earlier hearing loss at high frequenc y than at low frequency within the hearing range. At 10-12 years of age, th e elevations of BAEP thresholds and the declines of BAEP amplitudes in olde r animals were also observed. As the differences in the parameters are smal l, it was suggested that only a moderate hearing loss occurred with onset l ate in life in common marmoset similar to that in CBA/Ca mice. Based on the results obtained in this study, BAEP latencies appear to be more sensitive indicators than BAEP thresholds and amplitudes for the early detection of hearing impairment. (C) 1999 Elsevier Science B.V. All rights reserved.