Age-related changes in auditory brain-stem responses of Mongolian gerbil

Abstract

As part of a large study of age-related hearing loss, the Mongolian gerbil as an animal model is evaluated. Part of this effort involves monitoring electrical potentials recorded from the auditory nerve and brain stem. The gerbils are born and raised in an acoustically treated quarters where the median sound level is 35 dBA. Test signals are 1.8-ms tone pips ranging from 1–16 kHz in octave steps. By age 22–24 months, auditory sensitivity is decreased by about 10 dB at most frequencies although there are large differences between animals. By age 36 months, mean threshold changes are largest at 8 and 16 kHz, about 35 dB, and decrease to 10–20 dB at lower frequencies. The mean data for the 36-month group form an audiometric configuration that is qualitatively similar to that observed for 60- to 65-year-old human males and 70-year-old human females. Individual differences are large with some animals having nearly normal hearing and others having hearing losses of 50–70 dB at all test frequencies. [Work supported by NINCDS PO NS-25039.]