Effects of age and stimulus intensity of the far field auditory brain stem potentials in the laboratory mouse

Abstract

The vertex-positive, volume-conducted far field response was used to evaluate age-related changes of the 8th cranial nerve and auditory brainstem in the anesthetized C57BL/6 mouse. Responses were obtained from stimuli as low as 10 dB (within the 10-20 kHz bandpass). When latencies were compared between 16- and 35-day-old subjects, the older mice had a P₁ component which was .175 msec faster, a P₂ which was .505 msec faster, a P₃ which was .953 msec faster, and a P₄ which was 1.315 msec faster. A retest of the younger mice showed that much of this retrocochlear latency decrease occurred between 16 to 18 days postpartum. The latencies of the younger mice were also less likely to decrease as the stimulus intensity was increased from 30 to 70 dB, and this effect was most pronounced at higher neural levels. These age-related changes bear considerable relationship to the development of susceptibility of audiogenic seizures in the mouse.