Brainstem auditory evoked potentials characteristics in mice: the effect of genotype

Brainstem auditory evoked potentials (BAEPs) elicited by sound clicks were recorded as a function of stimulus intensity in pentobarbital anesthetized C57BL/6J and BALB/c male mice, 2.5 months old. At high stimulus intensities the BAEPs of both strains consisted of 4 positive and 4 negative waves (labelled P1-P4 and N1-N4, correspondingly). However, great interstrain differences were observed. BALB/c mice were characterized by higher thresholds, less amplitudes, beginning with P1 peak, longer latencies and steeper in slope latency-intensity profiles. The data suppose that by this age C57BL/6J mice have better auditory acuity, than BALB/c, and in BALB/c mice the pronounced abnormalities appear to arise in cochlear-auditory nerve system. Analysis of BAEPs using interpeak latencies (IPLs) and amplitude ratios intensities (ARs) profiles technique demonstrated no general trend that could fit for all IPLs as well as for all Ars changes by varying stimulus intensity. The obtained interstrain and interpeak differences in BAEPs parameters suggest that auditory information processing may vary greatly as a function of brainstem level.