Figure 3.

Hearing Phenotype of Mpzl2-Mutant (Mpzl2^ko/ko) Mice

(A) Representative click-evoked ABR recordings at decreasing intensities (dB SPL) in 4-, 8-, and 12-week-old wild-type and Mpzl2-mutant mice. Waves are labeled I–IV and reflect the evoked activity of the auditory nerve (I) and ascending points of the auditory pathway in the midbrain (II–IV). As the stimulus level is reduced, amplitudes of ABR waves decrease and latencies of waves increase. The lowest intensity at which the ABR-wave profile is higher than the background-noise signal is the threshold (bold line; WT, blue; Mpzl2-mutant mice, green).

(B) ABR thresholds, in response to click and 8–40 kHz tone bursts, of the different genotypes and age groups.

(C and E) ABR wave I amplitude/intensity (C) and latency/intensity (E) curves in response to click stimuli of increasing intensities were determined in 4- and 12-week-old wild-type and Mpzl2-mutant mice.

(D and F) Peak amplitude of ABR waves I, II, and IV (D) and interpeak latencies I-II, II-IV, and I-IV (F) in response to a 70 dB SPL click stimulus in 4- and 12-week-old wild-type and Mpzl2-mutant mice. Data are shown as means ± SEM. Statistical significance: ^∗p < 0.05; ^∗∗p < 0.01.