Figure 6.
ABRs are abnormal in Sef mutant mice. a, ABRs from 12-week-old wild-type (WT; top) and homozygous (−/−; bottom) animals at 5 dB increments from 60 to 70 dB, click stimulus. Waves i–v are indicated. The mutant animal responds to sound, but the peaks are small, even at high SPLs. b, Representative traces from a wild-type (WT; top) and a homozygous (−/−; bottom) animal presented with a 16 kHz stimulus at 50 dB. The morphology of the late peaks is clearly abnormal in the SefKST223 mutant. The first two waves are distinct, but the later activity does not resolve into clearly identifiable waves. c, Average thresholds for wild-type (blue; n = 8 ears) and homozygous (red; n = 16 ears) animals presented with pure tone stimuli from 5 to 45 kHz. There is no change in threshold at any frequency. d, Amplitudes measured for waves i and ii in response to a 70 dB click stimulus. Individual responses are plotted with filled symbols, and average responses are plotted with open symbols. The average amplitude for both waves is significantly reduced in heterozygous (green; n = 16 ears) and homozygous (red; n = 13 ears) animals, with several animals exhibiting poor responses that fall well outside the wild-type (blue; n = 10 ears) range (*p < 0.05, ANOVA). e, Average latencies are unaffected in the same animals. f, The threshold for each peak was determined in wild-type (blue; n = 8 ears) and homozygous (red; n = 16 ears) animals presented with a 16 kHz stimulus. Waves i and ii occur at normal SPLs, but the later responses (iii–v) occur at significantly higher intensities in mutants compared with wild types (p < 0.02, ANOVA). Error bars indicate SD for each average.