| First Author | Kamiya K | Year | 2014 |
| Journal | Proc Natl Acad Sci U S A | Volume | 111 |
| Issue | 25 | Pages | 9307-12 |
| PubMed ID | 24920589 | Mgi Jnum | J:212101 |
| Mgi Id | MGI:5578076 | Doi | 10.1073/pnas.1405322111 |
| Citation | Kamiya K, et al. (2014) An unusually powerful mode of low-frequency sound interference due to defective hair bundles of the auditory outer hair cells. Proc Natl Acad Sci U S A 111(25):9307-12 |
| abstractText | A detrimental perceptive consequence of damaged auditory sensory hair cells consists in a pronounced masking effect exerted by low-frequency sounds, thought to occur when auditory threshold elevation substantially exceeds 40 dB. Here, we identified the submembrane scaffold protein Nherf1 as a hair-bundle component of the differentiating outer hair cells (OHCs). Nherf1(-/-) mice displayed OHC hair-bundle shape anomalies in the mid and basal cochlea, normally tuned to mid- and high-frequency tones, and mild (22-35 dB) hearing-threshold elevations restricted to midhigh sound frequencies. This mild decrease in hearing sensitivity was, however, discordant with almost nonresponding OHCs at the cochlear base as assessed by distortion-product otoacoustic emissions and cochlear microphonic potentials. Moreover, unlike wild-type mice, responses of Nherf1(-/-) mice to high-frequency (20-40 kHz) test tones were not masked by tones of neighboring frequencies. Instead, efficient maskers were characterized by their frequencies up to two octaves below the probe-tone frequency, unusually low intensities up to 25 dB below probe-tone level, and growth-of-masker slope (2.2 dB/dB) reflecting their compressive amplification. Together, these properties do not fit the current acknowledged features of a hypersensitivity of the basal cochlea to lower frequencies, but rather suggest a previously unidentified mechanism. Low-frequency maskers, we propose, may interact within the unaffected cochlear apical region with midhigh frequency sounds propagated there via a mode possibly using the persistent contact of misshaped OHC hair bundles with the tectorial membrane. Our findings thus reveal a source of misleading interpretations of hearing thresholds and of hypervulnerability to low-frequency sound interference. |
