Cochlear outer hair cell electromotility enhances organ of Corti motion on a cycle-by-cycle basis at high frequencies in vivo.
Level 5 - mechanism / opinion, no new human data
Animal physiological study (non-human in vivo model)
PubMed 34686590 · doi:10.1073/pnas.2025206118
What was done
Researchers measured sound-evoked vibrations inside the living mouse cochlea to determine whether prestin-dependent somatic electromotility in outer hair cells (OHCs) operates fast enough in vivo to drive cycle-by-cycle amplification at high frequencies.
What was found
The top and bottom of OHCs moved in opposite directions at frequencies exceeding 20 kHz, indicating fast somatic length changes. These motions depended on prestin, were physiologically vulnerable, and dominated the cochlea's vibratory response to high-frequency sound despite the presence of low-pass filtering. Exact numerical values, sample sizes, and variances were not reported in the abstract.
Why it matters
These findings address a long-standing biophysical question by demonstrating that outer hair cell electromotility can overcome low-pass filtering to act as the primary high-frequency amplifier in the mammalian cochlea.
Limits
The study was conducted entirely in mice, providing only indirect evidence for human auditory physiology. The abstract omits sample size, exact quantitative measurements, effect sizes, and error margins.
Cited by
- supports Outer hair cells in the mammalian inner ear physically oscillate at audio frequencies up to 20,000 Hz in humans and up to 100,000 Hz in bats.