Analysis of outer hair cell electromechanics reveals power delivery at the upper-frequency limits of hearing.
Level 5 - mechanism / opinion, no new human data
Level 5 by design analogy (biophysical modeling and secondary analysis of in vitro electrophysiological data)
PubMed 35673856 · doi:10.1098/rsif.2022.0139
What was done
The author calculated the electrical power consumption and mechanical power output of the outer hair cell (OHC) membrane-motor complex. The analysis was conducted using previously published voltage-clamp measurements from isolated OHCs and cell membrane patches to model prestin-mediated electromechanics.
What was found
Mechanical power output peaked at an optimal frequency far exceeding the low-pass cutoff suggested by nonlinear capacitance and the whole-cell resistive-capacitive (RC) corner frequency. This high-frequency power output was facilitated by a -90° phase shift in membrane electrical charge displacement, manifested as imaginary-valued nonlinear capacitance. Specific numerical power outputs and frequencies were not reported in the abstract.
Why it matters
It provides a biophysical mechanism explaining how mammalian outer hair cells can overcome cellular RC filtering to deliver mechanical amplification at high acoustic frequencies.
Limits
The study is a mathematical and biophysical re-analysis of previously published in vitro patch-clamp datasets without new experimental data. The abstract provides no specific quantitative power or frequency values, and findings from isolated cells and patches may not fully capture intact in vivo cochlear micromechanics.
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.