Abstract
Human audition can distinguish frequencies that are only 0.2% apart as well as perceive millionfold differences in acoustic pressure. These properties stem from sound-induced nanoscale vibrations in sensory epithelium of the inner ear. The epithelium is composed of three layers; sensory hair-cell, supporting-cell, and extracellular-matrix layers. Although each layer seem to show different vibration properties in vivo, this characteristics has not yet been precisely determined. In this study, we have developed an imaging system that can record the tomography and motion of the epithelium. The underlying technique is based on a commercial optical coherence tomography (OCT) system. We equipped the system with a powerful, broadband light source. This arrangement allows us not only to achieve depth resolution of ～1.8 μm in the tomographic image but also to pursue amplitude and phase of nanoscale vibrations in each of the three layers in a live guinea pig. The system has a potential to reveal physical networks across the three layers and thereby it may contribute to identification of a force transport mechanism underlying biomechanical amplification in the cochlea.
