Sound-Driven Motion of Human Cochlear Structures Depends on Organ of Corti Integrity

Optical coherence tomography (OCT) was used to image and measure the passive sound-driven displacements of cochlear structures in situ through the intact round window membrane of fresh human cadaveric specimens at 12 to 30 hours postmortem. We find that the anatomical integrity of the organ of Corti (OoC) affects cochlear structural motion. OoC with high integrity (erect with supporting cells) have small osseous spiral lamina (OSL) motion. Conversely, OoC with low integrity (flattened without supporting cells) have large OSL motion. For the ratio of motion between the basilar membrane (BM) and OSL (BM/OSL), OoC with high integrity has large BM/OSL motion while a cochlear partition without OoC has small BM/OSL motion. Furthermore, the high-integrity OoC has reticular lamina surface motion that is lower than the BM, whereas low-integrity OoC has similar reticular lamina and BM motion. This relationship between OoC anatomical integrity and cochlear structural motion will have consequential effects on sound transduction.