The remarkable sensitivity, frequency selectivity, and dynamic range of the mammalian cochlea relies on longitudinal transmission of minuscule amounts of energy as passive, pressure-driven, basilar membrane (BM) traveling waves which are actively amplified at frequency-specific locations. Transmission of passive waves through viscous tissue situated in a viscous media is not an easy task. Here we describe mechanical properties of the tectorial membrane (TM) which facilitate this transmission. From mechanical measurements of isolated segments of the TM, we discovered that the stiffness of the TM is reduced when it is mechanically stimulated at physiologically relevant magnitudes and at frequencies below their frequency place in the cochlea. The reduction in stiffness functionally uncouples the TM from the organ of Corti, thereby minimizing energy losses during passive traveling wave propagation. Stiffening and decreased viscosity of the TM at high stimulus frequencies can potentially facilitate active amplification, especially in the high-frequency, basal turn, where energy loss due to internal friction within the TM is less than in the apex. This prediction is confirmed by neural recordings from several frequency regions of the cochlea.
|Title of host publication
|Mechanics of Hearing
|Subtitle of host publication
|Protein to Perception - Proceedings of the 12th International Workshop on the Mechanics of Hearing
|American Institute of Physics Inc.
|Published - 15 Jan 2016
|12th International Workshop on the Mechanics of Hearing: Protein to Perception - Cape Sounio, Greece
Duration: 23 Jun 2014 → 29 Jun 2014
|12th International Workshop on the Mechanics of Hearing: Protein to Perception
|23/06/14 → 29/06/14