How much do somatic and hair bundle motility contribute to cochlear amplification?

Abstract

In this study we investigated a hydromechanical model of the cochlea in order to study the possible effects and relative contributions of stereocilia forces and somatic electromotility in outer hair cells (OHC) to cochlear amplification. The cochlear complex is modeled by a multi-compartmental model and the tectorial membrane (TM) is modeled by an untuned transmission line and these couple into each other to contribute to basilar membrane (BM) movement. The motivation behind this model was the experimental observation of traveling waves on the TM. In the absence of the model's somatic forces, we can cause stereocilia forces alone to only generate a small increase in the BM to stapes velocity ratio relative to when both sources are present. This indicates that the somatic motility is the main contributor to cochlear amplification in this model. However, when somatic forces are present, the stereociliary forces, otherwise ineffectual, can contribute substantially to cochlear amplification. © 2011 American Institute of Physics.