A flexible anatomic set of mechanical models for the organ of Corti

Abstract

We build a flexible platform for the study of the mechanical performance of the organ of Corti (OoC) in the transduction of basilar membrane (BM) vibrations to motion of an inner hair cell bundle (IHB). In this platform, each anatomic component of the OoC is described by an equation of motion that can be followed in time. We propose an initial set of models that attempt to capture the nonlinearities of somatic and bundle motility, but can nevertheless be easily handled. The anatomic components that we consider are the outer hair cells (OHCs), the outer hair cell bundles, Deiters cells, Hensen cells, the IHB and various sections of the reticular lamina. We study endolymph fluid motion in the subtectorial gap and then the mutual interactions among the components of the OoC, including the pressure exerted by endolymph. Minute bending of the apical ends of the OHCs can have a significant impact on the passage of motion from the BM to the IHB, including possible critical oscillator behaviour, even without the assistance of tectorial motion, shearing, or bundle motility. Thus, the components of the OoC could cooperate to enhance frequency selectivity, amplitude compression and signal to noise ratio in the passage from the BM to the IHB. Our models also provide a mechanism that could contribute to appropriate amplification of the wave travelling along the cochlea.