A Role for the Otoliths in the Mechanics of Cochlear Homeostasis?

The role and function of the otolith organs might well hold continuing interest for those studying cochlear mechanics. The otoliths, utricle, saccule (and lagena in birds) are intriguing, not just because of their role in the evolutionary origins of inner ear function, but because, in mammals, their membranous structures are contained within the bony vestibule, directly in line with the action of the stapes[1]. Intriguingly they display highly-organised morphology[2]; [3]) and offer an apparently redundant low-frequency channel[4]. This duplication is puzzling considering cochlear low-frequency reception is generally less vulnerable than high. Unexplained is how pressures within the labyrinth are regulated[5]. A hypothesis is developed that the saccule's low-frequency pressure sensitivity may represent another function entirely, connected with the mechanics of cochlear homeostasis. A mathematical model is presented to illustrate how the otoliths may have two orthogonal modes, sensing otolith shear in differential mode, but sensing ambient pressure in common mode. [ABSTRACT FROM AUTHOR]