Micro- and nanomechanics of the cochlear outer hair cell

Outer hair cell electromotility is crucial for the amplification, sharp fre quency selectivity, and nonlinearities of the mammalian cochlea. Current mo deling efforts based on morphological, physiological, and biophysical obser vations reveal transmembrane potential gradients and membrane tension as ke y independent variables controlling the passive and active mechanics of the cell. The cell's mechanics has been modeled on the microscale using a cont inuum approach formulated in terms of effective (cellular level) mechanical and electric properties. Another modeling approach is nanostructural and i s based on the molecular organization of the cell's membranes and cytoskele ton. It considers interactions between the components of the composite cell wall and the molecular elements within each of its components. The methods and techniques utilized to increase our understanding of the central role outer hair cell mechanics plays in hearing are also relevant to broader res earch questions in cell mechanics, cell motility, and cell transduction.