Fluid Motion in the Mammalian Organ of Corti A Possible Source of the Second Filter

Abstract

A mechanical analysis of the functioning of the mammalian organ of Corti as deduced from experimental observations and electronmicro-scopic studies of the organ has been conducted. It was found that the arch of Corti is responsible for initiating a fluid motion in the spiral sulcus and reticular lamina which could stimulate the inner hair cells. A three-dimensional linear mathematical model with no arbitrary parameters is proposed to describe the force acting on the inner hair cell cilia as a function of arch displacement. Analysis of the model results show that the model (a) correctly predicts the form of the neural response for a low frequency square wave of arch motion, (b) demonstrates a physiologically reasonable time constant of 245 μsec, (c) shows a sharpening of neural stimulation of physiological importance, (d) can explain the qualitative difference of neural responses to arch motions of opposite polarity, (e) demonstrates a phase difference between outer and inner hair cell stimulation, and (f) appears to be chemically and metabolically vulnerable.