Motion of the otolithic membrane in the bullfrog sacculus

Accessory structures that overlie the sensory epithelia of the various inner ear organs play an important role in the transduction of mechanical perturbations by the underlying hair cells. It imposes a load (mass, offset in position) on individual hair bundles and is the medium that mechanically couples multiple hair bundles. Also, it may provide a preferred directionality of motion across the macula. In this manuscript, we present results on the mechanical properties of the otolithic membrane (OM) from the American bullfrog sacculus. Experiments were performed in which the motion of the OM, in response to a mechanical stimulus, was determined over an extended 2-D area. We find that the OM moves in phase with the stimulus, preferentially in the same direction as the applied stimulus. The decay in response amplitude is consistent with the OM being a homogeneous elastic material.