Studies of the Linear Vestibuloocular Reflex to Clarify Otolith Function

The vestibular organs consist of three semicircular canals, which sense angular acceleration, and two otolith organs, which sense linear acceleration. Although we are now exposed to various degrees of linear acceleration with the development of advanced methods of transportation, less is known about the function of the otolith organs relative to the function of the semicircular canals. There are several reasons for this: the morphological and functional characteristics of the otolith organs are complex; the otolith organs respond not only to dynamic head translation but also static head tilt with respect to gravity, and it is difficult to generate sufficient linear acceleration using a compact apparatus. To clarify otolith function, this article introduces recent progress in studies of the linear vestibuloocular reflexes, which are eye movements that compensate for linear translation or tilt.