Mechanics of Coriolis Stimulus

II. Turning Sensation Derived from the Semicircular Canal System

Abstract

Output from a single semicircular canal during Coriolis stimulus (cross-coupled rotation) was deduced by an approach of mechanics in a previous paper. Based on the estimate of the canal output, the turning sensation derived from the whole semicircular canal system was deduced in this paper. First, the aspect of integration of turning sensations derived from the individual semicircular canals was considered. Neural linkage concerned with the turning sensation from the semicircular canal system was hypothesized to be arranged so as to perceive head rotation having an axis identical to a stimulus motion. Then, turning sensations caused by a single Coriolis stimulus and cyclic Coriolis stimuli were estimated. When presented in the coordinate system fixed in a horizontally rotating device, the magnitude and the direction of turning sensation were shown to depend on the angular velocity of body rotation and the rotating angle of head movement (amplitude of head oscillation in the case of cyclic Coriolis stimuli) irrespective of the initial angle (center angle) of the head relative to the vertical axis. The propriety of the hypotheses produced by the present deduction was discussed.