To determine the dynamic characteristics of the labyrinthine righting system, transfer function of the system was calculated by using shoulder movements and righting movements of the head which appear during the standing position. The results computed were displayed as frequency response (i.e., gain and phase diagrams).
(1) In healthy subjects, frequency response of the system indicated an increase of gain with the increase in frequency of the body sway (i.e., derivative control action).
(2) In cases of bilateral loss of labyrintine excitability, gain diagram was flat and values of gains were low. These patients showed disturbances in the righting movements to rapid body sway.
(3) In those with a unilateral loss of labyrinthine excitability, frequency response was similar to that seen in healthy subjects who showed some irregularity in gain and phase diagrams.
These findings indicate that the labyrinth indeed plays an important role in provocation of the righting movements to short and rapid body sway.
