Analysis on Effects of Galvanic Vestibular Stimulation on Postural Stability using 3D Motion Analysis

This paper presents the analysis on effects of GVS(Galvanic Vestibular Stimulation) to mastoid process on postural balance and stability using 3 dimensional motion analysis. The experiments were performed by providing the experimental subjects a bipolar binaural galvanic vestibular stimulation during standing and walking, and then the postural stability was evaluated by 3 dimensional motion analysis system. Postural stability evaluation during standing was performed by a measurement of the deviation of the COP(center of pressure) of experimental subjects who was standing upright on the force plate and was given the currents of 0.5, 1 and 2 mA for 15 seconds. Postural stability evaluation in walking was performed by a measurement of straight walking status after giving the GVS with the currents of 0.5, 1 and 2 mA to the mastoid process located behind the ears. As the results of the experiments of the GVS, it was empirically proven that the changes in the many sensory organs including vestibular organ was interpreted by CNS(Central Nervous System) and feed back to body, which makes the posture and the walking stabilized. During standing, the galvanic current provided to the vestibular organ induced the human body to deviate toward the anode, and the magnitude of deviation of the COP presented in the form of sway on the force plate increased as the stimulus intensity increased. During walking, the GVS made the walking path of gait deviated toward anode, which can be a proof of the effectiveness the GVS on posture stability. The major contribution of our study is to provide a novel method for quantitative diagnosis of vestibular organ by investigating the sway of human body during motion using 3D motion analysis techniques, which is different from the previous approaches that only considered the standing condition. Furthermore, it provides a effective guideline for the GVS. Key-Words: Galvanic vestibular stimulation, Postural stability, Center of pressure, Motion analysis