Countercurrent enhances acceleration sensation in galvanic vestibular stimulation

This study reports that the effect of galvanic vestibular stimulation (GVS) can be enhanced by giving a countercurrent before the normal current stimulation in the forward direction. In order to investigate the effect of the countercurrent on GVS, we applied various kinds of amplitudes and durations of the countercurrent before the normal stimulation. The strength of the effect was measured by the subjective response and body sway. As a result, the enhancing effect by the countercurrent does not only appear in the objective response but also in the subjective reports and we found that the effect of the countercurrent was enhanced in response to the amount of charges of the countercurrent before normal stimulations. Our result implies that there is a capacitor on the current path that enhances the GVS effect by the countercurrent.