Magnitude effects of galvanic vestibular stimulation on the trajectory of human gait

This study examines the contribution of the vestibular system during differ ent magnitudes of galvanic vestibular stimulation (GVS) during human walkin g. Anodal threshold levels of GVS were determined for right and left sides for each subject. Seven conditions were tested (no stimulation, left and ri ght anode stimulation) at one, two and three times threshold. GVS was deliv ered to the mastoid processes at first heel contact and continued for the d uration of the trial. All subjects responded by deviating towards the anode while walking. In addition, the magnitude of deviation increased as the st imulus intensity increased. Our results demonstrate that the vestibular sys tem is sensitive to GVS intensity changes and responds by altering the magn itude of the response accordingly. These data provide a strong argument in support of a significant role for vestibular information during dynamic tas ks. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.