Guiding Human Navigation with Noninvasive Vestibular Stimulation and Evoked Mediolateral Sway

Galvanic vestibular stimulation (GVS) involves the noninvasive stimulation of vestibular afferents by applying low-intensity electrical current to the mastoids. One consistent effect of GVS administration is a mild, transient, and polarity-specific mediolateral postural sway (MPS). The present study examined whether evoked MPS can be used to communicate instructions to humans, guiding performance on a stressful navigation task through a virtual urban environment. Our experimental design consisted of three primary phases: thresholding, training, and testing. During individualized thresholding, participants stood on a multiaxis force platform and received GVS stimulation at increasing intensity with two polarity conditions: anodal/cathodal on right/left mastoid, or vice-versa. The stimulation intensities reliably eliciting MPS during thresholding were then applied to a training session that involved learning associations between stimulation polarity and directions (i.e., left, right, and straight). A participant then applied learned associations to a complex urban virtual navigation task. We found a polarity-specific and parametrically increasing MPS as a function of GVS stimulation intensity. Participants were able to rapidly learn GVS-to-direction associations, and they showed very high accuracy in applying learned associations to the navigation task. Results are discussed in the context of sensory augmentation research and identifying innovative methods for multisensory information transfer.