Galvanic Vestibular Stimulation: Data Analysis and Applications in Neurorehabilitation

A rapidly aging population worldwide has spurred interest in developing new strategies to cope with neural declines and neurodegenerative disorders. Noninvasive brain stimulation (NIBS) is increasingly being used to explore functional mechanisms of the brain and induce the therapeutic modulation of behavior, cognition, and emotion. Galvanic vestibular stimulation (GVS), a safe and well-tolerated NIBS technique, is capable of modulating activity in various cortical and subcortical areas involved in vestibular and multisensory processing. A key facet of GVS is that the resultant effects may, in part, be a function of the individual being treated and the stimulus waveform that is delivered. Yet, most GVS studies have utilized the same generic stimulus, chosen from a reduced repertoire of candidates, across all subjects. The future use and, ultimately, clinical adoption of this technology will rely on contributions from the signal processing community to customize stimuli that are optimized for their effect and to exert maximum influence on brain imaging biomarkers. We provide a signal processing-focused overview of the current GVS state of the art in neurorehabilitation, including general stimulation design, concurrent analysis with neuroimaging data, and suggestions for future directions.