Standardizing Stimulus Parameters for Noisy Galvanic Vestibular Stimulation.

Noisy galvanic vestibular stimulation (nGVS) delivers band-limited subsensory electrical noise at the mastoids to amplify vestibular signaling via stochastic resonance. This review synthesizes human studies involving healthy participants and proposes a practical stimulation protocol and reporting checklist to promote standardization of nGVS in vestibular research and clinical translation. Evidence supports the use of a bilateral bipolar mastoid montage; 1.75-10 cm2 electrodes; zero-mean Gaussian white noise with a 0-30 Hz passband (or 0-640 Hz when replicating prior work or testing cortical or perceptual hypotheses); participant-titrated subsensory intensities (typically 100-400 μA, with fixed protocols often 400-1,000 μA); and task-matched stimulation epochs of 10-30 seconds. Reports should specify the electrode polarity, passband and filter details, amplitude reference (peak, peak-to-peak, or root-mean-square), threshold procedures, and total stimulation dose. Under these conditions, nGVS has been shown to improve vestibulospinal outcomes (reduced postural sway and better gait stability), modulate vestibulo-ocular physiology, and lower vestibular motion detection thresholds. The effects scale with task difficulty and baseline vestibular function; tolerability was favorable at the subsensory level. Priorities for future research include head-to-head tests of montage and frequency, individualized dose-response and after-effect mapping, stratification by baseline vestibular status, and mechanistic biomarkers tied to behavior. Standardized parameters and reporting will enable robust meta-analyses and faster clinical translation.