Enhancement of vestibular motion discrimination by small stochastic whole-body perturbations in young healthy humans

ABSTRACT Noisy galvanic vestibular stimulation has been shown to improve vestibular perception in healthy subjects. Here, we sought to obtain similar results using more natural stimuli consisting of small-amplitude motion perturbations of the whole body. Thirty participants were asked to report the perceived direction of antero-posterior sinusoidal motion on a MOOG platform. We compared the baseline perceptual thresholds with those obtained by applying small, stochastic perturbations at different power levels along the antero-posterior axis, symmetrically distributed around a zero-mean. At the population level, we found that the thresholds for all but the highest level of noise were significantly lower than the baseline threshold. At the individual level, the threshold was lower with at least one noise level than the threshold without noise in 87% of participants. Thus, small, stochastic oscillations of the whole body can increase the probability of detecting subthreshold vestibular signals, possibly due to stochastic resonance mechanisms. We suggest that, just as the external noise of the present experiments, also the spontaneous random oscillations of the body associated with standing posture are beneficial by enhancing vestibular thresholds with a mechanism similar to stochastic resonance. The results are also relevant from a clinical perspective, since they raise the possibility of improving motion perception in people with elevated thresholds due to aging or vestibulopathy by means of small-amplitude motion perturbations. HIGHLIGHTS Small-amplitude motion perturbations of the whole body improve vestibular perceptual thresholds of motion discrimination in young healthy people Improvements occur at optimal levels of noise amplitude, idiosyncratic to each subject The findings are consistent with the phenomenon of stochastic resonance The new method can applied to people with elevated thresholds due to aging or vestibulopathy