Temporal correlations in postural sway moderate effects of stochastic resonance on postural stability.

The present work documents reanalysis of previous research by Priplata and colleagues (Priplata et al., 2002) into the effects of subthreshold vibratory stimulation to the plantar surface of the foot on postural stability during quiet standing. In stochastic resonance, stimulating a nonlinear system with noise can promote system stability. Stochastic resonance has been proposed to have clinical applications as an intervention that might help to stabilize posture. Insoles designed to stimulate the plantar surface of the foot with uncorrelated white-noise fluctuations have been shown to reduce a number of standard measures of postural variability. An important remaining concern is that the efficacy of stochastic-resonance applications is subject to strong individual differences. Our reanalysis of data from Priplata et al.'s original study provides evidence that effects of uncorrelated fluctuations in subthreshold vibratory stimulation are moderated by temporally correlated fluctuations in postural sway. We suggest how future development might capitalize on this finding to fine-tune existing stochastic-resonance applications to posture.