Noise-Enhanced Human Balance Control
Hebrew SeniorLife/Harvard Medical School
Last modified: May 16, 2006
With age and disease, there is a decline in somatosensory function that has also been associated with diminished motor performance. Recently, it has been shown that subsensory mechanical noise can improve sensory function in healthy young individuals, older adults, patients with diabetic neuropathy, and patients with stroke. Here our goal was to show that input noise can be used to improve sensorimotor function in humans. First, we examined whether the postural sway of both healthy young and healthy elderly individuals during quiet standing could be reduced by applying subsensory mechanical noise to the soles of the feet using a vibrating platform. With the application of noise, young and elderly subjects showed significant reductions in postural sway, and the postural sway of the elderly during input noise also resembled the sway of young subjects. To extend this work, we examined whether quiet-standing postural sway in young and elderly individuals can be reduced by applying subsensory mechanical noise to the feet using vibrating insoles. We found that vibrating insoles could significantly reduce postural sway in young and elderly individuals, and older adults improve more than young subjects. We further investigated whether subsensory mechanical noise applied to the soles of the feet via vibrating insoles can be used to reduce postural sway in patients with disease-related sensory loss, e.g., patients with diabetic neuropathy and patients with stroke. We also tested the hypothesis that baseline postural sway is directly correlated with both the sensory deficits of the individual and the amount of reduction of postural sway due to the application of input noise to the soles of the feet. It was found that the postural sway can be reduced with the application of noise in patients with sensory deficits, and higher levels of baseline postural sway result in greater improvements in balance control with input noise. Finally, we considered whether subsensory mechanical noise applied to the ankles via vibrating wraps could be used to reduce postural sway in healthy young and healthy elderly subjects. We found that vibrating ankle wraps can reduce postural sway in young and elderly individuals. The use of noise-based devices such as randomly vibrating shoe insoles or ankle wraps could provide a non-invasive technique for ameliorating postural instability due to age- or disease-related sensory loss.