2013 年 2 巻 1 号 p. 29-36
To maintain an erect posture, sensory information must be integrated from the vestibular, visual, and somatosensory systems. Additional somatosensory cues from the fingertips have been proposed to be able to improve postural stability during quiet standing. The present review paper focuses on the beneficial effect of light fingertip touch on postural control during quiet standing as follows: 1) First, the fundamental light touch procedure for the improvement of postural stability is introduced. 2) The effects of light touch on postural stability in instable persons, including elderly adults, infants, and patients with bilateral vestibular loss, congenital blindness, and somatosensory loss by diabetic neuropathy, are described, indicating that postural stability improves due to multisensory reweighting when a light touch stimulus is applied. 3) The relation between muscle activity and postural sway by light touch are described, demonstrating that the cross-correlation function between velocity information on the center of mass and the activity of the gastrocnemius muscle is stronger with somatosensory input by light touch than without it. 4) The effects of noise-like mechanical stimulation to the fingertips on postural stability are described based on the concept of stochastic resonance, which further enhances postural stability. The literature emphasizes that the effects of light touch on postural stability are purely caused by somatosensory information and not due to the mechanical support provided by the fingers. 5) In contrast to active touch, the efficacy of passive touch is summarized with respect to negligible friction between the skin and a touch device, leading to a decline in postural sway. 6) Finally, the effects of light touch in temporal relation to light touch, muscle activity, and postural sway, are interpreted, taking into consideration that light touch is effective for postural stability in many individuals, including patients with neuropathy, visual disorders, and diabetes.