THE PLANTAR SOLE IS A DYNAMOMETRIC MAP FOR HUMAN BALANCE CONTROL

THIS study investigated the role of the plantar cutaneous information in controlling human balance. We hypothesized that the cutaneous affer ent messages from the main supporting zones of the feet have sufficien t spatial relevance to inform the CNS about the body position with res pect to the vertical reference and consequently to induce adapted regu lative postural responses. Skin mechanoreceptors of anterior and/or po sterior areas of one or both soles of 10 standing subjects were activa ted by superficial mechanical vibration with high frequency and low am plitude. Variations of the subject's center of pressure (CoP) were rec orded. Spatially oriented whole-body tilts were observed for every sub ject. Their direction depended on the foot areas stimulated and was al ways opposite to the vibration-simulated pressure increase. These resp onses are found to subserve a postural regulative function and we sugg est that co-processing of the various cutaneous messages followed a ve ctor addition mode. (C) 1998 Lippincott Williams & Wilkins.