[The sensory organization in the posture stability with interruption induced by standing foam in normal subjects]

To investigate the sensory organization in the postural stability under sensory conflict induced by standing foam surface in normal individuals.

One hundred and six normal subjects were tested using the computerized posturography under the firm surface and foam surface with eye open and eye closed for 30 seconds respectively. The standing foam surface was to interrupt the somatosensory and closing eyes was to interrupt the visual input in the postural stability. The sway velocity (SV) of body under different sensory conflict condition was recorded as parameter of postural stability and the effect of organization between the vestibular, visions and somatosensory was analyzed quantitatively.

(1) The SV decreased when the visual cue or/and somatosensory cue be interrupted (P<0.01); (2) The decreased degrees of SV induced by the change of visual cue were (12.12+/-6.1)% and (30.58+/-9.69)% when the somatosensory cue be interrupted or not. The decreased degrees of SV induced by the change of somatosensory cue were (18.31+/-6.56)% and (36.25+/-8.90)% when the visual cue be interrupted or not. The decreased degrees of SV induced by the change of both somatosensory and visual cue were (46.21+/-8.67)%; (3) The most important sensory input for keeping balance is vestibular cue, followed by the somatosensory and visual cues and the relationship among these three sensory is nonlinear.

Through recording the postural stability quantitatively under different conditions of sensory conflict induced by standing foam surface or closing eyes, it is possible to evaluate the sensory organization of the three kinds of sensory input including the visual, somatosensory, and vestibular input in postural control. It exist the various balance strategy for keeping postural stability under sensory conflict in normal subjects. When one or two sensory input was interrupted in the static balance, the center nervous system has a complicated mechanism of sensory organization to keep balance even in the normal subject.