Sasaki Osamu, Usami Shin-ichi, Gagey Pierre-Marie, Martinerie Jacques, Le Van Quyen Michel, Arranz Patrick
Department of Otolaryngology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
Exp Brain Res. 2002 Nov;147(1):1-7. doi: 10.1007/s00221-002-1170-1. Epub 2002 Sep 13.
Stabilometry signals involve irregular and unpredictable components. The purpose of the present study was to investigate these signals with a nonlinear technique to examine how the complexity of the postural control system breaks down under altered visual conditions. We evaluated the dynamical similarities of the postural control system when the eyes were open or closed, or when there was optokinetic stimulation (OKS). A similarity index was calculated by the cross-correlation integral between the two dynamics: eyes open and eyes closed, or eyes open with OKS. Using this technique, dynamical changes were not observed between eyes-open and eyes-closed conditions. This result suggests that the nonvision condition does not produce any striking effect on the postural control system; instead, the eyes-open condition causes a decrease in the stochastic activity of the postural control system, which may originate mainly from the stiffness of the musculoskeletal systems. In contrast, the visual input of OKS affected the dynamics of the postural control system in nearly half of the subjects (group 2) despite showing no significant differences between the eyes-open condition and the other conditions for area as the conventional parameter. However, the other half of the subjects (group 1) did not experience any influence of OKS on their postural dynamics, despite showing significant differences between eyes-open and the other conditions for all traditional parameters. From the results for group 2, we hypothesize that OKS may induce the striking effect on dynamics properties of the multilink network system involving visual and vestibular cortex related to self-motion perception, which acts to decrease the stochastic activity in order to correct disturbed posture.
稳定测量信号包含不规则和不可预测的成分。本研究的目的是用一种非线性技术来研究这些信号，以检验在改变的视觉条件下姿势控制系统的复杂性是如何瓦解的。我们评估了眼睛睁开或闭上时，或存在视动刺激（OKS）时姿势控制系统的动态相似性。通过两种动态之间的互相关积分计算相似性指数：眼睛睁开和眼睛闭上，或眼睛睁开并伴有OKS。使用这种技术，在眼睛睁开和眼睛闭上的条件之间未观察到动态变化。这一结果表明，非视觉条件对姿势控制系统不会产生任何显著影响；相反，眼睛睁开的条件会导致姿势控制系统的随机活动减少，这可能主要源于肌肉骨骼系统的刚度。相比之下，尽管作为传统参数的面积在眼睛睁开条件和其他条件之间没有显著差异，但OKS的视觉输入在近一半的受试者（第2组）中影响了姿势控制系统的动态。然而，另一半受试者（第1组）在姿势动态方面没有受到OKS的任何影响，尽管在所有传统参数方面眼睛睁开与其他条件之间存在显著差异。根据第2组的结果，我们推测OKS可能会对涉及与自我运动感知相关的视觉和前庭皮层的多链路网络系统的动态特性产生显著影响，其作用是减少随机活动以纠正受干扰的姿势。
