Duarte Marcos, Zatsiorsky Vladimir M
Escola de Educação Física e Esporte, Universidade de São Paulo, Av. Mello Moraes 65, 05508-030 São Paulo, SP, Brazil.
Exp Brain Res. 2002 Sep;146(1):60-9. doi: 10.1007/s00221-002-1154-1. Epub 2002 Jun 27.
Maintenance of equilibrium was tested in conditions when humans assume different leaning postures during upright standing. Subjects ( n=11) stood in 13 different body postures specified by visual center of pressure (COP) targets within their base of support (BOS). Different types of visual information were tested: continuous presentation of visual target, no vision after target presentation, and with simultaneous visual feedback of the COP. The following variables were used to describe the equilibrium maintenance: the mean of the COP position, the area of the ellipse covering the COP sway, and the resultant median frequency of the power spectral density of the COP displacement. The variability of the COP displacement, quantified by the COP area variable, increased when subjects occupied leaning postures, irrespective of the kind of visual information provided. This variability also increased when vision was removed in relation to when vision was present. Without vision, drifts in the COP data were observed which were larger for COP targets farther away from the neutral position. When COP feedback was given in addition to the visual target, the postural control system did not control stance better than in the condition with only visual information. These results indicate that the visual information is used by the postural control system at both short and long time scales.
在人体直立站立时采取不同倾斜姿势的条件下，对平衡维持进行了测试。受试者（n = 11）站在支撑面（BOS）内由视觉压力中心（COP）目标指定的13种不同身体姿势中。测试了不同类型的视觉信息：视觉目标的持续呈现、目标呈现后无视觉以及同时提供COP的视觉反馈。使用以下变量来描述平衡维持：COP位置的平均值、覆盖COP摆动的椭圆面积以及COP位移功率谱密度的合成中频。无论提供何种视觉信息，当受试者采取倾斜姿势时，由COP面积变量量化的COP位移变异性都会增加。与有视觉时相比，如果去除视觉，这种变异性也会增加。在没有视觉的情况下，观察到COP数据存在漂移，对于远离中立位置的COP目标，漂移更大。当除了视觉目标之外还提供COP反馈时，姿势控制系统对姿势的控制并不比仅提供视觉信息的情况更好。这些结果表明，姿势控制系统在短期和长期尺度上都会利用视觉信息。
