Goodworth Adam D, Peterka Robert J
Division of Biomedical Engineering, Department of Science & Engineering, Oregon Health & Science University, Portland, Oregon, USA.
J Neurophysiol. 2010 Apr;103(4):1978-87. doi: 10.1152/jn.01064.2009. Epub 2010 Feb 10.
The control of upper body (UB) orientation relative to the pelvis in the frontal plane was characterized in bilateral vestibular loss subjects (BVLs) and compared with healthy control subjects (Cs). UB responses to external perturbations were evoked using continuous pelvis tilts (eyes open and eyes closed) at various amplitudes. Lateral sway of the lower body was prevented on all tests. UB sway was summarized using root-mean-square measures and dynamic behavior was characterized using frequency response functions (FRFs) from 0.023 to 10.3 Hz. Both subject groups had similar FRF variations as a function of stimulus frequency and were relatively unaffected by visual availability, indicating that visual orientation cues contributed very little to UB control. BVLs had larger UB sway at frequencies below ∼1 Hz compared with Cs. A feedback model of UB orientation control was used to identify sensory contributions to spinal stability and differences between subject groups. The model-based interpretation of experimental results indicated that a phasic proprioceptive signal encoding the angular velocity of UB relative to lower body motion was a major contributor to overall system damping. Parametric system identification showed that BVLs used proprioceptive information that oriented the UB toward the pelvis to a greater extent compared with Cs. Both subject groups used sensory information that oriented the UB vertical in space to a greater extent as pelvis tilt amplitudes increased. In BVLs, proprioceptive information signaling the UB orientation relative to the fixed lower body provided the vertical reference, whereas in Cs, vestibular information also contributed to the vertical reference.
研究了双侧前庭丧失受试者（BVL）在额面内上身（UB）相对于骨盆方向的控制情况，并与健康对照受试者（C）进行了比较。通过在不同幅度下连续倾斜骨盆（睁眼和闭眼）来诱发UB对外界扰动的反应。在所有测试中均防止下半身的侧向摆动。使用均方根测量总结UB摆动，并使用0.023至10.3 Hz的频率响应函数（FRF）表征动态行为。两个受试者组的FRF随刺激频率的变化相似，并且相对不受视觉条件的影响，这表明视觉方向线索对UB控制的贡献很小。与C相比，BVL在低于约1 Hz的频率下有更大的UB摆动。使用UB方向控制的反馈模型来确定对脊柱稳定性的感觉贡献以及受试者组之间的差异。基于模型对实验结果的解释表明，编码UB相对于下半身运动角速度的相位本体感觉信号是整体系统阻尼的主要贡献者。参数系统识别表明，与C相比，BVL在更大程度上使用将UB朝向骨盆定向的本体感觉信息。随着骨盆倾斜幅度增加，两个受试者组都在更大程度上使用将UB在空间中定向为垂直的感觉信息。在BVL中，表示UB相对于固定下半身方向的本体感觉信息提供了垂直参考，而在C中，前庭信息也对垂直参考有贡献。
