Department of Mechanical Engineering and Intelligent Systems, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.
Department of Life Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Sci Rep. 2021 Oct 13;11(1):20362. doi: 10.1038/s41598-021-99785-w.
Impairment of inferior olivary neurons (IONs) affects whole-body movements and results in abnormal gait and posture. Because IONs are activated by unpredicted motion rather than regular body movements, the postural dysfunction caused by ION lesions is expected to involve factors other than simple loss of feedback control. In this study, we measured the postural movements of rats with pharmacological ION lesions (IO rats) trained to stand on their hindlimbs. The coordination of body segments as well as the distribution and frequency characteristics of center of mass (COM) motion were analyzed. We determined that the lesion altered the peak properties of the power spectrum density of the COM, whereas changes in coordination and COM distribution were minor. To investigate how the observed properties reflected changes in the control system, we constructed a mathematical model of the standing rats and quantitatively identified the control system. We found an increase in linear proportional control and a decrease in differential and nonlinear control in IO rats compared with intact rats. The dystonia-like changes in body stiffness explain the nature of the linear proportional and differential control, and a disorder in the internal model is one possible cause of the decrease in nonlinear control.
橄榄下核神经元（IONs）的损伤会影响全身运动，导致异常步态和姿势。由于 IONs 是由未预测的运动而不是常规的身体运动激活的，因此 ION 损伤引起的姿势功能障碍预计涉及反馈控制以外的因素。在这项研究中，我们测量了经过药理学 ION 损伤（IO 大鼠）训练后用后腿站立的大鼠的姿势运动。分析了身体节段的协调性以及质心（COM）运动的分布和频率特征。我们确定损伤改变了 COM 功率谱密度的峰值特性，而协调和 COM 分布的变化较小。为了研究观察到的特性如何反映控制系统的变化，我们构建了站立大鼠的数学模型，并对控制系统进行了定量识别。与完整大鼠相比，IO 大鼠的线性比例控制增加，而微分和非线性控制减少。身体僵硬的张力障碍样变化解释了线性比例和微分控制的性质，内部模型的紊乱是非线性控制减少的一个可能原因。
