Differences in Movement Mechanics, Electromyographic, and Motor Cortex Activity Between Accurate and Nonaccurate Stepping
Differences in Movement Mechanics, Electromyographic, and Motor Cortex Activity Between Accurate and Nonaccurate Stepping
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DOI：
10.1152/jn.00360.2009
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发表时间：
2010-04-01
影响因子：
2.5
通讯作者：
Prilutsky, Boris I.
中科院分区：
文献类型：
--
作者：
Beloozerova, Irina N.;Farrell, Bradley J.;Prilutsky, Boris I.
Beloozerova IN, Farrell BJ, Sirota MG, Prilutsky BI。准确和不准确步进在运动力学、肌电图和运动皮层活动方面的差异。中国生物医学工程学报（英文版）。首次发表于2010年2月17日；doi: 10.1152 / jn.00360.2009。准确和不准确的运动在力学、肌肉和运动皮层活动上有什么不同？我们通过步行来解决这个问题。我们评估了全身力学（229个变量）、8块肢体肌肉的活动以及来自运动皮层的63个前肢表征神经元的活动，这些神经元在训练有素的运动中具有不同的爪子放置精度要求：在连续的表面上运动和沿着不同宽度的横向梯子运动。我们发现，随着精确度要求的提高，猫会采取更前倾的姿势（通过降低质心，旋转颈部和头部，增加远端关节的屈曲），并且踩在支撑表面上的空间变异性更小。在梯子上，与无约束运动相比，在整个站立过程中，手腕屈曲力矩较低，而在站立早期，踝关节和膝关节伸展力矩较高，髋关节力矩较低。爪的水平速度时程是对称的、光滑的，在不同的任务中没有差异。大多数其他机械变量也不依赖于精度要求。选定的远端肌肉略微增强了它们的活动，增加了精度要求。然而，在大多数运动皮层细胞中，与简单行走相比，精确行走时与步幅相关的频率调制的放电率均值、峰值和深度发生了显著变化。此外，在30%的神经元中，步幅相关的放电周期变短，20-25%的神经元活动或频率调制深度随着精度要求的增加而增加，尽管不是线性的。考虑到运动力学的相对较小的变化和运动皮层活动随着精度要求的增加而发生的实质性变化，我们得出结论，在练习准确步走时，运动皮层的活动反映了其他过程，可能涉及视觉信息与正在进行的运动的整合。
Beloozerova IN, Farrell BJ, Sirota MG, Prilutsky BI. Differences in movement mechanics, electromyographic, and motor cortex activity between accurate and nonaccurate stepping. J Neurophysiol 103: 2285-2300, 2010. First published February 17, 2010; doi:10.1152/jn.00360.2009. What are the differences in mechanics, muscle, and motor cortex activity between accurate and nonaccurate movements? We addressed this question in relation to walking. We assessed full-body mechanics (229 variables), activity of 8 limb muscles, and activity of 63 neurons from the motor cortex forelimb representation during well-trained locomotion with different demands on the accuracy of paw placement in cats: during locomotion on a continuous surface and along horizontal ladders with crosspieces of different widths. We found that with increasing accuracy demands, cats assumed a more bent-forward posture (by lowering the center of mass, rotating the neck and head down, and by increasing flexion of the distal joints) and stepped on the support surface with less spatial variability. On the ladder, the wrist flexion moment was lower throughout stance, whereas ankle and knee extension moments were higher and hip moment was lower during early stance compared with unconstrained locomotion. The horizontal velocity time histories of paws were symmetric and smooth and did not differ among the tasks. Most of the other mechanical variables also did not depend on accuracy demands. Selected distal muscles slightly enhanced their activity with increasing accuracy demands. However, in a majority of motor cortex cells, discharge rate means, peaks, and depths of stride-related frequency modulation changed dramatically during accurate stepping as compared with simple walking. In addition, in 30% of neurons periods of stride-related elevation in firing became shorter and in 20-25% of neurons activity or depth of frequency modulation increased, albeit not linearly, with increasing accuracy demands. Considering the relatively small changes in locomotor mechanics and substantial changes in motor cortex activity with increasing accuracy demands, we conclude that during practiced accurate stepping the activity of motor cortex reflects other processes, likely those that involve integration of visual information with ongoing locomotion.