Proximal versus distal control of two-joint planar reaching movements in the presence of neuromuscular noise.
Proximal versus distal control of two-joint planar reaching movements in the presence of neuromuscular noise.
复制标题
在存在神经肌肉噪声的情况下，两关节平面到达运动的近端与远端控制。
DOI：
10.1115/1.4006811
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Dingwell,JonathanB
中科院分区：
文献类型：
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作者：
Nguyen,HungP;Dingwell,JonathanB
确定人类神经系统如何应对神经运动噪音，对于理解人类如何实现准确的目标定向运动至关重要。在实验中，学习熟练任务的人往往比近端关节运动更能减少远端关节运动的变异性。这表明，他们可能对远端关节施加了比近端关节更大的控制。然而，原因尚不清楚，很大程度上是因为在实验上不可能直接控制每个关节的噪音或控制。因此，本研究使用2自由度扭矩驱动臂模型来确定在每个关节上独立施加的不同噪声和/或控制组合如何影响到达精度和进行运动所需的总功。信号相关的噪声被同时和独立地添加到肩部和肘部的扭矩中，以在平面伸展过程中引入终点误差。然后在每个关节上独立地和联合地应用反馈控制，以减少由于增加的神经肌肉噪声而导致的终点误差。运动方向和沿手臂的惯性分布被改变，以量化这些生物力学变化如何影响系统性能。终点误差和总网络作为相依测量进行计算。当每个关节在没有控制的情况下独立地受到噪声影响时，对于几乎所有到达方向和惯性比的组合，终点误差对远端(肘部)噪声比近端(肩部)噪声更敏感。当惯性更多地向前臂分布时，远端噪声对终点误差的影响更加明显。相反，当质量转移到上臂以达到各个方向的运动时，总的网络功减少。当两个关节都存在噪声并实施关节控制时，对于几乎所有到达方向和惯性比的组合，单独控制远端关节比单独控制近端关节更能减少终点误差。当更多的肿块分布在更近端时，仅在远端关节应用控制在减少终点误差方面更有效。同样，对于几乎所有到达距离和惯性比的组合，单独控制远端关节比单独控制近端关节需要更少的总网络工作量。通过选择性地应用控制来减少远端关节的变异性比近端关节的可变性，可以更有效地减少终点误差和能量成本。造成这种情况的原因是手臂本身的生物力学结构。
Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint alone for nearly all combinations of reaching direction and inertia ratio. Applying control only at the distal joint was more effective at reducing endpoint errors when more of the mass was more proximally distributed. Likewise, controlling the distal joint alone required less total net work than controlling the proximal joint alone for nearly all combinations of reaching distance and inertia ratio. It is more efficient to reduce endpoint error and energetic cost by selectively applying control to reduce variability in the distal joint than the proximal joint. The reasons for this arise from the biomechanical configuration of the arm itself.