Long-latency muscle activity reflects continuous, delayed sensorimotor feedback of task-level and not joint-level error
Long-latency muscle activity reflects continuous, delayed sensorimotor feedback of task-level and not joint-level error
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DOI：
10.1152/jn.00609.2012
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发表时间：
2013-09-01
影响因子：
2.5
通讯作者：
Ting, Lena H.
中科院分区：
文献类型：
--
作者：
Safavynia, Seyed A.;Ting, Lena H.
在上肢和下肢中，有证据表明，对机械扰动的短潜伏期肌电图 (EMG) 反应是根据肌肉拉伸或关节运动来调节的，而长潜伏期反应是根据任务级目标的实现来调节的，例如，运动。 g.，肢体运动的期望方向。我们假设长延迟响应是由任务级错误反馈持续调节的。之前，我们确定了一种基于误差的感觉运动反馈变换，它描述了站立平衡期间肌电图对斜坡和保持扰动的响应时间过程（Safavynia 和 Ting 2013；Welch 和 Ting 2008、2009）。在这里，我们的目标是 1）测试感觉运动转换在更丰富的扰动条件和姿势状态下的稳健性； 2）明确测试感觉运动转换是否基于任务级误差与关节级误差。我们开发了新颖的加速度脉冲扰动序列，这样当身体偏离所需的直立状态，同时从之前的扰动中恢复时，就会施加扰动。使用长延迟延迟（类似于 100 毫秒）之前的 EMG 之前的质心 (CoM) 运动学加权和来重建拮抗肌对中 EMG 响应的整个时间过程（类似于 4 秒）。此外，CoM 和关节运动轨迹在扰动序列期间变得不相关，使我们能够在相同的实验条件下明确比较任务级反馈与关节反馈。与 CoM 运动学相比，使用关节运动学重建 EMG 效果较差，并且需要非生理学的短延迟（类似于 10 毫秒）。因此，任务级变量的连续、长延迟反馈可能是调节上肢和下肢长延迟反应的常见机制。
In both the upper and lower limbs, evidence suggests that short-latency electromyographic (EMG) responses to mechanical perturbations are modulated based on muscle stretch or joint motion, whereas long-latency responses are modulated based on attainment of task-level goals, e. g., desired direction of limb movement. We hypothesized that long-latency responses are modulated continuously by task-level error feedback. Previously, we identified an error-based sensorimotor feedback transformation that describes the time course of EMG responses to ramp-and-hold perturbations during standing balance (Safavynia and Ting 2013; Welch and Ting 2008, 2009). Here, our goals were 1) to test the robustness of the sensorimotor transformation over a richer set of perturbation conditions and postural states; and 2) to explicitly test whether the sensorimotor transformation is based on task-level vs. joint-level error. We developed novel perturbation trains of acceleration pulses such that perturbations were applied when the body deviated from the desired, upright state while recovering from preceding perturbations. The entire time course of EMG responses (similar to 4 s) in an antagonistic muscle pair was reconstructed using a weighted sum of center of mass (CoM) kinematics preceding EMGs at long-latency delays (similar to 100 ms). Furthermore, CoM and joint kinematic trajectories became decorrelated during perturbation trains, allowing us to explicitly compare task-level vs. joint feedback in the same experimental condition. Reconstruction of EMGs was poorer using joint kinematics compared with CoM kinematics and required un-physiologically short (similar to 10 ms) delays. Thus continuous, long-latency feedback of task-level variables may be a common mechanism regulating long-latency responses in the upper and lower limbs.