Chen Yi-Ching, Lin Linda L, Lin Yen-Ting, Hu Chia-Ling, Hwang Ing-Shiou
Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung City, Taiwan.
Physical Therapy Room, Chung Shan Medical University Hospital, Taichung City, Taiwan.
Front Hum Neurosci. 2017 Nov 8;11:538. doi: 10.3389/fnhum.2017.00538. eCollection 2017.
Error amplification (EA) feedback is a promising approach to advance visuomotor skill. As error detection and visuomotor processing at short time scales decline with age, this study examined whether older adults could benefit from EA feedback that included higher-frequency information to guide a force-tracking task. Fourteen young and 14 older adults performed low-level static isometric force-tracking with visual guidance of typical visual feedback and EA feedback containing augmented high-frequency errors. Stabilogram diffusion analysis was used to characterize force fluctuation dynamics. Also, the discharge behaviors of motor units and pooled motor unit coherence were assessed following the decomposition of multi-channel surface electromyography (EMG). EA produced different behavioral and neurophysiological impacts on young and older adults. Older adults exhibited inferior task accuracy with EA feedback than with typical visual feedback, but not young adults. Although stabilogram diffusion analysis revealed that EA led to a significant decrease in critical time points for both groups, EA potentiated the critical point of force fluctuations [Formula: see text], short-term effective diffusion coefficients (Ds), and short-term exponent scaling only for the older adults. Moreover, in older adults, EA added to the size of discharge variability of motor units and discharge regularity of cumulative discharge rate, but suppressed the pooled motor unit coherence in the 13-35 Hz band. Virtual EA alters the strategic balance between open-loop and closed-loop controls for force-tracking. Contrary to expectations, the prevailing use of closed-loop control with EA that contained high-frequency error information enhanced the motor unit discharge variability and undermined the force steadiness in the older group, concerning declines in physiological complexity in the neurobehavioral system and the common drive to the motoneuronal pool against force destabilization.
误差放大（EA）反馈是一种有前景的提升视觉运动技能的方法。由于短时间尺度下的误差检测和视觉运动处理能力会随着年龄增长而下降，本研究考察了老年人是否能从包含更高频率信息以指导力跟踪任务的EA反馈中受益。14名年轻人和14名老年人在典型视觉反馈和包含增强高频误差的EA反馈的视觉引导下进行低水平静态等长力跟踪。使用稳定图扩散分析来表征力波动动态。此外，在对多通道表面肌电图（EMG）进行分解后，评估运动单位的放电行为和合并运动单位相干性。EA对年轻人和老年人产生了不同的行为和神经生理影响。与典型视觉反馈相比，老年人在EA反馈下的任务准确性较差，但年轻人并非如此。尽管稳定图扩散分析表明EA导致两组的关键时间点均显著减少，但EA仅增强了老年人的力波动临界点[公式：见正文]、短期有效扩散系数（Ds）和短期指数缩放。此外，在老年人中，EA增加了运动单位放电变异性的大小和累积放电率的放电规律性，但抑制了13 - 35 Hz频段内的合并运动单位相干性。虚拟EA改变了力跟踪中开环和闭环控制之间的策略平衡。与预期相反，在包含高频误差信息的EA中普遍使用闭环控制增强了老年组的运动单位放电变异性并破坏了力的稳定性，这与神经行为系统中生理复杂性的下降以及运动神经元池对抗力不稳定的共同驱动有关。
