Modulation of force below 1 Hz: age-associated differences and the effect of magnified visual feedback.
Modulation of force below 1 Hz: age-associated differences and the effect of magnified visual feedback.
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力的调节低于1 Hz：与年龄相关的差异和放大视觉反馈的效果。
DOI：
10.1371/journal.pone.0055970
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Christou EA
中科院分区：
文献类型：
--
作者：
Fox EJ;Baweja HS;Kim C;Kennedy DM;Vaillancourt DE;Christou EA
力输出的振荡在特定频率范围内变化，对于理解衰老和病理性运动控制具有重要意义。尽管之前的研究已经证明 0-1 Hz 的振荡可能会受到衰老和视觉运动处理的影响，但这些研究在此带宽内平均功率，并且没有检查低于 1 Hz 的特定频率的功率。目的是确定低于 1 Hz 的力的差分调制是否会导致与视觉反馈操作和老化相关的力控制变化。指导 10 名年轻人（25±4 岁，5 名男性）和 10 名老年人（71±5 岁，4 名男性）在 35 秒内外展食指，以最大等长力的 2% 精确匹配目标力。通过改变视角（0.05°、0.5°、1.5°）或 15 秒后将其移除来操纵视觉反馈。通过检查七个频率箱中的绝对功率和归一化功率来量化低于 1 Hz 的力调制。消除视觉反馈会增加 0–0.33 Hz 的归一化功率，并降低 0.66–1.0 Hz 的归一化功率。相反，视觉反馈的放大（视角为0.5°和1.5°）降低了0-0.16 Hz的归一化功率，并增加了0.66-1.0 Hz的归一化功率。与年轻人相比，老年人随着视觉反馈的放大而表现出力的变异性更大（P = 0.05）。此外，与年轻人相比，老年人表现出频率低于 1 Hz 的差力调制（P<0.05）。具体而言，老年人在 0–0.16 Hz 范围内表现出较高的标准化功率，在 0.66–0.83 Hz 范围内表现出较低的标准化功率。力调制的变化预测了力的可变性随视觉反馈放大的变化（R2 = 0.80）。我们的研究结果表明，低于 1 Hz 的力振荡与力控制相关，并会通过老化和视觉反馈进行修改。
Oscillations in force output change in specific frequency bins and have important implications for understanding aging and pathological motor control. Although previous studies have demonstrated that oscillations from 0–1 Hz can be influenced by aging and visuomotor processing, these studies have averaged power within this bandwidth and not examined power in specific frequencies below 1 Hz. The purpose was to determine whether a differential modulation of force below 1 Hz contributes to changes in force control related to manipulation of visual feedback and aging. Ten young adults (25±4 yrs, 5 men) and ten older adults (71±5 yrs, 4 men) were instructed to accurately match a target force at 2% of their maximal isometric force for 35 s with abduction of the index finger. Visual feedback was manipulated by changing the visual angle (0.05°, 0.5°, 1.5°) or removing it after 15 s. Modulation of force below 1 Hz was quantified by examining the absolute and normalized power in seven frequency bins. Removal of visual feedback increased normalized power from 0–0.33 Hz and decreased normalized power from 0.66–1.0 Hz. In contrast, magnification of visual feedback (visual angles of 0.5° and 1.5°) decreased normalized power from 0–0.16 Hz and increased normalized power from 0.66–1.0 Hz. Older adults demonstrated a greater increase in the variability of force with magnification of visual feedback compared with young adults (P = 0.05). Furthermore, older adults exhibited differential force modulation of frequencies below 1 Hz compared with young adults (P<0.05). Specifically, older adults exhibited greater normalized power from 0–0.16 Hz and lesser normalized power from 0.66–0.83 Hz. The changes in force modulation predicted the changes in the variability of force with magnification of visual feedback (R2 = 0.80). Our findings indicate that force oscillations below 1 Hz are associated with force control and are modified by aging and visual feedback.
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