Kerr Catherine E, Agrawal Uday, Nayak Sandeep
Alpert Medical School, Brown University, Providence RI, USA.
Division of Biology and Medicine, Brown University, Providence RI, USA.
Front Hum Neurosci. 2016 Feb 16;10:37. doi: 10.3389/fnhum.2016.00037. eCollection 2016.
Tai Chi (TC) is a slow-motion contemplative exercise that is associated with improvements in sensorimotor measures, including decreased force variability, enhanced tactile acuity, and improved proprioception, especially in elderly populations. Here, we carried out two studies evaluating the effect of TC practice on measures associated with sensorimotor processing. In study 1, we evaluated TC's effects on an oscillatory parameter associated with motor function, beta rhythm (15-30 Hz) coherence, focusing specifically on beta rhythm intermuscular coherence (IMC), which is tightly coupled to beta corticomuscular coherence (CMC). We utilized electromyography (EMG) to compare beta IMC in older TC practitioners with age-matched controls, as well as novices with advanced TC practitioners. Given previous findings of elevated, maladaptive beta coherence in older subjects, we hypothesized that increased TC practice would be associated with a monotonic decrease in beta IMC, but rather discovered that novice practitioners manifested higher beta IMC than both controls and advanced practitioners, forming an inverted U-shaped practice curve. This finding suggests that TC practice elicits complex changes in sensory and motor processes over the developmental lifespan of TC training. In study 2, we focused on somatosensory (e.g., tactile and proprioceptive) responses to the rubber hand illusion (RHI) in a middle-aged TC group, assessing whether responses to the illusion became dampened with greater cumulative practice. As hypothesized, TC practice was associated with decreased likelihood to misattribute tactile stimulation during the RHI to the rubber hand, although there was no effect of TC practice on measures of proprioception or on subjective reports of ownership. These studies provide preliminary evidence that TC practice both modulates beta network coherence in a non-linear fashion, perhaps as a result of the focus on not only efferent motor but also afferent sensory activity, and alters tactile sensations during the RHI. This work is the first to show the effects of TC on low level sensorimotor processing and integrated body awareness, and this multi-scale finding may help to provide a mechanistic explanation for the widespread sensorimotor benefits observed with TC practice in symptoms associated with aging and difficult illnesses such as Parkinson's disease.
太极拳（TC）是一种慢动作的冥想运动，与感觉运动指标的改善有关，包括力量变异性降低、触觉敏锐度增强和本体感觉改善，尤其是在老年人群中。在此，我们进行了两项研究，评估太极拳练习对与感觉运动处理相关指标的影响。在研究1中，我们评估了太极拳对与运动功能相关的振荡参数——β节律（15 - 30赫兹）相干性的影响，特别关注β节律肌间相干性（IMC），它与β皮质脊髓相干性（CMC）紧密相关。我们利用肌电图（EMG）比较老年太极拳练习者与年龄匹配的对照组以及新手与资深太极拳练习者之间的β IMC。鉴于先前在老年受试者中发现适应性不良的β相干性升高，我们假设增加太极拳练习会与β IMC的单调下降相关，但相反地发现新手练习者的β IMC高于对照组和资深练习者，形成了一条倒U形的练习曲线。这一发现表明，在太极拳训练的发展过程中，太极拳练习会引发感觉和运动过程的复杂变化。在研究2中，我们关注中年太极拳组对橡皮手错觉（RHI）的体感（如触觉和本体感觉）反应，评估随着累积练习的增加，对该错觉的反应是否会减弱。正如所假设的，太极拳练习与在橡皮手错觉期间将触觉刺激错误归因于橡皮手的可能性降低相关，尽管太极拳练习对本体感觉指标或自我所有权的主观报告没有影响。这些研究提供了初步证据，表明太极拳练习不仅以非线性方式调节β网络相干性，这可能是由于不仅关注传出运动而且关注传入感觉活动的结果，还会改变橡皮手错觉期间的触觉感受。这项工作首次展示了太极拳对低水平感觉运动处理和综合身体意识的影响，这一多尺度发现可能有助于为在与衰老和帕金森病等疑难病症相关的症状中通过太极拳练习观察到的广泛感觉运动益处提供一个机制性解释。
