Central nervous adaptations following 1 wk of wrist and hand immobilization
Central nervous adaptations following 1 wk of wrist and hand immobilization
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DOI：
10.1152/japplphysiol.00687.2007
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发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Nielsen, Jens Bo
中科院分区：
文献类型：
--
作者：
Lundbye-Jensen, Jesper;Nielsen, Jens Bo
已记录了与不同类型的身体活动相关的可塑性神经变化，但对伴随身体活动减少和固定而产生的中枢神经系统可塑性知之甚少。在本研究中，我们调查了 10 名身体健全的志愿者非优势手腕和手固定 1 周以及相应恢复期是否会发生可塑性神经变化。固定后，最大随意收缩扭矩下降，次最大静态收缩的变异性显着增加，但没有证据表明肌肉收缩特性发生变化。根据经颅磁刺激引起的运动诱发电位 (MEP) 估计，在静止和收缩期间，桡侧腕屈肌和拇短展肌的霍夫曼 (H) 反射幅度以及 H 斜率与 M 斜率的比率显着增加，而皮质脊髓兴奋性没有变化。皮质肌肉一致性测量源自静态收缩期间获得的脑电图和肌电图。固定后，与 MEP 延迟对应的滞后最大负累积量值相关的 15 至 35 Hz 范围内的皮质肌肉相干性降低。拆除石膏一周后，所有测量值均恢复至固定前水平。 H 反射幅度增加而 MEP 没有变化可能表明 Ia 传入神经的突触前抑制或激活后抑制在固定后减少。皮质肌肉一致性降低可能是由脊髓和皮质水平传入输入的变化或运动皮层下行驱动的变化引起的。需要进一步的研究来阐明固定后观察到的脊髓兴奋性增加和运动皮层与脊髓运动神经元活动之间的耦合减少的潜在机制。
Plastic neural changes have been documented in relation to different types of physical activity, but little is known about central nervous system plasticity accompanying reduced physical activity and immobilization. In the present study we investigated whether plastic neural changes occur in relation to 1 wk of immobilization of the nondominant wrist and hand and a corresponding period of recovery in 10 able-bodied volunteers. After immobilization, maximal voluntary contraction torque decreased and the variability of submaximal static contractions increased significantly without evidence of changes in muscle contractile properties. Hoffmann (H)-reflex amplitudes and the ratios of H-slope to M-slope increased significantly in flexor carpi radialis and abductor pollicis brevis at rest and during contraction without changes in corticospinal excitability, estimated from motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation. Corticomuscular coherence measures were derived from EEG and EMG obtained during static contractions. After immobilization, corticomuscular coherence in the 15- to 35-Hz range associated with maximum negative cumulant values at lags corresponding to MEP latencies decreased. One week after cast removal, all measurements returned to preimmobilization levels. The increased H-reflex amplitudes without changes in MEPs may suggest that presynaptic inhibition or postactivation depression of Ia afferents is reduced following immobilization. Reduced corticomuscular coherence may be caused by changes in afferent input at spinal and cortical levels or by changes in the descending drive from motor cortex. Further studies are needed to elucidate the mechanisms underlying the observed increased spinal excitability and reduced coupling between motor cortex and spinal motoneuronal activity following immobilization.