Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
Automotive Human Factors Research Center, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan.
Exp Physiol. 2020 Jun;105(6):950-965. doi: 10.1113/EP088194. Epub 2020 Apr 21.
What is the central question of this study? When performing skilful hand movement, motor command descends especially towards distal arm muscles. Does central command evoke a vascular response selectively in the distal arm muscles during skilful hand movement? What is the main finding and its importance? We found, using near-infrared spectroscopy, that unilateral skilful hand movement evoked a greater increase in oxygenation of the contralateral forearm muscle compared with that of the upper arm muscles. Mental imagery of the hand movement also increased oxygenation of the forearm muscle. These findings suggest that central command might contribute to the vasodilator response in the non-contracting forearm muscle during contralateral skilful hand movement.
The human hand is a special organ to perform skilful movement in daily life. To meet metabolic demands of the working distal arm muscles, central command might evoke neurogenic vasodilatation in the muscles. Based on our previous demonstration that a centrally generated vasodilator signal is transmitted bilaterally to skeletal muscles during exercise, centrally induced vasodilatation might occur in the non-contracting distal arm muscles during contralateral skilful hand movement. To examine this possibility, we used near-infrared spectroscopy to measure the relative concentrations of oxygenated haemoglobin (Oxy-Hb; as an index of regional blood flow) in the non-contracting arm muscles during skilful hand movement (two-ball rotation) in 22 subjects. Two-ball rotation increased Oxy-Hb of both forearm and upper arm muscles, with little changes in perfusion pressure and cardiac output. The increased Oxy-Hb was greater in the forearm muscle than in the upper arm muscles. The increased Oxy-Hb of the forearm muscle during two-ball rotation was greater than that during one-armed cranking performed with no load. Mental imagery of two-ball rotation increased Oxy-Hb of the forearm and biceps muscles. The increases in Oxy-Hb of both forearm and upper arm muscles during two-ball rotation were reduced by decreasing the level of task difficulty. Intravenous administration of atropine attenuated the increases in Oxy-Hb of the arm muscles during two-ball rotation. It is likely that contralateral skilful hand movement evokes a selective increase in Oxy-Hb of the non-contracting forearm muscle via a sympathetic cholinergic mechanism and that the increase in oxygenation might be mediated, at least in part, by central command.
这项研究的核心问题是什么？当进行灵巧的手部运动时，运动指令特别下传到远侧手臂肌肉。在灵巧的手部运动中，中枢命令是否会选择性地引起远侧手臂肌肉的血管反应？主要发现及其重要性是什么？我们使用近红外光谱发现，单侧灵巧的手部运动引起对侧前臂肌肉的氧合增加大于上臂肌肉。手部运动的心理意象也增加了前臂肌肉的氧合。这些发现表明，中枢命令可能有助于对侧灵巧手运动时非收缩前臂肌肉的血管扩张反应。
人类的手是日常生活中进行灵巧运动的特殊器官。为了满足工作中的远侧手臂肌肉的代谢需求，中枢命令可能会引起肌肉的神经源性血管扩张。基于我们之前的研究表明，在运动过程中，中枢产生的血管扩张信号被双侧传递到骨骼肌，因此，在对侧灵巧手运动期间，非收缩的远侧手臂肌肉可能会发生中枢诱导的血管扩张。为了检验这种可能性，我们使用近红外光谱技术在 22 名受试者中测量了在灵巧的手部运动（两个球旋转）期间非收缩手臂肌肉中的氧合血红蛋白（Oxy-Hb；作为区域血流的指标）的相对浓度。两个球旋转增加了前臂和上臂肌肉的 Oxy-Hb，而灌注压和心输出量变化不大。前臂肌肉的 Oxy-Hb 增加大于上臂肌肉。两个球旋转期间前臂肌肉的 Oxy-Hb 增加大于无负荷单臂曲柄运动期间。两个球旋转的心理意象增加了前臂和肱二头肌的 Oxy-Hb。两个球旋转期间前臂和上臂肌肉的 Oxy-Hb 增加减少了任务难度水平。静脉内给予阿托品可减弱两个球旋转期间手臂肌肉的 Oxy-Hb 增加。可能是对侧灵巧的手部运动通过交感胆碱能机制引起非收缩的远侧前臂肌肉的选择性 Oxy-Hb 增加，并且氧合的增加至少部分通过中枢命令介导。
