The effect of motor overflow on bimanual asymmetric force coordination.
The effect of motor overflow on bimanual asymmetric force coordination.
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DOI：
10.1007/s00221-016-4867-2
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发表时间：
2017-04
影响因子：
2
通讯作者：
Plow EB
中科院分区：
文献类型：
--
作者：
Cunningham DA;Roelle SM;Allexandre D;Potter-Baker KA;Sankarasubramanian V;Knutson JS;Yue GH;Machado AG;Plow EB
运动溢出，通常在单手运动的上下文中描述，是指在相对肢体运动期间“休息”肢体移动的自然趋势，并且被认为受到“休息”半球内的半球间相互作用和皮质内网络的影响。然而，目前尚不清楚运动溢出如何有助于不对称力协调任务的准确性，称为双手干扰，因为需要为每个肢体产生不相等的力和皮质脊髓输出。在这里，我们通过运动诱发电位（MEP）和运动溢出的调节，通过半球间抑制（IHI）和短皮质内抑制（SICI），使用经颅磁刺激的存在下，单手和双手等长力生产进行评估。所有结果均在左侧第一背侧骨间（测试手）肌肉中测量，该肌肉保持30%的最大随意收缩（MVC），而右手（调节手）保持静止，其MVC的10%，30%或70%。我们发现，当调节手产生更大的力时，活动测试手的MEP振幅降低，半球间抑制增加，这表明在双手不对称力的存在下运动溢出减少。此外，我们发现运动溢出较少（即测试半球MEP振幅降低）的受试者在所有条件下保持30%MVC的准确性较差。这些研究结果表明，电机溢出可能作为一个适应基板，以支持双手不对称的力量协调。
Motor overflow, typically described in the context of unimanual movements, refers to the natural tendency for a ‘resting’ limb to move during movement of the opposite limb and is thought to be influenced by inter-hemispheric interactions and intra-cortical networks within the ‘resting’ hemisphere. It is currently unknown, however, how motor overflow contributes to asymmetric force coordination task accuracy, referred to as bimanual interference, as there is need to generate unequal forces and corticospinal output for each limb. Here, we assessed motor overflow via motor evoked potentials (MEPs) and the regulation of motor overflow via interhemispheric inhibition (IHI) and short-intracortical inhibition (SICI) using transcranial magnetic stimulation in the presence of unimanual and bimanual isometric force production. All outcomes were measured in the left first dorsal interosseous (test hand) muscle, which maintained 30% maximal voluntary contraction (MVC) while the right hand (conditioning hand) was maintained at rest, 10%, 30% or 70% of its MVC. We have found that as higher forces are generated with the conditioning hand, MEP amplitudes at the active test hand decreased and interhemispheric inhibition increased, suggesting reduced motor overflow in the presence of bimanual asymmetric forces. Further, we found that subjects with less motor overflow (i.e. reduced MEP amplitudes in the test hemisphere) demonstrated poorer accuracy in maintaining 30% MVC across all conditions. These findings suggest that motor overflow may serve as an adaptive substrate to support bimanual asymmetric force coordination.