Further insight into the task-dependent excitability of motor evoked potentials in first dorsal interosseous muscle in humans
Further insight into the task-dependent excitability of motor evoked potentials in first dorsal interosseous muscle in humans
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DOI：
10.1007/s002210100842
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发表时间：
2001-10-01
影响因子：
2
通讯作者：
Yahagi, S
中科院分区：
文献类型：
--
作者：
Hasegawa, Y;Kasai, T;Yahagi, S
我们重新审视了相互矛盾的证据，其中第一背侧骨间肌 (FDI) 的运动诱发电位 (MEP) 的任务依赖性兴奋在日益复杂的手指任务中比在单独的手指运动任务中更强。在实验的第一步中，根据之前的发现，我们研究了复杂手指任务（精确度和力量握力）期间手部内部肌肉和外部肌肉之间显着的功能差异。在执行任务期间，对侧运动皮层施加最佳刺激强度的经颅磁刺激（TMS）。在两项任务中，同时记录 FDI、桡侧腕伸肌 (ECR) 和桡侧腕屈肌 (FCR) 肌肉的 MEP，同时背景肌电图活动逐步增加。精确握持时 TMS 的强度阈值较低。此外，依赖于背景肌电图活动的 FDI 肌肉的 MEP 振幅在这两项任务之间是不同的，即精确握力中的 MEP 振幅和回归系数大于强力握力中的 MEP 振幅和回归系数。尽管我们对 FDI 肌肉中 MEP 幅度和阈值的结果与之前报告的证据相似，但协同肌肉（特别是 ECR 肌肉）在执行这些任务期间的不同贡献是新的证据。由于皮肤传入效应对这两项任务没有差异，因此与 FDI 运动神经元连接的皮质运动神经元 (CM) 细胞似乎在精确抓握过程中通常比强力抓握过程中更活跃，并且在执行这些任务过程中协同肌肉的贡献不同。在实验的第二部分中，将复杂任务获得的结果与简单任务（孤立的食指弯曲）获得的结果进行了比较。 MEP 幅度取决于孤立食指屈曲期间的背景 EMG 活动，在受试者之间存在差异，即 MEP 幅度与 FDI 肌肉的背景 EMG 之间的关系显示出个体的、策略依赖性调节。有几种单独的运动策略可用于执行孤立的手指运动。目前的结果可以解释先前与 CM 系统在协调手指运动期间的贡献相关的矛盾证据。
We have reexamined the contradictory evidence in which task-dependent excitation of motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) muscle was stronger with increasingly more complex finger tasks than with individual finger movement tasks. In the first step of the experiment, based on previous findings, we investigated remark-able functional differences between intrinsic and extrinsic hand muscles during complex finger tasks (precision and power grip). During the performance of the tasks, the optimal stimulus intensity of the transcranial magnetic stimulation (TMS) was applied to the contralateral motor cortex. MEPs of the FDI, extensor carpi radialis (ECR), and flexor carpi radialis (FCR) muscles were recorded simultaneously with increased background EMG activity step by step in both tasks. The intensity threshold of TMS was lower in the precision grip. Furthermore, the MEP amplitudes of FDI muscle dependent on the background EMG activity were different between these two tasks, i.e., MEP amplitudes and regression coefficients in a precision grip were larger than those in a power grip. Although our results for MEP amplitude and threshold in the FDI muscle were similar to previous reported evidence, the different contributions of a synergistic muscle (in particular, the ECR muscle) during performance in these tasks was new evidence. Since there were no differences in cutaneous afferent effects on both tasks, corticomotoneuronal (CM) cells connected to FDI motoneurons seemed generally to be more active during precision than power gripping, and there were different contributions from synergistic muscles during the performance of these tasks. In the second part of the experiment, the results obtained from the complex tasks were compared with those from a simple task (isolated index finger flexion). MEP amplitudes, dependent on the background EMG activity during isolated index finger flexion, varied among subjects, i.e., the relationship between the MEP amplitude and the background EMG of the FDI muscle showed individual, strategy-dependent modulation. There were several kinds of individual motor strategies for performing the isolated finger movement. The present results may explain the previous contradictory evidence related to the contribution of the CM system during coordinated finger movement.