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首页> 外文期刊>Journal of Neurophysiology >Response preparation involves a release of intracortical inhibition in task-irrelevant muscles.
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Response preparation involves a release of intracortical inhibition in task-irrelevant muscles.

机译：响应制剂涉及在任务 - 无关肌肉中释放内耳关的抑制。

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Action preparation involves widespread modulation of motor system excitability, but the precise mechanisms are unknown. In this study, we investigated whether intracortical inhibition changes in task-irrelevant muscle representations during action preparation. We used transcranial magnetic stimulation (TMS) combined with electromyography in healthy human adults to measure motor-evoked potentials (MEPs) and cortical silent periods (CSPs) in task-irrelevant muscles during the preparatory period of simple delayed response tasks. In experiment 1 , participants responded with the left index finger in one task condition and the right index finger in another task condition, whereas MEPs and CSPs were measured from the contralateral nonresponding and tonically contracted index finger. During experiment 2 , participants responded with the right pinky finger whereas MEPs and CSPs were measured from the tonically contracted left index finger. In both experiments, MEPs and CSPs were compared between the task preparatory period and a resting intertrial baseline. The CSP duration during response preparation decreased from baseline in every case. A laterality difference was also observed in experiment 1 , with a greater CSP reduction during the preparation of left finger responses compared to right finger responses. Despite reductions in CSP duration, consistent with a release of intracortical inhibition, MEP amplitudes were smaller during action preparation when accounting for background levels of muscle activity, consistent with earlier studies that reported decreased corticospinal excitability. These findings indicate that intracortical inhibition associated with task-irrelevant muscles is transiently released during action preparation and implicate a novel mechanism for the controlled and coordinated release of motor cortex inhibition. NEW & NOTEWORTHY In this study, we observed the first evidence of a release of intracortical inhibition in task-irrelevant muscle representations during response preparation. We applied transcranial magnetic stimulation to elicit cortical silent periods in task-irrelevant muscles during response preparation, and observed a consistent decrease in the silent period duration relative to a resting baseline. These findings address the question of whether cortical mechanisms underlie widespread modulation in motor excitability during response preparation.
机译：动作准备涉及运动系统兴奋性的广泛调节，但具体机制尚不清楚。在这项研究中，我们调查了在行动准备过程中，皮质内抑制是否会改变与任务无关的肌肉表征。我们使用经颅磁刺激（TMS）结合肌电图对健康成人在简单延迟反应任务准备期间测量任务无关肌肉的运动诱发电位（MEP）和皮层静默期（CSP）。在实验1中，参与者在一个任务条件下用左手食指回应，在另一个任务条件下用右手食指回应，而MEP和CSP则是从对侧无反应和张力收缩的食指测量的。在实验2中，参与者用右小指回应，而MEP和CSP则是从紧绷的左食指测量的。在这两个实验中，在任务准备期和静息试验间基线之间比较MEP和CSP。在所有病例中，反应准备期间的CSP持续时间均比基线时缩短。在实验1中也观察到了偏侧性差异，与右指反应相比，在准备左指反应期间，CSP降低更大。尽管CSP持续时间缩短，与皮质内抑制的释放相一致，但考虑到肌肉活动的背景水平，在动作准备期间MEP振幅较小，这与早期报告皮质脊髓兴奋性降低的研究一致。这些发现表明，与任务无关的肌肉相关的皮质内抑制在动作准备期间短暂释放，并暗示了一种控制和协调释放运动皮质抑制的新机制。新的和值得注意的是，在这项研究中，我们观察到了在反应准备过程中，与任务无关的肌肉表征中释放皮质内抑制的第一个证据。在反应准备期间，我们应用经颅磁刺激在与任务无关的肌肉中诱发皮层静默期，并观察到静默期持续时间相对于静息基线的持续减少。这些发现解决了以下问题：在反应准备过程中，皮层机制是否是运动兴奋性广泛调节的基础。

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