在健康成年人中,休息时皮质脊髓兴奋性与任务间间隔无差异。

Corticospinal excitability at rest outside of a task does not differ from task intertrial intervals in healthy adults.

机构信息

Action Control Lab, Department of Human Physiology, University of Oregon, Eugene, OR, USA.

出版信息

Exp Brain Res. 2024 Sep;242(9):2263-2270. doi: 10.1007/s00221-024-06895-8. Epub 2024 Jul 24.

Abstract

Human corticospinal excitability (CSE) modulates during movement, when muscles are active, but also at rest, when muscles are not active. These changes in resting motor system excitability can be transient or longer lasting. Evidence from transcranial magnetic stimulation (TMS) studies suggests even relatively short periods of motor learning on the order of minutes can have lasting effects on resting CSE. Whether individuals are able to return CSE to out-of-task resting levels during the intertrial intervals (ITI) of behavioral tasks that do not include an intended motor learning component is an important question. Here, in twenty-five healthy young adults, we used single-pulse TMS and electromyography (EMG) to measure motor evoked potentials (MEPs) during two different resting contexts: (1) prior to engaging in the response task during which participants were instructed only to rest (out-of-task), and (2) ITI of a choice-reaction time task (in-task). In both contexts, five TMS intensities were used to evaluate possible differences in recruitment of corticospinal (CS) output across a range of inputs. We hypothesized resting state CSE would be greater during ITI than out-of-task rest, reflected in larger MEP amplitudes. Contrary to our hypothesis, we observed no significant difference in MEP amplitudes between out-of-task rest and in-task ITI, and instead found evidence of equivalence, indicating that humans are able to return to a stable motor resting state within seconds after a response. These data support the interpretation that rest is a uniform motor state in the healthy nervous system. In the future, our data may be a useful reference for motor disorder populations with an impaired ability to return to rest.

摘要

人类皮质脊髓兴奋性(CSE)在运动时发生变化,此时肌肉活跃,但在休息时也会发生变化,此时肌肉不活跃。这种静息运动系统兴奋性的变化可能是短暂的,也可能是持久的。来自经颅磁刺激(TMS)研究的证据表明,即使是相对较短的几分钟的运动学习,也可以对静息 CSE 产生持久的影响。个体是否能够在不包括预期运动学习成分的行为任务的试验间间隔(ITI)期间将 CSE 恢复到任务外的静息水平,这是一个重要的问题。在这里,在二十五名健康的年轻成年人中,我们使用单脉冲 TMS 和肌电图(EMG)在两种不同的静息状态下测量运动诱发电位(MEPs):(1)在参与者仅被指示休息的反应任务之前(任务外),以及(2)选择反应时间任务的 ITI(任务内)。在这两种情况下,使用五种 TMS 强度来评估在一系列输入下皮质脊髓(CS)输出的可能差异。我们假设静息状态 CSE 在 ITI 期间会大于任务外休息,表现在更大的 MEP 幅度上。与我们的假设相反,我们没有观察到任务外休息和任务内 ITI 之间 MEP 幅度的显著差异,而是发现了等效的证据,表明人类能够在响应后几秒钟内恢复到稳定的运动静息状态。这些数据支持这样一种解释,即休息是健康神经系统中的一种统一运动状态。在未来,我们的数据可能是运动障碍人群恢复能力受损的有用参考。

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