Graduate School of Human Life Sciences, Showa Women's University, Tokyo, Japan.
PLoS One. 2013 Nov 27;8(11):e82272. doi: 10.1371/journal.pone.0082272. eCollection 2013.
The ability to suddenly stop a planned movement or a movement being performed and restart it after a short interval is an important mechanism that allows appropriate behavior in response to contextual or environmental changes. However, performing such stop-and-restart movements smoothly is difficult at times. We investigated performance (response time) of stop-and-restart movements using a go/stop/re-go task and found consistent stop-and-restart difficulties after short (~100 ms) stop-to-restart intervals (SRSI), and an increased probability of difficulties after longer (>200 ms) SRSIs, suggesting that two different mechanisms underlie stop-and-restart difficulties. Next, we investigated motor evoked potentials (MEPs) in a moving muscle induced by transcranial magnetic stimulation during a go/stop/re-go task. In re-go trials with a short SRSI (100 ms), the MEP amplitude continued to decrease after the re-go-signal onset, indicating that stop-and-restart difficulties with short SRSIs might be associated with a neural mechanism in the human motor system, namely, stop-related suppression of corticomotor (CM) excitability. Finally, we recorded electroencephalogram (EEG) activity during a go/stop/re-go task and performed a single-trial-based EEG power and phase time-frequency analysis. Alpha-band EEG phase locking to re-go-signal, which was only observed in re-go trials with long SRSI (250 ms), weakened in the delayed re-go response trials. These EEG phase dynamics indicate an association between stop-and-restart difficulties with long SRSIs and a neural mechanism in the human perception system, namely, decreased probability of EEG phase locking to visual stimuli. In contrast, smooth stop-and-restart human movement can be achieved in re-go trials with sufficient SRSI (150-200 ms), because release of stop-related suppression and simultaneous counter-activation of CM excitability may occur as a single task without second re-go-signal perception. These results suggest that skilled motor behavior is subject to various constraints in not only motor, but also perceptual (and attentional), systems.
突然停止计划中的运动或正在进行的运动，并在短时间间隔后重新开始运动的能力是一种重要的机制，它允许根据上下文或环境变化做出适当的行为。然而，有时流畅地执行这种停止-重新开始的运动是困难的。我们使用 Go/Stop/Re-Go 任务研究了停止-重新开始运动的表现（反应时间），并发现短（~100ms）停止-重新开始间隔（SRSI）后存在一致的停止-重新开始困难，并且在较长（>200ms）SRSI 后，困难的可能性增加，这表明停止-重新开始困难有两种不同的机制。接下来，我们在 Go/Stop/Re-Go 任务期间使用经颅磁刺激研究运动肌肉中的运动诱发电位（MEPs）。在 SRSI 短（100ms）的 Re-Go 试验中，MEP 振幅在 Re-Go 信号起始后继续减小，表明 SRSI 短的停止-重新开始困难可能与人类运动系统中的神经机制有关，即停止相关的皮质运动（CM）兴奋性抑制。最后，我们在 Go/Stop/Re-Go 任务期间记录脑电图（EEG）活动，并进行单次试验的 EEG 功率和相位时频分析。仅在 SRSI 长（250ms）的 Re-Go 试验中观察到的向 Re-Go 信号的α波段 EEG 相位锁定在延迟的 Re-Go 反应试验中减弱。这些 EEG 相位动力学表明，SRSI 长的停止-重新开始困难与人类感知系统中的神经机制有关，即视觉刺激的 EEG 相位锁定概率降低。相比之下，在具有足够 SRSI（150-200ms）的 Re-Go 试验中，可以实现流畅的停止-重新开始的人类运动，因为停止相关抑制的释放和 CM 兴奋性的同时反向激活可能作为单个任务发生，而无需第二次 Re-Go 信号感知。这些结果表明，熟练的运动行为不仅受到运动系统的各种限制，还受到感知（和注意力）系统的各种限制。
