Doyle Louise M F, Yarrow Kielan, Brown Peter
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, 8-11, Queen Square, London WC1N 3BG, UK.
Clin Neurophysiol. 2005 Aug;116(8):1879-88. doi: 10.1016/j.clinph.2005.03.017.
Here, we investigate whether the event-related desynchronization (ERD) of spectral components of the cortical EEG in the beta (13-30 Hz) frequency range may, in part, index motor selection processes. Specifically, we sought evidence for a contralaterally dominant component of the beta ERD that is limited to trials in which motor selection is possible prior to any imperative cue to move, with attendant behavioural advantage.
We measured reaction time and assessed the lateralization of beta ERD in 12 healthy volunteers as they performed pre-cued choice reaction time tasks, in which warning S1 cues were either fully predictive about the laterality of a subsequent imperative S2 signal or provided no laterality information. We calculated 'lateralized ERD index' (LERDI), a parallel measure to the lateralized readiness potential in the time domain.
Trials with 100% S1-S2 congruency produced significantly shorter reaction times than trials with 50% S1-S2 congruency, where laterality information was unreliable. Beta LERDI indicated significantly greater lateralisation of the ERD in the warning-go interval and of event-related synchronization (ERS) following movement in the 100% condition than in the 50% condition. The lateralization of the beta ERD with respect to hand persisted, even when subjects were instructed to make movements of opposite laterality to those prompted.
Lateralized EEG changes occur in the beta band in the S1-S2 interval prior to movement, but only when informative warning cues allow early motor selection, as suggested by the shortening of reaction time. Furthermore, the enhanced contralateral ERS with 100% S1-S2 congruency suggests that this phenomenon is at least partly independent of afferent feedback, as the same movement was made in the 100 and 50% conditions.
Lateralized suppression of beta power prior to externally generated movements is associated with motor selection.
在此，我们研究皮质脑电图在β（13 - 30赫兹）频率范围内频谱成分的事件相关去同步化（ERD）是否能部分指示运动选择过程。具体而言，我们寻找证据证明β ERD的对侧优势成分，该成分仅限于在任何强制运动提示之前有可能进行运动选择的试验，且伴有行为优势。
我们测量了12名健康志愿者在执行预提示选择反应时间任务时的反应时间，并评估了β ERD的偏侧化情况。在这些任务中，警告性S1提示要么完全预测后续强制S2信号的偏侧性，要么不提供偏侧性信息。我们计算了“偏侧化ERD指数”（LERDI），这是一种在时域中与偏侧化准备电位平行的测量方法。
与S1 - S2一致性为50%（此时偏侧性信息不可靠）的试验相比，S1 - S2一致性为100%的试验产生的反应时间显著更短。β LERDI表明，在100%条件下，与50%条件相比，在警告 - 开始间隔期间ERD以及运动后事件相关同步化（ERS）的偏侧化程度显著更高。即使受试者被指示做出与提示相反偏侧性的动作，β ERD相对于手部的偏侧化仍然存在。
在运动前的S1 - S2间隔期间，β频段会出现偏侧化的脑电图变化，但只有当信息性警告提示允许早期运动选择时才会出现，反应时间缩短表明了这一点。此外，100% S1 - S2一致性时对侧ERS增强表明，这种现象至少部分独立于传入反馈，因为在100%和50%条件下做出的是相同的动作。
外部引发运动之前β功率的偏侧化抑制与运动选择相关。
