Androulidakis Alexandros G, Doyle Louise M F, Yarrow Kielan, Litvak Vladimir, Gilbertson Thomas P, Brown Peter
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, WC1N 3BG, UK.
Eur J Neurosci. 2007 Jun;25(12):3758-65. doi: 10.1111/j.1460-9568.2007.05620.x.
Synchronized oscillatory activity in the beta frequency band (13-30 Hz) can be detected in the cerebral motor cortex of healthy humans in the form of corticomuscular coherence. Elevated beta activity is associated with impaired processing of new movements and with more efficient postural or tonic contraction. Accordingly, beta activity is suppressed prior to voluntary movements, rebounding thereafter in the face of peripheral afferance. However, it remains to be established whether synchronized activity in the beta band can be up-regulated in a task-appropriate way independently of confounding changes in sensory afferance. Here we show that there is a systematic and prospective increase in beta synchrony prior to an expected postural challenge. This up-regulation of beta synchrony is associated with improved behavioural performance. We instructed nine healthy subjects to perform a reaction-time movement of the index finger in response to an imperative visual cue or to resist a stretch to the finger in the same direction. These events were preceded by congruent and less common incongruent warning cues. Beta synchrony was temporally increased when subjects were warned of an impending stretch and decreased following a warning cue signalling a forthcoming reaction-time task. Finger positions were less successfully maintained in the face of stretches and reaction times were longer when warning cues were incongruent. The results suggest that the beta state is modulated in a task-relevant way with accompanying behavioural consequences.
在健康人类的大脑运动皮层中，可以检测到β频段（13 - 30赫兹）的同步振荡活动，其形式为皮质 - 肌肉相干性。β活动增强与新动作处理受损以及更有效的姿势或强直收缩有关。因此，在自主运动之前β活动受到抑制，随后在面对外周传入信号时反弹。然而，β频段的同步活动是否能够以与任务相适应的方式独立于感觉传入的混杂变化而上调，仍有待确定。在这里，我们表明在预期的姿势挑战之前，β同步性存在系统性的前瞻性增加。这种β同步性的上调与行为表现的改善相关。我们指示九名健康受试者根据命令性视觉提示进行食指的反应时运动，或者抵抗手指向同一方向的拉伸。这些事件之前会出现一致的和不太常见的不一致的警告提示。当受试者被警告即将进行拉伸时，β同步性在时间上增加，而在发出即将进行反应时任务的警告提示后则降低。当警告提示不一致时，面对拉伸时手指位置的维持不太成功，反应时间更长。结果表明，β状态以与任务相关的方式受到调节，并伴有行为后果。
