Department of Psychology, Vanderbilt Vision Research Center, Center for Integrative and Cognitive Neuroscience, Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37240.
Department of Psychology, Vanderbilt Vision Research Center, Center for Integrative and Cognitive Neuroscience, Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37240
J Neurosci. 2020 Nov 25;40(48):9272-9282. doi: 10.1523/JNEUROSCI.2072-20.2020. Epub 2020 Oct 23.
The neural mechanisms of executive and motor control concern both basic researchers and clinicians. In human studies, preparation and cancellation of movements are accompanied by changes in the β-frequency band (15-29 Hz) of electroencephalogram (EEG). Previous studies with human participants performing stop signal (countermanding) tasks have described reduced frequency of transient β-bursts over sensorimotor cortical areas before movement initiation and increased β-bursting over medial frontal areas with movement cancellation. This modulation has been interpreted as contributing to the trial-by-trial control of behavior. We performed identical analyses of EEG recorded over the frontal lobe of macaque monkeys (one male, one female) performing a saccade countermanding task. While we replicate the occurrence and modulation of β-bursts associated with initiation and cancellation of saccades, we found that β-bursts occur too infrequently to account for the observed stopping behavior. We also found β-bursts were more common after errors, but their incidence was unrelated to response time (RT) adaptation. These results demonstrate the homology of this EEG signature between humans and macaques but raise questions about the current interpretation of β band functional significance. The finding of increased β-bursting over medial frontal cortex with movement cancellation in humans is difficult to reconcile with the finding of modulation too late to contribute to movement cancellation in medial frontal cortex of macaque monkeys. To obtain comparable measurement scales, we recorded electroencephalogram (EEG) over medial frontal cortex of macaques performing a stop signal (countermanding) task. We replicated the occurrence and modulation of β-bursts associated with the cancellation of movements, but we found that β-bursts occur too infrequently to account for observed stopping behavior. Unfortunately, this finding raises doubts whether β-bursts can be a causal mechanism of response inhibition, which impacts future applications in devices such as brain-machine interfaces.
执行和运动控制的神经机制既引起基础研究人员的关注，也引起临床医生的关注。在人类研究中，运动的准备和取消伴随着脑电图（EEG）β频带（15-29 Hz）的变化。以前使用执行停止信号（撤销）任务的人类参与者的研究描述了在运动起始前，感觉运动皮层区域的瞬态β爆发频率降低，而在运动取消时，内侧额区的β爆发增加。这种调制被解释为有助于行为的逐次控制。我们对执行扫视反转任务的猕猴（雄性和雌性各一只）额叶记录的 EEG 进行了相同的分析。虽然我们复制了与扫视起始和取消相关的β爆发的发生和调制，但我们发现β爆发发生的频率太低，无法解释观察到的停止行为。我们还发现β爆发在错误后更常见，但它们的发生率与反应时间（RT）适应无关。这些结果表明，这种 EEG 特征在人类和猕猴之间具有同源性，但对当前对β频带功能意义的解释提出了质疑。在人类中，与运动取消相关的内侧额皮质中β爆发的增加很难与猕猴内侧额皮质中调制时间太晚而无法促进运动取消的发现相协调。为了获得可比的测量尺度，我们记录了执行停止信号（撤销）任务的猕猴内侧额皮质的脑电图（EEG）。我们复制了与运动取消相关的β爆发的发生和调制，但我们发现β爆发发生的频率太低，无法解释观察到的停止行为。不幸的是，这一发现让人怀疑β爆发是否可以成为反应抑制的因果机制，这对脑机接口等设备中的未来应用产生了影响。
