Psychology Department, University of California, San Diego, La Jolla, California 92103.
J Neurosci. 2013 Nov 20;33(47):18481-91. doi: 10.1523/JNEUROSCI.3456-13.2013.
When an unexpected event occurs in everyday life (e.g., a car honking), one experiences a slowing down of ongoing action (e.g., of walking into the street). Motor slowing following unexpected events is a ubiquitous phenomenon, both in laboratory experiments as well as such everyday situations, yet the underlying mechanism is unknown. We hypothesized that unexpected events recruit the same inhibition network in the brain as does complete cancellation of an action (i.e., action-stopping). Using electroencephalography and independent component analysis in humans, we show that a brain signature of successful outright action-stopping also exhibits activity following unexpected events, and more so in blocks with greater motor slowing. Further, using transcranial magnetic stimulation to measure corticospinal excitability, we show that an unexpected event has a global motor suppressive effect, just like outright action-stopping. Thus, unexpected events recruit a common mechanism with outright action-stopping, moreover with global suppressive effects. These findings imply that we can now leverage the considerable extant knowledge of the neural architecture and functional properties of the stopping system to better understand the processing of unexpected events, including perhaps how they induce distraction via global suppression.
当日常生活中发生意外事件（例如汽车鸣笛）时，人们会对正在进行的动作（例如走入街道）进行减速。在实验室实验和日常情况下，意外事件后的运动减速都是一种普遍现象，但潜在的机制尚不清楚。我们假设意外事件会在大脑中招募与完全取消动作（即动作停止）相同的抑制网络。我们使用脑电图和独立成分分析在人类中进行研究，结果表明，成功的彻底动作停止的大脑特征在意外事件后也会显示出活动，而且在运动减速更大的块中更为明显。此外，我们使用经颅磁刺激来测量皮质脊髓兴奋性，结果表明意外事件会产生全局的运动抑制作用，就像彻底的动作停止一样。因此，意外事件会像彻底的动作停止一样，招募到一个共同的机制，而且具有全局抑制作用。这些发现意味着我们现在可以利用关于停止系统的神经结构和功能特性的大量现有知识，来更好地理解意外事件的处理过程，包括它们如何通过全局抑制来引起分心。
