Stevenson A J T, Chiu C, Maslovat D, Chua R, Gick B, Blouin J-S, Franks I M
School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
Department of Linguistics, University of British Columbia, Vancouver, BC, Canada.
Neuroscience. 2014 Jun 6;269:21-34. doi: 10.1016/j.neuroscience.2014.03.041. Epub 2014 Mar 28.
The rapid release of prepared movements by a loud acoustic stimulus capable of eliciting a startle response has been termed the StartReact effect (Valls-Solé et al., 1999), and premotor reaction times (PMTs) of <70 ms are often observed. Two explanations have been given for these short latency responses. The subcortical storage and triggering hypothesis suggests movements that can be prepared in advance of a "go" signal are stored and triggered from subcortical areas by a startling acoustic stimulus (SAS) without cortical involvement. Alternatively, it has been hypothesized that the SAS can trigger movements from cortical areas through a faster pathway ascending from subcortical structures. Two experiments were designed to examine the possible role of the primary motor cortex in the StartReact effect. In Experiment 1, we used suprathreshold transcranial magnetic stimulation (TMS) during the reaction time (RT) interval to induce a cortical silent period in the contralateral primary motor cortex (M1). Thirteen participants performed 20° wrist extension movements as fast as possible in response to either a control stimulus (82 dB) or SAS (124 dB). PMTs for startle trials were faster than for control trials, while TMS significantly delayed movement onset compared to No TMS or Sham TMS conditions. In Experiment 2, we examined the StartReact effect in a highly cortically represented action involving speech of a consonant-vowel (CV) syllable. Similar to previous work examining limb movements, a robust StartReact effect was found. Collectively, these experiments provide evidence for cortical (M1) involvement in the StartReact effect.
一种能够引发惊吓反应的大声听觉刺激促使准备好的动作快速释放，这一现象被称为惊吓反应启动效应（瓦尔-索莱等人，1999年），并且经常观察到运动前反应时间（PMT）小于70毫秒。对于这些短潜伏期反应，有两种解释。皮层下存储与触发假说认为，在“开始”信号之前就可以准备好的动作被存储在皮层下区域，并由令人惊吓的听觉刺激（SAS）触发，而无需皮层参与。另外，有人提出假说，SAS可以通过从皮层下结构上升的更快通路触发皮层区域的动作。设计了两个实验来检验初级运动皮层在惊吓反应启动效应中可能发挥的作用。在实验1中，我们在反应时间（RT）间隔内使用阈上经颅磁刺激（TMS），以在对侧初级运动皮层（M1）诱导出皮层静息期。13名参与者在听到控制刺激（82分贝）或SAS（124分贝）后，尽快进行20°的腕部伸展动作。惊吓试验的PMT比对照试验更快，而与无TMS或假TMS条件相比，TMS显著延迟了动作开始时间。在实验2中，我们在一个高度由皮层表征的动作（涉及辅音-元音（CV）音节的语音）中研究了惊吓反应启动效应。与之前研究肢体动作的工作类似，发现了强烈的惊吓反应启动效应。总体而言，这些实验为皮层（M1）参与惊吓反应启动效应提供了证据。
