Carlsen Anthony N, Chua Romeo, Timothy Inglis J, Sanderson David J, Franks Ian M
School of Human Kinetics, University of British Columbia, Vancouver, BC, Canada.
Exp Brain Res. 2008 Oct;190(4):453-61. doi: 10.1007/s00221-008-1487-5. Epub 2008 Jul 23.
Previous findings from experiments involving anticipation-timing tasks have indicated that a point in time may exist after which a participant is committed to producing a pre-programmed movement. For example, if a "stop" signal is given too long after a "go" signal but prior to movement initiation, the response is often still produced. It has been suggested that a startling stimulus may act to elicit a pre-programmed response in reaction time (RT) tasks without involvement of the cerebral cortex (Valls-Solé et al. 1999). The present experiment employed a startling stimulus to investigate the temporal course of motor preparation during a stop-signal anticipation-timing task. Participants timed a key release coincident with the sweep of a clock hand reaching a target. On some trials, the clock hand stopped prior to reaching the target (meaning participants were to refrain from responding), which was accompanied by either a startling acoustic stimulus (124 dB) or control stimulus (82 dB). Results from startle trials indicate that while some advance preparation of motor circuits was evident, subcortical pre-programming and storage of the motor command in circuits common to the voluntary and startle response pathways was not completed well in advance of response production.
先前涉及预期计时任务的实验结果表明，可能存在这样一个时间点，在该时间点之后参与者就会致力于做出预先编程好的动作。例如，如果在“开始”信号发出后过了很长时间但在动作开始之前给出“停止”信号，反应通常仍会产生。有人提出，在反应时间（RT）任务中，一个惊人的刺激可能会引发预先编程好的反应，而无需大脑皮层的参与（瓦尔 - 索莱等人，1999年）。本实验采用了一种惊人的刺激来研究在停止信号预期计时任务中运动准备的时间进程。参与者要在时钟指针扫过到达目标时同步按下按键。在一些试验中，时钟指针在到达目标之前停止（这意味着参与者应抑制反应），同时伴有惊人的听觉刺激（124分贝）或对照刺激（82分贝）。惊人刺激试验的结果表明，虽然运动回路的一些提前准备是明显的，但在自愿反应和惊吓反应途径共有的回路中，运动指令的皮层下预编程和存储并没有在反应产生之前就很好地完成。
