Preparation and Control of Movement

我们的许多行动都是由环境变化引发的，其中大多数行动可以在预期的变化之前做好准备。当在这些反应性情景中观察到熟练的人类动作时，一个人可能没有注意到动作准备、启动和执行之间所需的精细同步，但每一个都对动作的有效控制至关重要。这些过程的成功和失败在日常生活中的许多情况下都可以看到，从奥运会短跑运动员在优雅而平稳地追求目标的过程中为快速起跑做准备，到帕金森氏症患者，他们未能在路边迈出看似简单的一步，尽管似乎付出了最大的认知努力，但还是僵住了。该提案将研究人们如何使用各种方法在不同的环境背景下准备、发起和控制他们的行动。在过去，我们使用的一种方法是通过发出令人震惊的刺激和“GO”命令来探索运动准备过程。这种短暂的响声会引起惊吓反射，但似乎也会触发和释放任何计划、储存和准备启动的自愿运动。事实上，当我们考虑前面提到的两个例子时，已经表明短跑运动员非常快的反应时间(不到100毫秒)可能是类似惊吓的触发而不是错误启动的结果。我们还表明，在帕金森氏症患者中，Startle可以非常顺利和毫不费力地触发预先准备的动作。因为我们已经了解了惊吓反射的路径，所以当它与这种反射相互作用时，就有可能绘制出运动准备和启动的地图。这项建议旨在继续我们的研究努力，以调查运动准备和启动使用技术，如惊吓。第一系列实验将研究一组肌肉是如何准备好产生快速、准确和流畅的动作的。尽管我们通过将四肢移动到太空中的目标来轻松有效地与环境互动，但对单个关节肌肉协同效应的编程和控制仍然不清楚。最近我们提出，激动剂/拮抗剂的协同活动可能受皮质和皮质下大脑结构的控制。在这里，我们建议调查小脑是否参与调节协调动作的幅度和/或时间，例如简单的三相(激动剂-拮抗剂-激动剂)肌肉活动爆发。第二个系列的实验探索了复杂动作的反应准备。我们以前的大多数研究都使用STARTET来探索简单的、单组件的腕部或肘部伸展运动的准备。然而，多组分动作的准备、计时和排序过程需要高度的协调，这也将使用令人震惊的刺激进行研究。我们的第三个系列实验将研究当一个令人震惊的声音触发预先准备的反应时所涉及的过程。具体地说，我们将研究能够区分各种解释的实验方案，这些解释被提出来解释这种被称为StartReact效应的预期反应的触发。最后，我们将对惊吓的实验指标进行调查。我们实验室进行的许多研究都成功地使用了响亮的声刺激来检查在各种情况下的反应准备过程。然而，我们正在不断评估我们的实验方法，以确保我们的结果是有效的和可重复性的。

Many of our actions are triggered by changes in the environment and most of these actions can be prepared in advance of the anticipated change. When skillful human action is observed in these reactive situations one may be oblivious to the fine synchronization that is required between movement preparation, initiation and execution and yet each is vital to the effective control of action. Success and failure of these processes can be seen in many situations in everyday life, from the Olympic sprinter who prepares for a fast start out of the blocks in elegant smooth pursuit of their goal, to the Parkinson’s disease patient who fails to initiate a seemingly simple step over a roadside curb and freezes despite what appears to be maximum cognitive effort. This proposal will examine how people prepare, initiate and control their actions in various environmental contexts using a variety of methodologies. One method we have used to good effect in the past is to probe the processes of movement preparation by delivering a startling stimulus along with the “go” command. This brief loud sound causes a startle reflex but also appears to trigger and release any voluntary movement that is planned, stored and ready to initiate. Indeed when we consider the two examples mentioned earlier it has been shown that very fast reaction times of the sprinter (less than 100 milliseconds) may be the result of a startle like trigger and not a false start. We have also shown that startle can trigger prepared movements quite smoothly and effortlessly in patients with Parkinson’s disease. Because we have an understanding of the pathways responsible for the startle reflex, it then becomes possible to map movement preparation and initiation as it interacts with this reflex. This proposal is designed to continue our research efforts into the investigation of motor preparation and initiation using techniques such as startle. The first series of experiments will investigate how a group of muscles are prepared to produce fast, accurate and smooth movements. Although we easily and effectively interact with our environment by moving our limbs to targets in space, the programming and control of muscle synergies across a single joint is still not clearly understood. Recently we suggested that agonist/antagonist coordinated activity may be controlled by both cortical and subcortical brain structures. Here we propose to investigate whether the cerebellum is involved in modulating the amplitudes and/or timing of such coordinated actions as a simple triphasic (agonist-antagonist-agonist) muscle burst of activity. A second series of experiments explores response preparation for complex movements. Most of our previous studies used startle to probe movement preparation with simple, single component movements of either wrist or elbow extension. However, the process of preparing, timing and sequencing of multi-component movements requires high levels of coordination, which will also be studied using a startling stimulus. Our third series of experiments will examine the processes involved when a startling sound triggers a prepared response. Specifically we will examine experimental protocols that can differentiate between the various explanations that have been put forward to account for this triggering of intended responses known as the StartReact effect. Finally we will investigate the experimental indicators of startle. Many studies conducted in our lab have successfully used a loud acoustic stimulus to examine the process of response preparation under a variety of circumstances. However, we are constantly evaluating our experimental methodology to ensure our results are valid and reproducible.