Preparation and Control of Movement

我们的许多行动都是由环境的变化引发的，而这些行动中的大多数都可以在预期的变化之前做好准备。当在这些反应情境中观察到熟练的人类动作时，人们可能会忽略动作准备、开始和执行之间需要的精细同步，而每一个动作对于有效控制动作都是至关重要的。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准备快速起跑，优雅而平稳地追求他们的目标，到帕金森氏症患者无法在路边迈出看似简单的一步，尽管似乎尽了最大的认知努力，但却冻结了。该提案将研究人们如何准备，启动和控制他们的行动在不同的环境背景下使用各种方法。我们过去使用的一种很有效的方法是，通过在发出“走”命令的同时发出令人吃惊的刺激，来探测运动准备的过程。这种短暂的响亮声音会引起惊吓反射，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，当我们考虑到前面提到的两个例子时，已经表明短跑运动员的快速反应时间（少于100毫秒）可能是受到惊吓的结果，而不是错误的起跑。我们还发现，在帕金森病患者中，惊吓可以很顺利、毫不费力地触发有准备的动作。因为我们对惊吓反射的通路有了一定的了解，所以就有可能绘制出运动准备和开始与这种反射的相互作用。本提案旨在继续我们的研究工作，以调查运动的准备和启动使用技术，如惊吓。第一个系列的实验将研究如何准备一组肌肉产生快速，准确和平稳的运动。尽管我们可以通过将肢体移动到空间中的目标而轻松有效地与环境进行交互，但通过单个关节的肌肉协同作用的编程和控制仍然不清楚。最近我们提出激动剂/拮抗剂的协同活性可能受皮层和皮层下脑结构的控制。在这里，我们建议研究小脑是否参与调节这些协调动作的幅度和/或时间，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讨了对复杂动作的反应准备。我们之前的大多数研究都是用惊吓来探测简单的、单组分的手腕或肘部伸展运动的运动准备。然而，多组分动作的准备、计时和排序过程需要高水平的协调，这也将使用令人吃惊的刺激来研究。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一个准备好的反应时所涉及的过程。具体来说，我们将研究实验方案，以区分已经提出的各种解释，以解释这种被称为StartReact效应的预期反应的触发。最后，我们将探讨惊吓的实验指标。在我们实验室进行的许多研究已经成功地使用了响亮的声音刺激来检查在各种情况下的反应准备过程。然而，我们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.