Internally generated and externally triggered actions are physically distinct and independently controlled
Internally generated and externally triggered actions are physically distinct and independently controlled
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DOI：
10.1007/s00221-004-1911-4
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发表时间：
2004-06-01
影响因子：
2
通讯作者：
Haggard, P
中科院分区：
文献类型：
--
作者：
Obhi, SS;Haggard, P
在日常生活中，我们必须不断地平衡我们以某种方式行事的意图与外界强加给我们的反应。最近的神经影像学研究分别研究了这两类运动，但尽管我们的基本要求是有效地组织我们的内部产生和外部触发的行动，很少有研究探讨这两类运动之间的关系。我们测量了肌电图活动的权利第一背侧骨间肌，而受试者进行右食指按键无论是在内部产生的条件或外部触发的条件。此外，在试图探索这两种类型的行动的处理之间的关系，我们研究了反应时间（RT）和EMG活动的影响，在第三个“截断”的条件下，受试者被迫从一个有意的（内部产生的）模式的响应生产外部触发模式。结果表明，显着更大的肌肉激活的行动，内部产生的外部触发相比。截断引起的反应被延迟，平均为54.7毫秒，与简单的外部触发的反应相比，这表明运动系统不能利用预先存在的准备水平时，内部产生的和外部触发的动作之间切换。有趣的是，内部生成和外部触发的动作的独特EMG签名在截断中被保留。因此，受试者在两种类型的动作之间切换，而不是简单地修改正在进行的动作。这些结果为以前的神经成像工作提供了外围生理支持，表明内部产生的动作比外部触发的动作之前有更高水平的准备。目前的研究结果还提出了一个有趣的可能性，即运动系统分别处理这两类动作，即使所需的运动输出是相同的。
In everyday life we must constantly balance our intentions to act in a certain way with reactions that are imposed upon us by the outside world. Recent neuroimaging studies have examined these classes of movement separately but despite the fundamental requirement for us to efficiently organize our internally generated and externally triggered actions, few studies have examined the relationship between these two classes of movement. We measured EMG activity in the right first dorsal interosseous while subjects performed right index finger key presses either in an internally generated condition or an externally triggered condition. In addition, in an attempt to probe the relationship between the processing underlying these two types of action, we examined the effect on reaction time (RT) and EMG activity in a third "truncation" condition in which subjects were forced to switch from an intentional (internally generated) mode of response production to an externally triggered mode. Results indicated significantly greater muscle activation for actions that were internally generated as compared to externally triggered. Truncation caused responses to be delayed by, on average, 54.7 ms as compared with simple externally triggered responses, suggesting that the motor system cannot take advantage of preexisting levels of preparation when switching between internally generated and externally triggered actions. Interestingly, the unique EMG signatures of internally generated and externally triggered actions were preserved in truncation. Thus, subjects switched between the two types of action rather than simply modifying an ongoing action. The results provide peripheral physiological support for previous neuroimaging work suggesting that internally generated actions are preceded by greater levels of preparation than externally triggered actions. The present findings also raise the interesting possibility that the motor system processes these two classes of action separately even though the motor output required is the same.