Department of Psychology, University of Quebec in Montreal (UQAM), Montreal, QC, Canada.
Exp Brain Res. 2010 Sep;205(3):375-85. doi: 10.1007/s00221-010-2372-6. Epub 2010 Aug 3.
Chunking of single movements into integrated sequences has been described during motor learning, and we have recently demonstrated that this process involves a dopamine-dependant mechanism in animal (Levesque et al. in Exp Brain Res 182:499-508, 2007; Tremblay et al. in Behav Brain Res 198:231-239, 2009). However, there is no such evidence in human. The aim of the present study was to assess this question in Parkinson's disease (PD), a neurological condition known for its dopamine depletion in the striatum. Eleven PD patients were tested under their usual levodopa medication (ON state), and following a 12-h levodopa withdrawal (OFF state). Patients were compared with 12 healthy participants on a motor learning sequencing task, requiring pressing fourteen buttons in the correct order, which was determined by visual stimuli presented on a computer screen. Learning was assessed from three blocks of 20 trials administered successively. Chunks of movements were intrinsically created by each participant during this learning period. Then, the sequence was shuffled according to the participant's own chunks, generating two new sequences, with either preserved or broken chunks. Those new motor sequences had to be performed separately in a fourth and fifth blocks of 20 trials. Results showed that execution time improved in every group during the learning period (from blocks 1 to 3). However, while motor chunking occurred in healthy controls and ON-PD patients, it did not in OFF-PD patients. In the shuffling conditions, a significant difference was seen between the preserved and the broken chunks conditions for both healthy participants and ON-PD patients, but not for OFF-PD patients. These results suggest that movement chunking during motor sequence learning is a dopamine-dependent process in human.
在运动学习过程中，已经描述了将单个运动分解为整合序列，我们最近证明，这个过程涉及动物中的多巴胺依赖机制（Levesque 等人，在 Exp Brain Res 182:499-508，2007 年；Tremblay 等人，在 Behav Brain Res 198:231-239，2009 年）。然而，在人类中没有这样的证据。本研究的目的是在帕金森病（PD）中评估这个问题，PD 是一种已知其纹状体多巴胺耗竭的神经疾病。11 名 PD 患者在其通常的左旋多巴药物（ON 状态）下进行测试，并在 12 小时的左旋多巴停药（OFF 状态）后进行测试。患者与 12 名健康参与者在运动学习序列任务上进行比较，该任务要求按正确顺序按下 14 个按钮，这由计算机屏幕上显示的视觉刺激来确定。学习是通过连续进行的三个 20 次试验的块来评估的。在学习期间，每个参与者内在地创建运动的块。然后，根据参与者自己的块对序列进行打乱，生成两个具有保留或破坏块的新序列。这些新的运动序列必须在第四个和第五个 20 次试验的块中分别执行。结果表明，在学习期间，每个组的执行时间都有所提高（从第 1 块到第 3 块）。然而，虽然健康对照组和 ON-PD 患者中出现了运动分块，但 OFF-PD 患者中则没有。在打乱条件下，对于健康参与者和 ON-PD 患者，在保留块和破坏块条件之间存在显著差异，但对于 OFF-PD 患者则没有。这些结果表明，在人类运动序列学习中，运动分块是一个多巴胺依赖的过程。
