O'Boyle D J, Freeman J S, Cody F W
Department of Psychology, University of Manchester, UK.
Brain. 1996 Feb;119 ( Pt 1):51-70. doi: 10.1093/brain/119.1.51.
In separate experiments, we studied the temporal accuracy and precision of self-paced, repetitive finger-tapping in two groups of 12 patients with Parkinson's disease and a group of 12 controls matched to the patients with respect to age and general cognitive state. One group (I) of patients was studied initially following 12-15 h abstinence from normal levodopa medication ('off') and again, subsequently, approximately 1 h after ingestion of a single normal dose ('on'). A second group (II) of patients, each of whom had bilaterally asymmetrical neurological signs, was tested using 'worse' and 'better' hands separately. Within each session, subjects were tested repeatedly on a tapping task during which they were required to produce a regular series of self-timed inter-tap intervals, the target duration (550 ms) of which had been established previously during an initial period of tapping in synchrony with the beats of a regular metronome. We employed Wing and Kristofferson's (1973) model of control of motor timing to partition the total variance (TV) about the mean inter-response interval (IRI) produced during the self-paced phase of each run into separate components ['clock' variance (CV) and 'motor-delay' variance (MDV)] attributable to hypothetical 'clock' and 'motor-implementation' processes. Although the mean self-paced IRI of parkinsonian patients was generally shorter than that of controls, only during the 'on' medication condition (Group I) was it significantly so. By comparison with control values, and those observed during the 'on' medication condition, values of TV, CV and MDV in Group I were all significantly higher when subjects were 'off' medication. During the 'on' medication condition, only CV was significantly higher than the control value. In Group II, values of TV, CV and MDV associated with use of the 'worse' hand were all significantly higher than both control values and those associated with use of the 'better' hand. Values of these variables when subjects used the 'better' hand did not, however, differ significantly from control values. The theoretical import of these results is discussed in the light of several important procedural, statistical and computational issues and we conclude that TV, CV, and MDV may all vary significantly as a function of the efficacy of dopaminergic transmission in the basal ganglia.
在单独的实验中，我们研究了两组各12名帕金森病患者以及一组12名在年龄和一般认知状态方面与患者相匹配的对照组进行自定节奏、重复性手指敲击的时间准确性和精确性。一组（I）患者最初在停用正常左旋多巴药物12 - 15小时后（“关”期）进行研究，随后在摄入单次正常剂量药物约1小时后（“开”期）再次进行研究。第二组（II）患者，每人都有双侧不对称的神经学体征，分别使用“较差”和“较好”的手进行测试。在每个实验环节中，受试者在敲击任务中被反复测试，在此任务中他们需要产生一系列有规律的自定时敲击间隔，其目标持续时间（550毫秒）在之前与节拍器节拍同步敲击的初始阶段已经确定。我们采用Wing和Kristofferson（1973）的运动时间控制模型，将每次运行自定节奏阶段产生的关于平均反应间隔（IRI）的总方差（TV）划分为分别归因于假设的“时钟”和“运动执行”过程的单独成分[“时钟”方差（CV）和“运动延迟”方差（MDV）]。尽管帕金森病患者的平均自定节奏IRI通常比对照组短，但只有在“开”药状态（第一组）下才显著如此。与对照组值以及“开”药状态下观察到的值相比，第一组受试者“关”药时TV、CV和MDV的值均显著更高。在“开”药状态下，只有CV显著高于对照组值。在第二组中，与使用“较差”手相关的TV、CV和MDV值均显著高于对照组值以及与使用“较好”手相关的值。然而，受试者使用“较好”手时这些变量的值与对照组值没有显著差异。根据几个重要的程序、统计和计算问题讨论了这些结果的理论意义，我们得出结论，TV、CV和MDV可能都随基底神经节中多巴胺能传递的功效而显著变化。
