Merchant Hugo, Luciana Monica, Hooper Catalina, Majestic Stacy, Tuite Paul
Instituto de Neurobiologia, UNAM, Campus Juriquilla, Mexico, USA.
Exp Brain Res. 2008 Jan;184(2):233-48. doi: 10.1007/s00221-007-1097-7. Epub 2007 Sep 9.
Interval timing deficiencies in Parkinson's disease (PD) patients have been a matter of debate. Here we test the possibility of PD heterogeneity as a source for this discrepancy. Temporal performance of PD patients and control subjects was assessed during two interval tapping tasks and during a categorization task of time intervals. These tasks involved temporal processing of intervals in the hundreds of milliseconds range; however, they also covered a wide range of behavioral contexts, differing in their perceptual, decision-making, memory, and execution requirements. The results showed the following significant findings. First, there were two clearly segregated subgroups of PD patients: one with high temporal variability in the three timing tasks, and another with a temporal variability that did not differ substantially from control subjects. In contrast, PD patients with high and low temporal variability showed similar perceptual, decision-making, memory, and execution performance in a set of control tasks. Second, a slope analysis, designed to dissociate time-dependent from time-independent sources of variation, revealed that the increase in variability in this group of PD patients was mainly due to an increment in the variability associated with the timing mechanism. Third, while the control subjects showed significant correlations in performance variability across tasks, PD patients, and particularly those with high temporal variability, did not show such task correlations. Finally, the results showed that dopaminergic treatment restored the correlation effect in PD patients, producing a highly significant correlation between the inter-task variability. Altogether, these results indicate that a subpopulation of PD patients shows a strong disruption in temporal processing in the hundreds of milliseconds range. These findings are discussed in terms of the role of dopamine as a tuning element for the synchronization of temporal processing across different behavioral contexts in PD patients.
帕金森病（PD）患者的间隔计时缺陷一直是一个有争议的问题。在此，我们测试了PD异质性作为这种差异来源的可能性。在两项间隔敲击任务和一项时间间隔分类任务中评估了PD患者和对照受试者的时间表现。这些任务涉及数百毫秒范围内的时间间隔处理；然而，它们也涵盖了广泛的行为背景，在感知、决策、记忆和执行要求方面存在差异。结果显示了以下重要发现。首先，PD患者明显分为两个亚组：一组在三项计时任务中具有较高的时间变异性，另一组的时间变异性与对照受试者没有显著差异。相比之下，时间变异性高和低的PD患者在一组对照任务中表现出相似的感知、决策、记忆和执行能力。其次，旨在区分与时间相关和与时间无关的变异来源的斜率分析表明，这组PD患者变异性的增加主要是由于与计时机制相关的变异性增加。第三，虽然对照受试者在任务间的表现变异性上显示出显著相关性，但PD患者，尤其是那些时间变异性高的患者，没有显示出这种任务相关性。最后，结果表明多巴胺能治疗恢复了PD患者的相关性效应，在任务间变异性之间产生了高度显著的相关性。总之
