School of Psychology and Psychiatry, Clayton Campus, Monash University, Victoria, Australia.
Mov Disord. 2011 Aug 15;26(10):1893-9. doi: 10.1002/mds.23757. Epub 2011 May 31.
The basal ganglia are involved in the preferential selection and suppression of competing responses. Parkinson's disease and Huntington's disease are 2 prototypical basal ganglia disorders that feature impaired inhibitory control, a function of poor conflict resolution. Previous saccadic studies showed that individuals with Parkinson's disease experience difficulty suppressing unwanted ocular motor responses, whereas evidence for a similar difficulty in Huntington's disease is more equivocal. Relative to saccades, few research studies have examined inhibitory control processes in the context of an ongoing smooth pursuit task. In this study, we examined the ability of 16 patients with Parkinson's disease and 12 patients with Huntington's disease to suppress automatic responses to irrelevant distracters that transiently appeared during the tracking of a moving visual stimulus. Compared with an equivalent number of age-matched controls, patients with Parkinson's disease generated proportionately more saccades to distracter stimuli. This was particularly evident for distracters appearing far away from the target. Conversely, whereas individuals with early-stage Huntington's disease and healthy controls made a comparable number of errors toward distracter stimuli, those in a more advanced clinical stage demonstrated significantly poorer inhibitory control. The current findings in parkinsonian patients replicate those previously reported in the saccadic and manual response literature, demonstrating difficulty inhibiting a competing motor response. However, in Huntington's disease we demonstrate for the first time that inhibitory control declines in more advanced-disease stages. This suggests that ocular motility may provide a sensitive marker of clinical disease progression in Huntington's disease.
基底神经节参与竞争反应的优先选择和抑制。帕金森病和亨廷顿病是两种典型的基底神经节疾病，其特征是抑制控制受损，即冲突解决能力差。以前的眼跳研究表明，帕金森病患者难以抑制不需要的眼球运动反应，而亨廷顿病患者则存在类似的困难，但证据并不明确。与眼跳相比，很少有研究在进行中的平滑追踪任务背景下检查抑制控制过程。在这项研究中，我们研究了 16 名帕金森病患者和 12 名亨廷顿病患者抑制与跟踪移动视觉刺激无关的分心物的自动反应的能力，这些分心物在跟踪过程中会短暂出现。与年龄匹配的对照组相比，帕金森病患者对分心物的眼跳比例更高。对于远离目标的分心物，这种情况尤其明显。相反，尽管早期亨廷顿病患者和健康对照组对分心物的错误反应数量相当，但处于更晚期临床阶段的患者表现出明显较差的抑制控制能力。目前在帕金森病患者中的发现与之前在眼跳和手动反应文献中报告的发现相吻合，表明抑制竞争运动反应存在困难。然而，在亨廷顿病中，我们首次证明抑制控制在更晚期疾病阶段下降。这表明眼球运动可能是亨廷顿病临床疾病进展的敏感标志物。
