Cognitive-Motor Neuroscience Group, Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology and The National Hospital for Neurology and Neurosurgery, University College London, 33 Queen Square, London, UK.
Exp Brain Res. 2011 Sep;213(4):435-45. doi: 10.1007/s00221-011-2793-x. Epub 2011 Jul 28.
Evidence from animal, clinical, and imaging studies suggests that the basal ganglia and their frontal connections mediate motor inhibition, but the role of dopamine remains unclear. The aim of our study was to investigate, for the first time, whether levodopa medication influences motor inhibition and conflict resolution on the conditional stop-signal reaction time task in patients with Parkinson's disease (PD) tested on or off their medication. Sixteen PD patients and 17 healthy controls performed the conditional stop-signal reaction time (SSRT) task, which requires inhibition of responses when a stop signal is presented on "critical" trials. Additionally, on "non-critical" trials, participants are instructed to ignore the stop signal and respond, thus generating conflict between motor inhibition and initiation; and conflict-induced slowing (CIS) on these "non-critical" trials. Levodopa medication did not significantly influence response initiation, inhibition (SSRT) or the measure of conflict resolution (CIS). Compared to healthy controls, PD patients showed significantly worse response initiation and inhibition both on and off their levodopa medication. Our results suggest that motor inhibition or conflict-induced slowing on the conditional stop-signal RT task are not altered by dopamine replacement in PD. This conclusion is consistent with evidence from animal studies and clinical pharmacological investigations suggesting a role for noradrenaline in motor inhibition and impulsivity.
来自动物、临床和影像学研究的证据表明，基底神经节及其额叶连接介导运动抑制，但多巴胺的作用仍不清楚。我们的研究目的是首次调查左旋多巴药物治疗是否会影响帕金森病（PD）患者在服用或停服药物时的条件停止信号反应时间任务中的运动抑制和冲突解决。16 名 PD 患者和 17 名健康对照者完成了条件停止信号反应时间（SSRT）任务，该任务要求在“关键”试验中出现停止信号时抑制反应。此外，在“非关键”试验中，参与者被指示忽略停止信号并做出反应，从而在运动抑制和启动之间产生冲突；以及在这些“非关键”试验中产生冲突诱导的减速（CIS）。左旋多巴药物治疗并没有显著影响反应启动、抑制（SSRT）或冲突解决的衡量标准（CIS）。与健康对照组相比，PD 患者在服用或停服左旋多巴药物时的反应启动和抑制都明显更差。我们的研究结果表明，多巴胺替代治疗不会改变条件停止信号 RT 任务中的运动抑制或冲突诱导的减速。这一结论与动物研究和临床药理学研究的证据一致，这些证据表明去甲肾上腺素在运动抑制和冲动性中起作用。
