Cohen Matthew L, Schwab Nadine A, Price Catherine C, Heilman Kenneth M
J Parkinsons Dis. 2015;5(4):961-70. doi: 10.3233/jpd-150672.
Planned and initiated actions frequently need to be terminated in favor of another action. It is known that many individuals with Parkinson's disease (PD) have more difficulty self-initiating movement (i.e., endogenously evoked movement)than moving in response to environmental stimuli (i.e., exogenously evoked movement). However, it is not known if individuals with PD display this same endogenous-exogenous asymmetry when needing to terminate, disengage, and reprogram movements.
This study used a novel reaction time (RT) paradigm to test whether patients with mild PD have subclinical deficits of endogenous movement initiation and endogenous movement reprogramming.
Twelve non-demented individuals with PD on medication and 15 demographically similar healthy control (HC)participants completed an experimental paradigm that examined their RTs (key press) following self-selected valid action preparation (endogenous cues) versus valid exogenously presented cues. The paradigm also assessed participants' ability to rapidly stop their endogenous or exogenous preparation following an invalid cue and execute an alternative action (key press).
Participants with PD produced similar RTs as controls following endogenous and exogenous valid cues, and following invalid exogenous cues. However, following invalid endogenous cues, PD participants were slower than HC participants to stop an endogenous preparation and execute an alternative action.
Despite having mild disease and being on dopaminergic medication, these individuals with PD displayed deficits in motor disengagement and reprograming of self-selected actions. Future studies should examine how this phenomenon influences every day actions, as well as possible treatments for this deficit.
计划和启动的行动常常需要为了另一行动而终止。已知许多帕金森病（PD）患者在自我启动运动（即内源性诱发运动）方面比响应环境刺激而运动（即外源性诱发运动）存在更多困难。然而，尚不清楚PD患者在需要终止、脱离和重新规划运动时是否表现出同样的内源性-外源性不对称。
本研究采用一种新颖的反应时间（RT）范式来测试轻度PD患者是否存在内源性运动启动和内源性运动重新规划的亚临床缺陷。
12名正在服药的非痴呆PD患者和15名人口统计学特征相似的健康对照（HC）参与者完成了一个实验范式，该范式检查了他们在自我选择的有效动作准备（内源性线索）与有效外源性呈现线索后的反应时间（按键）。该范式还评估了参与者在接收到无效线索后迅速停止其内源性或外源性准备并执行替代动作（按键）的能力。
PD患者在接收到内源性和外源性有效线索后以及接收到无效外源性线索后的反应时间与对照组相似。然而，在接收到无效内源性线索后，PD参与者比HC参与者更慢地停止内源性准备并执行替代动作。
尽管这些PD患者病情较轻且正在服用多巴胺能药物，但他们在自我选择动作的运动脱离和重新规划方面存在缺陷。未来的研究应检查这种现象如何影响日常行为以及针对这种缺陷的可能治疗方法。
