McDonald Louise M, Griffin Harry J, Angeli Aikaterini, Torkamani Mariam, Georgiev Dejan, Jahanshahi Marjan
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
PLoS One. 2015 Aug 18;10(8):e0135149. doi: 10.1371/journal.pone.0135149. eCollection 2015.
Paradoxical kinesis has been observed in bradykinetic people with Parkinson's disease. Paradoxical kinesis occurs in situations where an individual is strongly motivated or influenced by relevant external cues. Our aim was to induce paradoxical kinesis in the laboratory. We tested whether the motivation of avoiding a mild electric shock was sufficient to induce paradoxical kinesis in externally-triggered and self-initiated conditions in people with Parkinson's disease tested on medication and in age-matched controls.
Participants completed a shock avoidance behavioural paradigm in which half of the trials could result in a mild electric shock if the participant did not move fast enough. Half of the trials of each type were self-initiated and half were externally-triggered. The criterion for avoiding shock was a maximum movement time, adjusted according to each participant's performance on previous trials using a staircase tracking procedure.
On trials with threat of shock, both patients with Parkinson's disease and controls had faster movement times compared to no potential shock trials, in both self-initiated and externally-triggered conditions. The magnitude of improvement of movement time from no potential shock to potential shock trials was positively correlated with anxiety ratings.
When motivated to avoid mild electric shock, patients with Parkinson's disease, similar to healthy controls, showed significant speeding of movement execution. This was observed in both self-initiated and externally-triggered versions of the task. Nevertheless, in the ET condition the improvement of reaction times induced by motivation to avoid shocks was greater for the PD patients than controls, highlighting the value of external cues for movement initiation in PD patients. The magnitude of improvement from the no potential shock to the potential shock trials was associated with the threat-induced anxiety. This demonstration of paradoxical kinesis in the laboratory under both self-initiated and externally-triggered conditions has implications for motivational and attentional enhancement of movement speed in Parkinson's disease.
在帕金森病的运动迟缓患者中观察到了反常运动。反常运动发生在个体受到相关外部线索强烈激励或影响的情况下。我们的目的是在实验室中诱导出反常运动。我们测试了避免轻度电击的动机是否足以在服用药物的帕金森病患者和年龄匹配的对照组的外部触发和自我发起条件下诱导出反常运动。
参与者完成了一种电击回避行为范式，其中一半的试验如果参与者移动不够快可能会导致轻度电击。每种类型的试验中有一半是自我发起的，一半是外部触发的。避免电击的标准是最大运动时间，根据每个参与者在先前试验中的表现使用阶梯跟踪程序进行调整。
在有电击威胁的试验中，与无潜在电击试验相比，帕金森病患者和对照组在自我发起和外部触发条件下的运动时间都更快。从无潜在电击试验到潜在电击试验运动时间改善的幅度与焦虑评分呈正相关。
当有动机避免轻度电击时，帕金森病患者与健康对照组一样，运动执行速度显著加快。这在任务的自我发起和外部触发版本中均有观察到。然而，在外部触发条件下，帕金森病患者因避免电击的动机而导致的反应时间改善比对照组更大，这突出了外部线索对帕金森病患者运动发起的价值。从无潜在电击试验到潜在电击试验改善的幅度与威胁诱发的焦虑有关。在实验室中自我发起和外部触发条件下反常运动的这一证明对帕金森病运动速度的动机和注意力增强具有启示意义。
