Manohar S G, Husain M
Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
NPJ Parkinsons Dis. 2015 Dec 17;1:15026. doi: 10.1038/npjparkd.2015.26.
Abnormalities in reward processing may be a critical part of understanding nonmotor manifestations of Parkinson's disease (PD). Dysfunction in dopaminergic pathways, which signal upcoming rewards, might result in altered motivation by incentives. To examine this proposal, we studied 16 patients with PD, both ON and OFF their normal dopaminergic medication, comparing them with healthy controls. Participants performed a speeded saccade task to obtain monetary rewards. Crucially, we manipulated the reward available from trial to trial, by presenting an auditory incentive precue before each saccade. The effects of incentives on pupil dilatation (an index of autonomic response) were measured. Individuals with PD showed diminished autonomic reward effects, compared with age-matched controls. When tested ON medication, pupil responses to reward increased, demonstrating that dopaminergic drugs can restore reward sensitivity. These findings reveal blunted autonomic responses to incentives in PD, which can be modulated by dopaminergic drugs.
奖赏处理异常可能是理解帕金森病（PD）非运动表现的关键部分。多巴胺能通路功能障碍会发出即将到来的奖赏信号，这可能导致动机因激励而改变。为了验证这一假设，我们研究了16名PD患者，分别在服用和未服用常规多巴胺能药物的情况下，将他们与健康对照者进行比较。参与者执行快速扫视任务以获得金钱奖励。至关重要的是，我们通过在每次扫视前呈现听觉激励预线索，逐次操纵可获得的奖励。测量了激励对瞳孔扩张（自主反应指标）的影响。与年龄匹配的对照组相比，PD患者的自主奖赏效应减弱。在服用药物进行测试时，瞳孔对奖励的反应增加，表明多巴胺能药物可恢复奖赏敏感性。这些发现揭示了PD患者对激励的自主反应迟钝，且可被多巴胺能药物调节。
