Patients with Parkinson’s disease have reduced reward sensitivity related to dopaminergic neuron loss, which is associated with impairments in reinforcement learning. Increasingly, however, dopamine-dependent reward signals are recognized to play an important role beyond reinforcement learning. In particular, it has been shown that reward signals mediated by dopamine help guide the prioritization of events for long-term memory consolidation. Meanwhile, studies of memory in patients with Parkinson’s disease have focused on overall memory capacity rather than what is versus what isn’t remembered, leaving open questions about the effect of dopamine replacement on the prioritization of memories by reward and the time-dependence of this effect. The current study sought to fill this gap by testing the effect of reward and dopamine on memory in patients with Parkinson’s disease. We tested the effect of dopamine modulation and reward on two forms of long-term memory: episodic memory for neutral objects and memory for stimulus-value associations. We measured both forms of memory in a single task, adapting a standard task of reinforcement learning with incidental episodic encoding events of trial-unique objects. Objects were presented on each trial at the time of feedback, which was either rewarding or not. Memory for the trial-unique images and for the stimulus-value associations, and the influence of reward on both, was tested immediately after learning and 2 days later. We measured performance in Parkinson’s disease patients tested either ON or OFF their dopaminergic medications and in healthy older control subjects. We found that dopamine was associated with a selective enhancement of memory for reward-associated images, but that it did not influence overall memory capacity. Contrary to predictions, this effect did not differ between the immediate and delayed memory tests. We also found that while dopamine had an effect on reward-modulated episodic memory, there was no effect of dopamine on memory for stimulus-value associations. Our results suggest that impaired prioritization of cognitive resource allocation may contribute to the early cognitive deficits of Parkinson’s disease.

中文翻译：

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多巴胺与帕金森病中奖赏相关记忆的优先排序有关。

帕金森病患者与多巴胺能神经元丢失相关的奖赏敏感性降低，这与强化学习的障碍有关。然而，越来越多的人认识到依赖于多巴胺的奖励信号在强化学习之外发挥着重要作用。特别是，已经表明由多巴胺介导的奖励信号有助于指导长期记忆巩固事件的优先级。同时，对帕金森病患者记忆力的研究集中在整体记忆容量上，而不是什么和不记得什么，留下了关于多巴胺替代对奖赏和记忆的时间依赖性的影响的悬而未决的问题影响。目前的研究试图通过测试奖励和多巴胺对帕金森病患者记忆力的影响来填补这一空白。我们测试了多巴胺调节和奖励对两种形式的长期记忆的影响：中性物体的情景记忆和刺激价值关联的记忆。我们在单个任务中测量了两种形式的记忆，将强化学习的标准任务与试验独特对象的偶然情节编码事件相适应。在反馈时，每次试验都会呈现对象，这要么是有回报的，要么是没有回报的。对试验独特图像和刺激值关联的记忆，以及奖励对两者的影响，在学习后立即和 2 天后进行测试。我们测量了帕金森氏病患者的表现，他们测试了多巴胺能药物的开或关，以及健康的老年对照受试者。我们发现多巴胺与奖励相关图像的记忆选择性增强有关，但它不影响整体记忆容量。与预测相反，这种效果在即时记忆测试和延迟记忆测试之间没有差异。我们还发现，虽然多巴胺对奖励调节的情景记忆有影响，但多巴胺对刺激价值关联的记忆没有影响。我们的研究结果表明，认知资源分配的优先顺序受损可能导致帕金森病的早期认知缺陷。但它并没有影响整体内存容量。与预测相反，这种效果在即时记忆测试和延迟记忆测试之间没有差异。我们还发现，虽然多巴胺对奖励调节的情景记忆有影响，但多巴胺对刺激价值关联的记忆没有影响。我们的研究结果表明，认知资源分配的优先顺序受损可能导致帕金森病的早期认知缺陷。但它并没有影响整体内存容量。与预测相反，这种效果在即时记忆测试和延迟记忆测试之间没有差异。我们还发现，虽然多巴胺对奖励调节的情景记忆有影响，但多巴胺对刺激价值关联的记忆没有影响。我们的研究结果表明，认知资源分配的优先顺序受损可能导致帕金森病的早期认知缺陷。