Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, Technische Universitat Dresden, Dresden, Germany.
Faculty of Psychology, Chair of Lifespan Developmental Neuroscience, Technische Universitat Dresden, Dresden, Germany.
Int J Neuropsychopharmacol. 2018 Jul 1;21(7):649-655. doi: 10.1093/ijnp/pyy019.
Perceptual decision making is the process through which available sensory information is gathered and processed to guide our choices. However, the neuropsychopharmacological basis of this important cognitive function is largely elusive. Yet, theoretical considerations suggest that the dopaminergic system may play an important role.
In a double-blind, randomized, placebo-controlled study design, we examined the effect of methylphenidate in 2 dosages (0.25 mg/kg and 0.5 mg/kg body weight) in separate groups of healthy young adults. We used a moving dots task in which the coherency of the direction of moving dots stimuli was manipulated in 3 levels (5%, 15%, and 35%). Drift diffusion modelling was applied to behavioral data to capture subprocesses of perceptual decision making.
The findings show that only the drift rate (v), reflecting the efficiency of sensory evidence accumulation, but not the decision criterion threshold (a) or the duration of nondecisional processes (Ter), is affected by methylphenidate vs placebo administration. Compared with placebo, administering 0.25 mg/kg methylphenidate increased v, but only in the 35% coherence condition. Administering 0.5 mg/kg methylphenidate did not induce modulations.
The data suggest that dopamine selectively modulates the efficacy of evidence accumulation during perceptual decision making. This modulation depends on 2 factors: (1) the degree to which the dopaminergic system is modulated using methylphenidate (i.e., methylphenidate dosage) and (2) the signal-to-noise ratio of the visual information. Dopamine affects sensory evidence accumulation only when dopamine concentration is not shifted beyond an optimal level and the incoming information is less noisy.
知觉决策是一个过程，通过这个过程，可用的感觉信息被收集和处理，以指导我们的选择。然而，这一重要认知功能的神经精神药理学基础在很大程度上仍是难以捉摸的。然而，理论考虑表明，多巴胺系统可能起着重要作用。
在一项双盲、随机、安慰剂对照的研究设计中，我们分别在两组健康的年轻成年人中研究了哌醋甲酯（两种剂量：0.25 毫克/千克和 0.5 毫克/千克体重）的作用。我们使用了一个移动点任务，其中移动点刺激的方向连贯性被操纵在 3 个水平（5%、15%和 35%）。漂移扩散模型被应用于行为数据，以捕捉知觉决策的子过程。
研究结果表明，只有漂移率（v），反映了感觉证据积累的效率，而不是决策标准阈值（a）或非决策过程的持续时间（Ter），受到哌醋甲酯与安慰剂给药的影响。与安慰剂相比，给予 0.25 毫克/千克的哌醋甲酯增加了 v，但仅在 35%连贯性条件下。给予 0.5 毫克/千克的哌醋甲酯没有引起调制。
数据表明，多巴胺选择性地调节知觉决策过程中证据积累的效率。这种调制取决于两个因素：（1）使用哌醋甲酯调制多巴胺系统的程度（即哌醋甲酯剂量）；（2）视觉信息的信号噪声比。只有当多巴胺浓度没有超出最佳水平，并且传入信息噪音较小时，多巴胺才会影响感觉证据的积累。
