Sporn Sebastian, Galea Joseph M
School of Psychology and Centre for Human Brain Health, University of Birmingham, Birmingham, United Kingdom.
Department of Clinical and Movement Neuroscience, Queens Square Institute of Neurology, UCL, London, United Kingdom.
PLoS One. 2025 Jan 31;20(1):e0316894. doi: 10.1371/journal.pone.0316894. eCollection 2025.
Reward is a powerful tool to enhance human motor behaviour with previous research showing that during a sequential reaching movement, a monetary incentive leads to increased speed of each movement (motor vigour effect), whilst reward-based performance feedback increases the speed of transition between movements (movement fusion effect). The neurotransmitter dopamine plays a central role in the processing of reward signals and has been implicated to modulate motor vigour and regulate movement fusion. However, in humans, it is unclear if the same dopaminergic mechanism underlies both processes. To address this, we used a complex sequential reaching task in which rewards were based on movement times (MT). Crucially, MTs could be reduced via: 1) enhanced speed of individual movements (motor vigour effect) and/or 2) enhanced speed of transition between movements (movement fusion effect). 95 participants were randomly assigned to a reward or no reward group and were given either 2.5mg of the dopamine antagonist haloperidol or a placebo (control group). An independent decision-making task performed prior to the main experiment suggested that haloperidol was active during the sequential reaching task (positive control). We did not find evidence that haloperidol affected the facilitatory effects of reward on movement fusion. However, we found that haloperidol negated the reward-based effects on motor vigour. Therefore, our results suggest that a D2-antagonist differentially influences reward-based effects on movement vigour and movement fusion, indicating that the dopaminergic mechanisms underlying these two processes may be distinct.
奖励是增强人类运动行为的有力工具，先前的研究表明，在连续伸手动作过程中，金钱激励会导致每个动作的速度加快（运动活力效应），而基于奖励的绩效反馈会提高动作之间转换的速度（动作融合效应）。神经递质多巴胺在奖励信号处理中起核心作用，并且被认为可调节运动活力和控制动作融合。然而，在人类中，尚不清楚这两个过程是否基于相同的多巴胺能机制。为了解决这个问题，我们使用了一项复杂的连续伸手任务，其中奖励基于运动时间（MT）。至关重要的是，MT可以通过以下方式降低：1）提高单个动作的速度（运动活力效应）和/或2）提高动作之间转换的速度（动作融合效应）。95名参与者被随机分配到奖励组或无奖励组，并给予2.5毫克多巴胺拮抗剂氟哌啶醇或安慰剂（对照组）。在主要实验之前进行的一项独立决策任务表明，氟哌啶醇在连续伸手任务期间是有效的（阳性对照）。我们没有发现证据表明氟哌啶醇会影响奖励对动作融合的促进作用。然而，我们发现氟哌啶醇消除了基于奖励对运动活力的影响。因此，我们的结果表明，D2拮抗剂对基于奖励的运动活力和动作融合的影响不同，这表明这两个过程背后的多巴胺能机制可能是不同的。
