Medical Innovation Center/SK Project, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Department of Neuroscience, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
Sci Adv. 2023 Mar 10;9(10):eade5420. doi: 10.1126/sciadv.ade5420.
To obtain more of a particular uncertain reward, animals must learn to actively overcome the lack of reward and adjust behavior to obtain it again. The neural mechanisms underlying such coping with reward omission remain unclear. Here, we developed a task in rats to monitor active behavioral switch toward the next reward after no reward. We found that some dopamine neurons in the ventral tegmental area exhibited increased responses to unexpected reward omission and decreased responses to unexpected reward, following the opposite responses of the well-known dopamine neurons that signal reward prediction error (RPE). The dopamine increase reflected in the nucleus accumbens correlated with behavioral adjustment to actively overcome unexpected no reward. We propose that these responses signal error to actively cope with lack of expected reward. The dopamine error signal thus cooperates with the RPE signal, enabling adaptive and robust pursuit of uncertain reward to ultimately obtain more reward.
为了获得更多特定的不确定奖励，动物必须学会主动克服缺乏奖励的情况，并调整行为以再次获得奖励。但支持这种应对奖励缺失的神经机制仍不清楚。在这里，我们在大鼠中开发了一项任务，以监测在没有奖励后主动转向下一个奖励的行为切换。我们发现腹侧被盖区中的一些多巴胺神经元在意外的奖励缺失时表现出增加的反应，而在意外的奖励时表现出减少的反应，与信号奖励预测错误（RPE）的著名多巴胺神经元的相反反应一致。在伏隔核中反映的多巴胺增加与主动克服意外无奖励的行为调整相关。我们提出，这些反应信号错误以主动应对缺乏预期奖励。因此，多巴胺误差信号与 RPE 信号协同作用，使不确定奖励的适应性和稳健追求最终获得更多奖励。
