At the core of value-based learning is the nucleus accumbens (NAc). D1- and D2-receptor-containing medium spiny neurons (MSNs) in the NAc core are hypothesized to have opposing valence-based roles in behavior. Using optical imaging and manipulation approaches in mice, we show that neither D1 nor D2 MSNs signal valence. D1 MSN responses were evoked by stimuli regardless of valence or contingency. D2 MSNs were evoked by both cues and outcomes, were dynamically changed with learning, and tracked valence-free prediction error at the population and individual neuron level. Finally, D2 MSN responses to cues were necessary for associative learning. Thus, D1 and D2 MSNs work in tandem, rather than in opposition, by signaling specific properties of stimuli to control learning.

基于价值的学习的核心是伏核（NAc）。假设NAc 核心中含有 D1 和 D2 受体的中型多棘神经元(MSN)在行为中具有相反的基于价态的作用。通过对小鼠进行光学成像和操作方法，我们发现 D1 和 D2 MSN 均不发出价信号。D1 MSN 反应是由刺激引起的，无论效价或偶然性如何。D2 MSN 由线索和结果引起，随着学习动态变化，并在群体和个体神经元水平上跟踪无价预测误差。最后，D2 MSN 对提示的反应对于联想学习是必要的。因此，D1 和 D2 MSN 通过发出刺激的特定属性信号来控制学习，从而协同工作，而不是相反。