Mounting evidence shows that dopamine in the striatum is critically involved in reward-based reinforcement learning^1,2. However, it remains unclear how dopamine reward signals influence the entorhinal–hippocampal circuit, another brain network that is crucial for learning and memory^3,4,5. Here, using cell-type-specific electrophysiological recording⁶, we show that dopamine signals from the ventral tegmental area and substantia nigra control the encoding of cue–reward association rules in layer 2a fan cells of the lateral entorhinal cortex (LEC). When mice learned novel olfactory cue–reward associations using a pre-learned association rule, spike representations of LEC fan cells grouped newly learned rewarded cues with a pre-learned rewarded cue, but separated them from a pre-learned unrewarded cue. Optogenetic inhibition of fan cells impaired the learning of new associations while sparing the retrieval of pre-learned memory. Using fibre photometry, we found that dopamine sends novelty-induced reward expectation signals to the LEC. Inhibition of LEC dopamine signals disrupted the associative encoding of fan cells and impaired learning performance. These results suggest that LEC fan cells represent a cognitive map of abstract task rules, and that LEC dopamine facilitates the incorporation of new memories into this map.

越来越多的证据表明，纹状体中的多巴胺与基于奖励的强化学习密切相关^1,2。然而，目前尚不清楚多巴胺奖励信号如何影响内嗅海马回路，这是另一个对学习和记忆至关重要的大脑网络^3,4,5。在这里，使用细胞类型特异性电生理记录⁶，我们表明来自腹侧被盖区和黑质的多巴胺信号控制着外侧内嗅皮层（LEC）第 2a 层扇形细胞中提示奖励关联规则的编码。当小鼠使用预先学习的关联规则学习新的嗅觉线索-奖励关联时，LEC 扇形细胞的尖峰表示将新学习的奖励线索与预先学习的奖励线索分组，但将它们与预先学习的未奖励线索分开。扇形细胞的光遗传学抑制损害了新联想的学习，同时保留了对预习记忆的检索。使用光纤光度法，我们发现多巴胺向 LEC 发送新奇诱导的奖励期望信号。LEC 多巴胺信号的抑制破坏了扇形细胞的关联编码并损害了学习能力。