Long-term memory (LTM) formation depends on the conversed cAMP response element-binding protein (CREB)-dependent gene transcription followed by de novo protein synthesis. Thirsty fruit flies can be trained to associate an odor with water reward to form water-reward LTM (wLTM), which can last for over 24 hours without a significant decline. The role of de novo protein synthesis and CREB-regulated gene expression changes in neural circuits that contribute to wLTM remains unclear. Here, we show that acute inhibition of protein synthesis in the mushroom body (MB) αβ or γ neurons during memory formation using a cold-sensitive ribosome-inactivating toxin disrupts wLTM. Furthermore, adult stage-specific expression of dCREB2b in αβ or γ neurons also disrupts wLTM. The MB αβ and γ neurons can be further classified into five different neuronal subsets including αβ core, αβ surface, αβ posterior, γ main, and γ dorsal. We observed that the neurotransmission from αβ surface and γ dorsal neuron subsets is required for wLTM retrieval, whereas the αβ core, αβ posterior, and γ main are dispensable. Adult stage-specific expression of dCREB2b in αβ surface and γ dorsal neurons inhibits wLTM formation. In vivo calcium imaging revealed that αβ surface and γ dorsal neurons form wLTM traces with different dynamic properties, and these memory traces are abolished by dCREB2b expression. Our results suggest that a small population of neurons within the MB circuits support long-term storage of water-reward memory in Drosophila.

长期记忆（LTM）的形成取决于逆转的cAMP反应元件结合蛋白（CREB）依赖性基因转录，然后进行从头合成蛋白。可以训练口渴的果蝇将气味与水奖励相关联，以形成水奖励LTM（wLTM），可以持续24小时以上而不会明显下降。的角色从头蛋白质合成和神经回路CREB调控的基因表达变化，有助于wLTM仍不清楚。在这里，我们显示了使用冷敏核糖体失活毒素在记忆形成过程中对蘑菇体（MB）αβ或γ神经元的蛋白质合成的急性抑制作用会破坏wLTM。此外，dCREB2b的成年阶段特异性表达αβ或γ神经元中的α也破坏wLTM。可以将MBαβ和γ神经元进一步分为五个不同的神经元子集，包括αβ核心，αβ表面，αβ后部，γ主干和γ背侧。我们观察到，要进行wLTM检索，需要从αβ表面和γ背神经元子集进行神经传递，而αβ核心，αβ后部和γmain是必不可少的。dCREB2b在αβ表面和γ背神经元中的成年阶段特异性表达抑制wLTM的形成。体内钙成像显示，αβ表面和γ背神经元形成了具有不同动态特性的wLTM迹线，并且这些记忆迹线被dCREB2b废除了表达。我们的结果表明，MB回路中的一小部分神经元支持果蝇中水奖励记忆的长期存储。