Mushroom body subsets encode CREB2-dependent water-reward long-term memory in Drosophila.

ABSTRACT: 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) ?? or ? neurons during memory formation using a cold-sensitive ribosome-inactivating toxin disrupts wLTM. Furthermore, adult stage-specific expression of dCREB2b in ?? or ? neurons also disrupts wLTM. The MB ?? and ? neurons can be further classified into five different neuronal subsets including ?? core, ?? surface, ?? posterior, ? main, and ? dorsal. We observed that the neurotransmission from ?? surface and ? dorsal neuron subsets is required for wLTM retrieval, whereas the ?? core, ?? posterior, and ? main are dispensable. Adult stage-specific expression of dCREB2b in ?? surface and ? dorsal neurons inhibits wLTM formation. In vivo calcium imaging revealed that ?? surface and ? 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.

SUBMITTER: Lee WP 

PROVIDER: S-EPMC7418956 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature