Exclusion and Co-expression of Aversive Olfactory Long-Term Memories in Drosophila

Long-term memory(LTM)allows animals to use remote past experiences to guide current and future decisions.One of the widely-used animal models for LTM research is the fruit-fly Drosophila melanogaster,which can form different types of LTM after different learning paradigms[1-6].Spaced training-induced LTM(spLTM),perhaps the most studied Drosophila LTM,requires multiple repeated learning trials with a 15-min resting interval between each trial.For decades,spLTM has been considered the only aversive olfactory LTM that can last for>7 days[1].Recently,two other types of LTM,context-dependent LTM(cLTM)[5]and merged LTM(mLTM)[6],have been discovered with the same long duration as spLTM,and can be formed with only one aversive learning trial.