Dissociation of rugose-dependent short-term memory component from memory consolidation in Drosophila

Extensive investigations show several molecular and neuroanatomical mechanisms underlying short-lived and long-lasting memory in Drosophila. At the molecular level, the genetic pathway of memory formation, which was obtained through mutant research, seems to occur sequentially. So far, studies of Drosophila mutants appear to support the idea that mutants defective in short-term memory (STM) are always associated with long-term memory (LTM) impairment. At the neuroanatomical level, distinct memory traces are partially independently distributed. However, whether memory phase dissociation also exists at the molecular level remains unclear. Here, we report on molecular separation of STM and consolidated memory through genetic dissection of rugose mutants. Mutants in the rugose gene, which encodes an evolutionarily conserved A-kinase anchor protein, show immediate memory defects as assayed through aversive olfactory conditioning. Intriguingly, two well-defined consolidated memory components, anesthesia-resistant memory and protein synthesis-dependent LTM, are both normal in spite of the defective immediate memory after 10-session massed and spaced training. Moreover, rugose genetically interacts with cyclic AMP-protein kinase A signaling during STM formation. Considering our previous study that AKAP Yu specifically participates in LTM formation, these results suggest that there exists a molecular level of memory phase dissociation with distinct AKAPs in Drosophila.