Parallel processing of appetitive short- and long-term memories in Drosophila

International audienceIt is broadly accepted that long-term memory (LTM) isformed sequentially after learning and short-term memory(STM) formation, but the nature of the relationship betweenearly and late memory traces remains heavily debated[1–5]. To shed light on this issue, we used an olfactory appe-titive conditioning inDrosophila, wherein starved flieslearned to associate an odor with the presence of sugar[6]. We took advantage of the fact that both STM and LTMare generated after a unique conditioning cycle [7, 8 ]todemonstrate that appetitive LTM is able to form indepen-dently of STM. More specifically, we show that (1) STMretrieval involves output fromgneurons of the mushroombody (MB), i.e., the olfactory memory center [9, 10 ], whereasLTM retrieval involves output fromabMB neurons; (2) STMinformation is not transferred fromgneurons toabneuronsfor LTM formation; and (3) the adenylyl cyclase RUT, whichis thought to operate as a coincidence detector betweenthe olfactory stimulus and the sugar stimulus [11–14], isrequired independently ingneurons to form appetitiveSTM and inabneurons to form LTM. Taken together, theseresults demonstrate that appetitive short- and long-termmemories are formed and processed in paralle