Long-term memory encoding engram neurons are established by the transcriptional cycling

Long-term memory (LTM) is formed by repetitive training trials with rest intervals and LTM formation requires transcription factors, including CREB and c-Fos. Researchers found that ERK activity is increased during rest intervals to induce transcriptional cycling between c-Fos and CREB in a subset of mushroom body neurons. Significantly, LTM is encoded in these mushroom body neurons, and blocking outputs from these neurons suppress recall of LTM whereas activating these neurons produces memory-associated behaviors.