 In all systems studied, the cAMP signaling cascade has been identified as one of the major biochemical pathways involved in modulating both neuronal and behavioral plasticity. … More recently, elucidation of the role of CREB-mediated transcription in long-term memory in flies, LTP and long-term memory in vertebrates, and long-term facilitation in A. californica [a sea slug] suggest that CREB may constitute a universally conserved molecular switch for long term memory. (1998: 438)