Understanding mechanisms of memory retrieval and its deficits, and detection of memory underlying neuronal plasticity is greatly impeded by a lack of precise knowledge of memory underlying brain circuits. We addressed these questions by mapping Arc/Arg 3.1 mRNA expression at the multiple rostro-caudal levels of the brain following platform search in the water-maze spatial task at 24 hr and 1 mo in memory retention as compared to swimming and naïve controls. We have recently found dissociation in activity of entorhinal cortex, CA3 and CA1 over a period of memory consolidation: while the entorhinal cortex and CA3 demonstrated a robust learning-specific signal during both recent and long-term memory recalls, CA1 specific activity was almost entirely limited to recent memory retrieval (Gusev, Alkon and Gubin, SFN, 2004). Following recent memory tests, we so far observed a learning-specific signal in the parietal, visual (I, IIL, IIM), motor, sensorimotor (I) and retrosplenial but not sensorimotor (II) cortices...