A constraint on cAMP signaling.

Studies in invertebrates and vertebrates have demonstrated a critical role for cAMP signaling and adenylyl cyclase (AC) activity in learning and memory. In this issue of Neuron, Pineda et al. show that in the hippocampus, reduction of AC activity via the inhibitory G protein G(i) is critical for memory formation, suggesting that a balance of inhibitory and stimulatory regulators of AC is required for optimal cAMP signaling.