The role of protein biosynthesis and ene expression in learning has been well documented. Similarly, the role of activation of glutamate receptors in neuronal plasticity have been shown repeatedly. In our studies we found that L-glutamate, acting through different kinds of its receptors may stimulate expression of c-fos and other genes encoding components of transcroption factors both in vivo and in vitro. We have also documented elevated expression of c-fos after induction of long lasting long term potentiation and variaous forms of behavioral training. In this paper these data are reviewed and a hypothesis, suggesting that neuronal nuclei may act as information integration device in memory formation is proposed.