It is widely assumed that synapses are a basic substrate of memory. While in neocortex, two-photon imaging is casting light on the relationship between learning and synaptic turnover, such a relationship is still obscure in the hippocampus. We want to establish a direct link between synaptic plasticity and learning in the hippocampal CA1 of live animals, and to examine how stress influences this function through some of its established molecular mediators. To this aim we use optical imaging of dendritic spines in the basal aspect of hippocampal CA1 (Attardo et al., 2015; Ulivi et al., 2019 and Castello-Waldow et al., 2020) to investigate long-term synaptic turnover in live animals learning to perform a memory task that requires the hippocampus.