Memory formation requires changes in neuronal networks connectivity based on modifications in strength and number of synapses. The mechanisms driving these changes have been intensively studied, but mostly under naive conditions, i.e. in animals that have not been cognitively challenged. Better characterization of synaptic requirements supporting memory formation can emerge from studies focusing on synaptic changes in memory-encoding structures while or after the animal model is cognitively challenged. Here, with this concept in mind, we review the literature describing structural, functional and molecular alterations developing in the hippocampus when animals are asked to form memories. We also briefly discuss the interest of this approach for disclosing pathological mechanisms in memory disorders, which might otherwise not be observed in naive conditions. © 2014.