We study the molecular mechanisms of synaptic plasticity, the property of synapses of being regulated by their own activity and which is thought to underlie learning and memory. A fundamental problem in the study of synaptic plasticity is how the synapse can store, during prolonged periods of time, information on previous synaptic activity. A way to investigate this is by developing methods to interfere with synaptic memory maintenance, i.e., by altering the processes involved in their storage. In particular, we evaluate if targeting essential components of the postsynaptic densities, like the enzyme calcium/ calmodulin kinase II (CaMKII), the NMDA- and AMPA- type glutamate receptors, or their interactions, allows to revert plastic changes previously induced. For this, we record synaptic transmission in rat hipocampal slices, using cellular models of synaptic plasticity (long term potentiation and depression; LTP and LTD) and different electrophysiological and pharmacological techniques. In a second research line, we investigate the physiological properties of principal neurons of the olfactory cortical amygdala, a region implied in processing and associative learning of emotionally relevant sensory information. We study the subthreshold membrane potential oscillations and neuronal resonance in the theta frequency range displayed by these neurons, as well as synaptic transmission and plasticity properties of olfactory connections to this area, during postnatal development.