Brain functions are the result of the coordinated activity of large networks of neurons, which are composed by many different cell types. As a consequence, the specific properties of synaptic communication between different types of neurons play a pivotal role in shaping the computational power and network activity of specific brain regions. Research in my laboratory is focused on the hippocampus, which is an area of the brain involved in higher cognitive functions, such as learning and memory, and is often affected by important neurological illnesses like epilepsy, schizophrenia and Alzheimer’s disease. In particular, we are interested in the synaptic properties of GABAergic inhibitory interneurons, which are a very heterogeneous cellular population, with wide anatomical and functional diversity. Additionally we are trying to unravel the network properties of Cajal-Retzius cells, which are a neuronal population involved in guiding cortical development, whose computational functions remain poorly understood. Methodologically, we use state-of-the-art electrophysiological techniques in vitro such as paired recordings from anatomically identified connected neurons and optogenetic control of specific cellular populations. We hope that relating different neuronal types to clear network functions may lead to a better understanding of the cellular and molecular basis of hippocampal activity, and generate important insight into the organizing principles of cortical networks in the normal brain and during disease.