We will describe the impact of biological sex determinants (hormones and chromosomes) in the hippocampus, a brain region essential for memory. We will present data using optogenetic-coupled electrophysiology, fiber photometry and in vivo electrophysiology with silicon probes showing how gonadal and brain synthesizes hormones regulate at the synaptic, cellular and network levels the activity of genetically defined population of inhibitory GABAergic neurons. We will talk about how sexual differentiation of the brain determines sex-hormonal regulation of hippocampal function. He will also present data showing how cell-type specific sex differences in transcriptional profile of hippocampal excitatory and inhibitory neurons could help us to understand sex-biased neurodevelopmental disorders.Ā