NeuroNexus A1x16-5mm-100-413-A16 probes were used to record sharp-wave ripples (SWRs), theta and gamma oscillations from striatum pyramidale (SP) of mouse hippocampal CA1. Aromatase is responsible for estradiol synthesis. In their Nature Communications paper, Alicia Hernández-Vivanco et al. with Liset Menendez de la Prida and Pablo Méndez at Instituto Cajal tested aromatase regulation of parvalbumin expressing (PV) inhibitory neurons. Their results demonstrate that sex hormones regulate brain activity through inhibitory neurons.