Abstract

The gonadotropin-releasing hormone (GnRH) neurons have an unusual neuronal phenotype in that they migrate from the nose into the brain during embryogenesis to ultimately control reproductive hormone secretion and fertility in all vertebrates. The GnRH neurons embed themselves into a neuronal network that enables them to generate two different types of episodic activity that drive “pulse” and “surge” patterns of hormone secretion. Studies in genetically manipulated mice using viral tract-tracing, electrophysiology, and a range of in vivo optogenetic and chemogenetic approaches are beginning to shed light on the key neuronal circuitries responsible for driving these different modes of episodic activity.