The electrovomeronasogram: field potential recordings in the mouse vomeronasal organ

Mammalian vomeronasal neurons (VSNs) located in the sensory epithelium of the vomeronasal organ (VNO) detect and transduce molecular cues emitted by other individuals and send this information to the olfactory forebrain. The initial steps in the detection of pheromones and other chemosignals by VSNs involve interaction of a ligand with a G protein-coupled receptor and downstream activation of the primary signal transduction cascade, which includes activation of ion channels located in microvilli and the dendritic tip of a VSN. The electrovomeronasogram (EVG) recording technique provides a sensitive means through which ligand-induced activation of populations of VSNs can be recorded from the epithelial surface using an intact, ex vivo preparation of the mouse VNO. We describe methodological aspects of this preparation and the EVG recording technique which, together with single-cell recordings, contributed significantly to our understanding of mammalian vomeronasal function, the identification of pheromonal ligands, and the analysis of mice with targeted deletions in specific signal transduction molecules such as Trpc2, Gαo, V1R, or V2R receptors.