Illuminating the Diversity of Electrical Synapse Form and Function

While the nervous system is organized by two main types of connections between neurons, electrical and chemical synapses, most studies focus upon the contribution of the molecularly complex and functionally diverse chemical synapse. Electrical synapses, in contrast, are perceived as simple, neuronal gap junction channels between contacts, often thought to be replaced in early development by more sophisticated chemical synapses. However, recent work and new tools push for the redefining of electrical synapse molecular architecture and function to allow for an updated interpretation of their ongoing contributions to neural circuit formation and function. Here, we describe fresh insight into neuronal gap junction structure, function, and molecular composition within invertebrate (nematodes, drosophila) and vertebrate (zebrafish, rabbit, rodent) model organisms across a variety of time periods and brain regions. Through molecular, genetic, connectomic, and functional explorations, our results argue for a new appreciation of electrical synapse heterogeneity. Based on these and other points of emerging new evidence, we argue for increased consideration of electrical synapses as complex and diverse structures which interact with chemical synapses to drive circuit formation and function.