Electrical Coupling in Caenorhabditis elegans Mechanosensory Circuits

Electrical synapses formed by gap junctions are widespread in the human brain as well as in simpler nervous systems. The nematode Caenorhabditis elegans, with its completely mapped connectome of 302 neurons and approximately 4000 electrical synapses, is therefore well suited to investigate the functional importance of electrical coupling in neuronal microcircuits. We have found that hub-and-spoke gap junction circuit in C. elegans mediates the integration of mechanosensory information to control nose touch avoidance behavior. A combination of lateral facilitation between active inputs and inhibitory shunting to inactive inputs implements an analog coincidence detector, a property that might be shared with other hub-and-spoke circuits. We also describe transgenic methods for the synthetic insertion of ectopic gap junctions, which may have broad experimental applications.