Action potentials contribute to neuronal signaling in C. elegans

The physical properties of nematode neurons have led many to believe that neuronal signals in worms are passively propagated. Here, the authors present evidence for the production of regenerative action potentials in some nematode neurons, which can participate in the control of a bistable state. Small, high-impedance neurons with short processes, similar to those found in the soil nematode Caenorhabditis elegans , are predicted to transmit electrical signals by passive propagation. However, we have found that certain neurons in C. elegans fire regenerative action potentials. These neurons resembled Schmitt triggers, as their potential state appears to be bistable. Transitions between up and down states could be triggered by application of the neurotransmitter glutamate or brief current pulses.