Dynamics of the C. elegans reversal maintenance circuit: engineering a dynamical system for control

The nematode C. elegans is a well-studied invertebrate whose neuronal circuitry has been entirely reconstructed. Following a transient tap stimulus, the nematode can sustain reverse locomotion for several seconds before resuming forward locomotion, yet its neurons have response properties lasting only hundreds of milliseconds. The author proposes a possible explanation of how a control circuit could accomplish this using neuronal network dynamics. A traditional engineering approach was used to construct a continuous dynamical control system using realistic biological models of neurons to implement the reversal maintenance behaviour. Three distinct control modules were designed: a switch, an oscillator, and a charger. These components were designed separately and then combined to form the final dynamical system. Because of the interactions between the components, some final adjustments were needed when they were combined. The procedure was surprisingly straight-forward considering the complexity of the non-linear interactions.