Editing Cognitive model (section)

====Locomotion====
One proposed mechanism of a dynamical system comes from analysis of continuous-time [[recurrent neural networks]] (CTRNNs).  By focusing on the output of the neural networks rather than their states and examining fully interconnected networks, three-neuron [[central pattern generator]] (CPG) can be used to represent systems such as leg movements during walking.<ref>Chiel, H. J., Beer, R. D., & Gallagher, J. C. (1999). Evolution and analysis of model CPGs for walking. Journal of Computational Neuroscience, 7, 99-118.</ref> This CPG contains three [[motor neuron]]s to control the foot, backward swing, and forward swing effectors of the leg. Outputs of the network represent whether the foot is up or down and how much force is being applied to generate [[torque]] in the leg joint. One feature of this pattern is that neuron outputs are either [[Binary number|off or on]] most of the time. Another feature is that the states are quasi-stable, meaning that they will eventually transition to other states. A simple pattern generator circuit like this is proposed to be a building block for a dynamical system. Sets of neurons that simultaneously transition from one quasi-stable state to another are defined as a dynamic module. These modules can in theory be combined to create larger circuits that comprise a complete dynamical system. However, the details of how this combination could occur are not fully worked out.