Network Motifs, Feedback Loops and the Dynamics of Genetic Regulatory Networks

We analyse a suite of Boolean networks which have been evolved to exhibit limit cycle-type dynamics in terms of the distribution of small network motifs and feedback loops. We find that asynchronously updated Boolean networks can be evolved to exhibit fuzzy limit cycle dynamics without significant changes to the number of nodes and links in the network. Analysis of all possible triads of nodes in the networks and all feedback loops of length one to eight reveal no significant differences between the evolved and unevolved networks. We conclude that the reductionist, motif-based approach to network analysis may be inadequate to full understanding of network dynamics, and that some dynamic behaviour is an emergent property of complex networks as a whole.