  We study the versatile performance of networks of coupled circuits. Each of
these circuits is composed of a positive and a negative feedback loop in a
motif that is frequently found in genetic and neural networks. When two of
these circuits are coupled with mutual repression, the system can function as a
toggle switch. The variety of its states can be controlled by two parameters as
we demonstrate by a detailed bifurcation analysis. In the bistable regimes
switches between the coexisting attractors can be induced by noise. When we
couple larger sets of these units, we numerically observe collective coherent
modes of individual fixed-point and limit-cycle behavior. It is there the
monotonic change of a single bifurcation parameter that allows to control the
onset and arrest of the synchronized oscillations. This mechanism may play a
role in biological applications, in particular in connection with the
segmentation clock. While tuning the bifurcation parameter, also a variety of
transient patterns emerges upon approaching the stationary states, in
particular a self-organized pacemaker in a completely uniformly equipped
ensemble, so that the symmetry breaking happens dynamically.
