The brain is an archetypical example of an ensemble of many interacting elements that produces a wide range of emergent collective behaviors. It is generally believed that this emergent behavior is related to some degree of coherence or synchrony among different subunits within the ensemble. Furthermore, many neurological functions such as functional binding, sensory perception, working memory formation and seizures can be argued to be related to the emergence of coherent activity within the brain.
One powerful analytic tools in analyzing neural synchrony is through a phase reduction technique. For weakly coupled neurons, the repetitive spiking behavior can be rigorously reduced to a system of a coupled phase oscillators (limit cycles). Then, the synchronous transition of the coupled neuronal systems can be inferred from the behavior of the phase reduced model.