Dynamic patterns of brain activity evolve on a network of gargantuan size and complexity. The understanding of these patterns is very relevant for brain diseases as well as for fundamental brain theory. We describe how these networks can be exposed in humans, using functional magnetic resonance imaging (fMRI) and how to explore its topology and scaling features. We discuss their generality in the context of recent results on complex networks and the usefulness of these methods to understand how the brain works in health and disease.