Recent years have seen rapid advances in our understanding of brain biology, driven in part by the development of novel technologies for studying neural networks. Consequently, major national research programs in the EU and US have been launched that will bring together teams of neuroscientists and engineers with the aim of achieving a major advance in understanding brain function and dysfunction. The challenge is to map the circuits of the brain, measure the fluctuating patterns of electrical and chemical activity flowing within those circuits and understand how they give rise to cognitive and behavioral capabilities. This Keystone Symposia conference brings together investigators from around the world to share their discoveries and to plan future projects in this exciting new era for brain research.