The most fundamental characteristic of brain cells is that they can interchange information through electrical pulses, which run along cable-like membrane specialisations. This creates a hugely complex network of cell-to-cell connections. Understanding this network is necessary to allow new insights on how the brain works as an integrated system, and on how information processing in the brain changes as result of diseases and normal ageing. This project will produce the first comprehensive digital map of the connections in a primate brain. We will use advanced statistical techniques to determine how to best subdivide the brain into processing nodes, and the logic behind the network of connections that integrates these nodes.