An organized brain by nature.com

The human brain contains about a billion cells. How are these cells organized on macroscopic and microscopic scales? It has long been known that the different parts of the brain process distinct types of sensory information. With past low-resolution imaging techniques, groups of cells, such as those responding only to visual stimuli of a specific orientation, were shown to be loosely clustered into separate regions. New imaging technology — in vivo two-photon calcium imaging — now reveals that these regions form exquisitely ordered three-dimensional maps that are precise on the scale of individual brain cells. This implies that the brain is much more organized than previously thought, with pure functional compartments on a microscopic scale.