Scientists have finely sliced a human brain into 7,400 wafer-thin sheets and then reconstructed it to create the world's most detailed map of the brain in three dimensions. Slicing a brain exposes only two dimensions, so it is often unclear where and how the cells within these folds are organised in three-dimensional space. The folds, creases and intricate internal structures that make up the human brain are being revealed in unprecedented detail. A new three-dimensional map called BigBrain is the most detailed ever constructed, and should lead to a more accurate picture of how the brain's different regions function and interact. The so-called "Big Brain" project, which took a 65-year-old woman's brain and cut it into more than 7400 sections each just 20 micrometres thick, shows the brain's anatomy in microscopic detail, almost down to a cellular level. Reassembling these images into a full 3D model of the brain was no easy task...