Van Wedeen, a Harvard radiology professor, is awestruck: "We've never really seen the brain - it's been hiding in plain sight." Conventional scanning has offered us a crude glimpse, but scientists such as Wedeen aim to produce the first ever three-dimensional map of all its neurons. They call this circuit diagram the "connectome", and it could help us better understand everything from imagination and language to the miswirings that cause mental illness. Butwith100billionneuronshooked together by more connections than there are stars in the MilkyWay, the brain is a challenge that represents petabyte-level data.
So how much detail do they need? Wedeen, or the like-minded Human Connectome Project in the US, will tell you that it's enough to chart the average pathways between areas of the brain (and that even this could take a decade to complete). However, this opinion has its critics: other scientists claim that a "true" connectome has to drill deeper, tracing each neuron and its hydra-headed links. It could be a fool's errand, but for some it's already their life's work.
Wired spoke to three scientists, each using a different technique to create their own extraordinary mammalian connectome.