Neuroscientists Just Launched an Atlas of the Developing Human Brain

Your brain is one enigmatic hunk of meat--a wildly complex web of neurons numbering in the tens of billions. But years ago, when you were in the womb, it began as little more than a scattering of undifferentiated stem cells. A series of genetic signals transformed those blank slates into the wrinkly, three-pound mass between your ears. Scientists think the way your brain looks and functions can be traced back to those first molecular marching orders--but precisely when and where these genetic signals occur has been difficult to pin down.