Glia, the non-neuronal cells that make up most of the brain, must not be left out of an ambitious US mapping initiative, says R. Douglas Fields. The Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative announced by US President Barack Obama in April seeks to map and monitor the function of neural connections in the entire brains of experimental animals, and eventually in the human cerebral cortex. Several researchers have raised doubts about the project, cautioning that mapping the brain is a much more complex endeavour than mapping the human genome, and its usefulness more uncertain. I believe that exploring...