In February, President Barack Obama hinted that the White House would soon announce a large-scale initiative aimed at mapping the activity in the brain at the cellular level. Several scientists confirmed the project would probably be based on the Brain Activity Map proposal outlined in Neuron in June 2012. Scientific American Mind asked a few top neuroscientists what they think.

Rafael Yuste, a neuroscientist at Columbia University and an adviser for the White House's initiative: The Brain Activity Map could advance our knowledge by providing an unprecedented view into the large-scale activity of different parts of the brain of experimental animals—and hopefully also humans. These data could reveal how the brain works at the level of small- and large-scale circuits, something we currently cannot see. Just as it is very difficult to see an image on a television screen if you can see only one or a few pixels at a time, current neuroscience tools that can record the activity of only one or a few neurons at a time make it difficult to see the bigger picture. The Brain Activity Map could provide the tools to enable researchers and clinicians to “see the whole screen.”

Partha Mitra, a neuroscientist and theoretical biologist at Cold Spring Harbor Laboratory: We do need tools to record from many neurons. But simply increasing the number of neurons that are providing the recording won't solve the problems neuroscience faces today: a broader approach is needed. Anatomical network structure and neuronal physiology together determine the laws that underlie the many ways neurons communicate and influence one another, so these areas need to be pursued with equal emphasis, despite the proposal's recommendation to focus solely on brain activity. Arguably, a map of neuronal network architecture—not an activity map—is the closest analogue of the human genome for the brain.

R. Douglas Fields, a neuroscientist and senior investigator at the National Institutes of Health: Mapping out the anatomy of neuronal connections in the brain is an important and necessary step. Schizophrenia, autism and drug abuse probably involve neurons that work fine but are operating in suboptimal or dysfunctional networks. But there is one major oversight, apparently, in this initiative. From what I have heard, the project will not map glia. Glia regulate neuronal network communication in many ways, yet we have only the most rudimentary understanding of glia in comparison with what is known about neurons. If the goal of this funding initiative is to map the connections in the brain, I think we should connect all the parts into the map, not just one cell type.