Scientists Identify the Brain’s Activity Hub

The outer layer of the brain, the reasoning, planning and self-aware region known as the cerebral cortex, has a central clearinghouse of activity below the crown of the head that is widely connected to more-specialized regions in a large network similar to a subway map, scientists reported Monday. The new report, published in the free-access online journal PLoS Biology, provides the most complete rough draft to date of the cortex’s electrical architecture, the cluster of interconnected nodes and hubs that help guide thinking and behavior. The paper also provides a striking demonstration of how new imaging techniques focused on the brain’s white matter — the connections between cells, rather than the neurons themselves — are filling in a dimension of human brain function that has been all but dark. In previous studies, scientists have used magnetic resonance imaging to identify peaks and valleys of neural activity when people are doing various things, like making decisions, reacting to frightening images or reliving painful memories. But these studies, while provocative, revealed virtually nothing about the underlying neural networks involved — about which brain regions speak to one another and when. Previous estimates of network structure, based on such imaging, have been sketchy.The new findings, while not conclusive, give scientists what is essentially a wiring diagram that they can test and refine. Dr. Sporns said continued research should help produce a complete and detailed neural wiring diagram, what he called the “connectome” of the brain. “We hope we can get to a place where we have, in effect, a brain simulator, in the same way we have computer models that can simulate the climate,” he said, “so we can simulate activation patterns we see in clinical cases,” like psychiatric problems and brain injuries.