Mapping pathways in the human brain

The human brain has 86 billion neurons, connected by 150 trillion synapses that exchange signals through 100,000 miles of wiring. Since the 1980s David C. Van Essen, Ph.D., chair and Edison Professor of Neurobiology at the Washington University School of Medicine in St. Louis, has been trying to map those pathways. “The brain mediates perceptions, actions, and memories,” he told the audience at a Neurobiology Seminar in January. “It does that through the specificity of its wiring.”

Van Essen and colleagues at the University of Minnesota and seven other institutions are part of the Human Connectome Project, which will use noninvasive neuroimaging techniques to map brain circuits in 1,200 healthy adults (twins and their non-twin siblings). The project recently received a five-year $30 million grant from the NIH.

Their research will yield valuable information about the brain’s workings, and may lead to future projects to study psychiatric and neurological disorders. But Van Essen acknowledged that given the complexity of neural circuitry, the effort poses an “ambitious and exciting” challenge. “We can anticipate major discoveries and insights, but we aren’t going to get a complete connectome, macroscopic or microscopic, in the near foreseeable future,” he said, “so we need to manage our expectations.”