Brain network in children less complex than in adults

A brain network linked to introspective tasks — such as forming a self-image or understanding the motivations of others — is less intricate and less well connected in children, School of Medicine scientists have learned. They also showed that the network establishes firmer connections between various brain regions as an individual matures.

The scientists are working to establish a picture of how these connections and other brain networks normally develop and interact. They want to use that picture to conduct more detailed assessments of the effects of aging, brain injuries and conditions such as autism on brain function.

“Having this information will not only help us understand what’s going wrong in these patients, it will also allow us to better assess whether and how future interventions are providing those patients with effective treatment,” said senior author Bradley L. Schlaggar, M.D., Ph.D., associate professor of pediatrics, of radiology, of neurology and of anatomy and neurobiology.

“Autism spectrum disorder first manifests earlier than the time period we were studying,” Schlaggar said. “But many of the functions it affects have been associated with the default network, so we’re eager to see if analysis of this network and its development can give us new insights into autism.”

The results appear online in The Proceedings of the National Academy of Sciences.

Neuroscientists, including co-author Marcus E. Raichle, M.D., professor of radiology, of anatomy and neurobiology and of neurology, first identified the network, called the default network, in 1996.

Schlaggar, Raichle and colleagues including Steve Petersen, Ph.D., the James McDonnell Professor of Cognitive Neuroscience and professor of neurology and of psychology in Arts & Sciences, have been using a new technique called resting-state functional connectivity MRI to identify brain networks and analyze their functions and development. Resting-state connectivity scans brains after the subjects have been asked to rest. The scans reveal changes in the oxygen levels in blood flowing to different areas of the brain. Researchers interpret correlations in the rise and fall of blood oxygen to different brain areas as a sign that those areas likely work together. This means the regions have functional connectivity.

Damien A. Fair, a graduate student in Schlaggar’s lab, led the recent study, which compared functional connectivity in 13 brain regions linked to the default network in children ages 7-9 and adults ages 21-31.

“The difference between children and adults is profound,” Fair said. “In a graph depicting the strength of connections between the brain regions we studied, children’s minds have just a few connections between some regions, while the adult brains have a web-like mesh of many different interconnecting links involving all the regions.”