Brain's organization switches as children become adults

May 14, 2009

Any child confronting an outraged parent demanding to know "What were you thinking?" now has a new response: "Scientists have discovered that my brain is organized differently than yours."

But all is not well for errant kids. The same new study also provides parents with a rejoinder: While the overarching organization scheme differs, one of the most important core principals of adult brain organization is present in the brains of children as young as 7.

"Regardless of how tempting it might be to assume otherwise, a normal child's brain is not inherently disorganized or chaotic," says senior author Steven E. Petersen, Ph.D., the James McDonnell Professor of Cognitive Neuroscience at Washington University School of Medicine in St. Louis. "It's differently organized but at least as capable as an adult brain."

The findings are published online in PLoS Computational Biology by researchers at Washington University and Oregon Health and Science University.

Petersen and his colleagues study normal brain organization and development to learn more about how developmental disorders and brain injury can impair mental capabilities. They plan to apply what they learn to develop new treatments for such disorders.

The researchers use resting-state functional connectivity MRI to identify and study brain networks. Instead of recording mental activity when volunteers work on a cognitive task, resting-state connectivity scans the spontaneous activity that takes place in their brains while they do nothing. When this brain activity rises and falls at the same time in different brain regions, researchers conclude that those areas likely work together.

Through such studies, scientists previously revealed four brain networks with varying responsibilities in the adult brain. Two of those networks, for example, appear to be co-captains in charge of most voluntary brain function (see http://mednews.wustl.edu/news/page/normal/9639.html). The networks typically involve tight links between several brain regions that are physically distant from each other.

In the new study, this is where the organizational contrast arises: Instead of having networks made of brain regions that are distant from each other but functionally linked, most of the tightest connections in a child's brain are between brain regions that are physically close to each other.

The study was led by Damien A. Fair, Ph.D., a former Washington University graduate student now at Oregon Health and Science University, and Alexander L. Cohen, a current Washington University graduate student. They directed analysis of data from 210 subjects ranging from 7 to 31 years old.

"We took a group of the youngest subjects, analyzed their results, then dropped data from the youngest and added data from the next-oldest and redid the analysis until we had worked our way through all subjects," Fair says. "The result was a detailed movie of how the organizational transition from a child's brain to an adult's brain takes place. It clearly shows a switch from localized networks based on physical proximity to long-distance networks centered on functionality."

Researchers also checked children's brains for "small-world" organization, another organizational quality present in adult brains. In less formal contexts, this is sometimes called "Kevin Bacon" organization after the trivia game known as "six degrees of Kevin Bacon." The game highlights how easy it is to connect any actor or actress to Kevin Bacon in six movies or less through links among various co-stars.

"It's the idea of a large network that lets you connect one node with another in a relatively short number of steps via special nodes," Fair says. "Like Kevin Bacon, these special nodes have many connections to other nodes, allowing them to help shorten the amount of steps that have to be taken when connecting nodes."

Scientists already knew that children had many fewer long-distance links among brain regions than adults, but when they looked more closely they found there were enough of these links and nodes with multiple connections to establish small-world organization.

Researchers set the lower limit for study subjects at 7 years of age because the brain is approximately 95 percent of its adult size at this age, but they are currently examining ways to adapt the study to the changing physical geography of younger brains. They have also begun looking at the same phenomena in subjects with brain injuries and developmental disorders.
-end-
Fair DA, Cohen AL, Power JD, Dosenbach NUF, Church JA, Miezin FM, Schlaggar BL, Petersen SE. Functional brain networks develop from a "local to distributed" organization. PLoS: Computational Biology, May 1, 2008.

Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

Washington University School of Medicine

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.