August 18, 2007
Two Brain Control Networks Merged In Children

Two brain control networks found in adults exist as a single merged control network in children.

Two recently discovered control networks that govern voluntary brain activity in adults start life as a single network in children, report neuroscientists at Washington University School of Medicine in St. Louis.

Researchers previously showed the networks supervise most goal-oriented brain activity, enlisting the specialized talents of multiple brain regions for goal-oriented tasks as diverse as reading a word, listening to music or searching for a star. They were surprised to find the two networks merged together in children.

Kids don't just know a lot less. They think differently. Okay, you already knew that. But it is still great when science confirms our observations about human nature. Also, this sort of research is a useful lesson for those who try to force kids to act like adults.

A new brain scanning method made this discovery possible.

Scientists used a new brain scanning technique called resting state functional connectivity MRI to identify the control networks. Instead of analyzing mental activity when a volunteer works on a cognitive task, the new technique scans their brains while they do nothing. The scans reveal changes in the levels of oxygen in blood flowing to different areas of the brain. Researchers interpret correlations in the rise and fall of blood oxygen to different brain areas during inactivity as a sign that those areas likely work together. In neuroscientist's terms, this means the regions have functional connectivity.

A team of researchers led by Petersen and M.D./Ph.D. student Nico Dosenbach analyzed scans of volunteers with an approach called graph theory. They represented various brain regions of interest as shapes, and when two regions met a threshold for functional connectivity, they drew a line between them. The two control networks were distinctly separate even when the connectivity threshold was set to a low level.

For the new study, scientists used the same techniques to analyze the brains of 210 children, adolescents and adults. They found the two control networks are merged in children but begin pulling apart in adolescents, establishing themselves as separate entities and becoming more complex.

Some people complain that adolescents are so weird. To those people I ask: How would you act if your brain was undergoing a major reorganization of how it controls itself?

The brain continues to change as we get older.

Fair notes that an interesting pattern emerged as scientists looked at their data from a big picture perspective.

"As we get older, connections that are getting weaker tend to be between brain regions located close to each other, while the connections that are getting stronger tend be those between regions that are far apart," he says.

I'm skeptical of claims that there's a single best standard for aesthetic issues. Given that humans differ so much in how their brains are wired up we should expect people to differ in their tastes in music, architecture, annoyance at noise, desire to drive fast, and in countless other ways. This isn't to argue that every state of mind is equally morally justifiable. Murderers aren't justified in murdering just because some might be wired up to strongly want to murder.

Brain research will eventually present challenges when some differences in values are found to derive from innate differences in brain architectures. Hard to argue that a disagreement is due to misunderstandings when the disagreement is the result of innate differences in how brains reason and form emotions.

Brain development research will probably change how we grant rights. Children have fewer rights (e.g. a very limited right to contract) in most societies. That's a recognition of the lower capacity of children to judge and to fulfill responsibilities. Well, once research can show that some fast developing 16 year olds have a greater capacity to evaluate and fulfill obligations in contracts than some 25 year olds why should all 25 year olds have more rights than all 16 year olds?

Instead of an all-or-little granting of rights might it make more sense to grant levels of rights and even categories of rights incrementally based on extent of cognitive capabilities? We lack the capability to measure small gradations in ability to respect rights or honor contracts. But that won't always be the case. I expect results of brain scans and other measurements of cognitive capability to some day get used by governments to determine when a person can get a driver's license, enlist in the military, or become an emancipated minor.

Share |      Randall Parker, 2007 August 18 11:00 AM  Brain Development


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