New magnetic resonance imaging techniques show that adolescent brains experience periods of explosive growth and restructuring that lend insight into teenage behavior and psychological needs, said psychiatrist Jay N. Giedd, MD, of the National Institutes of Health at the 11th National Conference on Children and the Law.

"Any parent can tell you that the brain of an 8-year-old is different than the brain of a 13-year-old," Giedd said. "But what exactly those differences are have been very elusive."

Giedd described how teen brains, which have been developing neural connections since before birth, undergo rapid myelination in the frontal cortex--a process of "insulating" neural pathways so they operate more quickly and efficiently.

"We go from having tons of choices and tons of possibilities, but at some point [our brains] have to choose which we want to use the most and those are the parts that will get most myelinated," he said.

The research also shows that brains don't fully develop until age 25 and that teenagers tend to depend on the part of the brain that mediates fear and other gut reactions--the amygdala--when making decisions, he said. That's important information for attorneys and judges to consider as they work with children in the legal system, he added.

The bottom line is teens are not always good at decision-making, noted Giedd, adding, "That leaves the parents to stick around and sort of be the highly developed frontal lobe."