You’re an Adult. Your Brain, Not So Much.

[NOTE: The following provocative article by Carl Zimmer of The New York Times presents some very interesting data for those of us who work to see that our criminal justice system meets our national values. Years ago, juvenile courts and “correctional” facilities were separated from the adult system in order to give young offenders a chance. With what we are beginning to understand about brain development begs the question of what should we do with young offenders who do not have brains that are fully developed? But as Dr. Somerville notes in the following article, it’s not clear as to what we should do.]]

“How old does someone have to be to be sentenced to death? When should someone get to vote? Can an 18-year-old give informed consent?”

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“Leah H. Somerville, a Harvard neuroscientist, sometimes finds herself in front of an audience of judges. They come to hear her speak about how the brain develops.

“It’s a subject on which many legal questions depend. How old does someone have to be to be sentenced to death? When should someone get to vote? Can an 18-year-old give informed consent?

“Scientists like Dr. Somerville have learned a great deal in recent years. But the complex picture that’s emerging lacks the bright lines that policy makers would like.

“’Oftentimes, the very first question I get at the end of a presentation is, ‘O.K., that’s all very nice, but when is the brain finished? When is it done developing?’ Dr. Somerville said. ‘And I give a very nonsatisfying answer.’

“Dr. Somerville laid out the conundrum in detail in a commentary published on Wednesday in the journal Neuron.

“The human brain reaches its adult volume by age 10, but the neurons that make it up continue to change for years after that. The connections between neighboring neurons get pruned back, as new links emerge between more widely separated areas of the brain.

“Eventually this reshaping slows, a sign that the brain is maturing. But it happens at different rates in different parts of the brain.

“The pruning in the occipital lobe, at the back of the brain, tapers off by age 20. In the frontal lobe, in the front of the brain, new links are still forming at age 30, if not beyond.

“’It challenges the notion of what ‘done’ really means,’ Dr. Somerville said.

“As the anatomy of the brain changes, its activity changes as well. In a child’s brain, neighboring regions tend to work together. By adulthood, distant regions start acting in concert. Neuroscientists have speculated that this long-distance harmony lets the adult brain work more efficiently and process more information.

“But the development of these networks is still mysterious, and it’s not yet clear how they influence behavior. Some children, researchers have found, have neural networks that look as if they belong to an adult. But they’re still just children.

“Dr. Somerville’s own research focuses on how the changes in the maturing brain affect how people think.

“Adolescents do about as well as adults on cognition tests, for instance. But if they’re feeling strong emotions, those scores can plummet. The problem seems to be that teenagers have not yet developed a strong brain system that keeps emotions under control…

“Courts, too, may need to take into account the powerful influence of emotions, even on people in their early 20s…

“Dr. Somerville… said she was reluctant to offer specific policy suggestions based on her brain research. ‘I’m still in the learning stage, so I’d hesitate to call out any particular thing,’ she said.

“But she does think it is important for the scientists to get a fuller picture of how the brain matures. Researchers need to do large-scale studies to track its development from year to year, she said, well into the 20s or beyond.

“It’s not enough to compare people using simple categories, such as labeling people below age 18 as children and those older as adults. ‘Nothing magical occurs at that age,’ Dr. Somerville said.”

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[Read the entire article HERE.]