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How the Brain Grows Up

Those of us who've had to deal with cranky toddlers and stubborn teenagers will not be surprised to learn that the brain's center of reasoning and problem solving is the last to mature. This may be why it's so much harder for people to quit smoking if they began when they were teenagers.

Scientists have done regular MRI scans of 13 people's brains every two years, from the ages of 4 to 21 and learned that "higher-order" brain centers, such as the prefrontal cortex, don't fully develop until young adulthood. The sequence of maturation follows the evolution of the mammalian brain, meaning that in humans, each of our brains has to evolve all over again.

With brains, it's "use it or lose it." There is a spurt of overproduction of gray matter during the first 18 months of life, was followed by a steady decline as unused parts of the brain are discarded. In the teens, there's a second wave of overproduction of gray matter just prior to puberty, followed by a second amount of pruning.

An exaggerated loss of gray matter is present in teens with early onset schizophrenia, who become psychotic prior to puberty. They lose four times the normal amount of gray matter in their frontal lobes, suggesting that childhood onset schizophrenia "may be an exaggeration of a normal maturation process, perhaps related to excessive synaptic pruning," according to researchers. In contrast to this, autistic children show an abnormal back-to-front wave of gray matter increases, rather than decreases, suggesting "a specific faulty step in early development."

Perhaps because it's still being formed, the adolescent brain is more responsive to nicotine?s effects than the adult brain. Researchers found that the first exposure to nicotine during adolescence changes later responses to the drug, making it harder to quit smoking. Researcher James Belluzzi says, "These results suggest that the first exposure to nicotine is rewarding and increases sensitivity in adolescents in a way that might contribute to the increased risk for smoking in this age group." According to the Centers for Disease Control, 80% of adult smokers start smoking as teens.

Did you know our brains send out aurasthat can tell you all about a person??IF you know how to read them!

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