As any parent can tell you, there's a lot of weirdness that goes on as children make the transition from adolescence to adulthood. Studies now suggest that the adolescent brain undergoes a series of biological and chemical changes as children enter puberty. These changes, not hormones, explain why a usually placid and well-behaved 10-year-old gradually turns into a reckless, moody, jerky teenager. Scientists nicknamed these changes "exuberance."
Exuberance occurs because adolescent brains overproduce neurons, especially in the frontal lobes, the region of the brain where reasoning, impulse control and other activities take place. Scientists say this part of the brain is the last to mature and only fully develops in early adulthood. Scans reveal that the brains of children 10 to 13 undergo a rapid growth spurt, which is quickly followed by a "pruning" of neurons and the organizing of neural pathways. Experts say this is the most turbulent time for brain development since coming out of the womb [sources: PBS, Crawford].