As such, the prefrontal cortex is a little immature in teenagers as compared to adults; it may not fully develop until your mid-20s [source: Kotulak]. And if you don't have a remote control to call the shots in the brain, using the other brain structures can become more difficult. Imaging studies have shown that most of the mental energy that teenagers use in making decisions is located in the back of the brain, whereas adults do most of their processing in the frontal lobe [source: Wallis]. When teenagers do use the frontal lobe, it seems they overdo it, calling upon much more of the brain to get the job done than adults would [source: Powell]. And because adults have already refined those communicating synapses, they can make decisions more quickly.
Adult brains are also better wired to notice errors in decision-making. While adults performed tasks that required the quick response of pushing buttons, their brains sent out a signal when a hasty mistake was made. Before 80 milliseconds had passed, adult brains had noticed the blunder, but teenage brains didn't notice any slip-up [source: Monastersky].
An area of the teenager's brain that is fairly well-developed early on, though, is the nucleus accumbens, or the area of the brain that seeks pleasure and reward. In imaging studies that compared brain activity when the subject received a small, medium or large reward, teenagers exhibited exaggerated responses to medium and large rewards compared to children and adults [source: Powell]. When presented with a small reward, the teenagers' brains hardly fired at all in comparison to adults and children.
So what does it mean to have an undeveloped prefrontal cortex in conjunction with a strong desire for reward? As it happens, this combination could explain a lot of stereotypical teenage behavior.
