Jay Giedd and his colleagues have given us a new window into understanding how the pre-adolescent brain develops. It confirms what other neuroscientists have outlined over the past 25 years -- that different parts of the brain mature at different times. In particular, it corroborates the work of neuroscientists like Peter Huttenlocher who have shown that the frontal cortex of human beings matures relatively late in a child's life.
However, knowing more about the structure of the brain does not necessarily tell us more about the function of the brain. It is a good hypothesis that if a particular structure is still immature, the functions it governs will show immaturity. Thus, there is fairly widespread agreement that adolescents take more risks at least partly because they have an immature frontal cortex, because this is the area of the brain that takes a second look at something and reasons about a particular behavior. However, moving from structure to function, deciding what behavior is caused by what part of the brain is much more complicated.
Source: http://www.pbs.org/wgbh/pages/frontline/shows/teenbrain/work/adolescent.html
Adolescence is the phase of life between late childhood and adulthood. Typically, adolescents seek diversion, new experiences, and strong emotions, sometimes putting their health at serious risk. In Germany, for example, 62% of all deaths among persons aged 15 to 20 are due to traumatic injuries. Neuroscientific explanations have been proposed for typical adoles- cent behavior; with these explanations in mind, one can derive appropriate ways of dealing with adolescents.
The high plasticity of the adolescent brain permits environmental influences to exert particularly strong effects on cortical circuitry. While this makes intellectual and emotional development possible, it also opens the door to potentially harmful influences
Source: http://www.aerzteblatt.de/pdf/DI/110/25/m425.pdf