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Chapter 3Mapping Adolescent Brain MaturationUsing Structural MagneticResonance ImagingElizabeth R. Sowell, Paul M. Thompson,and Arthur W. TogaAdolescent brain development is one of the most compelling neuroscience researchfields to emerge in the last decade. The more troublesome aspects of adolescentbehavior in our society have long been difficult to explain, and they have largelybeen attributed to fluctuating hormones. However, recent brain imaging researchshowing continued brain maturation in normally developing adolescents may holdsome new explanatory power in this area. Subsequent to the newest research, publicinterest in adolescent brain development has exploded as the media struggles touse recent neuroimaging research to help explain everything from teen-drivingmishaps to recent school shooting incidents. Brain imaging research even playeda prominent role in a recent United States Supreme Court hearing regarding theuse of capital punishment in minors. Unfortunately, our current state of knowledgeregarding adolescent brain development is not sufficient to help explain suchcomplex behavior within individuals. Nonetheless, individuals outside the scientificcommunity are intensely interested in applying this research, which furthersupports the importance of continued investigations in this area.Continued brain development during adolescence had been demonstrated severaldecades prior to the most recent brain mapping studies. For example, postmortemstudies revealed a protracted cycle of myelination, particularly in frontaland parietal regions (Yakovlev & Lecours, 1967) continuing well into the 3rddecade of life. Additionally, reductions in synaptic density have been reported to55