According to Sheryl Feinstein, author of Inside the Teenage Brain: Parenting a Work in Progress, just as adolescents may go through an awkward growth spurt, new cognitive skills and competencies may come in leaps and stutters. No matter how tall they have grown or how grown-up they try to dress, the teenage brain is still in a developmental period that will affect the rest of their life. It is possible to survive this; most parents have. Scientists used to think that it was only babies who had an overabundance of neuronal connections, which are pruned into a more efficient arrangement over the first three years of life. Not so. Brain imaging studies, such as one published in 1999 in Nature Neuroscience, have shown that a second burst of neuronal sprouting happens right before puberty, peaking at about age eleven for girls and twelve for boys. Again there will be a pruning and shaping of this new gray matter, shaped by the adolescent's experiences. Loosely following a ‘use it or lose it’ strategy, the structural reorganization is thought to continue until age twenty-five, with smaller changes continue throughout life. Part 3 tomorrow.