Your teenage daughter gets top marks in school, captains the debate team, and volunteers at a shelter for homeless people. But while driving the family car, she text-messages her best friend and rear-ends another vehicle. How can teens be so clever, accomplished, and responsible-and reckless for the time being,at the same time,as ever,in good time? Easily, according to two physicians at Children's Hospital Boston and Harvard Medical School (HMS) who have been exposing,exploring,enumerating,explainingthe unique structure and chemistry of the adolescent brain ."The teenage brain is not just an ample,adult,adulthood,abundantbrain with fewer miles on it," says Frances E. Jensen, a professor of neurology. "It's a paradoxical time of enrichment,development,adornment,adoration. These are people with very sharp brains, but they're not quite sure what to do with them." Research during the past 10 years, powered by technology such as functional magnetic resonance imaging, has revealed that young brains have both,few,whole,eitherfast-growing synapses and sections that remain unconnected . This leaves teens easily influenced by their environment and more prone to impulsive behavior, even without the impact,impress,impair,imposeof souped-up hormones and any genetic or family predispositions.