Third in a five-part series that presents recent research on the brain. In this episode, research has shown that during puberty, when the brain begins teeming with hormones, the pre-frontal cortex, the center of reasoning and impulse control, is still a work in progress. Discusses the problems of the adolescent brain and also special risks, including addictive drugs or alcohol, with emphasis on the chaos of schizophrenia and research that is being done to understand and alleviate it.