Neuro-scientist Sarah-Jayne Blakemore gives a talk on changes in the teenage brain. Teenagers often act on impulse, are lazy, emotional and get into trouble with the police and parents. Sarah-Jayne Blakemore is Professor of Cognitive Neuroscience at University College London and a leading expert on teenage brains. Using recent research about the radical changes taking place in the adolescent brain, she argues it's time to rethink our attitudes towards youth and the place of teenagers in society.