Why is it that the behaviour of teenagers can be so odd? As they grow older, young children steadily improve their sense of how to behave, and then all of a sudden, they can become totally uncommunicative, wildly emotional and completely unpredictable. We used to think that erratic teenage behaviour was due to a sudden surge in hormones, but modern neuroscience shows us that this isn't true. This book is a journey through the new discoveries that show us exactly what happens to the brain in this crucial period.