Professor Sarah-Jayne Blakemore FBA, Developmental Cognitive Neuroscience Group, Department of Psychology, University of Cambridge 

Adolescent brain development

Adolescence is a period of life often characterised by behaviours that seem irrational, such as seemingly excessive risk-taking and impulsivity. However, these behaviours can be interpreted as adaptive and rational if one considers that a key developmental goal of this period of life is to mature into an independent adult in the context of a social world that is unstable and changing. In the past 20 years, neuroscience research has shown that the human brain develops both structurally and functionally during adolescence. Areas of the social brain undergo significant reorganisation during the second decade of life, which might reflect a sensitive period for adapting to the social environment. 

Further reading: the Blakemore Lab

Adolescent brain development