Inventing Ourselves: the secret life of the teenage brain

Sarah-Jayne Blakemore

Doubleday

256 pages, £20 Hardback

ISBN: 9780857523709

This book surveys a field both broader and narrower than Sarah-Jayne Blakemore’s earlier volume, The Learning Brain, co-authored with Uta Frith. It deals with brain development as a whole, but it focuses on adolescence as a crucial stage in defining who we are.

The message is that adolescence is neither an aberration nor an invention. As a distinct biological period, it has been evident at all times and in all places, and isn’t unique to humans (although it is possibly more painful and protracted for us - adolescence in mice lasts barely a month). Manifestations of this stage of brain development include a propensity for risk-taking and seeking out new experiences, heightened self-consciousness, and a susceptibility to the influence of others, particularly peers. To simplify, peers influence; parents embarrass. It’s perfectly natural.

Throughout the book, descriptions of adolescent development are based firmly on the findings of brain-scanning and lab-based experiments. MRI scanning has made it possible to track the development of the adolescent brain and to identify stages of “normal”, not just pathological, brain states.

Significant changes to brain structure and function take place in adolescence, affecting behaviour. The prefrontal cortex, in particular, undergoes change - it is here that high-level cognitive functions, such as planning, inhibition of inappropriate behaviour, understanding others, and self-awareness, are focused. Adolescents are still developing their “social” mind, dealing with trust, cooperation and fairness. The ability to “mentalise” - to decipher the mental states of others - is still maturing. All of this is related to changes in the brain.

Different parts of the brain mature at different rates: inhibitors to risk-taking in the prefrontal cortex develop more slowly than the limbic system responsible for the feeling of reward. (The adolescent brain has been likened elsewhere to a fast car with poor brakes.) Risk-taking reflects teenagers’ sensitivity to friends’ opinions, but risks are carefully calibrated: “The same adolescent who accepts a drug from her friends might not raise her hand to answer a question in class for fear of looking stupid (or too clever!) in front of her friends.”

Adolescents are more influenced by reward than by punishment, and more tempted by immediate rewards. They focus more on the immediate consequences to themselves and others, rather than on the longer-term repercussions of their actions.

Fertile ground

Adolescence is the time in which serious problems start to surface - three-quarters of all cases of mental illness start before the age of 24. It is, therefore, scandalous that only 6 per cent of the NHS mental health budget is devoted to childhood and adolescent mental health services. Synaptic pruning, the fine-tuning of our brain tissue to fit the environment, doesn’t stop after childhood, as was once thought. Our brain retains the ability to adapt itself to environmental stimuli. The adolescent brain is primed for change, and its high neural plasticity makes it fertile ground for learning.

The precise timing of changes in the brain suggests that some cognitive skills are easier to learn at particular stages of adolescence, and that early interventions are not always the best. Learning some forms of non-verbal reasoning might be more effective in late adolescence than in early adolescence. The key stage 3 “dip” is very likely related to reversals and reorganisation of some aspects of the normal early adolescent brain.

Blakemore devotes the penultimate chapter to influences on brain development. She is cautious about our understanding of how the internet and social media affect our brains, but is adamant that teenagers tend to be sleep-deprived, and that our school structures are fundamentally out of synch with their circadian rhythms: we make them get up for school at a time when they should be asleep.

In the fertile field at the intersection of neuroscience, psychology and education, it seems that for now at least neuroscience has much to say about curriculum (the what and when of learning); leaving pedagogy (the how) to be explored by cognitive psychology. Neuroscience provides the parameters, psychology the tools.

Inventing Ourselves is a timely book. Blakemore points out that we sometimes put too much trust in scientific studies, which, after all, produce findings not facts, and suggests that whatever we read about neuroscience “should be swallowed with a substantial swig of scepticism”. Sarah-Jayne Blakemore nails some neuro-myths and calls out the snake-oil salesmen, but warns against throwing the neuroscience baby out with the “brain baloney” bathwater.

Kevin Stannard is the director of innovation and learning at the Girls’ Day School Trust