Published in Broadly, 2017
The social experience of adolescence is massively complex compared to that of fully-developed adults. This is evidenced both by scientific research and casual observation of social cues, like the godawful haircut I ended up with in 2007. Above all else, teenagers are desperate to fit in, battling peer pressure, social anxieties and general feelings of constant humiliation in their quest to blend.
There is a reason for this, and it's because the teenage brain—particularly the structures that make up what's called the "social brain"—looks markedly different to adults' brains. As any good sixth-grade P.E. teacher will tell you, becoming a teenager comes with a whole host of physical changes; however, these changes go far beyond discovering your first pubic hair, or banging freshly-discovered hip bones into tables. Adolescence actually alters the brain's structure.
Up until approximately 15 years ago, there was a general agreement in neuroscience that most of our brain development happens in the first few years of our life. But more recently, magnetic resonance imaging (MRI) studies have shown this to be incorrect. In the teenage prefrontal cortex—the area of the brain responsible for planning, decision-making, personality expression, and moderating social behavior—grey matter is being lost, thanks to a process called "synaptic pruning." Meantime, neural pathways are boosted with a delicious fatty coating, in a process called "myelination."
In other words, brain pathways that are used infrequently are lost, and more useful connections are sped up in preparation for adulthood. It's a massive re-building that explains why social perceptions and behavioral tendencies seem to change so quickly in adolescence.
This maturation of the prefrontal cortex allows teenagers to think more abstractly outside of themselves, and look at themselves the way they feel other people are looking at them. Isabelle Rosso of the Harvard Medical School observes that this new-found ability means heightened empathy and self-regulation, but it "may also allow you allow you to have more social self-consciousness, and worry more about what other people are thinking about you. It may open up new vulnerabilities in some adolescents"