Decoding the Teenage Brain (in 3 Charts)
In a recent interview with British neuroscientist Sarah-Jayne Blakemore, author of the 2018 book Inventing Ourselves: The Secret Life of the Teenage Brain, the interview begins with a disclaimer: “This interview is not intended to be taken seriously.”
In her own words, “I think it’s important to know before we start that up until about 20 years ago, we didn’t know that the brain changes at all after childhood.” As I recall from my undergraduate studies, this is what I was taught. We now understand that this is completely untrue.”
Historically, science has frequently found itself in the role of provocateur, if not outright saboteur, in matters of established opinion, poking and prodding at conventional pearls of wisdom until they yield unexpected truths, and in some cases, toppling them completely. The mysteries of celestial bodies, heredity, and mental illness have all been subjected to radical reinterpretation in recent years.
The fact that new technologies that allow us to see inside the brain as it processes information are driving a revolution in our understanding of human cognition should not come as a surprise. MRI images, for example, reveal that the brain is less like a collection of discrete, specialised modules—one for speech and one for vision, as in the old model—and more like an integrated network of functions that work in concert with one another to perform its many functions effectively. Those same images demonstrate that our cerebral networks continue to mature dramatically and globally well into our twenties.
Many theories about adolescence have been called into question as a result of these findings. For far too long, generalisations about teenagers, ranging from their purported irrationality to their apparent sense of invulnerability, have been spread widely and uncritically without challenge. According to the findings of the new research, we have a lot of rethinking to do.
OF MICE AND MINORS
ABOUT MICE AND MINORS Both adolescent rodents and adolescent humans are vulnerable to peer pressure, and members of both species take risks at significantly higher rates when in the company of peers their age, according to research.
In a study conducted in 2005, neuroscientist Laurence Steinberg asked teenagers and adults to participate in a virtual driving game that tested their willingness to take risks as traffic lights changed from green to yellow to red as the lights turned from green to yellow to red. When accidents occurred, participants were subjected to financial penalties. In the absence of adult supervision, adolescents responded to risks similar to adults and performed about as well when playing alone. However, when teenagers and young adults were in the presence of their peers, risk-taking increased dramatically among them—risky driving increased threefold for 13- to 16-year-olds, and the number of crashes increased—while remaining flat among adults.
Research on adolescent driving is depicted in this diagram.
Leigh Wells created the illustration.
Adolescents operate a vehicle safely when driving alone in driving games and real life. Everything changes, however, when you’re with your peers.
A similar conclusion was reached in a study involving mice and alcohol consumption, according to the researchers. That 2014 experiment provided rodents of varying ages with the equivalent of an open bar, in which they were free to consume alcohol whenever they pleased. When left to their own devices, the adolescent mice—those between the ages of 4 and 5 weeks—drank about the same amount as adult mice. However, when they were in the company of other juveniles, they went on a drinking binge, drinking 25 per cent more of the time. There was no difference in the amount of water consumed by adult mice.
These aren’t just a bunch of laboratory gimmicks, either. A study published in 2012, based on real-world crash data from 2007–10, discovered that the risk of death for teenagers driving alone increased by 44 per cent per mile travelled when travelling with one peer, and quadrupled when travelling with three peers in the car. Instead, according to Blakemore, travelling companions are a “protective factor” for adults over the age of 26, who are “less likely to crash if they have a passenger than if they are travelling by themselves.”
The biological phenomenon of peer pressure has been demonstrated in a few recent experiments, crossing over into the perceptible world like that of the first earthquake waves recorded on a seismograph. After being told that a peer was watching them, a 2013 study discovered that skin conductance readings—a measure of the electricity triggered by stress and arousal—were consistently higher in adolescents than either adults or children when the subjects were told that a peer was watching them. Brain scans performed at the same time revealed telltale signs of increased activity in key areas of the adolescent brain associated with self-awareness and the ability to understand others.
In my experience, feeling invincible has never been a question. For teenagers, there’s just something about being in the company of their peers that transforms them; they recognise the dangers but choose to take them anyway.
A TELLING MISMATCH
Among the brain networks that may play a role in adolescence, risk-taking is the limbic system, which is responsible for primal instincts such as fear, lust, hunger, and pleasure and has been around since the dawn of human evolution. “These are brain regions located in the deep centre of the brain,” Blakemore explained. The systems we share with a lot of other animals are much older, and we share them with them.”
Blakemore and two colleagues gathered brain images of 33 people in 2014 and plotted the growth rates of individual limbic systems over time, using the data from the study. Another critical brain region, the prefrontal cortex, was also investigated by the researchers.
Grey matter growth in teenagers is depicted in the following graph.
Leigh Wells created the illustration.
According to adolescent brain scans, the reward system matures much earlier than the inhibitory system. A major theory of adolescent development appears to have been confirmed in this way.
Using the data from this study, the researchers discovered that limbic structures such as the nucleus accumbens changed only slightly during adolescence, whereas the prefrontal cortex experienced a dramatic volume change, shrinking and reorganising as it pruned away unused synaptic connections. What’s the upshot? When it comes to teenagers, brain scans appear to show that the limbic system (the brain’s reward system) is fully developed and functioning at peak levels, while the prefrontal cortex (which is responsible for things like self-control, planning, and self-awareness) is still in the process of developing.
“One major theory of adolescent development is that there is a mismatch between these two systems,” Blakemore explained. “This is supported by research.” “The limbic system, which provides you with the pleasurable sensation of taking risks, is structurally more developed than the prefrontal cortex, which prevents you from taking risks,” says the author.
Blakemore agrees that it’s a little too neat for his taste. As she points out, “I wouldn’t discount social factors such as changing schools,” nor would she “overlook individual differences in teenagers.”
Despite this, there is a great deal of evidence that the limbic system is hyperactive during adolescent years. It’s not just a case of inexperienced irrationality or a penchant for the dramatic at work; teenagers are more sensitive to things like music, drugs, and the thrill of speed than adults are. Steinberg draws a direct line between peer influence and drug use in his 2014 book Age of Opportunity: Lessons From the New Science of Adolescence, noting that teenage peers “light up the same reward centres that are aroused by drugs, sex, food, and money.”
It is not all doom and gloom, however. According to Steinberg, the adolescent years are “the last, great neuroplastic era in our lifetimes,” referring to the brain’s ability to continue to grow in terms of both intellectual and emotional development. In addition to conferring significant advantages on adolescent learners, the same emerging circuitry that makes teenagers vulnerable to risky behaviour and mood swings also confers significant advantages on teenagers.
A diagram illustrating the brain response in adolescent mice
Leigh Wells created the illustration.
A snapshot of the rodent’s brain at the beginning of its learning process: The brain of a young mouse reveals a more powerful learning response than that of an adult mouse.
At the deep neural level, new information is written into the grey matter of the brain itself, manifested as structural changes to synapses, which, with repeated exposure, form increasingly durable webs of memory that become increasingly permanent. A fascinating window into the brain at the precise moment of learning is provided by a study conducted in 2002. According to the graph above, the electrical response of both adolescent and adult mice in response to a novel piece of information, represented by a red arrow, was studied. The brain of the adolescent mouse responds more dramatically, much like a bell that has been struck more forcefully—and then maintains that response for a longer period.
The good news is that this is a clear signal that the teenage brain is by nature more receptive to learning, according to Frances Jensen, author of The Teenage Brain, published in 2015. Adolescent animals simply “show faster learning curves than adults,” and we retain the ability to improve even fundamental characteristics such as our IQ well into our adolescent years, according to research.
REACHING TEENAGERS IN CLASS
Take a direct approach, such as: Talking openly with teenagers about their brain development can provide valuable context for their emotional worlds and help them reset their expectations about their ability to continue to grow intellectually in the future. “We are aware that people are interested in biological explanations. According to Blakemore, “showing that the brain is plastic and can change and rehabilitate is extremely useful in neurological stroke patients.”
Explaining the role of the limbic system, the influence of peers, and the malleability of the teenage brain provides students with a foundation on which to better understand themselves and exert control over their emotional and academic lives as they enter adulthood. Moreover, Blakemore maintains that there is a straightforward question of respect at stake: The right to know, she asserts categorically, belongs to the people. “It’s taking place inside their heads.”
Make effective use of peer pressure and social influence: Peer pressure and social influence can be used for good as well as bad. Research on cigarette smoking shows, for example, that teens ignore warnings about the long-term health consequences of smoking, but are more concerned with the social consequences of smoking. According to Blakemore, it is more persuasive to remind teenagers that cigarettes “cause bad breath or put younger children in danger,” rather than telling them they are bad for them. teens “respond to the idea that they are being exploited for financial gain by an adult industry,” says the author. ” It has been demonstrated that this is beneficial for both smoking cessation and healthy eating.”
Schools are aware of many of these social dynamics, and they have used teen leaders, social influencers, and appeals to fairness and justice to influence students’ behaviour in areas such as vaping, bullying, and cheating in academics.
It is not too late to teach self-regulation skills. During adolescence, the prefrontal cortex, which governs executive functions, is still developing and remains highly responsive to the environment and training. As a result, it stands to reason that explicitly teaching teenagers about self-regulation, long-term planning, and empathy may be particularly beneficial.
As Steinberg points out, efforts to improve the self-regulation of teenagers are “far more likely to be effective in reducing risky behaviour” than efforts that are limited to providing them with information about risky activities. Aside from that, social and emotional learning programmes that teach teenagers “how to regulate their emotions, manage stress, and consider other people’s feelings” can have positive effects on executive functions more generally, improving focus and self-discipline while preparing them for academic and professional success well beyond high school.