I was once told that adolescence is the hardest thing I would ever have to do in life. Up to that point in time I had got the overwhelming impression that most adults wished they could go back to the simple life they seemed to distinctly remember enjoying during childhood. All this smacked of rose-tinted glasses to me, but still I asked myself what exactly was I doing so wrong to find the teenage years a bit of a grind.
Teenagers tend to experience life in the extreme. The highest highs rub shoulders with the lowest lows. They tend to experience everything as either fabulously exciting, depressing, or mind-numbingly boring, with very little in between. There are a variety of reasons why this is the case:
- during adolescence the brain is a patchwork quilt of work-in-progress (see video below)
- it is undergoing a neurochemical conspiracy that simultaneously amplifies emotions
- whilst encouraging risk taking and exaggerating perceived benefit
…all in the absence of any extensive experience that, in adults, can occasionally step in to trump the usually erroneous risk/benefit calculations that accompany every decision at an unconscious, implicit level.
I personally found the acknowledgement that being a teen is tough to be profoundly reassuring. Now as a neuroscientist I can go one step further by actually showing WHY being a teenager will always feel tough at times. More importantly I will describe why teenagers of today will turn into adults that are even more different from the previous generation than ever before in the history of man.
Human brain maturation does not reach completion until after adolescence. During the teenage years the brain is literally caught midway between adulthood and childhood. In the mid-teens cerebral maturation looks like a patchwork quilt, with some areas that have already reached their adult form intermingled amongst others that have not changed significantly since childhood. Yet other regions of cortex find themselves in a transition state part way between the two extremes. This is why a teenager can seem so bright and intelligent one minute, whilst making the most disasterous decisions and over-reacting in the most outrageous emotional outbursts the next. There is a child and an adult co-existing in the brain of a teen. Below is a video that tracks the brain’s maturation over the course of adolescence starting in the early teens and ending in late teens (blue colour = mature cortex; so keep an eye out for how much green, yellow, orange and red is still in the mix throughout most of adolescence).
The process of adolescent brain maturation, counterintuitively, does not involve an increase in the thickness of the brain’s outer surface (the cortex). On the contrary, it actually involves a reduction in cortical thickness – as less important synaptic connections and brain pathways are “pruned” away; presumably to free up resources for more intensively-used neural networks. This process enables the brain to function more and more efficiently the more certain behaviours are repeatedly performed and elaborated upon. Skills that we acquire with a great deal of time and effort during childhood are performed effortlessly by the time we reach adulthood.
The human brain will adapt to any environment with which many, many hours are spent interacting. These days the real life immediate environment of a teenager’s home, school, playground, social settings etc in which they spend their waking hours is increasingly supplemented by a wide variety of virtual and online spaces and places into which innumerable hours are poured. This means that digital natives – kids that cannot remember a time before the internet – are going through their “synaptic pruning” maturation phase of accelerated teen brain development synergistically with virtual, as well as real, worlds. The brains that result from this interactive process will be specialised differently to those honed during a twentieth century adolescence.
Cause for alarm? Well, maybe yes, maybe no. It will undoubtedly be a mixed bag. Brain specialisation to improve efficiency in the execution of one behaviour will always come at the expense of specialisation that could have been invested in something else. This is displacement.
When time spent playing massive multiplayer online games (MMOG) entirely displaces time spent engaging in old fashioned face-to-face interaction with a friend or group of friends certain brain areas will be improved in preference to others. That teenager would develop superior visuospatial, rapid task-switching and quick decision making abilities, but at the expense of social skills; unless time is also invested in extensive face-to-face communication with peers. Social networking and instant messenging services actually takes this social displacement to a whole different level by actively disrupting what little time is acutally spent in the company of real people.
Teen social lives are increasingly becomeing less about the face-to-face and much more about face-down-to-phone. The right to choose which smartphone alerts they do and don’t respond to are waived in favour of a slavish dependency. The attention of many teens is immediately diverted to any BBM, Twitter, Facebook etc alert that squarks and vibrates from their smartphone – regardless of where they are or who they are with. This constant disruption must surely degrade the quality of in person social interaction and brain specialisation supporting this vital skill. So does this mean the art of conversation is utterly doomed?
If teens can be made aware of the need to take control of their digital consumption then there is hope. Otherwise they’ll find themselves distinctly uncomfortable being in the same room as other people and will much prefer to communicate through the written word – a scenario that will inevitably leave them feeling empty. Brains that evolved to communicate much more effectively through body language than speech will inevitably miss the physical presence of another person when communication becomes exlusively remote. Not to mention the fact that physical touch is one of the primary ways in which a brain is inspired to activate brain circuitry that makes a human being feel safe, secure and content.
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At the onset of puberty the grey matter reaches maximum thickness and that key process of maturation, neuronal pruning, begins in the adolescent brain. This process does not occur uniformly across the whole brain but instead starts at the back of the brain and gradually progresses towards the front over a period of several years. Research at the National Institute of Mental Health in the US has tracked these changes using MRI to create a colour-coded animation that gradually progresses from an early teenage brain to a late teenage brain with red indicating where the grey matter is thickest, yellow a little thinner, green a little thinner again and finally the thinnest (and most mature) brain areas in blue:
If you pause the video after about 2-3s you can see the status of the brain in the mid-teens – it is quite literally suspended half way between the adult and child form – some brain areas have fully matured by this point in life (blue), but there is a vast patchwork of reds, yellows and greens indicating many brain areas that are still in their childlike form. If you re-start the video you’ll notice right at the end the very last brain area to go from “almost mature” green to “fully mature” blue is at the front of the brain, within the prefrontal cortex. The dorsolateral part of the prefrontal cortex (the upper side parts of the brain region residing behind your forehead) is responsible for impulse control in the mature fully developed brain.
Adults who have brain damage in areas of the prefrontal cortex lose their ability to control their anger – reacting in a highly aggressive manner at the slightest provocation. Remind you of anyone? When the hormones of adolescence are running riot, teenagers can often find themselves in situations that induce feelings of helplessness and frustration, which invariably finds expression as anger. This happens because prefrontal brain areas that are used to exert control over impulsive behaviours in adults are not yet fully developed. The important thing to remember is that late development of these important brain areas is not necessarily a mistake and may not, frustrating as it may be for the poor, long-suffering parents, be a bad thing. The inability of teens to control their aggression and arguments that their crankiness causes may actually help to break reliance on parental support, encouraging them to test the waters of independence in preparation for independent adult life.
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Neuroplasticity – the ability of the brain to adapt to the specific demands of the environments in which a person spends their waking hours. It occurs via reinforcement of connections between some brain cells (neurons) and weakening those between others. Neuroplasticity is at an all time high during childhood. This is primarily why kids seem to be able to absorb information like a sponge and pick up new skills so effortlessly.
Children’s brains are in a special, highly-adaptive state, enabling them to pick up new abilities very easily and develop a large repertoire of them very rapidly in preparation for adult life. That’s not to say that you cannot teach an old dog new tricks – it’s just that older brains have to put in more time and effort to pick up new skills. As with all things, the more you do something the easier it becomes. It may sound odd but, in a manner of speaking, you need to learn to learn, and then it comes easy. Older people tend to not bother trying to learn as intensively as during childhood, so when they do try, as they are out of the habit of learning, it all seems much harder. The trick is to never stop learning. Get back in the habit of learning, as you were naturally inclined to be during childhood, and learning becomes much easier, because your brain goes back into the “learning mode” i.e. your brain’s neuroplasticity increases.
The more a specific mental function is practiced, whether performing coordinated body movements, reading, engaging in conversation, experimenting with imagination, music, gadgets, whatever, the quicker, more accurately and more easily it can be performed the next time round. From day-to-day these improvements are usually not very noticable. But across a timeframe of weeks or months these tiny, incremental progressions add up into great leaps forward.
Any particular mental function involves a different set of brain areas that must communicate with each other via rapid fire electrical messages. Connections between brain areas that regularly work together to perform a specific mental function are strengthened, whilst others that are rarely used are eventually chopped away. That is one of the most surprising findings about brain development. You would think that the more you learn the more brain cells are created and the brain gets larger. In actual fact the complete opposite is true. Over the course of adolescence, as the ability to write, calculate, communicate, use tools, acquire knowledge and many other skills improve, a whopping great 33% of the brain’s neurons are trimmed away. And that’s a fact. Adolescence is all about pruning away brain cells that aren’t providing a useful function in order to free up precious resources and make way for extra connections to be made between brain cells that ARE often used.
The upshot is that the more complex, rich and varied a person’s experiences over the course of their childhood, the more complex, rich and varied the connections between its brain cells; ultimately translating into a broader repertoire of capabilities. The importance of a parent’s influence on the development of a child’s brain cannot be over-emphasised. Parents either do or do not provide a stimulating environment in which to stretch and challenge their child’s brain. They may or may not efficiently guide, nurture and encourage the development of skills, new experiences and abilities. This does not have to incur expense. Encouraging a young brain to explore and engage with their environment, to communicate openly and to feel free to ask as many questions as they want is key to enabling a brain to develop.
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