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.
In addition to these brainblogs you can follow Dr Jack on Twitter to catch his daily #braintweet.
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.
In addition to these weekly blogs you can follow Dr Jack on twitter to catch his daily #braintweet.