Our brain changes every day, whatever our age. Neuroscientist Sarah-Jayne Blakemore of the department for cognitive neuroscience at University College London, says: "Each time we recognise a new face, learn a new word, we make changes in our brain structure. In a changing environment, the normal brain can't help but learn."
Her new book, The Learning Brain, written with colleague Uta Frith, reviews the latest findings on how 'natural' learning can be shaped and asks can education make better brains?
The emphatic conclusion is that it can. When teachers pass on their knowledge, they help enrich neural networks in pupils' brains. In teaching a child to read, for instance, we profoundly alter the architecture of that child's brain, increasing the connections between the nerve cells. And where there are problems in a growing brain, such as dyslexia or attention deficiency hyperactive disorder, a good teacher can help ameliorate them.
"Education is to the brain," conclude Blakemore and Frith, "what gardening is to a landscape."
The contents of the human skull do, of course, constitute quite a significant landscape. A baby is born with around a hundred billion nerve cells and, by the time that baby reaches adulthood, about a hundred trillion interconnections have been forged between those nerve cells - an unimaginable network of learning.
To a large extent the direction of this growth is determined by the DNA of the cells that fused to create the baby in the first place - but from the moment of conception, it is also influenced by the environment in which the brain grows. We may have a "language instinct", for instance, but the language we end up speaking is determined by the language we're exposed to in childhood. Nature and nurture are thus deeply interrelated.
"Most research points to influences being about fifty-fifty genetic and environmental," says Dr Blakemore. "You can see it in developmental disorders like autism, dyslexia or ADHD. These are genetic or biological in origin, but environmental factors obviously interact to affect the way the child develops."
In their book, she and Professor Frith, a leading world expert on autism and dyslexia, explain developmental disorders through a powerful image.
They describe a number of automatic "start-up mechanisms" in the brain, kicking in at predetermined points in a learner's life to enable fast-track learning in various domains such as language or number. A specific learning disorder occurs when a particular module fails to start up, possibly also stopping others from developing too.
However, Frith and Blackmore point out that there's also a "general learning system" in the brain that can take over if a start-up doesn't happen. It's not as quick or efficient, but - given expert cultivation - most brains can compensate to some extent for developmental problems.
Experience suggests this is best achieved by "patient and slow repetition of foundational elements that are normally taken for granted, and by providing explicit rules" - a formula familiar to special needs teachers.
So, the more neuroscience can tell us about the way brains function, the better equipped teachers should be to tend their pupils' cognitive landscape. Indeed, The Learning Brain looks forward to a "new science of learning", an interdisciplinary science informed by neurophysiology, psychology and education.
Dr Blakemore emphasises that this learning must be seen as a life-long process. There are certain critical periods of growth (although neuroscientists now prefer to call them "sensitive periods", which has a less scary ring to it) when there's a massive increase in the number of interconnections between brain cells, followed by a period of "pruning" - which can be seen as fine-tuning the brain to the learner's needs.
Dr Blakemore had the opportunity to investigate one of the sensitive periods of early infancy six years ago when seconded to the Houses of Parliament to compile a report on the most appropriate educational provision for young children.
Neuroscientific findings in the Nineties had led to a craze in the US for hot-housing young children - "enriching" their experiences to provide more data for the brain cells to work on. But a review of the research led her to reject this idea. "After reviewing all the evidence, I concluded that, while deprivation is certainly bad for the brain, hyper-enrichment isn't necessarily good for it. There's no evidence that hot-housing is beneficial to brain development. It may even be damaging, but there's no evidence yet one way or the other."
She also points to lack of hard evidence about the current hot topic of when children should begin formal learning of literacy skills. However, since she's considering keeping her own summer-born son back a year so that he starts school at five rather than four, she clearly has her suspicions.
In recent years, Dr Blakemore has turned her attention to another possible sensitive period of brain development - adolescence. While the proliferation and pruning of brain cell connections in infancy encompasses most areas of the brain, the changes in the adolescent brain are specifically associated with regions of the cortex, including the prefrontal cortex. This is the area of the brain that deals with the higher order activities of planning, self-awareness, selecting behaviour, and certain types of memory - sometimes referred to as "executive functions".
The prefrontal cortex is the most recent part of the human brain to evolve, so it's not surprising that its internal wiring seems to take longer than older areas.
Not only is there a dramatic reorganisation of connections related to the executive functions during this period, but there's also a significant increase in "myelination". Myelin is a white sheath of fat and protein that gradually develops around transmitter cells, insulating them and increasing the speed of interconnectivity. "Myelination goes on into your 20s,"
explains Dr Blakemore, "and it massively increases the speed of transmission between cells - it can be up to a hundred times faster."
These changes imply that there should be an improvement during the teens and early 20s in an individual's ability to focus attention, make decisions, exercise self-control and manipulate the memory to carry out more than one task at a time. There are also likely to be subtle but significant developments in awareness both of oneself and of others, including the ability to understand another person's viewpoint - although these changes in social cognition may be temporarily obscured or confused by the effects of hormonal changes during puberty.
It's clear therefore that the brain continues to grow and change over the first 20 years of life, and teaching methods at different stages in the educational process should, of course, be sensitive to these changes. The younger the learner, the more brain development is general. As students reach adolescence, neural connections in most areas should be well established, but those in the regions associated with the executive functions continue to be fragile and malleable.
It would seem to make sense therefore, for primary teachers to concentrate on a more general, holistic approach to education, helping establish the overall architecture of the brain.
They should also take into account that their pupils' attention span is likely to be shorter than adults', decision-making more difficult, and working memory less efficient. As Dr Blakemore says: "Some tasks that seem negligible to adults are quite taxing for children."
During the secondary years, teachers should be able to assume that overall interconnectivity is established, and concentrate on the still fragile areas in the prefrontal cortex, helping students become steadily more capable of selective attention, decision-making, planning and multi-tasking.
But as well as cultivating the cerebral landscape, teachers also need to be aware of other, potentially harmful, environmental influences that could undermine their work.
Susan Greenfield, director of the Royal Institution, recently drew attention to the possible adverse effects of too much screen-based activity on developing brains.
In the same week, a new study from the Institute of Psychiatry suggested cannabis use in adolescence can also be seriously damaging. "It seems cannabis can be a profound environmental factor during this sensitive period of brain development," says Dr Blakemore.
"It may lead to over-pruning or inhibit pruning of the connections between the cells;we don't know. But this study puts it beyond doubt that cannabis use in adolescence is associated with an increasingly high risk of schizophrenia and clearly affects the development of their brains."
Brains are highly plastic. This means that learning is always possible.
Even when things go wrong neurologically or environmentally, the right sort of teaching, appropriate to the particular learner concerned, should be able to compensate for all but the most profound disability or deprivation.
Brains develop over time The neural networks in the brain go through several waves of proliferation and pruning during childhood and adolescence (and it's possible there may be even further fine-tuning in adulthood).
These periods of fine tuning make the brain less flexible but more efficient. Myelination, development of insulating white matter around transmitter cells which speeds up interconnectivity, also develops over time. Teaching should be sensitive to learners' development .It's possible that inappropriate experiences (such as rushing learners to achieve before they're sufficiently mature) might actually inhibit effective learning.Brains are influenced by environmental factors. Dramatic reorganisations of the brain described above result from genetic programming, but are also affected by environmental factors.