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The Ever-Changing Brain

A single, curious, process may underlie addiction, brain training and much of our ability to learn. How do we learn new skills? How do we recover brain function after debilitating injuries? To adapt to our surroundings, explore, discover and grow is what makes us human. What allows us to do all this? It sounds more like a question for a philosopher than a scientist1, but neuroscience provides a brilliant explanation.

From set in stone to nothing is concrete

Once a modern heresy as fanciful as electricity or magnetism in their time, neuroplasticity has taken centre stage in how we think about the brain.

For hundreds of years, scientists thought the brain developed in childhood, then from maturity to the grave nothing grew. It was thought every brain followed the same schematic, so that in any two brains the same precise areas handled the same functions. The brain was unchangeable in structure and set in stone. Hence it should be possible to map the brain in it’s entirety, and apply that map to everybody. Known as localisationism, it had and still has a profound impact on how we live our lives. Assume for a moment the brain has set areas for specific functions, and is incapable of change. If you were born with a defect or dysfunction in one area, you would not be able to do some things, and could never learn. A child born with any learning difficulty would find it a lifelong disability . Or, if you were lucky enough to be born with a “complete” brain, then suffered an accident or illness, the damage would be permanent.

As early as the 1860s, physicians were seeing evidence to the contrary. Sometimes patients made remarkable recoveries after injuries, rediscovering the use of limbs, use of language or other things which should have been impossible. The famed neuroscientist Paul Broca claimed to have proven that we speak exclusively using the left hemisphere. Yet, just 3 years later Jules Cotard reported children with massive brain damage to the left hemisphere were able to speak normally. So while it was likely that the left hemisphere was responsible for speech, it wasn’t a hard rule; young brains were capable of reorganising to use some other brain area. Did this mean the adult brain could change too? Could new cells develop in adults? Could existing cells take on different functions?

Labelled diagram of the brain from an old textbook

For a long time it was too radical a shift in thinking. As a species, we love a simple explanation. There’s nothing we like more than reducing a subject down to a textbook, a Snopes article, or a clickbait blog post. Why shouldn’t the brain act like some large, complex, but ultimately predictable machine? The attraction of identifying areas of the brain responsible for particular tasks, naming them, and proclaiming our new understanding was strong. Areas associated with speech, movement and memory were found and named. Throughout the twentieth century the majority of doctors and neuroscientists accepted localisationism as gospel. When published at all, papers and studies mentioning “plasticity” met with scorn and ostracism. Finally, after decades, a determined group of scientists turned the tide and in the end some detractors even apologised.

Pioneers and pariahs

So what is neuroplasticity? Put simply, it is the ability of your brain to change throughout your lifetime. Sometimes due to external stimuli, but often and far more impressively, your brain can change itself.

Brain damage is the death of neurons and the connections between them. Neuroplasticity meanwhile, allows you to grow new connections between neurons, rewiring your brain. Taking advantage of plasticity, brain damage can be mitigated, your mind can adapt, and new skills can be learnt throughout life.

In the time since you started reading this article, hundreds of people worldwide will have suffered a stroke2. Strokes are unpredictable, unpreventable, and can be debilitating in the extreme. It’s common for a stroke to cause brain damage, and in many cases the patient will never recover full functionality. In 1959, Pedro Bach-y-Rita suffered a stroke that paralysed his face, as well as half of his body and left him unable to speak. At the time, doctors thought he had no hope of recovery and would be in an institution for the rest of his life. With the help of his son, Pedro would come to make an amazing recovery, going back to full-time teaching, hiking and travelling. There was no plan, no miracle drugs or genius doctors3 – just a man and his son working long hours every day. Starting with crawling and repetitive movements like dish washing, they built up to ever more complex tasks. Each task would help retrain his brain to perform a type of motor movement, repeated hour after hour, week after week. A year later at the modest age of 68, Pedro had made an almost full recovery. His recovery was so astounding that it inspired his other son, Paul, to return to practising medicine. Paul Bach-y-Rita would become a leading proponent of neuroplasticity, making a huge difference to the lives of stroke and balance disorder victims.

Michael Merzenich is perhaps the most ambitious neuroplastician. Chaotic and brilliant in equal measure, he has helped to develop some of the most interesting practical uses for plasticity. His work demonstrates it exists throughout life and has extraordinary potential. In their early experiments, Merzenich and his team focused on micro-mapping monkey brains using tiny electrodes, carefully stimulating limbs and sensory areas to see which areas activated. These incredibly detailed maps showed how the brains of individuals were wired. They then taught the monkeys to listen to specific sounds, practice skills, or adapt to restricted limb movement4. Repeating the mapping process afterwards, they saw clear evidence of brain functions moving location and changing in size. Among other things, they were able to prove the brain varied in each individual; could rearrange itself in response to injury; repurposed areas previously used by other limbs; and could specialise to do common tasks faster. These irrefutable, anatomical proofs of neuroplasticity were not easily accepted by mainstream medicine. For a long time, Merzenich and his associates were mocked, their results dismissed as conjecture and pseudo-science. Eventually though, the weight of evidence turned the tide. As for Merzenich, he went on to found companies making software to help language-impaired, learning disabled, children and the elderly. All used the principles of plasticity to help people train their brains5.

The Woman Who Changed Her Brain, by Barbara Arrowsmith-Young

A fantastic read, if you get the chance.

Some people are born to change the world. Barbara Arrowsmith-Young is one of those, a paragon of human potential. Despite growing up with multiple learning difficulties and struggling through school, she has achieved remarkable success. Having issues with reading, arithmetic and comprehension, she got through school by relying on her memory. It wasn’t until University that she discovered the names for her conditions and devised her own mental exercises to tackle her deficits. It was an extraordinary thing to do. Not only was nobody else (even those with formal training and research budgets) coming up with these kinds of exercises, she was the patient, treating herself. Nor did she stop there. After incredible mental effort and perseverance, Barbara was able to overcome her difficulties and went on to found a school. The Arrowsmith School treats children with learning difficulties, using tailored programs to improve weak cognitive skills. The difference to the lives of people who were previously “written off” is astounding. It’s tempting to believe there is no learning difficulty which can’t be treated.

Changing the brain

Plasticity is a relative phenomenon. The ability of the brain to adapt doesn’t mean you can grow an extra brain or that you will develop telepathy. To change how the brain works often requires prolonged, intense work and highly tailored activities. Nor is it a panacea – sometimes the brain is too damaged, or a similar area isn’t available to be repurposed.

In a broad sense, one brain is much like another. Think about how you move during everyday tasks, like eating dinner or opening doors. When you’re using your hand, you will also often be using your arm, even if just to hold the hand steady. It’s very likely the brain region which controls your hand is next to the region which controls your arm. Your arm and your hand often work together (or even at the same time), so it’s more efficient to do it that way. The same is true of your leg and foot, your lips and jaw, and many other adjoining regions. The rules of efficiency, genetics and everyday life predict that certain regions of our brains will usually lie next to each other. Some parts of the brain’s structure are also more suited to handling movement, or sensory input, or abstract thought, than others. Thus the brain maps of localisationism are accurate in a general sense, so you can forgive people for taking them at face value. Many aspects of localisationism are still valid and taught today, alongside plasticity6.

Marvel's Daredevil

The wildly popular Netflix show Daredevil7 actually uses neuroplasticity as a plot device. Not-a-spoiler-alert: The main character is blind, and his other senses are more acute, giving him enhanced hearing and balance amongst other things. Allowing for exaggeration and ignoring the other…less scientific…elements of the series, this is possible. A vast amount of your brain’s real estate handles vision and processing imagery. Studies show that if someone stops using these areas, they are cannibalised by other functions including other senses8.

You can also take advantage of neuroplasticity without becoming a latex-clad comic-book vigilante. As well as helping stroke and brain damage victims to recover, neuroplasticity has been used to amputate phantom limbs9, treat dyslexia and OCD.

Use it or lose it, pal!

Having an ever-changing brain is amazing, but not everything about it works in our favour. The constant state of change and competition which exists in your brain has downsides.

For one, you have to keep using skills and functions if you want to retain them. We’ve all experienced the feeling of being “a little rusty” at something we used to do all the time, and this is partly due to neuroplasticity. When we practice a fine motor skill, like piano or calligraphy, our brains adapt to perform these tasks better and with greater accuracy. Were you to have an MRI scanner at home, you could actually watch the change in your brain as you get better at a hobby. But, if we then give up the piano and take up yodelling, the well-adapted piano networks will begin to fade. It’s not as simple as one skill overwriting another, but as our brains have a finite capacity, if you want to keep aceing recitals you have to keep practicing. The same applies to languages, and even to limbs. Suppose for some reason you stopped using your left arm altogether for six months, perhaps due to a serious injury. Afterwards, you would need to learn how to use it all over again (though perhaps muscle atrophy would be the first problem).

River flowing through a deep gorgeImagine a stream flowing down a shallow channel in a sandy hill. The rushing water takes the easiest route to the bottom, and so the channel becomes a groove, then a trench, and a gorge. As time goes by, the stream becomes a waterfall, and carves a deeper path through the hill. This is the power, and the problem, with plasticity – the more a path is used, the stronger it becomes.

This is why we find it so difficult to change our thinking, to overcome an addiction or to break a bad habit. Every time the existing path activates, we feel a reward and the path strengthens. This may prove to be the root of addictions, habits, and even OCD. Imagine rather than the chemical pay-off from indulging, the bigger problem with addiction is reinforcement of a brain circuit. What if those who suffer from OCD are just experiencing a runaway form of neuroplasticity, compelled to repeat the same rituals due to overpowering mental pathways? The chemical reward may be inevitable, so perhaps to treat these problems we can prevent the reinforcement instead. They say a little knowledge is a dangerous thing, but where OCD is concerned, the reverse seems to be true. For some sufferers, knowing that faulty or over-effective brain wiring is the cause has been key to their emancipation. Each time they experience an urge, they can label it as a brain malfunction and then attempt to refocus on something else10. This in turn helps them to reclassify and ultimately ignore the compulsion, and with continued effort, the mental pathway slowly weakens. With the help of plasticity, OCD and addiction sufferers may be able to treat themselves.

Like most biological functions, neuroplasticity appears to be less effective as we age. We don’t fully know why yet, but many scientists suggest the cause is just general deterioration as we get older. Thus every year papers are written about how ageing and how we can expect to lose function or neurons with age. As we’ve seen though, accepted science can be wrong. Michael Merzenich for one believes it is, and has begun exploring the possibilities. The nucleus basalis area is active throughout childhood, and associated with learning. In one experiment, his team stimulated this area in adult rats, and were able to train the older rats as effectively as children. He suggests that the key to keeping our brains limber as we age is to keep them stimulated and in training. Bombarding the brain with new experiences, as we do in childhood, seems to be the key. That’s one of the reasons why trying to learn a new language or skill later in life is beneficial, but why is it so much harder? Inputs to the brain, like eyesight and hearing definitely deteriorate. Mental function may also deteriorate, but its difficult to separate cause from effect, and studies are ongoing. Against accepted wisdom, Merzenich would argue the problem is mostly due to the brain being out of practice, and the wrong kind of training.

It’s become a cliché to describe the human brain as the most complex machine in the Universe. Ask yourself this though: as well as all the other fantastic things our brains are capable of, how many machines do you know which can repair, adapt and improve themselves?

Further (better) reading:

Notes:

  1. Etymological aside: the word “scientist” only entered popular usage around 1834. Before that, those that we call scientists today were called philosophers, or philosophers of science. It’s strange to think that Newton, Gallileo and many other founding fathers would never have been called scientists.
  2. State of the Nation: Stroke Statistics 2016, Stroke Association UK. https://www.stroke.org.uk/sites/default/files/state_of_the_nation_2016_110116_0.pdf
  3. George Bach-y-Rita is a psychiatrist, so while he is a doctor (and may well be a genius doctor!), neuroscience certainly wasn’t his specialism at the time.
  4. Experiments carried out by Merzenich and his team included temporarily sewing fingers together, severing nerves (which did then repair), and in one case, amputating fingers. It is sad that the discoveries which came from this research were reached this way.
  5. It would be remiss to discuss the history of stroke treatment, neuroplasticity, or even neuroscience, without mentioning Edward Taub. However, it’s difficult to mention Taub without also discussing the Silver Spring monkeys, PETA and inviting a whole world of pain. I think it’s important to note that: once the animals concerned were liberated, their lives were sadly not significantly improved; every single charge against Taub was eventually overturned; everything he (and his contemporaries) did was, ultimately, legal at the time.
  6. Earlier I mentioned Paul Broca, and alluded to Broca’s area, which is responsible for many functions in speech production. This is accurate, but the difference these days is designation as an approximate area and that in some individuals it may be very different. Identifying something of this importance in the 1860s is still exceptionally badass.
  7. Yes, I know Daredevil was a fictional character in the comic universe long before the Netflix TV series. I also know of the eponymous film starring Ben Affleck and Jennifer Garner (I have it on DVD!). Let’s stick to the current, more mainstream adaptation.
  8. In one memorable experiment carried out by Alvaro Pascual-Leone et al, sighted participants were kept totally blindfolded. In just five days, scans showed their brains had begun to reorganise. Participants reported “seeing” hallcuinations or intense visual images in response to auditory and touch stimuli.
  9. I’ve raved about V.S. Ramachandran’s work and books on this book before, but honestly, you could do a lot worse than to read The Tell-Tale Brain. In Chapter 1, he describes the fascinating condition of phantom limbs, and how their successful treatment more-or-less knocks localizationism on the head at a single stroke.
  10. The “Four Step” therapy devised by Dr Jeffrey Schwartz is becoming a widely-used treatment for OCD. Supported by neuroplasticity and using knowledge to empower patients, it helps sufferers to treat themselves when symptoms occur. More at http://www.ocduk.org/four-steps or in Schwartz’s books.
  • Greg Wood

    Fascinating article Dan. The final point about why the brain appears to be slower to learn as we age is key and the experience of most adults would appear to support this – but if the likes of Merzenich can demonstrate otherwise, it really opens up the possibility of re-training post serious illness such as strokes, which tend to happen later in life of course.

  • Thanks Dad!