Your brain is plastic. What this means is that it is adaptable. For example, if part of your brain is damaged, other parts can take over the same functions. Your brain is much more powerful than you realise. The trick is to unleash the power.
The old idea was that brain structure was fixed. After a young age, you had your quota of brain cells, with tens of thousands dying every day for the rest of your life. That's been discredited. Evidence shows the creation of new brain cells even in the elderly.
The old idea was brain localisation: particular parts of the brain perform particular things, like sight and touch. If you lost those parts of the brain, you lost those functions permanently. The new idea is plasticity: functions can be performed by different parts of the brain.
Norman Doidge is a psychiatrist who became interested in brain plasticity. He spent several years studying the latest research and visiting the world's leading neurology researchers. The result is a fascinating and inspiring book, The Brain that Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science (New York: Viking, 2007).
Several of the brain scientists he interviewed spent decades struggling against orthodoxy. Doidge tells about brain plasticity through their stories.
"I met a scientist who enabled people who had been blind since birth to begin to see, another who enabled the deaf to hear; I spoke with people who had had strokes decades before and had been declared incurable, who were helped to recover with neuroplastic treatments; I met people whose learning disorders were cured and whose IQs were raised; I saw evidence that it is possible for eighty-year-olds to sharpen their memories to function the way they did when they were fifty-five. I saw people rewire their brains with their thoughts, to cure previously incurable obsessions and traumas." (p. xv)
Suppose you have a stroke, damaging part of your brain. If the stroke is in your left hemisphere, you may have difficulty using the right half of your body and difficulty speaking. The usual treatment is a few weeks of physical and speech therapy, a bit each day. Most patients compensate for limited right-hand function by using their left hand more.
Edward Taub developed a new therapy, commonly called restraint-induced movement therapy. In order to force the brain to develop connections in new areas, the good limb is prevented from moving and the damaged one is exercised for many hours every day, with tasks of gradually increasing difficulty. Maybe at first you can use your right hand to pick up a ball and put it through a large hoop. You do this hundreds of times, and when you're ready you proceed with a smaller ball and a smaller hoop, and so on to other more challenging tasks.
This sort of training triggers a different part of the brain, not normally used for controlling the hand, to take over the functions. Constraint-induced movement therapy can be used years after a stroke, with remarkable results. In many cases nearly full capability can be regained.
Consider a completely different problem: phantom limb pain. When someone loses an arm or a leg, in war or an accident, often they experience severe pain apparently coming from the missing limb. Sometimes this persists for decades. V. S. Ramachandran tackled this as a problem in the brain. Doidge says, "According to Ramachandran, pain, like the body image, is created in the brain and projected onto the body" (p. 190). Ramachandran developed a therapy that gradually trained the brain to eliminate the pain.
Many people, as they get older, assume their brains will run down, with loss of memory and acuity. This is a self-fulfilling prophecy, because the brain responds to challenge. If you don't challenge your brain, it will indeed decline. But this isn't nearly as relentless as commonly believed. Michael Merzenich has developed exercises for the brain. By spending hours on specially designed mental exercises, elderly people can dramatically improve both on the exercises and in general mental performance. Learning a language in old age can help improve memory generally.
Long-term change in the brain only occurs when you're concentrating on a task, not if you're just going through the motions. Doidge says multitasking has limitations: "While you can learn when you divide your attention, divided attention doesn't lead to abiding change in your brain maps" (p. 68).
One of the amazing stories told by Doidge is that physical changes in the brain can be brought about by thought alone. The usual idea is that the brain responds to external stimuli but that the mind cannot initiate change. This materialistic philosophy is challenged by studies by Alvaro Pascual-Leone. In one experiment, he taught two groups of people some piano basics. One group practised using actual pianos; the other group practised only in their minds. After six hours of practice over three days, the two groups had similar changes in their brain maps and similar improvements in actual performance.
Doidge says "imagining an act engages the same motor and sensory programs that are involved in doing it. We have long viewed our imaginative life with a kind of sacred awe: as noble, pure, immaterial, and ethereal, cut off from our material brain. Now we cannot be so sure about where to draw the line between them" (p. 213). Amazingly, you can strengthen your muscles by simply imagining that you're exercising them.
When you develop a habit, it's built into the brain. That's why changing bad habits is so difficult and why developing good habits from an early age is important.
Brain plasticity has great relevance to universities. As teachers, we shouldn't assume that students have fixed mental capacities. Rather than seeing our job as encouraging and selecting students who are naturally talented, the message from brain plasticity is that anyone can transform their capacities through rigorous mental training. Doidge says "postmortem examinations have shown that education increases the number of branches among neurons. An increased number of branches drives the neurons further apart, leading to an increase in the volume and thickness of the brain. The idea that the brain is like a muscle that grows with exercise is not just a metaphor" (p. 43). The implication is that encouraging students to develop effective habits of ongoing learning is crucially important.
Doidge says, "After a brief period of practice, as when we cram for a test, it is relatively easy to improve because we are likely strengthening existing synaptic connections. But we quickly forget what we've crammed - because these are easy-come, easy-go neuronal connections and are rapidly reversed. Maintaining improvement and making a skill permanent require the slow steady work that probably forms new connections ... some people, the 'tortoises,' who seem slow to pick up a skill, may nevertheless learn it better than their 'hare' friends - the 'quick studies' who won't necessarily hold on to what they have learned without the sustained practice that solidifies the learning" (pp. 199-200).
When it comes to research, the belief in natural talent is pervasive: either you've got the capacity or you don't. Brain plasticity tells something different: doing the work creates the brain needed to do it.
Doidge includes a fascinating appendix about culture and the brain. He gives examples of how culture affects perception, not only in the usual way of culture affecting the way we interpret our perceptions but in a biological way: our perceptual apparatus is itself affected by culture. Included in culture is communication technology. The medium is indeed the message: it rewires the brain.
If you know anyone who has a disability or who simply isn't living up to their potential, read The Brain that Changes Itself and be inspired at the possibilities.
30 September 2008
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