Science writer Norman Doidge's right brain quizzes his left brain about their newly discovered elasticity | May 16, 2009
Article from: The Australian
ON the eve of a joint tour to Australia, the right hemisphere of Norman Doidge, author of The Brain that Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Sciences, sat down to speak with his left hemisphere for Review.
The interview was at times contentious: not surprising, perhaps, given the recent research hypothesis that argues that in some people the left hemisphere is responsible for up-beat moods and telling consistent narratives, while the right focuses more on finding inconsistencies.
Doidge's book is about the human brain's astonishing ability to change its own structure and function, as told through stories of the scientists, doctors and patients who together have brought about these transformations. Doidge argues that this discovery of neuroplasticity is the most important change in our understanding of the brain in 400 years.
RH: Forgive me if I give you a hard time, but it's my evolutionary tendency to play gotcha. In The Brain that Changes Itself, you argue that the view of the human brain that we've had has been incorrect for four centuries. Are you saying all those brilliant neuroscientists were simply mistaken?
LH: I'd be more diplomatic. It seems that to make certain kinds of errors, it helps to have a particularly high IQ. And neuroscientists have high IQs.
Mainstream neuroscience, going back to Descartes, had a mechanistic view of the brain as a machine with parts, each part performing one mental function in a single location. This idea is with us when we speak of the brain being like a computer. But the mechanistic view gave rise to what I have called the doctrine of the unchanging brain because it assumed that our brain circuits are all genetically predetermined, formed and finalised in childhood or before, and that our brains are hard-wired (another machine metaphor).
This view gave rise to a neurological nihilism: it assumed that in all cases people born with a learning disorder, whose brains failed to develop properly or who had a brain injury had to live with it because machines do many glorious things but they don't grow new parts or change themselves. It meant it was pointless to try to preserve an ageing brain because the only way machines change is to wear out.
RH: So the doctrine of the unchanging brain is also wrong?
LH: It is spectacularly wrong because not only can the brain change its circuits, that is its modus operandi, that's how it actually works. The Nobel Prize in Medicine in 2000 went to Eric Kandel, who showed that when learning occurs, genes in the neurons (the nerve cells in the brain) are turned on to make new proteins, which form new connections between them and their adjacent neurons, so that new processing abilities arise.
Michael Merzenich and others have shown that with repetition, these circuits become better at what they do. These findings have been used to remedy learning disorders that were supposedly inborn. We are not, it turns out, merely the galley slaves of our selfish gene masters.
RH: And these people think brain change is triggered by ...?
LH: Using brain scans they have demonstrated that it is triggered by mental experience: sensing, feeling, learning, acting, thinking, even, at times, imagining.
RH: It's a radical theory ...
LH: No! Neuroplasticity is not a theory, it is a fact. The experiment has been done thousands of times. The first clinical fruits of this revolution are here. Some learning disorders that were incurable a decade ago are now curable. The best treatment we have for strokes that cause paralysis of a hand or foot (developed by Edward Taub) involves triggering the brain to undergo plastic change.
Even the senses are plastic. In the film about my book, you can watch a blind man sinking a basketball because of a new neuroplastic technique. Stanley Karansky, a retired medical doctor, was 89 and his memory, alertness, driving ability were all slipping. He did exercises I describe, developed by a company called Posit Science, which reversed all that. Those exercises double people's language processing speed, so that they can remember as well as they could when they were typically 10 years younger and sometimes 25 years younger. This has been shown in good control studies at the Mayo Clinic and the University of Southern California.
RH: Are you saying that all brain conditions are curable? That the brain is infinitely malleable?
LH: No. That would be replacing an overly rigid model of the brain with an overly flexible one. There are terrifying cerebral catastrophes. I am not hoping to have a stroke and have to rehabilitate myself to score debating points with you. Retraining the brain is hard work, even when it is possible. And there are prerequisites: there has to be healthy tissue to take over from the unhealthy; you need to be able to pay attention; you have to be motivated. The required mental functions must be intact.
But that leaves a lot of disorders where results are possible. Recently the neuroplasticians have reported that, in some cases, people with multiple sclerosis, cerebral palsy, some brain injuries, some balance problems can retrieve or redevelop some lost mental functions. We have a study that memory problems caused by chemotherapy (chemo-brain) can improve, and anecdotal reports that memory loss from Lyme disease, and even HIV, have also responded to brain exercises. Brilliant work at the Howard Florey Institute in Melbourne has shown that certain kinds of exercise can delay the onset of genetically based neurological illnesses in animals.
RH: Isn't there a danger of raising false hope by talking about these exceptional cases?
LH: There's an essential, noble, stoical tradition in which physicians -- when everyone else is consumed with wishful thinking -- take a stand on the side of reality and inform dying patients that they must put their affairs in order or that they must simply adjust to a disease.
I admire that. But you'd better be damned sure when you say to someone that they really can't get better. Those who have got better from learning disorders are not exceptions, except that they are among the first to get these new treatments. More than a 1.5 million schoolchildren in the US have been helped by a reading program called Fast ForWord, which retrains the auditory cortex.
RH: Does this have implications beyond the clinic and the classroom?
LH: Huge. Plasticity requires that we re-examine culture. Most think the relationship between the brain and culture is a simple one: the human brain produces culture. In fact culture also moulds our brain. Just as children with learning disorders can develop new processors, different cultures cultivate different kinds of brains, en masse.
The Sea Gypsies, a tribe off the coast of Thailand, learn to see clearly under water when they dive to a depth of 10m in their hunt for food: the culture has developed a super sense.
We have experiments that show that Easterners and Westerners perceive objects differently, which requires different wiring, so that they have to retrain their brains when they emigrate. Culture shock is brain shock.
RH: If the brain is so plastic, why is it so hard for us to change cultures, or to get over bad habits or discard an accent?
LH: In those cases, plasticity itself is the culprit. A habit is a form of trained behaviour, a well-rehearsed mental routine. Trained neurons become faster and more efficient than untrained ones, and out-compete other neuronal coalitions. One of the most important things I learned was that plasticity is responsible both for many of our most flexible and our most rigid behaviours.
I call this "the plastic paradox". Plasticity is like snow on a ski hill in winter. Because the snow is pliable and plastic, you can take many paths down that hill, you can be flexible. If you have a good first run, chances are your next run down will be pretty close to that first path, and if you keep it up you will develop tracks in the snow, and then those tracks become ruts and you can't easily get out of them. Your path becomes rigid. We are learning how to create roadblocks to ruts so people are forced to go around them.
RH: But do studies show that, even if some parts of the brain are plastic, some are not at all?
LH: So far wherever we've looked, we've found that some plasticity exists. Even in the right hemisphere. Gotcha!
The Brain that Changes Itself is published by Scribe.