Hardwired Dogma

Train Your Mind, Change Your Brain: How a New Science Reveals Our Extraordinary Potential to Transform Ourselves
by Sharon Begley

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Conventional wisdom in neuroscience held that the adult mammalian brain is fixed in two respects: no new neurons are born in it, and the functions of the structures that make it up are immutable, so that if genes and development dictate that this cluster of neurons will process signals from the eye, and this cluster will move the fingers of the right hand, then by god they'll do that and nothing else come hell or high water. There was good reason why all those extravagantly illustrated brain books show the function, size, and location of the brain's structures in permanent ink. As late as 1999, neurologists writing in the prestigious journal Science admitted, "We are still taught that the fully mature brain lacks the intrinsic mechanisms needed to replenish neurons and reestablish neuronal networks after acute injury or in response to the insidious loss of neurons seen in neurodegen- erative diseases."

That is not to say that scientists failed to recognize that the brain must undergo some changes throughout life. After all, since the brain is the organ of behavior and the repository of learning and memory, when we acquire new knowledge or master a new skill or file away the remembrance of things past, the brain changes in some real, physical way to make that happen. Indeed, researchers have known for decades that learning and memory find their physiological expression in the formation of new synapses (points of connection between neurons) and the strengthening of existing ones; in 2000, the wise men of Stockholm even awarded a Nobel Prize in Physiology or Medicine for the discovery of the molecular underpinnings of memory.

But the changes underlying learning and memory are of the retail variety-strengthening a few synapses here and there or sprouting a few extra dendrites so neurons can talk to more of their neighbors, like a household getting an extra phone line. Wholesale changes, such as expanding a region that is in charge of a particular mental function or altering the wiring that connects one region to another, were deemed impossible.

Also impossible was for the basic layout of the brain to deviate one iota from the authoritative diagrams in anatomy textbooks: the visual cortex in the back was hardwired to handle the sense of sight, the somatosensory cortex curving along the top of the brain was hardwired to process tactile sensations, the motor cortex was hardwired to devote a precise amount of neural real estate to each muscle, and the auditory cortex was hardwired to field transmissions from the ears. Enshrined from clinical practice to scholarly monographs, this principle held that in contrast to the ability of the developing brain to change in significant ways, the adult brain is fixed, immutable. It has lost the capacity called neuroplasticity, the ability to change its structures and functions in a fundamental way.

To some extent, the dogma was understandable. For one thing, the human brain is made up of so many neurons and so many connections-an estimated 100 billion neurons making a total of some 100 trillion connections-that changing it even slightly looked like a risky undertaking, on a par with opening up the hard drive of a supercomputer and tinkering with a circuit or two on the motherboard. Surely that was not the sort of thing nature would permit and, in fact, something she might take steps to prevent. But there was a subtler issue. The brain contains the physical embodiment of personality and knowledge, character and emotions, memories and beliefs. Even allowing for the acquisition of knowledge and memories over a lifetime, and for the maturation of personality and character, it did not seem reasonable that the brain could or would change in any significant way. Neuroscientist Fred Gage, one of the researchers invited by the Dalai Lama to discuss the implications of neuroplasticity with him and other Buddhist scholars at the 2004 meeting, put the objections to the idea of a changing brain this way: "If the brain was changeable, then we would change. And if the brain made wrong changes, then we would change incorrectly. It was easier to believe there were no changes. That way, the individual would remain pretty much fixed."

The doctrine of the unchanging human brain has had profound ramifications, none of them very optimistic. It led neurologists to assume that rehabilitation for adults who had suffered brain damage from a stroke was almost certainly a waste of time. It suggested that trying to alter the pathological brain wiring that underlies psychiatric diseases, such as obsessive-compulsive disorder (OCD) and depression, was a fool's errand. And it implied that other brain-based fixities, such as the happiness "set point" to which a person returns after the deepest tragedy or the greatest joy, are as unalterable as Earth's orbit.

But the dogma is wrong. In the last years of the twentieth century, a few iconoclastic neuroscientists challenged the paradigm that the adult brain cannot change and made discovery after discovery that, to the contrary, it retains stunning powers of neuroplasticity. The brain can indeed be rewired. It can expand the area that is wired to move the fingers, forging new connections that underpin the dexterity of an accomplished violinist. It can activate long-dormant wires and run new cables like an electrician bringing an old house up to code, so that regions that once saw can instead feel or hear. It can quiet circuits that once crackled with the aberrant activity that characterizes depression and cut pathological connections that keep the brain in the oh-god-something-is-wrong state that marks obsessive-compulsive disorder. The adult brain, in short, retains much of the plasticity of the developing brain, including the power to repair damaged regions, to grow new neurons, to rezone regions that performed one task and have them assume a new task, to change the circuitry that weaves neurons into the networks that allow us to remember, feel, suffer, think, imagine, and dream. Yes, the brain of a child is remarkably malleable. But contrary to Ramón y Cajal and most neuroscientists since, the brain can change its physical structure and its wiring long into adulthood.

Copyright © 2007 by Sharon Begley.

About the Author

Sharon Begley, science columnist for The Wall Street Journal, inaugurated the paper's "Science Journal" in 2002. She was previously the senior science writer at Newsweek, covering neuroscience, genetics, physics, astronomy, and anthropology. The co-author of The Mind and the Brain, she has won many awards for her articles She is a frequent guest on radio and television, including The Charlie Rose Show, Today Weekend, CBS's The Early Show, and Imus in the Morning. She lives in New Jersey.