Can the brain heal and preserve itself—or even improve its functioning—as we get older?
For some time, many scientists have tended to think of our brains as machines, most commonly as computers, destined to break down over time under the strain of age and use. In recent years, however, research in neuroscience has begun to show the inadequacy of this metaphor for describing the physiology of the brain. It turns out that our brains, like our bodies in general, are far more likely to waste away from underuse than to wear down from overuse.
As people reach middle age, exercising the brain and the body to which it is attached—keeping both active—becomes more important. It is one of the few reliable ways to offset the natural wasting process and the damaging influence of our unnaturally sedentary modern lives. It also points to new possibilities for the brain to heal itself in the face of disease and trauma.
In the late 1970s, research by Mark Rosenzweig of the University of California at Berkeley and Michael Merzenich of the University of California at San Francisco and others began to show that the brain’s circuitry changes microscopically with experience and activity. Dr. Rosenzweig and colleagues found that, with environmental stimulation, the brains of animals grew in key areas. Dr. Merzenich discovered that if an animal stopped using a body part, the brain area that processed sensory input from that part weakened or was taken over to perform another function. These findings have since been replicated many times.
The mainstream view in neuroscience and medicine today is that the living brain is actually “neuroplastic”—meaning that its “circuits” are constantly changing in response to what we actually do out in the world. As we think, perceive, form memories or learn new skills, the connections between brain cells also change and strengthen. Far from being hard-wired, the brain has circuits that very rapidly form, uniform and reform.
We still have a lot to learn about the brain and its powers of recovery, of course. But increasingly we have the evidence to conclude that we have been seeing our brains the wrong way for too long. Metaphors often conceal as much as they reveal. One day, we may well marvel at how odd it was that, for several centuries, we chose to view our ever-changing, activity-craving, animate brains as fixed, passive, inanimate machines.
Source: The Wall Street Journal, February 7, 2015
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