The Brain: How The Brain Rewires Itself

Not only can the brain learn new tricks, but it can also change its structure and function--even in old age

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Illustration for TIME by David Plunkert

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The same is true when cognitive techniques are used to treat depression. Scientists at the University of Toronto had 14 depressed adults undergo CBT, which teaches patients to view their own thoughts differently--to see a failed date, for instance, not as proof that "I will never be loved" but as a minor thing that didn't work out. Thirteen other patients received paroxetine (the generic form of the antidepressant Paxil). All experienced comparable improvement after treatment. Then the scientists scanned the patients' brains. "Our hypothesis was, if you do well with treatment, your brain will have changed in the same way no matter which treatment you received," said Toronto's Zindel Segal.

But no. Depressed brains responded differently to the two kinds of treatment--and in a very interesting way. CBT muted overactivity in the frontal cortex, the seat of reasoning, logic and higher thought as well as of endless rumination about that disastrous date. Paroxetine, by contrast, raised activity there. On the other hand, CBT raised activity in the hippocampus of the limbic system, the brain's emotion center. Paroxetine lowered activity there. As Toronto's Helen Mayberg explains, "Cognitive therapy targets the cortex, the thinking brain, reshaping how you process information and changing your thinking pattern. It decreases rumination, and trains the brain to adopt different thinking circuits." As with Schwartz's OCD patients, thinking had changed a pattern of activity--in this case, a pattern associated with depression--in the brain.

HAPPINESS AND MEDITATION

COULD THINKING ABOUT THOUGHTS IN A new way affect not only such pathological brain states as OCD and depression but also normal activity? To find out, neuroscientist Richard Davidson of the University of Wisconsin at Madison turned to Buddhist monks, the Olympic athletes of mental training. Some monks have spent more than 10,000 hours of their lives in meditation. Earlier in Davidson's career, he had found that activity greater in the left prefrontal cortex than in the right correlates with a higher baseline level of contentment. The relative left/right activity came to be seen as a marker for the happiness set point, since people tend to return to this level no matter whether they win the lottery or lose their spouse. If mental training can alter activity characteristic of OCD and depression, might meditation or other forms of mental training, Davidson wondered, produce changes that underlie enduring happiness and other positive emotions? "That's the hypothesis," he says, "that we can think of emotions, moods and states such as compassion as trainable mental skills."

With the help and encouragement of the Dalai Lama, Davidson recruited Buddhist monks to go to Madison and meditate inside his functional magnetic resonance imaging (fMRI) tube while he measured their brain activity during various mental states. For comparison, he used undergraduates who had had no experience with meditation but got a crash course in the basic techniques. During the generation of pure compassion, a standard Buddhist meditation technique, brain regions that keep track of what is self and what is other became quieter, the fMRI showed, as if the subjects--experienced meditators as well as novices--opened their minds and hearts to others.

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