In Our Prime (24 page)

The twentieth century's infatuation with behaviorism—we are what we do—led scientists to view the brain as a miniature computer, an infinitely sophisticated mechanism for reasoning, calculation, memory, and language. Feelings were unscientific.

The very notion that emotions could be measured or studied in laboratory experiments seemed ridiculous. Besides, who cared? Most scientists did not assume there was any link between one's emotional state and one's physical health. And if one existed, the body was the source.

When Davidson embarked on studying the brain in graduate school in 1972, EEGs were state of the art. But in the last fifteen years, neuroimaging, particularly functional magnetic resonance imaging (fMRI) and other imaging methods, have revolutionized the field. Indeed, the influence of fMRIs has been compared to the
impact of the telescope
on astronomy. Of the sixty-one people employed in his lab, about one-third are physicists who work on new technology and methods. Brain imaging gives neuroscientists a much fuller picture of what goes on in our heads. Although our understanding of how the layer of gray and white
matter works is still in its infancy, the glimpse inside has convinced most scientists that the brain and the body are much more intertwined than anyone suspected.

Descartes, it seems, was wrong after all—at least from the standpoint of today's neurologists. It looks like Baruch Spinoza, the moody seventeenth-century Dutch philosopher and excommunicated Jew, who never lived to see most of his work published, was right to argue that the mind and body are not two separate entities but simply different expressions of the same thing. In Spinoza's cosmology, there is only one unique infinite and indivisible substance, and that is God or Nature. “
Spinoza prefigured in a remarkable way
some of the ideas on emotion, feelings, and ethics that are now taking shape as a result of modern neuroscience,” said the neurologist Antonio Damasio, author of the book
Looking for Spinoza.
Our emotions are, in fact, bound to our physical health and critical to our survival.

How that connection operates is still a mystery. What happens inside your body to produce that feeling of frustration when you get stuck in traffic, and how does that frustration cause your blood pressure to rise? How can the circuitry in the brain accelerate heart rate or weaken the immune system? Health psychology is the field that studies the link between emotion, stress, and physical health, but to Davidson “health psychology is a brainless enterprise.”

“These events happen to you in the outside world and somehow they affect your health,” he said. “But what are the mechanisms for how that occurs—that's never really been asked. From where I sit, the brain has to be in the equation, because the way the social world gets under the skin is via the brain.”

Through a series of experiments, Davidson and a handful of other neuroscientists have helped to upend more than three hundred years of thinking about the dualism of mind and body. In 1996, he and his colleagues published one of the first studies to show that disturbing pictures caused a response in the human amygdala. Davidson found that neural circuits in that region of the brain became particularly busy when people got angry, upset, or depressed. He discovered that negative
emotions and stress set off the right prefrontal cortex, while joy and enthusiasm set off circuits in the left prefrontal cortex.

Davidson's early experiments with monks and meditation suggested it might be possible to purposefully alter the neurological activity in the brain and gain control over one's emotions.
In one study, monks who had spent
at least three years alone or about ten thousand hours on a retreat—the “Olympic athletes of meditation”—were monitored as they meditated in a state of “unconditional loving-kindness and compassion.” They all showed an unusually strong pattern of synchronized gamma-wave activity, a movement of brain cells that is generally associated with concentration and emotional control.

Scientists interested in meditation were exploring whether it could induce physiological changes in the brain and the immune system. In 1997, Davidson convinced a few dozen workers at a biotechnology company outside Madison to learn mindfulness meditation, a method rooted in Buddhist practices in which a person trains to control his thoughts, and then identifies and banishes those that produce anxiety. Once a week, for two months, Davidson's associate brought meditation tapes and Tibetan chimes to the office and led a group of scientists, marketers, lab technicians, and managers in meditation for three hours. Before each session, their brains were wired and measured. Davidson's team found that the average emotional state of the employees had shifted into a more positive zone—that there were significant increases in activity in several areas of the left prefrontal cortex, the joy center, compared with workers who did not receive any training.
One possibility, Davidson hypothesizes
, is that neurons in the left prefrontal cortex are capable of blocking disturbing messages sent by the amygdala. Even more intriguing, participants showed signs of strengthened immunity; the number of antibodies they produced after a flu shot were higher than that of the control group. The experiment did not prove that meditation caused the boost to the immune system, but it did suggest that the experience of meditating might accomplish the extraordinary feat of modifying the brain's structure.

Stephen Kosslyn, a Harvard psychologist
who has collaborated with Davidson, said this study “fits into the whole neuroscience literature
of expertise . . . where taxi drivers are studied for their spatial memory and concert musicians are studied for their sense of pitch.” Kosslyn was referring to an experiment involving London cabbies, whose famously rigorous training requires that they master 320 routes comprising 25,000 streets. Brain imaging showed that the posterior hippocampus, the peapod-shaped area related to memory, was enlarged. The more experienced the driver, the larger the rear hippocampus. Those drivers might have had bigger hippocampi all along, but Kosslyn believed there was another cause: “If you do something, anything, even play Ping-Pong, for twenty years, eight hours a day, there's going to be something in your brain that's different from someone who didn't do that.”

Davidson is convinced that a cause-and-effect connection exists. “
Neuroplasticity”—the ability of the brain to change
—“is the most important idea in neuroscience in the last decade,” he said. “More than any other organ in our body . . . the brain is built to change in response to experience.” Scientists agree that the brain is more adaptable than anyone thought. What no one knows is how much more. Davidson argues that with practice people can learn to modify their brain activity through mindfulness training or meditation like the monks, who seemed able to control their concentration and emotions by generating synchronized gamma waves. These “neurally inspired behavioral interventions,” as Davidson calls them, may reduce the danger of stress-related diseases like cardiovascular illnesses and diabetes later in life, as well as the premature aging of our cells.
An experiment published in 2009
and financed by the National Institutes of Health suggested this might be possible. Researchers found that high-risk African American patients who meditated over five years were roughly half as likely to suffer heart attacks, strokes, and deaths compared with a group of similar patients who were counseled about diet and lifestyle.

In 2011, a group of scientists at Massachusetts General Hospital reported
that they found direct proof that meditation was the cause of alterations in the brain's structure. People who meditated half an hour every day for eight weeks developed more gray matter, the densely packed outer layer of nerve cells, in the hippocampus and other regions of the brain associated with learning and emotional regulation. At the same time, the
density of gray matter in the amygdala, the stress center, decreased. “This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing,” said Sara Lazar, one of the study's authors at the hospital's Psychiatric Neuroimaging Research Program.

In Davidson's eyes, “there is no more effective way to produce localized and specific changes in the brain than behavioral or mental interventions.”

Until the twenty-first century, the prevailing view was that mental decline started in midlife. There were reasons to think so. At around 40, the brain, with its 100 billion neurons, begins to shrink in both weight and volume by about two percent every decade. The ventricles, which contain the fluid that surrounds and cushions each part of the brain, protecting it from knocks and jolts the way an amniotic sac cradles a fetus, grow larger as gray matter disappears. At the same time, the spaces or fissures between the undulating grooves on the brain's thin outer layer become more defined. Connections between neurons thin out like male-pattern baldness, and the synapses—the places where neurons fire chemical transmitters—become increasingly sparse. The flow of blood and oxygen to the brain also begins to contract ever so slightly. Across the brain's white matter—those bundles of nerve cell transmitters that are wrapped and insulated in a fatty molecule called myelin—small lesions can sometimes appear.
Myelin itself can deteriorate
and the brain's ability to repair the DNA inside weakens. Most vulnerable of all is the prefrontal cortex, the brain's executive office, where high-level planning and organization of complex behaviors take place.

Such physical alterations sound ominous and seem to point to irrevocable loss. But that is far from the whole story. If mental agility declines with age, why then is wisdom, one of the most valued measures of brain functioning, consistently associated with old age?

Scientists began questioning assumptions
about aging and mental decline in the late 1920s and early 1930s. Edward Lee Thorndike, a psychologist who helped found the modern field of educational psychology, was one of the first to challenge conventional thinking about
declining brainpower. Drawing on his experience with testing subjects for the U.S. military in World War I, Thorndike later conducted research on adult learning, asking people between 14 and 50 to perform different tasks like memorizing passages of poetry. He concluded that there were no meaningful differences in the abilities of 25- and 45-year-olds, the early years of middle age.

In the 1970s
, a handful of psychologists pointed out that conclusions about aging and mental losses were often based on the frailest and most impaired segment of the population, the five percent of elderly people who lived in nursing homes. Like the originators of the MIDUS strategy, they decided to examine what extra abilities might accompany aging instead of searching only for deficits—to look at the half of the glass that was full.

Other studies had design flaws.
Some differences in test results
between younger and older adults were due to the particular vocabulary used on an exam or a familiarity with certain professions rather than with age. Testing memory in the elderly and college students by asking them to remember pairs of nonsense words skewed against older people. Students, accustomed to competing in all sorts of tests, were keen to do well, while the elderly were not especially motivated to work hard to remember meaningless terms.

A more fundamental problem that has always bedeviled researchers is how to measure what is variously called brainpower, wisdom, mental acuity, or general intelligence. Embedded in all the political fights about bias in standardized tests is a conceptual question: Should intelligence be thought of as a single item that can be cleanly measured on a scale like a pound of beef?

Over the last three decades, research has established how simplistic much of the theorizing about intelligence has been, and that it cannot be accurately defined by a series of questions social scientists make up and label “intelligence tests.” When people talk about wisdom, they generally include numerous attributes in the definition, including knowledge, analytic capability, open-mindedness, resilience, empathy, humility, and adaptability. This is why some leading theorists in the field, like Robert J. Sternberg, Howard Gardner, John Horn, and Mihaly Csikszentmihalyi,
have promoted what has been called alternative or more flexible theories of intelligence. Wisdom is not simply having the ability to handle complex calculus; it requires practical and emotional savvy as well. Brainpower does not exist in a vacuum, sealed off like a computer in a climate-controlled room. That is the problem with intelligence testing.
Most people do not naturally
put the everyday objects and materials they use or are surrounded with into abstract categories, which is the type of thinking that characterizes a modern scientific perspective. This was an insight that Alexander Luria, a Soviet psychologist, had after traveling to Central Asia in the 1930s to study cognitive development. Luria asked subjects whether a “log” belonged in the same category as an “ax” and a “hammer.” City dwellers tended to say no, that a log was not a tool. But in the Uzbekistan countryside, the residents said yes. “We say a log is a tool because it works with tools to make things,” one responded. Another added, “We have a saying, take a look in the field and you'll see tools.” On a modern IQ test, the Uzbek's answer would be marked incorrect, even though it points to a more flexible and perhaps more creative understanding of what a tool is.

Paul Baltes, one of the originators of life span theory
and a member of the MIDUS I team, thought wisdom meant expertise in everyday life, what he referred to as “wisdom in action.” In 1980, Baltes joined the Max Planck Institute for Human Development in Germany to help found the Berlin Wisdom Project and conduct research on what it means to be wise and how wisdom might be nurtured. His method was to pose hypothetical situations: “A 15-year-old girl wants to get married right away. What should one/she consider and do?” The wise response, according to Baltes, is: “Marriage is typically not a good idea for 15-year-olds, but there are certain instances—if the girl is an orphan, say, or has a terminal illness, or lives in a different historical period or culture than our own—when marriage might work out, depending on the girl's state.” Observers may question just how meaningful these vignettes are, but they do illustrate an expanded notion of brainpower. In addition to intelligence, Baltes's definition of wisdom emphasized an individual's awareness of particular historical circumstances as well as the vast range of values and cultures that co-exist with one's own. The Wisdom Project
chose the early 60s as the age when wisdom most likely peaked. Baltes, a frequent collaborator of Brim's who died in 2006, believed that in the brain experience could outrun biology. The notion that the brain is capable of continually changing in response to practical knowledge mirrors the underlying assumption of their life span theories that experience shapes one's psychological development.