Why couldn't Mick Jagger "get no satisfaction"?
"He just wasn't trying hard enough," says Gregory Berns, a neuroscientist and psychiatrist at Emory University in Atlanta.
Berns should know. As a scientist and author of "Satisfaction: The Science of Finding True Fulfillment," scheduled to arrive in bookstores this week, Berns has examined satisfaction from the inside out -- looking at the exquisite interplay between brain structure and experience -- and from the outside in. He has studied people who engage in an array of activities, including solving crossword puzzles, running ultra marathons and engaging in sadomasochistic sex. The explanation for why some people pursue these activities, and why they find them satisfying, can be found deep inside the brain.
"I used to think that we want pleasure and happiness, and now I don't think that is the case at all," says Berns. "Happiness and pleasure are passive emotions, and you don't have to do much to achieve those feelings. I think of satisfaction in terms of a much more active component. Nature never said you had to be happy. It said you had to learn to adapt to the world."
Satisfaction is one of a number of positive emotions such as joy, love and happiness to which psychologists and neuroscientists have only recently started paying attention.
Dubbed "positive psychology" by University of Pennsylvania psychologist Martin Seligman in 1998, the focus of this work contrasts sharply with the preoccupation with dysfunction and emotional pain that has dominated psychology and psychiatry for much of its history.
"People who study positive psychology really are interested in what makes life worth living," says Shelly Gable, professor of psychology at UCLA.
Until recently, this research has been largely focused on behavior, on self-reports of emotional states and various other approaches to cognitive assessment. In the words of psychiatrists, the observation has been much more phenomenological than biological.
A small group of neuroscientists such as Berns has tried to discover what happens in people's brains during such nuanced emotional experiences as happiness, satisfaction, motivation, even social conformity. It is relatively simple to frighten people who are undergoing a brain scan and see what parts of their brains light up; it's quite another to contrive a study that will explore these subtle emotional states.
From his and others' neuroscientific findings, Berns has concluded that satisfaction requires two important ingredients that nature has designed our brains to crave: novelty and challenge. But what points on our intricate cortical map, what neurotransmitters and hormones actually transform a novel and challenging experience into the gratifying state of satisfaction?
Berns has concluded that the answer lies in a generous portion of the neurotransmitter dopamine and a surprising dose of the so-called stress hormone cortisol, bathing a slab of brain structure called the striatum.
The functions of these structures can be found in any medical textbook on the brain. The striatum, a pair of arches located at the center of the skull, acts as a kind of air traffic control center in our brains, receiving loads of information from the frontal lobes. It also has the largest number of dopamine receptors of any region in the brain.
Dopamine neurons are concentrated near the pituitary gland and the brain stem, and are released when something unexpected or novel occurs. Because the highest density of receptors is in the striatum, the neurotransmitter is drawn to that region of the brain, which then decides what information it should pay attention to and what it should ignore.
Our brains are rich with dopamine during adolescence, a period of life known for its impulsive behavior and wild enthusiasm. As we grow older, though, dopamine requires a greater stimulus to get flowing. That is why, Berns thinks, we need to give it some inspiration through activities that are novel and challenging.
Dopamine and the striatum long have been associated with general feelings of happiness and well-being. But Berns is not simply looking at happiness; he is trying to tease out the specific biology of satisfaction, and for that he went one step further in examining the function of the stress hormone cortisol.
Cortisol is released when the body is exposed to a physically, mentally or psychologically stressful situation. And because stress has been linked to medical conditions including heart disease and depression, the conventional medical wisdom is that stress should be avoided.
Berns doesn't agree with this view of the dangers of cortisol. He suggests that cortisol has a number of beneficial qualities -- for example, it can gear up the body to run or fight or do whatever it needs to deal with the stress. Cortisol levels rise with vigorous physical exercise and under the right circumstances can elevate mood, increase concentration and even improve memory.