Bliss and the Brain
A Society for Neuroscience Briefing

While many researchers have tracked the molecular mechanisms of depression, fear and anger, they mostly ignored happiness. In recent years, however, a cadre of scientists has turned their focus to this positive emotion. Studies indicate that pleasant feelings are associated with certain brain responses that appear to vary in intensity between individuals. The research may lead to new ways to pump up happiness in unhappy humans.

A warm breeze enters the window. A jogger trots by with his black lab. Purple and yellow crocuses bloom below.

You are happy.

Scientists are just now finding out how the brain enters into this idyllic picture. One line of research indicates that certain activity in the front part of the brain, the prefrontal cortex, is essential for joy. And perennial optimists appear to have pumped up activity in this brain area. The new research is leading to:

A better understanding of how the brain contributes to overall emotion. Insights into why some people are happier than others.

New methods to boost pleasant feelings in human beings.
Brain-damaged patients provided some of the first clues on how the brain handles positive emotion. For example, researchers found that patients who were prone to pathological laughing or bursts of euphoria tend to have damage on the right side of the brain.

In contrast, patients who were prone to pathological crying or depression tend to have damage on the left side of the brain. The studies suggest that normally the left side plays a role in happy feelings, while the right side aids negative feelings.

Research in healthy individuals backs this theory and provides evidence that the prefrontal cortex is key (see illustration below). For example, measures of brain activity indicate that pleasant film clips, pleasant tastes and cash incentives increase left-side brain activity near the forehead. Unpleasant film clips, unpleasant tastes and a threat of cash loss raise right-side brain activity near the forehead.

Furthermore, studies suggest that certain people's ability to see life through rose-colored glasses links to a heightened left-sided brain function. A scrutiny of brain activity indicates that individuals with natural positive dispositions have trumped up activity in the left prefrontal cortex compared with their more negative counterparts.

Infants even show this difference. For example, babies who tend to cry when separated from their mothers also tend to have lower left and higher right-sided prefrontal activity compared with non-wailers.

Evidence suggests that the left-siders may better handle stressful events on a biological level. For example, studies show that they have a higher function of cells that help defend the body, known as natural killer cells, compared with individuals who have greater right side activity. Left-sided students who face a stressful exam have a smaller drop in their killer cells than right-siders. Other research indicates that generally left-siders may have lower levels of the stress hormone, cortisol.

Scientists currently are investigating how genes may account for the different variables. Some studies that examined general well-being already indicate that genes possibly explain about 40 to 50 percent of people's differing happiness levels.

A recent evaluation of the happiness levels of over 100 chimps as well as their family history determined that genes play a large role in the emotion. Human twins who share the same genetic makeup are more similar in how happy they are compared with twins who do not share the same genetic makeup, according to another report.

Could this research suggest that you'll have to settle for a life of mild satisfaction? Do the signs of summer make you happy, but not as happy as that person with different genes and more left-sided brain activation? Will life's stressors affect you more than left-siders?

Cheer up.

Researchers suspect that you have some control. For one, certain techniques may be able to alter your brain circuitry. An ongoing study is testing whether a life of meditation among Buddhist monks affects their prefrontal brain activation. Other research is examining the brain and health effects of an eight-week meditation program on biotechnology employees.

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