Pinpointing the hubs of emotions

Scans: Researchers are discovering what goes on in your head when you feel strong emotions.

Medicine & Science

July 05, 2004|By Robert S. Boyd | Robert S. Boyd,KNIGHT RIDDER/TRIBUNE

Love chocolate? Hate being snubbed? Turned on by sexy pictures? Turned off by an ugly face?

Scientists are making rapid strides in identifying where and how your brain handles such feelings, from the overwhelming flush of romantic love to the shivers a favorite piece of music sends down your spine.

Brain researchers are using technologies that measure blood flow, electromagnetic radiation and other events going on in your head when you experience strong emotions. They believe their work can help deal with problems such as obesity, drug addiction, sex crimes and mental disease.

Their effort has also inspired a new field of "behavioral finance" or "neuromarketing," which studies what happens in the heads of consumers, investors and gamblers as they decide whether and how much risk to take.

"Studies of the brain are teaching us how, why and when investors make decisions to buy and sell," said Richard Peterson, a psychiatrist and financial consultant in San Francisco.

Commercials

Advertising agencies are beginning to use brain imaging to study what goes on in consumers' minds when they look at a product or an ad, Peterson said. The goal is to help create more effective commercials.

Neuromarketing worries critics such as Gary Ruskin, the executive director of Commercial Alert, an organization founded by Ralph Nader that works to block advertising in schools and public areas.

"It is wrong to use a medical technology like brain scans for marketing," Ruskin said. More effective marketing of food or tobacco products could lead to more obesity or smoking, he cautioned.

Brain researchers' most powerful tools are Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI), complementary technologies that reveal the brain at work. Both are found in most hospitals and neurological laboratories.

In the PET system, people lie in a scanner while a mild radioactive fluid traces the flow of blood through their brain. More blood flows to brain cells, or neurons, that are most active at the time. A radiation detector identifies the cells that are turned on when a person experiences emotions such as fear, hunger, pleasure or disgust.

An fMRI, in contrast, uses powerful magnets and radio waves to create pictures of the brain in action. The extra blood flowing to activated brain cells carries more oxygen, which alters the magnetic field in that area. Radio waves pin down the exact location. Color images - red for high intensity, yellow, green and blue for lower levels - identify which brain structures are busier than others.

An even newer technique is magnetoencephalography (MEG), which identifies tiny magnetic fields generated by electrical activity in neurons. MEG can time events to thousandths of a second, far more precisely than fMRI.

Structures

Studies have shown that certain brain structures play relatively greater roles is particular emotions. For example, the amygdala, a walnut-size organ buried deep in the brain, is associated with fear.

Researchers point out that these structures don't act in isolation. Rather, the brain cells in each area influence - and are influenced by - other regions through networks of circuits linking billions of neurons.

Antonio Tataranni, a nutrition expert at the National Institutes of Health's branch office in Phoenix, is trying to unravel the connections between human brain activity and obesity. He found that six regions in the brains respond differently depending on whether the subjects were hungry or full, fat or thin.

Tataranni took PET scans of volunteers after they had gone without food for 36 hours, and again after a hearty meal. He discovered significant changes in the way six different sites in the volunteers' brains responded to hunger and fullness.

Of interest were 11 formerly obese men and women. Tataranni said this group is "at high risk for relapse" because their brain scans resembled those of fat people more than thin ones. "We are now working on the vastly more important and complicated questions of which of these neural differences may cause obesity in the first place," Tataranni said.

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