Mind Readers

Scanning technology promises to map the brain's pathways, but some fear its ability to expose a patient's secrets and lies.

Science & Research

December 10, 2004|By Dennis O'Brien | Dennis O'Brien,Sun Staff

As a research tool, it's a window into the brain with the potential to improve and even save lives. Functional magnetic resonance imaging helps scientists understand how we function every day, how we learn and remember faces, how we perceive the world around us.

Parkinson's disease, Alzheimer's, schizophrenia and the effects of cocaine, nicotine and other drugs are all less mysterious after a decade of fMRI studies.

But researchers are also using brain scan technology to probe what some ethicists consider troubling areas -- digging into our heads to ferret out our urges, motives and prejudices.

fMRI studies have detected signals that could help label an individual's personality, tell whether a drug addict is prone to relapse, pinpoint signs of racial prejudice or show how a pedophile's brain reacts to the sight of young boys.

Last week, a radiologist at Temple University School of Medicine announced that fMRI shows potential for use as a lie detector. Two other recent studies have reached similar findings.

The technology is not yet sophisticated enough to determine with great reliability if someone is fabricating a story or yearning to take drugs or engage in abusive sex. But some critics worry that fMRI, or some future scanning technology, will reach a point where it invades our privacy and opens doors to abuse.

As they do now with polygraphs, employers could require job candidates to submit to brain scans, and police investigators could request them from criminal suspects.

"In principle, very personal information could be obtained from scanning people," said Martha Farah, a psychologist and director of the Center for Cognitive Neuroscience at the University of Pennsylvania. "It's not the case of being able to look at any one scan and say this person fits this profile. But I think we're not that far away from it."

Researchers defend their work, arguing that test subjects volunteer for the studies and that fMRI work is designed to increase understanding of how the brain functions. Any future technology, they say, would improve the tools that they now use to probe illnesses, test theories about brain-related problems and even detect liars.

"Should we investigate a new technique, this different way of doing something, to see if it's possibly a new gold standard? I think the answer is yes," said Dr. Scott Faro, the Temple radiologist who released the fMRI-as-polygraph findings at a radiology conference last week.

How do the scans work? Researchers have known for years that specific regions of the brain are activated by stress, pleasure and concentration. They have also identified areas that control speech, memory, learning and physical movement.

For example, in the mid-1990s, scientists discovered that cells in the prefrontal cortex are instrumental in remembering a face or a voice. They also know that the amygdala, an organ near the bottom of the brain, is activated by fear.

But specific brain activities -- and which stimuli activate which areas of the brain -- can vary from one individual to the next. Regions of the brain don't act in isolation, either, but influence one another through networks of circuits linking billions of neurons.

"When you do any tests, you see activity in many common areas, and reading the signals is extremely complicated," said Dr. Michael Kraut, a radiologist at the Johns Hopkins School of Medicine.

Scientists use several tools to probe the brain, including computerized tomography (CT scans) and positron emission tomography (PET scans).

But many experts say fMRI is their most productive technology, employing powerful magnets and radio waves to create detailed, fixed images which -- unlike traditional X-rays -- can pinpoint changes in soft tissue. The image is created by detecting changing radio frequency signals within a magnetic field that envelops a patient who lies on a table inside a cylindrical tube.

Developed in the early 1990s, functional MRI identifies regions in the brain where blood flow increases when a subject performs a particular task, such as viewing a picture, touching a fingertip or responding to a question. The process of carrying oxygen-rich blood to brain cells alters the magnetic field within specific regions, and the radio waves help pin down exact locations.

Color images -- red for high intensity, yellow, green and blue for lower levels -- identify which brain regions are busier than others. Researchers have used the technology for some unusual studies.

Two years ago, for example, Stanford University scientists showed that the amygdala regions of extroverts and optimists tended to become activated more often when they viewed happy facial expressions.

In a 2001 study, researchers at the Central Institute for Mental Health in Mannheim, Germany, found that images shown to a convicted pedophile of young boys in underwear activated brain regions that were unaffected in normal test subjects.

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