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October 14, 2005 Science Magazine
A Lying Matter
Rather than longer noses, compulsive liars have about 25% more white matter in the prefrontal cortex, according to a study at the University of Southern California (USC) in Los Angeles.
   Researchers have long known that brain activity changes, causing peripheral symptoms such as sweating, during the act of lying. But the new study is the first to look at pathological liars and whether they exhibit differences in brain structure.
   A team led by Adrian Raine and Yaling Yang, neuroscientists at USC, used magnetic resonance imaging to compare brain structures in 12 pathological liars, 16 people with antisocial problems other than lying, and 21 normal controls. The liars had more white matter--the fibers connecting neurons--in areas behind the forehead responsible for personality, judgment, and complex planning, the team reports in the October issue of the British Journal of Psychiatry.

Cutaway skull showing brain of chronic liar.
CREDITS: YALING YANG/USC

   Raine says more white matter implies more neural connectivity. That, he speculates, may facilitate lying, which is "harder than telling the truth." But the liars also had about 15% less gray matter in the region, meaning they have fewer neurons--possibly relating to "disinhibited, antisocial behavior," says Raine.
   The study may have "profound consequences for the way we view immoral [behavior]," says Sean Spence, a psychiatrist at the University of Sheffield, U.K., because it shows that a fundamental moral quality "is constrained by biology." Whether lying changes the brain--or whether brain peculiarities make one more prone to lying--is still an open question.

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