Brain scans might one day replace polygraphs as the best lie detectors, new research suggests.

Different parts of the brain are activated by lying versus honest statements, two studies have found, and lies create activity in more locations. The differences can be measured by functional magnetic resonance imaging (fMRI) scans.

"There may be unique areas in the brain involved in deception that can be measured with fMRI," said Temple University researcher Scott Faro, who led a study announced today. "We were able to create consistent and robust brain activation related to a real-life deception process."

In the research, six volunteers were asked to shoot a toy gun with blanks and then lie about their participation. Four volunteers who did not shoot were asked to tell the truth about what went on.

Scientists did a polygraph and fMRI on each. In all questions, both tests distinguished between truths and lies. Importantly, the fMRI revealed more areas of the brain firing when a person lied.

The results were presented today at a meeting of the Radiological Society of North America. The study was small, however, and more research is needed, Faro and his colleagues say. The conclusions nonetheless are similar to a comparable study announced in July by researchers at the Medical University of South Carolina.

Polygraphs can be fooled, scientists say, because they measure arousal, not necessarily deception. A polygraph records respiration, blood pressure and the skin's ability to conduct electricity, something that increases when you perspire.

A 2002 study by the National Academy of Sciences concluded that the federal government should not rely on polygraph examinations for weeding out spies or other security risks among current or prospective employees.

Polygraph tests are based on "on weak scientific underpinnings," the Academies report stated.

Faro said his new study suggests there is a consistency in brain patterns, detectable by fMRI, that might go beyond conscious control.

"We have just begun to understand the potential of fMRI in studying deceptive behavior," Faro said. "We plan to investigate the potential of fMRI both as a stand-alone test and as a supplement to the polygraph with the goal of creating the most accurate test for deception."