fMRI documents risk anticipation center in the brain

You're doing 50 mph in a 35 mph zone. Suddenly, out of the corner of your eye, you notice what look like the black-and-white markings of a police car. Your heart rate speeds up, and you automatically take your foot off the gas pedal. The anterior cingulate cortex region in the brain may have prompted that speedy reaction, according to researchers at Washington University in St. Louis.

Investigators there used functional MR imaging to document increased activation in the anterior cingulate cortex during situations in which we perceive a high likelihood of error.

"Our brains are better at picking up subtle warning signs than previously thought," said Joshua Brown, Ph.D., a research associate in psychology at Washington.

In a two-phased study published in the February issue of Science, Brown and colleagues used fMRI to examine participants responding to a series of visual cues on a computer screen. They first performed a behavioral study on 18 subjects to develop a computer model to predict patterns of brain activation during the experiment. They then verified the computer model predictions using fMRI on 16 subjects.

The visual cues included a series of white or blue dashes that quickly changed into small arrows pointing to the right or left. Study subjects pushed certain buttons depending on the direction of the arrow. To introduce conflict, the researchers would occasionally bring in a larger arrow after the small arrow, indicating that subjects were to push the opposite button.

The time spacing between showing a small arrow followed by a large arrow was then modified until there was a 50% error rate associated with an initial blue dash compared with a 4% error rate associated with an initial white dash.

Once subjects began to learn that blue dashes were more likely to lead to high error rates, just the sight of the blue dash was enough to increase fMRI activity in the anterior cingulate cortex, according to the researchers.

While the study results don't directly show how to treat certain disorders, they do shed light into how this part of the brain works in healthy individuals, Brown said.

The findings could serve as a basis for better understanding of certain mental illnesses, such as schizophrenia and obsessive-compulsive disorder. Someone with schizophrenia, for instance, may have an underactive anterior cingulate cortex that would not pick up on societal cues about inappropriate behavior, Brown said.

Conversely, this area of the brain may be overactive in someone with obsessive-compulsive disorder, identifying all situations as having a high likelihood of error, causing the person to act too cautiously.

The investigators plan to use fMRI with computer modeling in future studies, including explorations into how much the magnitude of the consequence of an error affects brain activation, Brown said.

For more information from the online Diagnostic Imaging archives:

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National Institutes of Health builds network to support brain research

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