Functional MRI tracks risk alert

You're doing 50 mph in a 35-mph zone when you think you notice a police car. Your heart rate speeds up and your foot automatically moves to the brake. The anterior cingulate cortex may have prompted that speedy reaction, according to researchers at Washington University in St. Louis.

Sixteen subjects were studied with functional MRI while they pushed buttons in response to a series of visual cues. But investigators threw in some distractions, which resulted in a greater error rate associated with a particular visual cue. When that cue flashed on a screen, participants immediately became anxious, even before they could respond. Activity in the anterior cingulate cortex was strongest at those times (Science Feb. 18, 2005;307[5712]: 1118-1121).

While a healthy anterior cingulate cortex may help people avoid speeding tickets, knowledge of how the region works can improve understanding of people with schizophrenia, who may have an underactive ACC, and those with obsessive compulsive disorder, in whom it may be overactive.