Part of the brain may be able to sense danger and provide early warnings to help humans escape, according to a study that provides new evidence of the brain’s “sixth sense.”
In the study, researchers found that a region in the brain known as the anterior cingulated cortex (search) (ACC) may monitor subtle changes in the environment — even without people being aware of it — and use this information to adjust behavior.
Previous studies have suggested that activity in the ACC, which is located in the front of the brain, increases when people have to make a difficult decision or after they make a mistake.
"But now we find that this brain region can actually learn to recognize when you might make a mistake, even before a difficult decision has to be made,” says researcher Joshua Brown, PhD, a research associate in psychology at Washington University in St. Louis, in a news release. “So the ACC appears to act as an early warning system; it learns to warn us in advance when our behavior might lead to a negative outcome, so that we can be more careful and avoid making a mistake."
Researchers say the ACC has been studied intensely in recent years because it plays an important role in the brain’s processing of complex and challenging tasks.
In this study, researchers looked at whether the role of the ACC goes beyond detecting errors or a state of conflict to detecting the likelihood of making an error. To test this theory, researchers conducted an experiment that required healthy young people to respond to a series of cues on a computer screen.
Simulating Conflict to Study the Brain
The participants had to quickly push one of two buttons on a keyboard depending on the direction of an arrow flashed on the screen. To simulate conflict, researchers occasionally inserted a second, larger blue arrow that required the participants to switch gears and push the opposite button.
According to the researchers the idea was that you eventually get to the point where you have competing tendencies — to push the right or left buttons — both are active in the brain at the same time, which creates conflict.
Researchers adjusted the delay time before the larger arrow appeared over many trials so that each participant eventually pushed the wrong key about 50 percent of the time.
Scans of the participant’s brain activity during the tasks showed that eventually just showing the blue color associated with the larger arrow was enough to spark activity in the ACC, and this effect strengthened over time.
Researchers say the findings show that the ACC had “learned” the significance of the blue cue and had begun to adjust behaviors accordingly, at least on a subconscious level.
“It appears that this area of the brain is somehow figuring out things without you necessarily having to be consciously aware of it," says Brown. "It makes sense that this mechanism exists because there are plenty of situations in our everyday lives that require the brain to monitor subtle changes in our environment and adjust our behavior, even in cases where we may not be necessarily aware of the conditions that prompted the adjustment. In some cases, the brain's ability to monitor subtle environmental changes and make adjustments may actually be even more robust if it takes place on a subconscious level."
New Clue for Mental Disorders?
Abnormalities in the ACC are also linked to many serious mental problems, such as schizophrenia and obsessive-compulsive disorder (OCD), and researchers say their findings may offer new clues about these disorders.
"Our results suggest how impairment of the ACC mechanisms in schizophrenia can lead to breakdowns in the early warning system, so that the brain fails to preempt or control inappropriate behavior," says Brown. "On the other hand, in individuals with obsessive-compulsive disorder, the ACC might warn of an impending problem even when no problem is imminent."
By Jennifer Warner, reviewed by Brunilda Nazario, MD
SOURCES: Brown, J. Science, Feb. 18, 2005; vol 307: pp 1118-1121. News release, Washington University in St. Louis.
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