Newswise — Researchers have determined how circuits in the frontal lobe of the brain work together to keep attention on track and minimize errors, a finding that could hold keys to a better understanding of attention disorders. The research appears in the Feb. 13 issue of the journal Science.
"The frontal lobes have long been thought to play a role in regulating attention, but it has been unknown how the brain monitors and assesses the need for increased attentiveness, or how the frontal lobes interact to maintain attention," said Cameron S. Carter, professor of psychiatry and psychology at UC Davis School of Medicine and Medical Center and senior author of the Science article.
"We were able to show in our functional MRI study that the brain is especially sensitive to states when it is being pulled towards making more than one response at a time, and that it uses these states to identify near misses as well as actual errors. We showed that one region of the frontal lobes detects conflicting responses, and another region then responds by ramping up attention. Our study showed in considerable detail how these two regions work together to keep attention on track and minimize error rates."
In the study, Carter and his colleagues used functional magnetic resonance imaging, or MRI, to analyze brain activity in volunteers as they performed a tricky color-naming test. The test asks study subjects to read color names out loud. Some of the names are printed in matching ink — the word red in red ink, for example — but others are printed in mismatched ink — the word green in yellow type, for instance.
Naming the colors takes longer, and mistakes are more common, when name and color don't match. Using MRI, the researchers were able to map the increased mental effort involved in naming mismatched colors to the anterior cingulated cortex or ACC. When the test subjects encountered conflicting color names, their ACCs were significantly more active than when they encountered matching color names.
Added to previous research, the new MRI findings constitute strong evidence that the ACC is activated in response to situations requiring heightened attention and thought, according to Carter, a psychiatrist specializing in imaging cognitive functions of the brain.
However, the researchers don't believe the ACC produces increased attention on its own. In their MRI studies, the investigators found that another region of the brain, the prefrontal cortex, kicks into high gear right after the ACC lights up.
"When increased attention is needed, it appears that the ACC signals the prefrontal cortex to execute an increase in cognitive control," Carter says.
Working together, the two brain regions appear to facilitate rapid attention adjustments. After a difficult trial, the study subjects performed the color-naming test faster and more accurately — with less activity in the ACC and more activity in the prefrontal cortex — suggesting these regions of the brain are recruited in situations where heightened attention is required.
The new insights could lead to better understanding and improved treatments for disorders of attention such as attention-deficit disorder and schizophrenia, Carter said. While drugs are available to treat the delusions and hallucinations of schizophrenia, these medications have little impact on the severe attention problems associated with the illness. According to Carter, attention problems tend be the strongest predictor of how well individuals with schizophrenia will do in the community.
Researchers from five institutions collaborated on the study. In addition to UC Davis, the institutions are the University of Missouri-Columbia in Columbia, Mo.; the University of Pittsburgh in Pittsburgh, Pa.; Princeton University in Princeton, N.J.; and the University of Minnesota in Minneapolis.
Copies of all news releases from UC Davis Health System are available on the Web at http://news.ucdmc.ucdavis.edu
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