Emotional stress lights up same region on fMRI as physical pain

November 6, 2003
By C.P. Kaiser

For centuries, the ache of a broken heart has been the domain of poets, while the pain of a broken bone has fallen to the care of doctors. But new research has found that they are neural cousins, showing activation of similar brain regions.

Functional MRI tracked the brain activation patterns of college students who thought they were being snubbed socially. The regions of the brain they used to soothe the pain of exclusion are known to be involved with dampening physical pain as well.

ìBecause of the adaptive value of mammalian social bonds, the social attachment system, which keeps the young near caregivers, may have piggybacked onto the physical pain system to promote survival,î the authors wrote. The study was published in the Oct. 10 issue of Science.

Naomi I. Eisenberger, Ph.D., and colleagues from the University of California, Los Angeles and Macquarie University in Sydney, Australia, believe that drugs can be targeted to these regions to help patients with extreme cases of social anxiety or depression.

The researchers acquired three fMR scans of nine female and four male college students while they played a virtual ball-tossing game. Participants were told they were playing with two other players also undergoing fMR scans, but they were actually playing against a preprogrammed computer.

For the first scan (implicit social exclusion), researchers told the participants that technical difficulties would allow them only to watch the other ìplayers.î The second scan was a control scan during which players interacted without any exclusionary conditions.

For the last scan (explicit social exclusion), participants received seven throws and were then excluded when the pre-set computer game stopped throwing the ball to them for the remainder of the scan (about 45 throws). Afterward, each student reported his or her level of distress at being excluded by the other players.

During both social exclusion conditions, the anterior cingulate cortex was more active in students who reported greater distress. During the explicit exclusion scans, however, the right ventral prefrontal cortex was also activated. This region, part of the conscious thinking system, helps regulate negative emotion. Specifically, it dampens negative effect, said coauthor Matthew D. Lieberman, Ph.D., an assistant professor of psychology at UCLA.

For this region to be activated, however, people must consciously think about negative emotion. In the explicit exclusion condition, participants knew that they were being intentionally excluded. As result, they thought about the social snub, which activated the ventral prefrontal area to help alleviate the pain, Lieberman said.

No such activation was needed during the implicit exclusion phase because participants attributed their lack of play to technical difficulties.

Researchers will next use fMRI to examine how the cingulate cortex response to a social exclusion stressor links up with the bodyís response to other stressors. When activated too frequently, biological bodily stress responses lead to major health risks, Lieberman said.

ìWe think those whose anterior cingulate is activated the most in response to social stressors may also show the biggest biological stress response in the body,î he said. ìThese people are more likely to be at risk in terms of adverse health outcomes.