An explanation has finally been found for the feeling of physical pain that accompanies the emotional pain of social rejection. Apparently, being excluded from a group results in the same pattern of brain activity associated with physical pain, investigators from the University of California, Los Angeles (UCLA), reported in the October 10, 2003, Science. The investigators made that discovery when they used functional MRI (fMRI) to monitor the brain activity of 13 undergraduates while the students played a computer game designed to make them feel excluded. Social exclusion produced significantly greater activity in the dorsal anterior cingulate cortex, an area of the brain previously shown to become more active with physical pain.

“Going back 50,000 years, social distance from a group could lead to death,” said Naomi Eisenberger, a PhD candidate in Social Psychology at UCLA. Thus, “we may have evolved a sensitivity to anything that would indicate that we are being excluded, and that automatic alarm may be a signal to re-establish social bonds before harm befalls us.”

The students in the study, who played a virtual ball-tossing game while undergoing their fMRI scans, were led to believe that they were playing with two other students. In reality, they were playing with a preset computer program.

Initially, the students were told that technical difficulties were preventing them from being connected to the system, so they could only watch the other “players” when the game started. The intent was to monitor brain activity with the students unable to participate but not believing that they had been intentionally excluded. Further fMRI scans were obtained with the students fully participating in the game and with them being excluded. In the exclusion scenario, the students were thrown the ball seven times and then the computerized players threw only to each other for the rest of the fMRI scan (about 45 more throws).

The students reported feeling ignored and excluded when the computerized players left them out of the ball-tossing game, and those reports showed a positive correlation with the increase in dorsal anterior cingulate cortex activity on fMRI at that time. This finding paralleled previous studies of physical pain, emphasized the investigators.

The anterior insula and right ventral prefrontal cortex also became more active when the students were intentionally excluded. Although increased anterior insula activity was not significantly associated with self-reported distress from being excluded, a negative relationship emerged between such distress and the rise in right ventral prefrontal cortex activity. Furthermore, there was a negative association between the greater right ventral prefrontal cortex and dorsal anterior cingulate cortex activity that occurred on fMRI with intentional exclusion. These findings suggest that the right ventral prefrontal cortex “may play a self-regulatory role in mitigating the distressing effects of social exclusion,” the investigators speculated.

Interestingly, the dorsal anterior cingulate cortex seemed to mediate the negative association between right ventral prefrontal cortex activity and the distress that the students felt when they were intentionally excluded. When the investigators controlled for anterior cingulate cortex activity, the association was no longer significant—a finding similar to the results of prior studies of the self-regulation of physical pain.

It was not possible to assess any association there may have been between dorsal anterior cingulate cortex activity and emotional distress from exclusion due to “technical difficulties” without letting the students know they had been misled, so the investigators refrained from such an analysis. However, they did observe greater dorsal anterior cingulate cortex activity but not increased right ventral prefrontal cortex activity under these conditions.

The implication: The dorsal anterior cingulate cortex registered the exclusion but did not generate a self-regulatory response. “Explicit awareness of exclusion may be required before individuals can make appropriate attributions and regulate the associated distress,” the investigators suggested.

—Timothy Begany

Suggested Reading
Eisenberger NI, Lieberman MD, Williams KD. Does rejection hurt? An fMRI study of social exclusion. Science. 2003;302:290-292.
Panksepp J. Neuroscience. Feeling the pain of social loss. Science. 2003;302:237-239.
Sawamoto N, Honda M, Okada T, et al. Expectation of pain enhances responses to nonpainful somatosensory stimulation in the anterior cingulate cortex and parietal operculum/posterior insula: an event-related functional magnetic resonance imaging study. J Neurosci. 2000;20:7438-7445.

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