April 28, 2008

Brain Responds to Changes in Social Standing

Headshot photos of 3 people, one ranked with 3 stars, one with 2 stars and the last with 1 star and the caption 'YOU MOVED UP!' near the bottom

Scientists have identified brain regions that react to changes in how people perceive their social ranking. The findings could have implications for understanding how health and behavior are affected by social status.

Researchers have long known that many species, including humans, have social hierarchies that affect mating and other behaviors important for survival. A growing body of evidence suggests that social ranking can also influence both physical and mental health. Human studies have hinted that inferior status can raise the risk for cardiovascular disease and earlier death. Yet little is know about how the human brain translates social factors into health risks.

To learn more about how the brain responds to social competition and rankings, Dr. Caroline Zink and her colleagues at NIH’s National Institute of Mental Health (NIMH) created an artificial social hierarchy. They asked 72 volunteers to play an interactive computer game while their brains were analyzed with functional MRI. Players were told they were not in direct competition with others. But through several rounds of games, the volunteers were repeatedly shown photos of both a higher-ranked (3-star) and a lower-ranked (1-star) person, supposedly playing simultaneously in another room. In fact, all the games were rigged, and the 2 other people were simulated.

As described in the April 24, 2008, issue of Neuron, the perceived hierarchies seemed to bring out a competitive streak in the volunteers, even though they were instructed to ignore the other players’ rankings. Simply viewing an image of a higher-ranked player activated an area near the front of the brain that seems to help size people up, making interpersonal judgments and assessing social status. Photos of inferior players led to significantly less activation in these regions.

In the first round of games, the researchers kept the players’ rankings stable. But in the second round, the rankings shifted after some games. This unstable hierarchy—where players might gain or lose status—led to activation of brain circuits that process the intentions and motives of others. When volunteers performed better than a higher-ranked rival, the brain turned on regions that control action planning. When volunteers were supposedly bested by an inferior player, activated brain regions were associated with emotional pain and frustration.

The participants who reported having the most positive mood while highly ranked also had greater activation of emotional pain circuitry when their status was threatened. In other words, those who felt more joy when they won also felt more pain when they lost.

“The processing of hierarchical information seems to be hard-wired, occurring even outside of an explicitly competitive environment, underscoring how important it is for us,” Zink said. In follow-up studies, she and her colleagues plan to examine the brain’s response to social hierarchy in patients who have mental illnesses like schizophrenia or autism, which are marked by social and thinking deficits.

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