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A Nicaraguan actor performs a typical Nicaraguan gesture: 'I swear [promise],' one of several gestures test subjects viewed while researchers measured their neural activity. ((PLoS One))

Joining the thumb and index finger while spreading out the remaining fingers may mean "OK" for Americans, but how the gesture is perceived may change as people from different cultures interact, a new study has found.

Researchers at UCLA studying the response to hand gestures say brain activity depends on both the conveyor of the message and the gesture itself.

In a study published Wednesday in the Public Library of Science journal PLoS One, UCLA researchers Istvan Molnar-Szakacs and Marco Iacoboni found subjects responded more strongly to cultural gestures when they were performed by an actor of a similar culture.

"Culture has a measurable influence on our brain and, as a result, our behavior," Molnar-Szakacs said in a statement. "Researchers need to take this into consideration when drawing conclusions about brain function and human behavior."

When humans and other primates witness a known hand gesture, their brains become active in the same areas as if they had actually made the gesture themselves.

"We are the heirs of communal but local traditions," Iacoboni said in a statement. "Mirror neurons are the brain cells that help us in shaping our own culture."

These mirror neurons are a key component in explaining how the brain helps us learn from our environment and communicate with those around us. They play a key role in memory, empathy and general cognition.

Test subjects observed videos of two actors — one American and one Nicaraguan— making a series of wordless hand gestures. Some of these hand gestures were those common in American culture, such as the gestures for "OK" or the rubbing of bothindex fingers to indicate "shame on you." The two actors also performed gestures significant in Nicaragua, as well as a series of neutral gestures derived from sign language.

As expected, respondents had higher brain response when exposed to gestures they understood. But they also had a higher response when viewing hand gestures performed by an actor they would normally associate with those gestures.

"All in all, our research suggests that with mirror neurons, our brain mirrors people, not simply actions," said Iacoboni.