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Why the Giggles Make Us Smile

Laughter and cheers cause a buzz of activity in brain regions that control facial movement
Guys laughing



© ROYALTY-FREE/CORBIS
Sports fans pack stadiums and bars to support their favorite teams. Similarly, comedy lovers get a kick out of going to comedy clubs and theaters. These sorts of activities--sharing a laugh or in a game victory--are classic bonding experiences. Previous research has shown that mirror neurons in our brains react to visual and verbal cues by trying to copy facial gestures and movements observed in others. A new study, published in this week's Journal of Neuroscience, shows that our brains are also wired to react to nonverbal sounds--especially positive ones.

A team led by Sophie Scott, a neuroscientist at University College London, used functional magnetic resonance imaging (fMRI) to determine the neural processing of vocal cues associated with four emotions: amusement, triumph, fear and disgust. Twenty subjects, while lying in an fMRI machine, listened to two-and-a-half second snippets of sounds conveying emotions: from a cheery "ha ha" or enthusiastic "woo hoo") to a fearful "aaah" and a grumpy "blech." In response to hearing the sounds, subjects not only showed activity in the region of the brain believed to process sound, but also in motor parts. The premotor cortical area--specifically the left posterior inferior frontal region--has previously been linked to the control of facial movements. And, according to Scott, these are the parts of the brain researchers would expect to be activated if someone "were going to make the actual facial expression or if they were going to make a noise."

When Scott's group looked more closely, however, they discovered that the various sounds elicited different responses. "What we basically see is that as the sounds get more positive," Scott reveals, "we get more activation in the lateral premotor areas and extending into the motor cortex bilaterally." She notes that the upbeat sounds were associated with fun activities such as watching sports or comedy shows. These amusement sounds "seem to have a different function than the negative emotions," she explains. "With things like laughter, we don't tend to just have an emotional experience. What you tend to do is, you see somebody laughing and you actually want to join in."

Marco Iacoboni, a neuroscientist at the University of California, Los Angeles, agrees that these positive emotions are more helpful for cohesive social interactions, noting that laughter and triumph aid in "empathy and for tuning in" to togetherness. About the study's findings as a whole, he notes: "It totally expands our understanding of neural mechanisms for mirroring," extending it beyond just responses to visual stimuli

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