If you’ve ever burst out in a fit of laughter from a friend’s off-the-cuff joke, you know it just feels different compared to a typical chuckle. New research argues that the same is definitely true for your brain.
Scientists in the UK and Italy examined the medical literature on laughter. They found evidence, particularly from epilepsy patients undergoing surgery, that truly spontaneous laughing involves largely different brain networks from those involved in voluntary, more conversational laughing. The research provides further insight into the nature of laughter and might even help us better understand how communication and social bonding have evolved in humans and other animals, the researchers say.
“Our review revisits a classic idea in neurology: that laughter—and likely many other socio-emotional behaviors—is controlled by two partially independent brain systems,” study author Fausto Caruana, a scientist with the National Research Council of Italy, told Gizmodo.
How the brain controls laughter
Some neurologists have long posited that laughing can be regulated by different brain networks. Unfortunately, it’s proven pretty hard to study laughing, particularly the spontaneous kind, in people using typical neuroscientific techniques, according to Caruana. As luck would have it, though, some brain doctors have been able to provoke gut-busting laughter in their patients without needing to be especially funny.
“My research group has collaborated for many years with the Epilepsy Surgery Center at Niguarda Hospital in Milan, where intracranial electrical stimulation is routinely performed in patients with drug-resistant epilepsy for clinical purposes. During discussions with neurologists, it emerged that in some cases electrical stimulation appeared to trigger sudden episodes of uncontrollable laughter,” Caruana said. “Intracranial stimulation offered a rare opportunity to explore its neural mechanisms directly in the human brain.”
Caruana and his team reviewed studies and reports involving epilepsy patients who underwent brain stimulation prior to surgery (this is used to pinpoint the regions linked to seizures) as well as animals.
From this data, the researchers made the case that spontaneous laughter is primarily governed by brain regions tied to motor control and emotional regulation, such as the pregenual anterior cingulate cortex and nucleus accumbens. Stimulating these regions to cause laughter also seems to boost people’s mood. Voluntary laughter, on the other hand, is tied to stimulation of the brain regions associated only with the motor control of laughing and smiling, and stimulating these regions alone doesn’t seem to boost people’s mood.
The team’s findings were published in the journal Trends in Neuroscience.
More left to learn
The researchers argue that spontaneous laughing might be a sign of an ancient brain pathway that isn’t exclusive to humans. They note that some non-human mammals are known to produce laughter-like vocalizations while seemingly engaging in play with others. Conversely, voluntary laughter is an important part of human conversation, often acting as a social lubricant.
“Understanding the distinction between spontaneous and voluntary laughter may therefore provide valuable insights into the evolution of communication and social cognition,” Caruana said.
Caruana also notes that some of the brain regions linked to spontaneous laughter are also linked to pain regulation, which may help explain why laughing can sometimes appear to have a pain-relieving effect.
“The evolutionary origins of this mechanism remain largely unknown and represent a particularly fascinating avenue for future research,” he said. “Understanding why a social vocalization became linked to pain regulation could reveal important principles about the evolution of both social behavior and emotional regulation.”
And there are likely many other things that we can learn about ourselves by better understanding how and why we laugh.
“Laughter is something of a Rosetta Stone for understanding a remarkably broad range of phenomena,” Caruana said.
Perhaps science will finally answer my deepest question about comedy: Why, oh why, is it so funny to see a man get hit in the groin with a football?
