Location of Sense of Humor Discovered

November 30, 2000

New York (MedscapeWire) Nov 30 -- Researchers may have found the location of sense of humor in the brain, according to their presentation at the 86th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA) in Chicago, Illinois.

Humor appreciation appears to be based in the lower frontal lobes of the brain, a location associated with social and emotional judgment and planning, according to imaging research. That might explain why people who have suffered strokes involving the lower frontal lobes of the brain may have alterations of personality which include loss of their sense of humor.

"A small part of the frontal lobes appears critical to our ability to recognize a joke," said Dean K. Shibata, MD, assistant professor of radiology at the University of Rochester School of Medicine in New York, and principal investigator of a study using functional magnetic resonance imaging (fMRI) to map activity in the brain while it is registering humor. "Although the purpose of humor and laughter is still largely unknown despite 2,000 years of speculation, having a sense of humor is a key part of our personalities and it can play a powerful role in balancing negative emotions, such as fear.

"There have been few studies of humor's place in the brain, but understanding the basis of positive emotions will likely be as helpful as understanding the negative ones," he said. "In the future, scans of brain activity might be used routinely by psychiatrists to assess patients who have mood disorders such as depression, which often is accompanied by a loss of humor. Using humor and other emotional stimuli might be helpful in bringing out functional brain abnormalities not shown by other techniques."

In the study, fMRI scans were performed on 13 people in a series of 4 exams. In the first exam, the people were asked to listen to laughter and laugh along internally. In the second, the people listened to the laughter but were asked not to laugh along. In the third scan, the people read written jokes, and in the fourth test they viewed a series of wordless cartoons.

Researchers found when the people laughed, activity was seen in the anterior supplemental motor area (SMA), a location near the top of the brain normally associated with planning movement and the initiation of speech. In contrast to laughter alone, when people viewed written jokes and cartoons, tasks which require more complex comprehension of humor, activity was most prominent in the ventromedial frontal lobe (VMF). All 4 scans showed activity in the nucleus accumbens, a small area in the base of the brain linked to pleasure and implicated as a key site in moderating drug addiction.

"As with almost any behavior, we found that laughing at a joke involves several parts of the brain," said Dr. Shibata. "Our imaging results show that while the ventromedial frontal lobe is likely the center for telling you what's funny, the accompanying laughter and feeling of mirth may be triggered by connections to other areas of the brain which are involved in motor control [moving the mouth] and positive emotions.

The anterior frontal lobes perform less obvious functions than other parts of the brain and in the past were regarded by some surgeons as expendable for daily functions, said Dr. Shibata. But as revealed by the outdated practice of frontal lobotomies, this area of the brain is responsible for much of our complex social and emotional behavior, he said.

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