The findings are reported in a Rotman Research Institute/University of Toronto study to be published in the April issue of the international journal Brain. The Rotman is part of Baycrest Centre for Geriatric Care in Toronto and is ranked among the top brain research institutes in the world.

The study is the first to show that the frontal lobe plays a pre-eminent role in our ability to appreciate humor and have a good belly laugh. Previous studies have implicated the right hemisphere and frontal lobes in general.

"We always thought of humor as a defining human attribute, but an intangible part of our personality," says Dr. Prathiba Shammi, a graduate of the University of Toronto's department of psychology. "Now we know humor can be tested and scientifically scrutinized."

Dr. Shammi led the study, which was her doctoral thesis, with supervision from Dr. Donald Stuss, director of the Rotman Research Institute, vice-president of research at Baycrest, and professor of psychology and medicine (neurology, rehabilitation medicine) at the University of Toronto.

HUMOR STUDY:Humor responses to written and verbal jokes, and cartoons, were compared in 42 consenting adults aged 18 to 70. Half the group had a brain injury (a single focal brain lesion to either the frontal or nonfrontal regions) caused by stroke, tumor or surgical removal. Their responses were measured against a normal control group comparable in gender, age and education.

The study found that people with right anterior frontal damage had the most disrupted ability to appreciate written and verbal jokes -- and funny cartoons -- compared to the normal control group and people with focal lesions elsewhere in the brain. Individuals with right frontal damage chose wrong punch lines to written jokes and did not smile or laugh as much at funny cartoons or verbal jokes. They showed a preference for silly slapstick humor -- surprising but illogical endings which are the hallmarks of such acts as The Three Stooges.

Implications of the Rotman/University of Toronto study go beyond the localization of humor. Historically, the right frontal lobe was seen as a "silent brain region" that was not important in mediating higher cognitive functions.

"Through studies such as this one, we have evidence that the frontal region plays a critical role in higher cognitive functions such as humor, emotions and personality," says Dr. Stuss. "It receives information from almost all other brain regions and integrates multiple types of information."

The ability to understand and produce humor requires the concerted functioning of several cognitive processes: working memory (holding a piece of information in mind while you manipulate it); cognitive shifting (looking at a situation in different ways or from different perspectives) and abstract thinking.

Damage to the frontal lobes has been historically related to changes in personality, with striking effects on a person\rquote s ability to tell jokes and respond to humor. Such individuals often exhibit silly euphoric behavior, inappropriate laughter, and have an addiction to telling jokes that are usually inappropriate in content.

The Baycrest Centre for Geriatric Care is an academic centre fully affiliated with the University of Toronto. The study was supported by the Medical Research Council of Canada.

JOKE AND PUNCH LINE:(similar to one used in the Humor Study)

A teenager is being interviewed for a summer job.

"You'll get 50 dollars a week to start off", says his boss. "Then after a month you'll get a raise to 75 dollars a week."

PUNCH LINE SELECTION:

A. "I'd like to take the job. When can I start?" (straightforward logical choice)

B. "That's great! I'll come back in a month." (correct funny choice - original punch line)

C. "Hey boss, your nose is too big for your face!" (slapstick ending - right frontal damaged patients are likely to choose)

Story Source:

Materials provided by University Of Toronto. Note: Content may be edited for style and length.