For Women, Laughter Is a Just Reward
Brain's 'reward centers' show heightened activity if something is funny, study finds
By Amanda Gardner
HealthDay Reporter
TUESDAY, Nov. 8 (HealthDay News) -- The path to a good belly laugh may be strikingly different between women and men.
New research has found that men's and women's brains process humor in different ways, and that personality types may also play a distinctive role in how people perceive things as funny or not.
When shown a funny cartoon, women showed more activation in the parts of the brain involved with feelings of reward, as well as language processing and working memory.
The findings, appearing in this week's issue of the Proceedings of the National Academy of Sciences, have implications that are no laughing matter.
"It's been well-documented that women tend to experience symptoms of depression twice as much as men," said Eiman Azim, a doctoral student in neuroscience at Harvard University who conducted the study while an undergraduate student at Stanford University. "This type of questioning might help us understand why emotive processing in women is different, and why they experience depression differently."
The research may also one day help individuals with cataplexy, a condition in which a sudden loss of motor control is set off by strong emotions, especially humor, the researchers said.
Both the brain's prefrontal cortex (important for language processing and memory) and the mesolimbic reward center are known to be activated by humor.
While some past studies had shown gender differences in how humor is used and appreciated, no one has yet looked at gender-based differences in how the brain responds to humor.
For this study, 10 females and 10 males underwent functional magnetic resonance imaging (MRI) while viewing 70 black-and-white cartoons. They were asked to rate each cartoon on a "funny scale," with 10 being the highest rating.
The behavioral responses to the cartoons, including reaction times, were essentially equivalent in the two groups. "It's not that they were getting something different out of the humor, or enjoying it differently," Azim said.
Many of the same brain regions were also used.
But there were differences, and the differences were surprising. During funny cartoons, women showed greater activation in the prefrontal cortex and the nucleus accumbens (NAcc), which is part of the mesolimbic reward center.
"It was surprising to find it in the two regions where we found it, but finding differences was not surprising," Azim said. "Men's and women's brains have evolved to process cognitive and emotive information somewhat differently. Looking at humor starts to reveal subtle differences in processing strategies."
The NAcc finding was the most surprising. This region is activated in all kinds of rewards, such as when you win at gambling or take cocaine.
"Females tended to activate this region more than men, and men tended to inactivate it during unfunny cartoons," Azim said.
Women also had more activation the funnier the cartoon was, while men tended to deactivate the center when they encountered an unfunny cartoon.
What does this mean?
"Females seem to be anticipating the reward less than men, and have greater activation when they get it," Azim explained.
If women's reward centers are more sensitive to stimuli, this may help explain the higher rate of depression among women, Azim said.
"It's a hypothesis, and more studies need to be done to verify it," Azim cautioned. "It indicates that there is a distinct strategy in ways men and women process humor, even though they are enjoying it the same."
A related study in the same issue of the journal found that personality traits, including extroversion and introversion, also have a bearing on how humor is processed.
More information
Visit Rx Laughter to get the latest on research into laughter and its relation to better health.
SOURCES: Eiman Azim, doctoral student, neuroscience, Harvard University, Boston; Nov. 7-11, 2005, Proceedings of the National Academies of Science
Copyright © 2005 ScoutNews, LLC. All rights reserved.
Gender divide in getting the joke
Scientists have uncovered hard evidence of a gender divide when it comes to appreciating humour.
A Stanford University team monitored brain activity when men and women looked at funny cartoons.
They found areas of the brain involved in language processing, memory and generating reward feelings were more likely to be activated in women.
It is hoped the Proceedings of the National Academy of Sciences study may provide insights into depression.
It may also lead to a better understanding of other medical conditions, such as cataplexy - a sudden loss of control of movement linked to the emotions.
OTHER FINDINGS
Men and women showed no significant difference in the number of cartoons they
rated as funny
Women were quicker at identifying material they considered unfunny
Lead researcher Professor Allan Reiss said: "The results help explain previous findings suggesting women and men differ in how humour is used and appreciated."
The prefrontal cortex, which is involved in language processing and memory, is known to play a role in humour appreciation.
And the Stanford team has shown that the mesolimbic reward centre - responsible for generating the positive feelings associated with events such as monetary gain - is also activated by humour.
The latest study used sophisticated scans to monitor the brains of 10 men and 10 women as they watched 70 black-and-white cartoons.
The researchers found similarities between the way that male and female brains respond to humour.
But some brain regions were activated more in women, including both the left prefrontal cortex and the mesolimbic reward centre.
The researchers say their findings suggest women place a greater emphasis on the language of humour, possibly employing a more analytical approach.
They also believe that the women in the study were less likely to expect the cartoons to be funny - so when they were, their pleasure centre lit up with greater intensity than their male counterparts.
Professor Reiss said: "Women appeared to have less expectation of a reward, which in this case was the punch line of the cartoon.
"So when they got to the joke's punch line, they were more pleased about it."
The researchers also found that the funnier the cartoon, the more the reward centre was activated in women.
That was not the case in men who seemed to "expect" the cartoons to be funny from the start.
Professor Reiss said the finding that women's reward centres might be more sensitive to emotional stimuli, if confirmed by follow-up studies, might explain why they appear to be more vulnerable to depression.
Professor Tonmoy Sharma, of the Clinical Neuroscience Research Centre in Dartford, Kent, said it was certainly the case that women were more likely to become depressed.
However, he told the BBC News website: "I would agree that women are much more analytical in terms of humour, but to extrapolate from this study, and draw conclusions about clinical depression is probably a step too far."
Source: BBC News Online, 08/11/2005