Whose Brain Is It?
by Leena Prasad

“Chai tea,” Tina says to the woman behind the counter.

Hema tries to suppress a chuckle.

“What’s so funny?” Tina asks.

“Nothing. It won’t be funny to you.”

“Try me, anyway.”

“Well chai in hindi means tea.”

“Oh,” Tina says and giggles. “Yeah, we like to appropriate other cultures words without considering what it means.”

“I don’t really care. But it does sound funny. I’ll have some tea tea please.”

“What makes something funny?” Hema says, as they sit down at a table wither their drinks.

“Well, maybe it has to do with something absurd. Like tea tea.”

They sip their drinks, considering the question.

“You know, I read somewhere that if a certain part of the brain is touched, it can cause laughter.”

“You mean, like in the inside, by a brain surgeon?”

“Yes, yes, during surgery, or when they are examining the brain.”

“So, the humor circuits are hardwired? I guess that makes sense. Everything is hardwired, I suppose.”

Hema could be describing the case reported in Nature magazine by neurosurgeon Itzhak Fried of University of California at Los Angeles. Fried made an accidental discovery while studying the brain of an epileptic patient, a 16-year-old girl. He was trying to diagnose the reason for her seizures by using an electric probe on her brain. Every once in a while, the girl would start laughing for no apparent reason. He realized that when the probe touched a specific area in her left frontal lobe she would laugh. If he increased the electric current, the girl would laugh with more intensity.

Much of research on humor has been done on brain abnormalities that cause inappropriate laughter. It is difficult to study “normal” humor because the definition of humor varies. But, researchers can look at the result of humor, i.e., how the laughter resonates within the brain circuits. Excluding laughter caused by tickling, laughing gas, or simply as social contagion, some recent studies examine the result of laughter on a healthy human brain as it responds to everyday humor.

The area that Fried was touching inside the 16-year-old girl’s brain is less than an inch-square and it’s called the supplementary motor area. In a study cited in the Brain journal, a PET scan revealed an increase in the blood flow in the supplementary motor area while subjects responded to humorous film clips.

“Do you think women laugh more than men?” Hema says.

“Hmmm… I’m tempted to say, probably yes, but I wonder if anyone has actually studied something like that?”

The answer is not as simple as per a study cited in the Proceedings of the National Academy of Sciences.  It’s not the quantity of laughter but the qualitative differences in the integration of the response in the male versus the female brain. A group of 10 men and 10 women were shown a series of cartoons and asked to rate the cartoons as being funny or not.  An fMRI scan showed that the left prefrontal cortex was activated more in the women than the men for the cartoons that both genders found to be funny.

“Whatever happens in the brain, I’ve read that laughing is good for you,” Tina says.

“Sure, it certainly feels good.”

Laughter produces generous release of the feel good hormone dopamine and activates the reward circuits of the brain, the mesolimbic region. This was also discovered by the fMRI scan in the experiment that evaluated the differences in gender-based reactions to funny cartoons.
“We now have laboratory evidence that mirthful laughter stimulates most of the major physiologic systems of the body,” says William Fry, M.D., a Stanford University psychiatrist. He says that twenty seconds of laughter, real or fake, can increase the heart rate for a few minutes.  Fry also says that laughter can potentially reduce the risk of heart attacks by reducing tension, stress, and anger and that it may even help in making people less susceptible to some diseases by warding off depression.
Yes, laughing feels good. More studies are required to map the exact brain areas complicit in causing this response. But, we can rest assured that a little laugher is indeed a “good medicine.”

References:

B. Wild (2003). Neural correlates of laughter and humour, Brain, 126 (10), 2121-2138 DOI: 10.1093/brain/awg226

E. Azim (2005). Sex differences in brain activation elicited by humor Proceedings of the National Academy of Sciences, 102 (45), 16496-16501 DOI: 10.1073/pnas.0408456102

http://www.justlaughter.com

Please send feedback and suggestions for future columns to leena@fishridingabike.com. Links to past columns are available at WhoseBrainIsIt.com and Leena’s writing portfolio is available at FishRidingABike.com. Leena has a journalism degree from Stanford University.

Dr. Nicola Wolfe is a neuroscience consultant for this column. She earned her Ph.D. in Clinical Psychopharmacology from Harvard University and has taught neuroscience courses for over 20 years at various universities.