Dean K. Shibata, M.D., has discovered that humor appreciation
- our ability to recognize a joke - appears to be based in the
lower frontal lobes of the brain. It is the first study that captures
images of the brain, using functional magnetic resonance imaging
(FMRI), to determine what areas become active when we experience
something humorous.
"Why do we laugh? No one really knows," Shibata said. "But knowing
which areas of the brain are involved gives us an idea of how humor is
processed, what functions it may be related to, and ultimately how
it may have developed. This is important because it provides insight
into social and emotional behavior, and how we communicate
and foster relationships."
Connecting the brain's response to humor, which plays a powerful role
in shaping our personalities, is significant for many reasons.
It could aid physicians in diagnosing and treating patients with mental
illness or mood disorders such as depression, by showing the brain's
response to positive stimuli. Traditionally, research has focused on the
brain's response to negative emotions such as fear.
It could provide surgeons with valuable pre-operative mapping of the brain
areas critical for maintaining the emotions and social behaviors that
make up our personalities.
It advances science, proving the value of new and sophisticated tools
that can provide glimpses into the brain and how it works.
It helps to demonstrate that mental activity, even one as evanescent
and complex as humor, has a physical correlate.
Other studies, involving stroke and seizure patients, have tried to
correlate brain abnormalities with either uncontrollable laughing episodes
or a loss of the sense of humor.
But in Shibata's research, MRI scans were performed on 13 normal
volunteers in a series of four exams. The scans directly visualized what
parts of the brain were involved when the subjects read written jokes,
viewed cartoons and listened to digital recordings of laughter.
The MRI scans showed that when the subjects saw the jokes and cartoons
- tasks that require a decoding of the humorous stimuli - the brain activity
was most prominent in the ventromedial frontal lobe. This suggests that the
frontal lobe is responsible for telling us what's funny.
But when they heard laughter and laughed along internally, a response
known as contagious laughter, the activity was centered in the anterior
supplemental motor area. That part of the frontal lobe near the top of the
brain is normally associated with planning complex movements and
initiating speech.
All four scans also showed activity in a small spot at the base of the
brain, called the nucleus accumbens, an interesting area associated
with positive emotions in animals and identified as a key site in moderating
drug addiction.
Activity in the nucleus accumbens is likely related to our feeling of mirth
after hearing a good joke and our "addiction" to humor, Shibata said.
http://www.urmc.rochester.edu/pr/News/finding.html
[from Adriatic Sea, nov. 30, 10 p.m. local time]
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