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The Laughing Spot

By Quinn Eastman

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Neuroscientists have discovered a focal pathway in the brain that, when electrically stimulated, causes laughter followed by a sense of calm and happiness.

These effects were observed in a 23-year-old woman with epilepsy who was being monitored for a seizure diagnosis, and the technique was then used two days later to help calm her during brain surgery while she was awake.

The behavioral effects of direct electrical stimulation of the cingulum bundle—a tract of neural fibers in the brain—were confirmed in two other epilepsy patients undergoing diagnostic monitoring. Emory neurosurgeons see the technique as a potentially transformative way to calm patients during awake brain surgery.

For protection of certain brain functions, patients may need to be awake and not sedated during surgery so that doctors can talk with them, assess their language skills, and gauge when they are getting close to critical areas.

“Even well-prepared patients may panic during awake surgery, which can be dangerous,” says Kelly Bijanki, assistant professor of neurosurgery. “One of our patients was especially prone to it because of moderate baseline anxiety. Upon waking from global anesthesia, she did indeed begin to panic. When we turned on her cingulum stimulation, she immediately reported feeling happy and relaxed, told jokes about her family, and was able to tolerate the awake procedure successfully.”

Understanding how cingulum bundle stimulation works could lead to better ways to treat depression, anxiety disorders, or chronic pain via deep brain stimulation. The stimulation, says doctors, immediately provoked “mirthful behavior, including smiling and laughing, and reports of positive emotional experience.”

“The patient described the experience as pleasant and relaxing and completely unlike any component of her typical seizure or aura. She reported an involuntary urge to laugh that began at the onset of stimulation and evolved into a pleasant, relaxed feeling.”

The cingulum bundle (depicted above during stimulation by Emory medical illustrator Bona Kim) lies under the cortex and curves around the midbrain like a girdle or belt —hence its Latin name. It links many brain areas together, like a “superhighway with lots of on and off ramps,” says Jon Willie, assistant professor of neurosurgery and neurology at Emory, who performed the surgeries.

The area that appears key to laughter and relaxation lies at the top front of the bundle.

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