Brain centre for laughter

09 February 2019

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The spot in the nervous system responsible for triggering laughter has been discovered during a brain operation. The finding could pave the way to new treatments for anxiety, depression, and pain...

"Laughter is the best medicine" - You have probably heard this before, and you instinctively know that laughing feels good at the time and leaves you more relaxed afterwards. But scientists had no idea that there is a specific spot in the brain that, when activated, can trigger genuine laughter and the other good feelings that go with it.

The laughter “switch” was discovered by Emory University neurosurgeon Kelly Bijanki and her colleagues while they were conducting open brain surgery to treat a patient with epilepsy. 

Characteristically during brain surgeries, and particularly for epilepsy, the patient remains awake during the procedure so that the surgeon can ensure that important brain functions, such as speech, won’t be affected by the intervention. Using an electrode, the Emory team were stimulating a region of their patient's nervous system called the cingulum bundle, a large group of nerve fibres that carry information between the different parts of the brain's emotional and memory circuits.

“Stimulating the cingulum bundle caused [the patient] to involuntarily laugh and smile, and she reported feeling happy and relaxed.”

The effects of the stimulation persistent for around 30 minutes afterwards, mimicking the afterglow we all feel after a good laugh. Afterwards, the patient said they “had happy memories of the surgery!”

The results have important implications for patients who undergo epileptic brain surgery in future. According to Bijanki, “in the United States alone, there are up to 10,000 epilepsy surgeries each year,” and it might be possible, she speculates, to apply similar stimulation in other patients to alleviate stress and anxiety at the time of the surgery.

On top of that, this new knowledge, which is published in the Journal of Clinical Investigation, might help doctors to develop new ways to treat anxiety, depression and pain. “We’re still a little way off from a non-invasive approach to get to this particular brain region, but the long term dream for this would be to use techniques that don’t require an implant or a surgery”, says Dr Bijanki.

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