Brain surgery is normally no laughing matter, but now neuroscientists at Emory University may have found a way to make it so. The team discovered that electrically stimulating a brain region known as the cingulum creates a mild euphoria complete with laughter, and used this to calm down a patient undergoing brain surgery where she needed to stay awake. The technique could be put to use as a kind of sedative or a treatment for anxiety, depression or chronic pain.

The cingulum is a bundle of white matter fibers that wraps around the midbrain in a C-shape, from the frontal lobe to the temporal lobe. The front section of the cingulum in particular has been linked to emotional responses, and has been studied in the past for its relation to depression.

The discovery was made in an epilepsy patient, who already had electrodes implanted in her brain in order to monitor and diagnose seizures. The team used these to stimulate the cingulum with small jolts of electricity, which caused the patient to laugh before experiencing what she described as a "pleasant, relaxed feeling."

The researchers then tested her mood by showing the patient faces and having her decide whether they looked happy, sad or neutral. The brain stimulation seemed to shift her interpretations towards the happy end of the scale. The team says this could suggest that the technique might find use as a possible treatment for depression.

Later, the team used the cingulum stimulation to help the patient through a potentially traumatic surgery. During some types of brain surgery, surgeons need to keep talking to patients in order to properly assess any issues that might arise with their language, sensory or emotional functions – but to do so, the patient needs to be conscious and can't be sedated. Understandably, that's not a particularly pleasant experience for the patient.

"Even well-prepared patients may panic during awake surgery, which can be dangerous," says Kelly Bijanki, lead author of the study. "This particular patient was especially prone to it because of moderate baseline anxiety. And 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."

The researchers confirmed the technique in two other patients by repeating the stimulation and behavioral testing. Their moods also improved, and they also laughed when the current was ramped up. One patient took memory, attention and language tests while undergoing stimulation, and although he performed normally for the most part, the team did notice a delay on his verbal recall during one test.

While more research will no doubt need to be done to assess how safe the technique is, the researchers say it could eventually be used to make for a more pleasant patient experience during awake surgeries, or as part of a deep brain stimulation treatment for depression, anxiety and chronic pain.

The research was published in the Journal of Clinical Investigation.