Neuroscientists at Emory University School of Medicine have discovered a focal pathway in the brain that when electrically stimulated causes immediate laughter, followed by a sense of calm and happiness, even during awake brain surgery. The effects of stimulation were observed in an epilepsy patient undergoing diagnostic monitoring for seizure diagnosis. These effects were then harnessed to help her complete a separate awake brain surgery two days later.

The behavioral effects of direct electrical stimulation of the cingulum bundle, a white matter tract in the brain, were confirmed in two other epilepsy patients undergoing diagnostic monitoring. The findings are scheduled for publication in the Journal of Clinical Investigation.

Emory neurosurgeons see the technique as a “potentially transformative” way to calm some patients during awake brain surgery, even those who are not especially anxious. For optimal protection of critical brain functions during surgery, patients may need to be awake and not sedated, so that doctors can talk with them, assess their language skills, and detect impairments that may arise from resection.

Illustration shows how an electrode was used to stimulate the cingulum bundle. Courtesy of American Society of Clinical Investigation.

“Even well-prepared patients may panic during awake surgery, which can be dangerous,” says lead author Kelly Bijanki, PhD, assistant professor of neurosurgery. “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.”

Outside of use during awake surgery, understanding how cingulum bundle stimulation works could also inform efforts to better treat depression, anxiety disorders, or chronic pain via deep brain stimulation.

Previous investigators have reported that direct electrical stimulation of other parts of the brain can trigger laughter, but the demonstration that anti-anxiety effects observed with cingulum bundle stimulation can provide meaningful clinical benefits make this study distinct, says senior author Jon T, Willie, MD, PhD, who performed the surgeries reported in the paper. He is assistant professor of neurosurgery and neurology at Emory University School of Medicine.

Lying under the cortex and curving around the midbrain, the cingulum bundle has a shape resembling a girdle or belt – hence its Latin name. The area that was a key to laughter and relaxation lies at the top and front of the bundle. The bundle is a logical target because of its many connections among brain regions coordinating complex emotional responses, Willie says. More here.