Stimulation effects were observed in an epilepsy patient undergoing diagnostic monitoring for seizure diagnosis, effects were harnessed to help complete a separate awake brain surgery two days later, and were confirmed in two other patients, as published in the Journal of Clinical Investigation.
Behavioral effects of direct electrical stimulation of the cingulum bundle was confirmed in 2 other epilepsy patients who underwent diagnostic monitoring. Neurosurgeons suggest the technique may be a potentially transformative way to calm patients during wake surgery. Outside of awake surgery understanding how cingulum bundle stimulation works may help efforts to better treat anxiety, depression, or chronic brain via deep brain stimulation.
Previously scientists have reported direct stimulation on other parts of the brain triggering laughter, but demonstration of anti-anxiety effects observed with cingulum bundle stimulation may provide meaningful clinical benefits that make this study unique, according to the scientists.
The cingulum bundle lays under the cortex and curves around the midbrain, resembling a belt. Areas important to laughter and relaxation are at the top and front of the bundle. The cingulum is a target due to its many connections among brain regions coordinating complex emotional responses. The location is distinct from other brain location that process reward because the bundle is a crossroads for white matter connecting several lobes.
Initial electrode placement locations were chosen in order to record brain activity and locate the onset of the first patient’s seizures. Initial electrode used to stimulate the bundle was inserted in a unique trajectory due to the patient’s previous surgeries from the rear leading to a broader extent of cingulum bundle being sampled and accessible for electrical stimulation.
The first patient described the experience as relaxing and pleasant unlike any component of typical seizures or aura, and reported an involuntary urge to laugh that evolved into a pleasant relaxed feeling. Cingulum bundle stimulation immediately elicited positive behavior including smiling. To test mood and thought process the patient was tested on how faces were viewed and interpreted as happy, sad, or neutral; stimulation shifted view to interpreting them as happy in effect called affective bias which is known to correspond with reduction in depressive symptoms and suggests potential of this method in treating depression.
2 other patients that underwent the procedure did not undergo awake surgery for epilepsy treatment; both smiled and reported mood elevation and pain relief, and experienced laughter at higher levels of currents. One of the patients took tests of attention, memory, and language during stimulation and performed normally with exception to delayed verbal recall on a list learning task.
The scientists suggest and envision cingulum bundle stimulation as a potentially applicable surgery for brain tumors as well as epilepsy, although further research is required the bundle may be a target for chronic deep brain stimulation therapies for mood, pain, and anxiety disorders.
