The researchers found an effective target for electrical stimulation in the brain to improve the mood of depressed patients. As reported in the journal Current Biology On November 29, stimulation of the brain area called the lateral overcurrent cortex (OFC) reliably improved the mood of the patients suffering from depression at the start of the study.
These effects did not appear in patients with mood symptoms, suggesting that brain stimulation normalizes mood-related neural circuits.
The stimulus induced an activity pattern similar to the pattern seen when the patient experienced a mood state naturally in the brain area connected to the OFC. Our results suggest that OFC is a promising new stimulus target for the treatment of mood disorders. "
San Francisco, University of California, Vikram Rao
Rao and Kristin Sellers of the Edward Chang lab found 25 epileptic patients in the brain for medical reasons and found the origin of the seizures. Many of these patients are depressed and are common in people with epilepsy. With the patient's consent, Chang used these electrodes to deliver small electrical pulses to the brain's part of the brain involved in mood control.
Previous studies have explored cardiovascular brain stimulation (DBS) for mood disorders, but their success depends crucially on target selection. The targets in the areas related to the deep mood of the brain did not always lead to a stable improvement.
In a new study, researchers focused attention and electrical stimulation on the OFC. OFC is a key hub for atmosphere related circuits. However, it is widely regarded as one of the less well-known brain regions.
"The OFC is a superficial target, but shares a rich interconnect with the brain areas involved in emotional processing," says Sellers. This makes this relatively small area of the brain an attractive target of therapeutic stimulation.
Researchers used implanted electrodes to stimulate OFC and other brain areas while collecting oral mood reports and questionnaire scores. This study found that unilateral stimulation of lateral OFCs resulted in an acute, dose-dependent mood improvement in subjects with moderate to severe basal depression. The change in brain activity observed by researchers after stimulation resembles when people feel better.
The results of this study show that mood can be improved immediately by electrical stimulation of relatively small areas of the brain. Mood disorders also add to the evidence that brain circuits are the result of dysfunction.
Researchers say there is a lot of work to be done before DBS can start routine clinical practice. The Chang team is currently investigating whether or not mood continues to improve over the long term with OFC stimulation. They also hope to develop medical devices for patients with hearing-resistant mood disorders that can only be stimulated when OFC monitors brain activity and maintains its activity within a healthy range.
Ultimately, it is ideal if the activity of the brain circuit associated with mood can be normalized indefinitely without the patient having to do anything. "