Researchers say they have found an “effective target” in the brain for electrical stimulation to improve the moods of patients suffering from the mental condition.
The findings, published in the journal Current Biology, show stimulation of a brain region called the lateral orbitofrontal cortex (OFC) reliably produced “acute” improvements.
The effects were not seen in patients without mood symptoms, which the researchers say suggests that the brain stimulation works to normalize activity in mood-related neural circuitry.
Dr. Kristin Sellers, of the University of California, San Francisco, said: “Patients said things like ‘Wow, I feel better,’ ‘I feel less anxious,’ and ‘I feel calm, cool and collected’. And just anecdotally, you could see the improvements in patients’ body language. They smiled, they sat up straighter, they started to speak more quickly and naturally.”
She added that “although OFC is a more superficial target, it shares rich interconnections with several brain regions implicated in emotion processing,” which made the relatively small brain area an attractive target for therapeutic stimulation.
A team led by Sellers and Dr. Vikram Rao in the lab of Professor Edward Chang studied 25 patients with epilepsy who had electrodes placed in the brain for medical reasons to pinpoint the origin of their seizures.
Many of the patients also suffered from depression, which is often seen in people with epilepsy.
With the patients’ consent, Prof Chang’s team took advantage of the electrodes to deliver small electrical pulses to areas of the brain thought to be involved in regulating mood. The researchers then used the implanted electrodes to stimulate OFC and other brain regions while collecting verbal mood reports and questionnaire scores.
“Stimulation induced a pattern of activity in brain regions connected to OFC that was similar to patterns seen when patients naturally experienced positive mood states,” said Rao. “Our findings suggest that OFC is a promising new stimulation target for treatment of mood disorders.”
Previous studies have explored deep brain stimulation (DBS) for mood disorders, but its success depends critically on target selection, as targets in other mood-related areas that are deeper in the brain haven’t always led to reliable improvements.