The lateral orbitofrontal cortex, just behind the eyes, seems to be key
Precisely placed zaps to the brain swiftly improved the moods of people with signs of depression. The results, achieved with implanted electrodes, bring scientists closer to understanding the nature of depression — and point to ways to treat it.
Neurologist Vikram Rao and neuroscientist Kristin Sellers, both of the University of California, San Francisco, and their colleagues studied 25 people who were undergoing treatment for epilepsy that involved electrodes implanted at various spots in the brain.
At the beginning of the experiment, published online November 29 in Current Biology, the researchers asked patients to take extensive mood tests, which showed some of these people had signs of mild to severe depression. Then the team began to stimulate different areas of the brain with the implanted electrodes. Shortly after the stimulation began, the scientists asked people to report their current mood, both verbally and on a tablet app.
Many of the targeted brain spots didn’t seem to have any effect on people’s mood. But when researchers stimulated a brain region that lies just behind the eyes, called the lateral orbitofrontal cortex, people reported feeling better. Only the patients who started out with moderate or severe depression scores saw this improvement; people who felt pretty good already didn’t have mood changes.
Mood relies on many parts of the brain working together. Because the lateral orbitofrontal cortex has widespread connections in the brain, the region may be especially poised to ease depression. The study focused on mood during only the brain stimulation. The team plans to test whether the stimulation can have effects that last longer.
V.R. Rao et al. Direct electrical stimulation of lateral orbitofrontal cortex acutely improves mood in individuals with symptoms of depression. Current Biology. Published online November 29, 2018. doi:10.1016/j.cub.2018.10.026.
L. Sanders. Giggling rats help reveal how the brain creates joy. Science News Online, November 10, 2016.