Sohal says the team hoped those recordings would help answer a basic question: “When patients are sitting there, or watching TV or talking with their family or waiting or being anxious, which regions of the brain are talking to each other?”
The patients agreed to keep a running log of their mood. And the team looked to see whether certain moods coincided with communication within specific networks in the brain.
The researchers thought they might find networks that were similar in a couple of people. But they were “really surprised” to learn that 13 of the 21 patients shared the same network, Sohal says.
Still, he says, it makes sense that communication between areas involved in memory and emotion would be associated with sadness. “Maybe you’re feeling down and so you start remembering times in your life when bad things have happened, or you are starting to remember those experiences and that is what is making you feel down,” he says.
The study couldn’t confirm that. It also couldn’t show whether the increase in communication was the result of a mood change or the cause of one.
Even so, Sohal says the finding may bring comfort to people with depression.
“As a psychiatrist, it’s incredibly powerful to just be able to say to patients, ‘Hey, I know there’s something happening in your brain when you’re feeling down.’ ”
In one sense, the new study merely confirms the results of early research on animals, says Dr. Joshua Gordon, who directs the National Institute of Mental Health.
“It’s finding a circuit, a piece of the brain that we kind of already knew was involved in mood — that’s the less-than-wow part,” he says. “The wow part is that it’s in human beings.”