Researchers Uncover A Circuit For Sadness In The Human Brain

Researchers Uncover A Circuit For Sadness In The Human Brain

Scientists may have caught a glimpse of what sadness looks like in the brain.
A study of 21 people found that for most, feeling down was associated with greater communication between brain areas involved in emotion and memory, a team from the University of California, San Francisco reported Thursday in the journal Cell.
“There was one network that over and over would tell us whether they were feeling happy or sad,” says Vikaas Sohal, an associate professor of psychiatry at UCSF.
The finding could lead to a better understanding of mood disorders, and perhaps new ways of treating them.
Previous research had established that sadness and other emotions involve the amygdala, an almond-shaped mass found in each side of the brain. And there was also evidence that the hippocampus, which is associated with memory, can play a role in emotion.
But Sohal and the other researchers were curious about precisely what these and other brain areas are doing when someone’s mood shifts.
“We really wanted to get at, you know, when you’re feeling down or feeling happy, what exactly is happening in the brain at those moments,” Sohal says.
You can’t get that information from brain scans, which don’t capture changes that happen in fractions of a second. So the team studied 21 people who were in the hospital awaiting brain surgery for severe epilepsy.
Before the surgery, doctors insert tiny wires into the brain and monitor its electrical activity for up to a week.
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.”
The study also provides a detailed map of what’s going on in the human brain, which is what doctors and scientists need to look for better treatments for patients with mood disorders.
“It’s really important that we find the circuits underlying mood so we can learn more about them and treat them with tools we are developing that are aimed at circuits.” Those tools include transcranial magnetic stimulation, which uses pulses of energy delivered through the skull to change the activity of brain circuits.
The study also shows the value of the BRAIN Initiative, which was launched by President Obama in 2013, Gordon says.
“The goals of the BRAIN Initiative are to develop tools we can use to get unprecedented access to, and understanding of, the brain,” Gordon says. “This study does both.”
The research team’s funding came in part from the Defense Advanced Research Projects Agency, a major supporter of the BRAIN Initiative.

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AILSA CHANG, HOST:

Scientists appear to have caught a glimpse of what sadness looks like in the brain. NPR’s Jon Hamilton reports that involves a distinct pattern of communication between brain areas involved in emotion and memory.

JON HAMILTON, BYLINE: There’s lots of evidence linking sadness and other emotions to a part of the brain called the amygdala. But a team of researchers wanted to know precisely what the amygdala and other brain areas are doing when someone’s mood is shifting. Vikaas Sohal is a psychiatrist at the University of California, San Francisco who was part of the team.

VIKAAS SOHAL: We really wanted to get at, you know, when you’re feeling down or when you’re feeling happy, you know, what exactly is happening in the brain at those moments?

HAMILTON: You can’t get that from brain scans. They’re too slow. So the team studied 21 people who were in the hospital to get brain surgery for severe epilepsy. Before the surgery, doctors insert tiny wires into the brain and monitor its electrical activity for up to a week. Sohal says the team hoped those recordings would help answer a basic question.

SOHAL: When patients are sitting there watching TV or talking with their family or just waiting or being anxious, you know, which regions of their brain are talking to each other?

HAMILTON: The patients agreed to keep a running log of their moods. Then the team looked to see whether certain moods were linked to communication within specific networks in the brain. And Sohal says some of them were.

SOHAL: What was really surprising to us was that it was the same network in most of the subjects. So in about two-thirds of the subjects, there was one network which over and over again would tell us whether they were feeling happy or sad.

HAMILTON: That network involved communication between the amygdala, which plays a role in emotion, and the hippocampus, which is critical to memory. The signals between these areas became much more intense at times when people reported feeling sad. Sohal says the finding published in the journal Cell may bring comfort to people with depression.

SOHAL: You know, as a psychiatrist, it’s incredibly powerful just to I think be able to say to patients, hey, we actually know there’s something happening in your brain when you’re feeling more down.

HAMILTON: Josh Gordon, who directs the National Institute of Mental Health, says in one sense, the study merely confirms earlier research on animals.

JOSH GORDON: 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. The wow part is that it’s in human beings.

HAMILTON: And he says it provides a detailed map of what’s going on in the human brain. Gordon says discoveries like this should eventually help patients with mood disorders.

GORDON: It’s really important that we find the circuits underlying mood so that we can learn more about them and treat them with the tools that we’re developing that are aimed at circuits.

HAMILTON: Tools like transcranial magnetic stimulation, which might someday be used to alter the specific brain circuit causing a patient’s depression. Jon Hamilton, NPR News.

(SOUNDBITE OF DR. DRE SONG, “XXPLOSIVE”) Transcript provided by NPR, Copyright NPR.

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