To come from experience to emotion, the brain touches ‘Sustain’

Be cut off in rush hour traffic and you can feel angry for the entire trip, or even click a noisy child in the back seat.

Get an unexpected smile from the same child and you may feel as a rush hour – and even those other drivers – are not that bad.

“The thing about emotion is that it generalizes. It brings the brain to a wider state,” says Dr. Karl DeisserothA psychiatrist and professor at Stanford University.

Deisseroth and a team of researchers have devised a statement about how that happens.

The process includes a signal that, after a positive or negative experience, lingers in the brain, the team report in the diary Science.

Experiences themselves work a bit like piano tones in the brain. Some are Staccato, who only produce a short eruption of activity that can lead to a reflexive reaction, such as honking to another driver, or smiling back to a child.

But more in -depth experiences can look more like a music note that is held at the Sustain pedal and is still audible when the next note is played, or that afterwards.

“You just need to be sustained long enough to merge with and communicate with other notes,” says Deisseroth. “And from our perspective this is exactly what emotion needs.”

If the team is right, it can help explain the emotional differences that are seen in some neuropsychiatric conditions.

For example, people in the autism spectrum often have difficulty recognizing emotions in others and regulating their own emotions. Schizophrenia can cause mood swings and reduced emotional expression.

But some researchers wonder whether this persistent signal is specific to emotion, a term without agreed definition in the scientific world.

“Certainly, [a sustained signal] happens in emotion, “says Lisa Feldman BarrettA professor in psychology at Northeastern University. “But it also happens in all kinds of other cases,” as when a person concentrates or remembers.

Emotional in the lab

Deisseroth and his team wanted to re -create the kind of experience that leads to an emotional reaction, but could be observed in a laboratory.

“We wanted something that would cause a negative emotion, but would not be painful,” he says.

They chose a fool of air, supplied on the cornea. That meant that they could use a machine that use ophthalmologists to detect glaucoma.

The puff pastry of this device is “certainly annoying, certainly aversive, but not painful,” says Deisseroth.

The team also thought it could provoke the same reaction from mice, an animal that dates from millions of years from before people.

It turned out that both mice and people flash reflexively in response to a trait. Both types also respond to multiple traits by squeezing their eyes.

The team then studied brain activity associated with these experiences. And they found two different phases with different brain circuits.

The first phase is like a staccato note on a piano. In the first two tenths of a second after a trek, there is a peak in the activity of brain circuits that process sensory input.

The second phase is more like a piano -nut from the Sustain pedal. During this period the activity appears in other circuits, including those involved in emotion.

When mice and people were constantly exposed to air boxes – and again – this persistent reaction became stronger with every stimulus.

Behavior also changed. Both mice and people squeezed more, and the people reported that they were more irritated by the experience.

“In the mice, although we don’t get those verbal reports, we saw this crucial generalization,” says Deisseroth. “It made them less inclined to look for rewards.”

That behavior, a failure to look for food and other rewards is a sign of stress or another negative state in mice.

Enter ketamine

To confirm the finding, the team did the experiment again. But this time both mice and people received an anesthesia called Ketamine. They thought the medicine could break a negative sensory experience of any emotional reaction that it would usually produce.

On ketamine, the second, persistent phase of brain activity was no longer present and the reactions to the aerial plays changed.

Mice and people would still flash reflexively after a Suffer air compartment. But they don’t. And people reported that they no longer found the air clouds annoying.

“If you remove this Sustain phase, you will also block the emotional response,” says Deisseroth.

Kind of Barrett says.

The study shows that persistent signals in the brain play a role in changing the brain state of a person or animal, she says. But that brain state can be a consciousness or focus, instead of an emotion.

Ketamine, she says, interferes with all these states.

“That tells us that the way the brain creates emotion is how it creates everything else – how it creates thoughts, how it creates perceptions, how it creates actions,” says Barrett. “It doesn’t do something special in emotion.”

Barrett also thinks that the aerial plays probably mean something different than a mouse than for a person.

“The human brain has this ability to abstract, to create meanings that go beyond motor and sensory differences,” she says.

Barrett’s worry about how emotions are studied extend to many other research.

The underlying problem, she says, is that scientists should not agree on a common definition of an emotion.