Get cut off in rush-hour traffic and you may feel angry for the whole trip, or even snap at a noisy child in the back seat.
Get an unexpected smile from that same kid and you may feel like rush hour — and even those other drivers — aren’t so bad.
“The thing about emotion is it generalizes. It puts the brain into a broader state,” says Dr. Karl Deisseroth, a psychiatrist and professor at Stanford University.
Deisseroth and a team of researchers have come up with an explanation for how that happens.
The process involves a signal that, after a positive or negative experience, lingers in the brain, the team reports in the journal Science.
Experiences themselves act a bit like piano notes in the brain. Some are staccato, producing only a brief burst of activity that may result in a reflexive response, like honking at another driver, or smiling back at a child.
But more profound experiences can be more like a musical note that is held with the sustain pedal and still audible when the next note is played, or the one after that.“You just need it to be sustained long enough to merge with and interact with other notes,” Deisseroth says. “And from our perspective, this is exactly what emotion needs.”