Singers performing a duet, jazz players riffing together effortlessly, paired-up dancers never skipping a step: great performers are so coordinated, they become one.
What are the mechanisms that regulate coordination and cooperation? Neurobiologists are learning more from some of nature’s foremost musical performers: songbirds.
The brains of duetting songbirds are linked together during performances, a new study published in Proceedings of the National Academy of Sciences has found.
The exchange of auditory feedback between the birds “momentarily inhibits motor circuits used for singing in the listening partner, which helps link the pair’s brains and coordinate turn-taking for a seemingly telepathic performance,” according to a news release.
It’s not telepathy – but almost, according to study coauthor Eric Fortune, a neurobiologist and associate professor at New Jersey Institute of Technology’s department of biological sciences.
“The birds hearing each other links their brains to act as one,” he told CNN.
“The male’s brain has expectations of what the female brain is going to do. The female brain has expectations of what the male brain is going to do. And when they start operating together, they’re tied,” Fortune added.
A songbird’s brain and a trampoline
The study focuses on what happens in the brains of male and female plain-tailed wrens – a species native to the Andes region, living in bamboo thickets – while they sing duets.
The duets of Pheugopedius euophrys are frantically paced call-and-response songs, and they take turns singing so rapidly, it sounds as if a single bird is singing, according to the study.
Working from the Yanayacu Biological Station’s lab in Ecuador, right by the active Antisana volcano, scientists specifically investigated an area of the songbirds’ brain known to control singing.
Researchers recorded the birds’ brain activity during duets using electrodes much thinner than a hair, Fortune explained. The team observed that when a bird sings, the neurons spike in activity, but when a bird hears a partner sing, the neurons quiet down.
The fact that neurons quiet down is especially significant, Fortune explained.
“Oftentimes, what happens is after you have inhibition, you have a rebound, and that rebound can change the timing of your own behavior,” he said.
Fortune compared that effect to that of jumping on a trampoline: “You bounce down, that’s kind of slow, but then you shoot off.”
The scientists hypothesize the release from inhibition could help a bird respond faster when it is its turn to sing.
According to Fortune, there are similarities between how the birds take turns singing and how humans do that while they converse.
“If you watch your own interactions with people, you’ll see that the other person starts talking a nanosecond after you stop uttering your last word – it’s really amazing,” he said.
What humans and robots can learn from songbirds
“Every achievement of humankind is based on cooperation, that is the feature of humans that has allowed us to do the amazing things we do,” Fortune said.
Learning more about how songbirds stay in sync during their singing performances can help illuminate the mechanics of coordination in humans, a complex phenomenon that involves many different types of information being exchanged among parties.
“A lot of us understand how hard it is to dance, and in part it’s because you are exchanging complex sets of information at different times – touch, vision, acoustic, you have to signal your intent, there has to be some set of variations, and it turns out to be a real mess.”
Songbirds, on the other hand, take turns in their duets in a more structured fashion, making it easier to analyze how cooperation works, according to Fortune.
Furthering our understanding of cooperation in songbirds could also help us build better robots, Fortune explained.
“Robots are actually more precise and better controlled than a human can control themselves, and yet robots can’t cooperate with us,” he said.
The brains of duetting songbirds link up to create “a single control system” spanning two individuals, according to Fortune. This could inspire the development of robots that can better form partnerships with humans.
“It’s this linkage of the control systems across individuals that is critical insight for roboticists,” Fortune said.