Male and female plain-tailed wrens sync their frantically-paced duets by inhibiting the song-making regions of their partner’s brain, says a new study.
The research sheds more light on what makes for a successful connection between performing duos, including in humans acting in concert during music and dance duets.
According to the research, published in the journal PNAS, the auditory feedback exchanged between duetting wrens momentarily inhibits the brain circuits in the listening partner which control body parts used for singing.
The scientists, including those from New Jersey Institute of Technology in the US, say this inhibition of the nerves in the brain helps link the pair’s musical minds, enabling them to coordinate turn-taking in a seemingly telepathic performance.
“You could say that timing is everything. What these wrens have shown us is that for any good collaboration, partners need to become ‘one’ through sensory linkages,” Eric Fortune, co-author of the study and neurobiologist at New Jersey Institute of Technology, said in a statement.
The researchers believe the findings have far-reaching implications in understanding the biology of cooperative interaction in some animals, including humans, whenever they are trying to produce a single behaviour as two performers.
“We are wired for cooperation, the same way as these jazz singing wrens,” Melissa Coleman, study corresponding author and associate professor of biology at Scripps College, said in a statement.
For the study, the team travelled to the heart of the bird’s music scene within remote bamboo forests on the slopes of Ecuador’s active Antisana Volcano.
The researchers recorded the brain activities of four pairs of native wrens as they sang solo and duet songs at the Yanayacu Biological Station’s lab where they camped.
They particularly analysed the activity of a specific brain region in the birds that had specialised active nerve cells for learning and making music.
During duet turn-taking — when the birds make tightly knit call-and-answer phrases that together sound as if a single bird is singing — the scientists said the wrens’ neurons fired rapidly when they produced their own syllables.
However, they said these neurons “quiet down significantly” as one wren begins to hear their partner’s syllables sung in the duet.
“You can think of inhibition as acting like a trampoline. When the birds hear their partner, the neurons are inhibited, but just like rebounding off a trampoline, the release from that inhibition causes them to swiftly respond when it’s their time to sing,” Mr Fortune explained.
Next when the scientists played recordings of wrens duetting while they were anaesthetised to a sleep-like state, the team found that the drug transformed the brain activity when the wrens heard their own music.
According to the study, the drug affects a major chemical that inhibits activity in the wrens’ brains called gamma-Aminobutyric acid, or GABA — that is also found in humans — causing bursts of activity.
“These mechanisms are shared or similar to what happens in our brains because we are doing the same kind of things. There are similar brain circuits in humans that are involved in learning and coordinating vocalizations,” Mr Fortune said.
The researchers say the songbirds have a rough song structure planned before they begin their duet, but add that the wrens are also flexible to adapt as they rapidly coordinate and receive constant input from their counterpart.
They believe the findings also offer a fresh look into how the brains of humans and other cooperating animals use cues to act in concert with each other – from flowing musical and dance performances, or even the disjointed feeling of inhibition commonly experienced today during video conferencing.
“The take-home message is that when we are cooperating well… we become a single entity with our partners,” Mr Fortune added.
