Spring brings warmer temperatures, fresh greenery, and the return of birdsong. Songbirds are known for performing species-specific tunes to attract mates and defend their territories. But how do birds learn these signature songs? Much like humans, it takes time and practice to master a skill.
To understand the brain signals involved in birds’ intrinsic desire to learn their songs, a research team from Duke University, North Carolina, closely studied how zebra finches practice their songs until they perfect them. Their findings, published in Nature, offer insights into the learning process in both birds and humans.
Extrinsic vs. Intrinsic Learning
When studying learning, it’s important to distinguish between extrinsic and intrinsic motivation. Extrinsic motivation comes from external factors like rewards or punishments, while intrinsic motivation is driven from within.
Although skills can be learned through both extrinsic and intrinsic motivation, intrinsic learning often leads to deeper, more lasting knowledge. Dopamine, a neurotransmitter, plays a crucial role in transmitting brain signals involved in learning, reward, and motivation between neurons. By tracking dopamine flow in the brain, scientists can better understand the molecular mechanisms behind intrinsic motivation to learn.
Zebra finches, native to Australia, are a favored model species for studying various traits, including vocal learning. Their simple yet complex vocalizations make them ideal for investigating how animals learn to master skills.
“The amount of effort that a juvenile bird makes to achieve vocal mastery is immense,” said Duke neuroscientist Richard Mooney in a press release, “It takes them about one month of solid practice every day, up to 10,000 renditions a day.”
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Practice Makes Dopamine
To study learning for its own sake, young male zebra finches that had memorized their male parent’s courtship song were kept in individual soundproof rooms. This setup allowed them to practice their singing without external interference. As the birds practiced, their initial random squeaks gradually turned into melodies that closely matched their parents’ songs.
As the birds slowly perfected their tunes, the research team also measured dopamine levels in the birds’ basal ganglia, a brain region involved in learning motor skills. They used optogenetics, a technique involving genetically modified proteins that glow when certain neurochemicals are released, to track brain activity — something that traditional methods, which measure electrical signals, cannot easily do.
What surprised the researchers was that whenever a bird practiced, dopamine levels in the basal ganglia increased. According to the press release, it didn’t matter whether the bird hit all the notes or missed some — any attempt at singing triggered the brain's reward pathways. Additionally, the better the bird performed relative to its age, the more dopamine was released, and vice versa.
Findings Apply Across Species
The study showed that dopamine, long known to be involved in externally driven learning, plays a key role in intrinsic motivation, too. Despite the lack of external feedback, the birds’ efforts to learn their songs demonstrate how intrinsic motivation can drive successful learning, independent of waiting for a reward or fearing punishment.
In addition to dopamine’s role, the researchers also identified acetylcholine as another important chemical messenger in the process.
“These findings translate across species,” said neurology professor John Pearson in the release. “The brain regions and neurochemicals involved — namely the basal ganglia, dopamine and acetylcholine — are shared by mice, primates, humans. Essentially every animal with a backbone.”
By studying how birds learn to sing, we can gain a better understanding of ourselves. Insights into dopamine signaling in the basal ganglia could also help improve our understanding of neurological diseases such as Parkinson’s and schizophrenia, as well as how we learn skills like playing an instrument or riding a bike.
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Having worked as a biomedical research assistant in labs across three countries, Jenny excels at translating complex scientific concepts – ranging from medical breakthroughs and pharmacological discoveries to the latest in nutrition – into engaging, accessible content. Her interests extend to topics such as human evolution, psychology, and quirky animal stories. When she’s not immersed in a popular science book, you’ll find her catching waves or cruising around Vancouver Island on her longboard.
