Published in the Wyoming Tribune Eagle Feb. 28, 2016, “UW songbird brain studies shed light”
By Barb Gorges
We are used to thinking about many animals standing in for humans in studies that will benefit us: rats, chimps, rabbits. But should we add songbirds to that list? They apparently work well for studying how we learn to speak.
At the February Cheyenne Audubon meeting, Karagh Murphy, a University of Wyoming doctoral candidate in the Zoology and Physiology Department, explained how Bengalese finches help her study how brains learn.
Learning by example, whether bird or human, takes place in two parts. First the student observes, or in the case of male birds learning to sing so they can defend their territory and attract mates, they listen. Then they attempt imitation, practicing by listening to themselves and getting feedback.
What Karagh wanted to know is if HVC neurons in the birds’ brains are active at both stages, hearing and doing. It’s just a simple matter of plugging a computer into the right place in a bird’s brain.
First though, you have to wrangle your subjects, capturing them in the walk-in-sized aviary, and then get them used to having the wispiest of cables attached to the tiny instrument on their heads. Otherwise, they are too stressed to sing.
Karagh recorded the firing pattern of the HVC neurons, producing something like the electrocardiogram that shows heart beats, and compared it to the spectrogram, another linear graph of peaks and valleys that visualizes the frequencies of the song she played for the bird to hear, and then the song the bird sang. Both spectrograms matched the peaks and valleys of the HVC neuron pattern, essentially showing the neurons are used for both auditory and motor output, the action of singing.
Recently, something very similar has been found in humans, called mirror neurons.
The second speaker was Jonathan Prather, an associate professor in the department’s neuroscience program. While Karagh has been studying males learning to sing, Jonathan has been figuring out what the female Bengalese finches want to hear.
Female birds don’t sing. At most, they produce call notes to communicate. But they enjoy listening to males sing and they judge them by their song to determine which one is the fittest potential mate, which will give them the fittest young.
Jonathan thought there might be a “sexy syllable,” some part of the song that would get the females excited, measured by how often the females call in response. He measured their responses as he played back songs he had manipulated.
Or maybe it was tempo, so he manipulated the recording to go faster in some trials, then slower in others. Or maybe the female birds would react differently to songs at different pitches. That would be similar to human women who, studies have shown, are attracted to men with deeper voices (connected to higher testosterone levels).
Apparently, female finches are looking for quantity and complexity, for males who sing in the most physically (neuromuscular-wise) demanding way. That means sweeping from high to low notes a lot, and really fast. Think how opera stars singing the most demanding repertoire get the biggest applause. A bird that can sing well is well-fed, healthy and of good breeding—perfect father material.
The field of neurobiology is more about figuring out human brains, but when birds are used as models, birdwatchers find it intriguing. The questions from the Audubon audience reflected their familiarity with birds.
Our songbirds in Wyoming are only seasonal singers, so birds from equatorial locations that sing year round are used to make trials more efficient. Would there be a difference?
Are female bird brains different from the male brains? Yes, because learning songs increases one part of the male brain, however, females have other roles that increase the size of other parts of their brain.
If a young bird never hears another bird sing, will it eventually sing? Not really, it will only babble in an unformed way, as human babies do when they start out.
If a young bird hears only the singing of a different species, will it learn that song instead? Yes, although not completely perfectly—there is some genetic influence on bird song.
And what about the mimics? What about birds like starlings and mockingbirds that learn to imitate lots of other birds’ songs and even some human vocalizations and mechanical noises? Karagh broke out in a grin. That line of study could keep her busy for her entire career.