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Scientist Studies Brain Process of Songbirds

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Scientist Studies Brain Process of Songbirds

Scientist Studies Brain Process of Songbirds

Scientist Studies Brain Process of Songbirds

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Sarah Woolley, a professor of behavior neuroscience in the psychology department of Columbia University, studies different species of finches to figure out how the brain recognizes and processes sounds and vocalizations.

MELISSA BLOCK, host:

From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.

ROBERT SIEGEL, host:

And I'm Robert Siegel.

How does the brain recognize and process vocal sounds? How do we learn to communicate with our voices? Well, those are questions that behavioral neuroscientist Sarah Woolley of Columbia University is working on. And she is doing it by studying bird brains, in particular the brains of finches.

When she came to our New York studio the other day, she told us that the ability to vocalize complex communication is where humans and some birds can learn and teach vocal communication most animals can't.

The communication she is talking about are bird songs, not simple bird calls. And it turns out that among birds, singing is an almost exclusively male activity. Male bird brains are different from female brains in this respect, so it's incumbent on the adult males to teach their male offspring to sing.

Dr. Woolley came armed with recordings of her finches to tutor me in the process of teaching and learning bird songs. We begin with a recording of a zebra finch.

(Soundbite of a zebra finch singing)

SIEGEL: Sounds...

Dr. SARAH WOOLLEY (Behavioral Neuroscientist, Columbia University): Isn't that charming?

SIEGEL: ...possibly baroque, that song.

Dr. WOOLLEY: Yeah, they're very charming.

SIEGEL: And if a young, male zebra finch grew up in isolation with no one to teach him that song, he would not learn that song?

Dr. WOOLLEY: He sings what's called isolate song. And it's still recognizable as the song of that species. But it is highly impoverished, unstructured acoustically and not attractive to a female.

SIEGEL: I see, which is what this is all about.

Dr. WOOLLEY: Right. The songs are used by males to attract females. And females judge the quality of males based on the quality of their song.

SIEGEL: Do such birds then, not thrive in mating with females?

Dr. WOOLLEY: They are not successful. Now, in the laboratory, we can set it up so that he's her only option, in which case, she'll go for it. However, if she is offered the opportunity to choose a male who sings a complex, or what he call sexy song, she will choose him and will ignore the male who's been raised in isolation, who sings an acoustically impoverished song.

SIEGEL: And is that a scientific term of art, a complex, sexy song?

Dr. WOOLLEY: Yes.

SIEGEL: It is, okay, good. And the females, all they do is call back. They don't sing.

Dr. WOOLLEY: That's right. Yeah. They judge the male's vocal production. That's right.

SIEGEL: Can we here that, that song once again?

(Soundbite of a zebra finch singing)

SIEGEL: And they would just repeat, that same song would repeat over and over again? Or there...

Dr. WOOLLEY: Yeah.

SIEGEL: ...are there variations on it or...

Dr. WOOLLEY: No. He sings that song continuously over and over and over again. And it makes our analysis of behavior and changes in behavior and how the brain turns that song into a meaningful social message much easier, than it would be for us to study species that sing multiple-song types, like the song sparrow, for example.

SIEGEL: Mm-hmm. But this finch matures very quickly, so you can actually raise a number of generations in relatively short period in a lab, yes?

Dr. WOOLLEY: Yes. And we can follow song development. We can follow how the song-learning process takes place, the different phases of song learning. We can draw parallels between those phases of song learning and the development of speech in humans. And we can analyze how the brain changes during that learning.

SIEGEL: Well, before we get to how the brain changes, if the grandfather of that bird we just heard, that finch, were to hear the song of the grandchild, the grandson of that finch, would the two songs be recognizable, that it's the same song being passed on from generation to generation of the birds?

Dr. WOOLLEY: Yes. They would be highly similar, although each male sings his own, unique version of that song by adding some unique components. When he learns a song, he does what he call improvise, as well.

SIEGEL: And that was the zebra finch.

Dr. WOOLLEY: That was the zebra finch. Each species sings its own species-typical song.

SIEGEL: And another finch you've worked with, I gather, is the Bengalese finch.

Dr. WOOLLEY: That's right.

(Soundbite of a Bengalese finch singing)

SIEGEL: That's the...

Dr. WOOLLEY: Right.

SIEGEL: ...the song of the Bengalese finch?

Dr. WOOLLEY: That's right. Yes.

SIEGEL: Something, which that bird presumably learned from a male tutor, probably his father.

Dr. WOOLLEY: That's right.

SIEGEL: This is something that - you should point out - not all birds or species can do this, can teach a song from generation to generation.

Dr. WOOLLEY: That's right. There are three different clades or taxonomic classes of birds who can learn. They're the parrots, hummingbirds and songbirds. Songbirds, by far, are the most well studied. And they have this unique ability to learn complex vocalizations when other animals can't do it. There is now good evidence that whales can copy sound vocalizations, but we don't really know how they're using them in a natural context. And in a laboratory, of course, a songbird is a lot easier to handle.

SIEGEL: What would happen if one kind of finch were placed in a cage or, in effect, with a tutor who is another kind of finch?

Dr. WOOLLEY: Right. So in the laboratory, one of the ways we asked the question of how does learning change perception and change the brain is by doing what we call cross-fostering and cross-tutoring birds. So we can take a baby zebra finch who's still in the egg or just hatched, and place it in the family of a Bengalese finch. So he grows up a zebra finch, but in the family of a Bengalese finch, and he learns the Bengalese finch song.

SIEGEL: And they will accept him as an...

Dr. WOOLLEY: They will. They will.

SIEGEL ...honorary Bengalese finch?

Dr. WOOLLEY: You can't do the reverse. Zebra finches are much less terrible as parents. But you can have a Bengalese finch raise different species of finches. And you can ask the question then, what can be learned that's different from your normal species song?

SIEGEL: Does he learn the song?

Dr. WOOLLEY: He learns the song, but he copies the song's syllables from the Bengalese finch foster parent. But then he sings it in a phrasing that is like a zebra finch.

(Soundbite of a zebra finch singing)

Dr. WOOLLEY: So that's a cross-tutored zebra finch. So he's learned the trill-like syllables of a Bengalese finch, but he sings them with these truncated phrases that are more typical of the zebra finch.

SIEGEL: Now, is that just telling us something about the physiology and the musculature of a bird? That it'll have this accent, I gather you refer to this as? Or are the brains of animals somehow programmed to sound one way, to make a song one way, and that that predetermination is then tempered by upbringing?

Dr. WOOLLEY: We know that young birds hatch with an innate ability to focus on the correct species information. So they will focus on their own species' songs if we offer them a variety of species' songs to focus on and or copy. So in the brain of a normally raised zebra finch, and in the brain of a normally raised Bengalese finch - meaning that they've both been raised by their own species -there is an area of the brain that processes sound, in which the neurons, or the brain cells that communicate with each other, fire more.

So they respond more to the songs of their own species. But when you cross-foster birds, those areas of the brain no longer distinguish between zebra finch versus Bengalese finch song. So experience, the experience of being raised in a family of Bengalese finches has affected the response behavior of the brain cells in that part of the brain.

SIEGEL: So does that say much for how we're conditioned or at least how birds are conditioned by nurture when they're little?

Dr. WOOLLEY: Well, it's clearly a combination. In fact, we, in science and neuroscience and in behavioral neuroscience, have put that argument to rest in that we all understand now that there is no separating nature and nurture. That the outcome of behavior and the outcome of the way the brain makes meaning of the outside world is a combination of both.

SIEGEL: Sarah Woolley, thank you very much for talking with us about this, and playing your bird songs for us.

Dr. WOOLLEY: You're welcome. Thank you.

SIEGEL: Sarah Woolley is a behavioral neuroscientist at Columbia University.

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