Transcript:TWIS.ORG Mar 02, 2010

Justin: Disclaimer! Disclaimer! Disclaimer!

The largest earth tremor recorded anywhere on the planet registered a 9.5 magnitude on the Richter scale. It occurred 50 years ago in Chile, the Gran Terremoto de Valdivia.

Fifty years later, people of Chile are no strangers to earthquakes. And despite the great magnitude and duration of the recent 8.8 Chilean building codes, engineering and retrofitting have saved many more lives than were lost.

If we know our history, we know that there are no such things as natural disasters. There are only disasters of man’s making. For ignorance of tectonics will not protect people from tremors. Not having seen a hurricane first hand doesn’t mean they are harmless.

Filling former floodplains with newly furnished homes is not going to dictate the future rainfall for that area. If you want to live on a mountain peak or a valley floor, by ocean frontage or in hillside retreat or wherever you prefer to place yourself on the planet, it comes with the responsibility of being prepared.

And while condemning ignorance of the future, much like the following hour of our programming, does not necessarily represent the views or opinions of the University of California at Davis, KDVS or its sponsors.

Nature is a consistent creature. If you watched her movements in the past, you will know where she will go in the future. The better we know her ways, the more prepared we will be to deliver This Week in Science, coming up next.

Good morning, Kirsten!

Kirsten: Good morning, Justin. We’re here. We came. We brought the science. That’s right. We’ve got all sorts of science-y goodness on the way, on the way.

Justin: This was a big week, a big science-y week.

Kirsten: Huge.

Justin: There was so much material out there.

Kirsten: I know and all we have is an hour. And in the second half of the show today, we have an interview which I’m excited about. We are going to be interviewing a couple of researchers from Duke University who have been sneaking peeks at the neurons inside bird brains just at the moment that learning of their song starts to take place.

Justin: Wow.

Kirsten: Yeah. So number one, how do you do that? How do you look at the neurons in the brain when learning – I mean, what? This just doesn’t – I think there are laser beams involved.

Justin: Wow.

Kirsten: Lasers, man.

Justin: Lasers in bird brains…

Kirsten: Exactly.

Justin: …in the second half hour of today’s show.

Kirsten: In the second half hour. And we have science news. I have stories about fishies and faces and new materials.

Justin: I’ve got YouPeg better than you do, perhaps.

Kirsten: You pegged? What?

Justin: Yeah. YouPeg better than you have yourself pegged.

Kirsten: Oh.

Justin: I have why cows are bad for babies, why cocaine might not be so bad for babies. And a quick peek at the…

Kirsten: Moo.

Justin: …evolution. Sniffing cow.

Kirsten: (Sniveling) cows.

Justin: Cow snorer.

Kirsten: That’s right. Oh, so let’s get going on the science news because it sounds like you’ve got some really fun stories. I want to hear what you have to say.

Big story for this week, material science has made a quantum leap.

Justin: Wow.

Kirsten: Yeah. So material science, it’s really important because materials…

Justin: Stuff matter.

Kirsten: …it’s what stuff is made out of.

Justin: It’s when energy sticks together and we can use it for stuff.

Kirsten: For stuff, exactly, for making materials. So some researchers, engineers at the Mechanical and Aerospace Engineering – where are they located actually? Here we go. No. No. I have no idea where they are.

Justin: We’ll find them.

Kirsten: Right. I thought I had an idea.

Justin: Better than undisclosed location working on secret materials.

Kirsten: Princeton.

Justin: Oh.

Kirsten: Princeton, your new alma mater.

Justin: What? Yeah. Princeton just sent me a thing. I guess it’s a free tuition to go to Princeton or whatever. Then I found that’s in New Jersey. I was like, “Whatever, I am not…I don’t care how fancy your school is. I’m not moving to New Jersey.”

Kirsten: Come on, New Jersey? It’s a place where we want to be.

Justin: No way. No way.

Kirsten: Well, okay. Emily Carter, female engineer which – that’s awesome in itself, has made this huge mathematical leap in material science. So 80 years, researchers have been working on a quantum quandary. I’m trying to get the alliteration in there.

Justin: Yeah, very good.

Kirsten: Oh, yeah thanks. So, they’ve been reworking a theory that was first proposed by physicists in the 1920’s called the Thomas-Fermi equation. It’s proposed by Llewellyn Hilleth Thomas and Enrico Fermi in 1927.

Now, the equation was this means of relating characteristics of atoms and molecules. So what it theorized is that the energy that electrons possess as a result of their motion – what’s called electron kinetic energy – can be calculated based on how electrons are distributed in a material.

So it’s kind of like pressure. Basically, if you take molecules and you apply a lot of pressure, put molecules into a smaller space wherein the pressure goes up. So if you put a lot of electrons into a small region, they’re going to have higher kinetic energy than if they’re in a larger distributed region.

And if you understand this relationship of how electrons are distributed and then how much energy they have, it can actually help you measure it and then also design materials because you can take atoms and molecules and say, “Well we want these atoms here and these electrons would be – and these orbitals on these atoms and so they would be distributed in this way.” And so engineers and physicists can actually take this relationship and start building materials from the electron level.

Justin: Wow.

Kirsten: Yeah. And this has been really – and this equation from the 1920s is a major part of it. Now in 1964, another step forward came when they actually realized that they could apply this equation to materials.

And then, since then, researchers have been working on it. And now what they do is they use supercomputers to try and model materials based on this equation. But it’s really processor-heavy because we don’t really or they haven’t exactly figured out a final working equation for relating kinetic energy, the electron kinetic energy to the distribution of electrons.

And so scientists, engineers have been looking for that relationship since the 1920s but really since the 1960s. And so, what they’ve been doing since the ’60s is using – calculating atom by atom, using computers, using just straight up math and saying, “Okay. We have this atom here. We have this atom here,” and trying to create these materials but they’ve only been able to calculate say, a hundred atoms at one time. But materials are made up of millions, billions of atoms, right?

Justin: Hella atoms in there.

Kirsten: Hella atoms, that’s right. That’s another story that we’ll get to in a second. And so, it’s been really difficult to actually accurately model materials and know exactly how they’re going to function and how they’re going to work.

And so along comes, Emily Carter at Princeton University, she and her graduate student have actually – using semiconductors. They’ve been able to model this relationship. And they’ve actually figured it out.

And what she says, “We needed to find out what we were missing that made the results so different between the semiconductors and metals. Then we realized that metals and semiconductors respond differently to electrical fields. So our model was missing this. And by finding an equation that worked for these two types of materials, we found a model that works for a wide range of materials.”

And they’ve published their finished paper, their equation in Physical Review B, journal of the American Physical Society and it provides a practical method for predicting the kinetic energy of electrons in semiconductors from only the electron density.

Now what this means is this extends the model from only being able to calculate maybe a hundred atoms at one time to hundreds of thousands to even millions and be able to make it much more efficient for it to use computers to be able to model materials.

And so it’s going to actually speed up the rate at which new materials are formed. And so what does this mean for you? This means maybe lighter materials and stronger materials to build your cars more safely. This means lighter materials for portable devices. This means harder materials for, you know, surfaces that need to be really hard. This is potentially going to have huge impacts into the things that we use every single day.

Justin: Metal pants.

Kirsten: Maybe metal pants.

Justin: Yes.

Kirsten: Yeah. So anyway, I think this is just a really exciting story, quantum leap in material science.

Justin: That’s awesome.

Kirsten: One equation, one equation, bam! Potentially huge, huge, huge results.

Justin: Yeah.

Kirsten: Yeah.

Justin: Go Fermi.

Kirsten: Yeah. I like Fermi as it is. Oh, and the hella reference that you came up with.

Justin: Yes. Oh, yeah.

Kirsten: There’s a Facebook fan page right now. There’s a movement afoot. A bunch of students are trying to get the SI prefix for 10^27 which – it does not have a prefix currently.

The highest prefix is currently yotta, so there’s a yotta mass, a yotta mass out there that’s 10^24, 10^27 not named. So this sigfig, 10^27 does not have a prefix. Northern California came up – I don’t know how – I think I was in high school when people started using the term hella.

And Northern California has had significant influences into science. And so students in Northern California are pushing to remember Northern California as a significant scientific influence by forever placing hella in front of all numbers with 10^27 significant figures.

Justin: That’s awesome.

Kirsten: There’s hella mass out there. That’s great, that’s great.

Justin: Okay. This is a study that I think or a story that I think might already be apparent, one need look no further than the auditions for American Idol?

Kirsten: Oh, that’s one of my favorite television right there.

Justin: Yeah. I mean, if you’ve watched them then you can see that there are people who honestly came in and believed that they had the golden voice. So after watching enough of those, you can see that the ancient Greek saying carved into the Temple of Apollo at Delphi, “Know thyself” is going unheeded by many people today.

Now shedding light on ancient wisdom is Simine Vazire, – gosh, it’s a different thing…

Kirsten: Pull it together.

Justin: Anyway, she’s a Ph.D. at Washington University, assistant professor of psychology in Arts and Sciences. She has found that the individual is very accurate in assessing their own internal neurotic traits like anxiety. We’re very good about noticing that we are being anxious or what have you.

While friends are better able to peg your intellect-related traits such as your intelligence, your creativity or the way that you are with other people. Strangers are just as good as your friends and ourselves at spotting the extroverted portion of our psychology, the extroversion.

And here’s the quote, “I think that it’s important to really question the knee-jerk reaction that we are our own best experts. Personality is not who you think you are, it’s who you are. Some people think by definition that we are the experts on our own personality because we get to write that story. But personality is not the story, it’s the reality. So you do get to write down your story about how you think you are and what you tell people about yourself.”

Kirsten: Mm hmm.

Justin: “But there is still a reality out there and guess what? Other people are going to see the reality regardless of what story you believe.”

Kirsten: So there’s maybe there are unspoken signals. There are things that you do that tell people…

Justin: Or spoken signal.

Kirsten: …or spoken.

Justin: Yeah.

Kirsten: But that tell people more about you than you necessarily – that you’d go out – than you planned to tell people.

Justin: Right. And it’s not even the stuff that you would plan to tell about yourself like we all have a self definition of who we are.

Kirsten: I don’t.

Justin: Well, you might.

Kirsten: No, I think I do.

Justin: You might. I mean, now me and Ali are like sideways glancing like, we know what we’re talking.

Kirsten: Yeah, okay.

Justin: No, I mean like – okay. So here’s – I’m going to go on a little bit. Personality, Vazire says, is pervasive in many things that we do — clothing choice is one; bedroom arrangement, oddly — I don’t know what that says about me, that’s frightening; website and Facebook profiles are other examples.

Kirsten: Right.

Justin: Everything you touch, you leave a mark of your personality.

Kirsten: Yup.

Justin: And you leave traces unintentionally even, that give off hints of your personality that you don’t necessarily know that you have.

Kirsten: This person’s been watching Caprica.

Justin: I don’t know what Caprica is.

Kirsten: Caprica, it’s a Sci-Fi program spinoff of Battlestar Galactica. And in it, one of the first – the first episode basically…

Justin: Best episode ever.

Kirsten: Best episode ever, man. They’re doing virtual reality stuff. And so, this daughter of this big techie guy gets killed but she leaves a bit of her personality because she’s created like this virtual avatar of herself in this virtual world.

Justin: Mm hmm.

Kirsten: And she created it based on all of the things that she left behind. And they go through this whole idea like, well, on the internet, whatever you do when you buy a coffee, you know, anything that you do in this world, you’re leaving a mark.

Justin: Right.

Kirsten: So, this person’s just been watching Caprica.

Justin: No. What’s really interesting about that though, that’s a great example, that’s a perfect example because if we all sat down and wrote our personality out for an avatar, chances are the avatar would act a lot differently than us…

Kirsten: Right, right.

Justin: …because what we want our personality to be, our best intention of who we actually are…

Kirsten: Is not.

Justin: …and what our affect is in the world is different.

Kirsten: Yeah. Yup, yup.

Justin: And the thing is other people can see that when we can be completely aware of it. One example is something like a bully perhaps who is actually insecure, trying to be liked and is, you know, feels really good about the fact that they’re interacting with people because that’s how they get along, right? We’re trying to interact with people but to everybody else they’re really rude and obnoxious, maybe even intimidating, right?

Kirsten: Mm hmm.

Justin: So, there’s like a difference between…

Kirsten: The perception, mm hmm.

Justin: …what we’re going out there for…

Kirsten: Yeah, I think that’s interesting. There is a difference in perception because you don’t perceive everything about yourself necessarily that you’re putting out subconsciously…

Justin: Mm hmm.

Kirsten: …or even consciously.

Justin: Or even consciously.

Kirsten: Yeah. Interesting! This week in space news, Ed Dyer sent in a story about how it feels to be torn apart. Well, not necessarily how it feels to be torn apart but a group of astrophysicists coming together from around the world. So it’s an international group working on an intergalactic project.

Justin: Galactic, cosmic conundrum.

Kirsten: Yes. They found a massive planet called “WASP-12b” outside of our solar system. And it’s really close to its host star, its parent star. And one of the conundrums about WASP-12b is that it’s really close to its parent star but it’s huge. It’s bigger than Jupiter. It’s like six times the size of Jupiter. It’s this giant planet.

Justin: Wow. Hey, that’s…

Kirsten: Well, maybe not six times, 50% larger.

Justin: Yeah.

Kirsten: And, yes! Six times Jupiter’s volume is what they’re saying. And it’s really, really, really hot. So, hotter than would be expected for even how close it is to its parent star.

So, there’s something going on inside this planet that has puffed it up really big and it’s got a lot of activity. It’s really hot and bloated. And what on earth made this happen?

Justin: Nothing on earth.

Kirsten: Because it’s – nothing on earth – because it’s closer to its star than Mercury is to our sun. And what they’ve done is they put a whole bunch of telescopes on it and tried to figure out what was going on.

They focus on tidal forces, so these magnetic forces that occur as the planet orbits, the star. And what they say that they’ve found is that it’s the effect of gravity of the parent star, because it’s so close, is inflating the size and making it blow apart. So, the star is actually tearing this planet apart. And this planet is in the last stages of its life.

Yeah, so it’s still going to live for a while for, you know, many million years. It will be around for us to look at. But we – it’s not often that you get the chance to take a look at a planet and its death throes.

Yeah, the forces acting on the planet have changed the shape of the planet so that it’s no longer spherical but rather more oblate, more like a football.

Justin: Wow.

Kirsten: Yeah, an American football, not made as a soccer football is…

Justin: That would be round.

Kirsten: …round, right.

The researchers say this is the first time that there is direct evidence that internal heating or tidal heating is responsible for puffing up the planet to its current size. WASP-12b is losing its mass to the host star, the tremendous rate of 6 billion metric tons each second. That’s a lot.

And so, at this rate the planet would be completely destroyed by its host star in about 10 million years. This might sound like a long time but, you know, it’s not really. And it’s going to live less than 500 times less than the current age of the earth. So, it’s going to die even before it reaches the age of the earth.

In other news even as this planet is being torn apart, other researchers looking at the heavens have found a baby planet. So, it’s out with the old and in with the new.

Justin: Look at the cute little baby planet.

Kirsten: A little baby planet. It’s the youngest extra solar planet around the solar type star. And they’ve named it BD+201790b. I love these names. There is logic in there somewhere.

So, this one, this is where I got the six times the mass of Jupiter. This is a giant planet, six times the mass of Jupiter. It’s 35 million years old which is about three times younger than the other youngest planet ever found. So, it is now the youngest planet ever found. And it’s good to find these young planets as well as the super old planets because it gives us an idea of how we can test planetary and solar system formation scenarios. So, it’s pretty cool.

Researcher Maria Cruz Galvez-Ortiz says, “The planet was detected by searching for very small variations in the velocity of the host star caused by the gravitational tug of the planet as it orbits the so-called ‘Doppler wobble technique’. Overcoming the interference caused by the activity was a major challenge but they had an array of large telescopes and the planet’s signature was revealed.”

Justin: Mm hmm.

Kirsten: Yeah, pretty cool.

Justin: Yeah. We’ve gotten that down pretty good now.

Kirsten: Yeah.

Justin: They find a new extra solar thing all over the place.

Kirsten: Extra solar planets all over.

Justin: All right, warning! Warning, danger, danger, danger, danger!

Kirsten: Danger.

Justin: Frequent contact with cows may be the cause of bacteria found in many women and that can cause life-threatening infections when passed to newborns. Yes, beware of women and cows.

The research team led by Michigan State University, it’s a Group B Streptococcus — it doesn’t sound good — could be a zoonotic – it’s the first time I’ve seen that word.

Kirsten: Zoonotic, yeah it’s foreign.

Justin: Zoonotic disease.

Kirsten: Yes.

Justin: Zoonotic meaning that it’s able to cross over to different species.

Kirsten: Species, mm hmm.

Justin: Yeah. And it may have significant public health implications, says Dele Davies, chairperson of MSU’s Department of Pediatrics and Human Development.

Group B Streptococcus also known as GBS, first recognized as a bacterium that leads to infections in the breasts of cows is now found in up to 36% of pregnant women’s digestive and even genital tracks.

When passed to newborns during pregnancy, the infection can lead to death. Although not all of the infants actually become sick. While GBS affects only one in every 2000 babies and there are prenatal tests out there that are able to identify it, Davis said, “Understanding how women are infected could greatly reduce the transmission rates.”

As part of the study, they looked at families that have livestock and collected and compared stool specimens and increased frequency of cattle exposure was significantly associated with the human infections.

One couple shared the same GBS strains as their cows suggesting the zoonotic transmission. Our study suggests that at least for some women, there’s an association between increased exposure to cattle and colonization of the bacteria through GBS human infection has been long suspected as originating from cows.

Several investigators have suggested that ongoing interspecies transmission is unlikely. So, these researches are published in PLoS ONE. Beware of cows. Beware of women. They’re dangerous.

Kirsten: Yeah, we are.

Justin: Dangerous.

Kirsten: That’s right. That’s right. Be wary. Be wary.

In other news, there’s some discriminating damselfish out there. I’d like to thank Ali for this story.

Justin: Discriminating damsels?

Kirsten: Discriminating damsels.

Justin: Aren’t they all?

Kirsten: Not damsels in distress but damselfish. They’re coral reef fish and what they do surprisingly, well it’s not so surprising, is that they use ultraviolet vision to tell the difference between their species and other similar species.

Researchers noticed that – and this is published in Current Biology – researchers noticed that this damselfish had UV – had markings on their faces that glowed in ultraviolet light. And seeing that there were these markings they went, “Hmm, I wonder what they’re used for.”

So, then they gave – they put male fish in tanks through a couple of tests. They exposed Ambon damselfish to the same species and different species, so those that would have similar UV markings and different UV markings.

And then they saw that the male’s territorial reactions were increased when they were in the presence of fish with the same UV markings as themselves. So, they were recognizing something about this.

And they put them in conditions when the UV markings could be seen and not seen. And so the territorial reactions were only in the condition where males of the same species and their UV markings were visible. If there was no UV marking visible, then there were no territorial reactions because the males didn’t recognize them as a threat.

So, what they’re demonstrating is that these particular markings is – they’re the way that these damsel fish recognize their own kind. They looked at further experiments and they found that the shape of the UV markings is specifically what the fish are reacting to – not the color, per se. So if like hot pink or hot blue or whatever.

Justin: No difference.

Kirsten: No difference but it’s the shape. And so from that, they’re like, “Let’s see. We came to the conclusion that the fish are using ultraviolet reflecting facial patterns to discriminate between their own species and other similar-looking fish species. And also, that they are reacting to the actual pattern not simply the UV light they were seeing.”

Differences between patterns on the faces of individuals suggest that Ambon damselfish may also be able to use the patterns for the discrimination of individuals in a manner directly comparable to the face-based recognition of individuals performed by humans.

Justin: Wow!

Kirsten: This means the damselfish are effectively exploiting a secret channel of communication among themselves and with other similar but harmless species, one which cannot be detected by the fish that prey on them. This ability to see in the ultraviolet seems to have been retained in some coral reef fishes whereas carnivorous fish and many higher animals including humans seemed to have lost it.


Justin: Interesting.

Kirsten: Yeah, this ability to see in the ultraviolet has been lost by their predators and even by us. We don’t have the receptors to be able to perceive ultraviolet light.

Justin: Yeah.

Kirsten: It’s pretty cool. Anyway, Current Biology, if you’re interested in reading up more about that or we’ll have a link to it on our website in the show belts.

Yeah, it’s 9 o’clock.

Justin: Oh, no.

Kirsten: I know. No cocaine and babies.

Justin: I wanted to, you know – like cocaine and baby story.

Kirsten: Okay go, can you do it quickly?

Justin: No.

Kirsten: No.

Justin: I can do it in a minute.

Kirsten: Okay.

Justin: Cocaine – hang on. Cocaine, long ago, an active ingredient in many medications and even popular in the soda, Coca-Cola, hence the name, is the first word associated with the 1980’s and is best known today as a powerful narcotic that can become so addictive as to rewire the brain’s pleasure reward system around it may not be as bad for children though as we once thought.

Children exposed to cocaine prenatally can have the flow of nutrients and oxygen interrupted putting such children at risk for premature birth, low birth weight and many other problems.

While this negative impact significantly affected children in subtle areas such as sustained attention and self regulated behavior, new research showed surprisingly little impairment in key areas such as growth, IQ, academic achievement and language functioning.

Basically, what does this mean? It means that an entire generation that was born in the ’80’s isn’t completely doomed.

Kirsten: That’s good to know. And on that note, we’re going to go take a break and we’ll be back after these messages with our interview with Todd Roberts and Richard Mooney from Duke University Medical Center about birds and lasers – Bird Brains and Lasers.

Justin: Birds with Lasers that shoot from their brains.

Kirsten: Be a part of the magic. Make some science music. Be heard on This Week in Science. We’re using your science music for our annual science music compilation.

If you’re a musician or knows somebody who is, why don’t you write us a song or get your friend to write us a song, science-y goodness in the form of music? For more information, email

Justin: Thank you for listening to TWIS. If you rely on this show for weekly science-y updates, please understand that we rely on your support to keep bringing those to you. Donate! Keep the science-y goodness on the air. We’ve made it very easy for you.

Go to our website, Click on the button that will allow you to donate $2, $5, $10 or if you like, you can donate any amount of money you choose as many times as you like. Again, just go to and donate today. We need your support and we thank you in advance for it.

And we’re back.

Kirsten: We are. And this is This Week in Science. Online, we have Dr. Richard Mooney, a professor of neurobiology at Duke University and Todd Roberts also at Duke University Medical Center. And they have done some really interesting research looking into bird brains. Welcome.

Richard: Hey, great to see you. This is Rich.

Kirsten: Hi, Rich.

Todd: Hi, this is Todd.

Justin: Hi Rich. Hi Todd. Welcome to This Week in Science.

Richard: Hey, it’s great to be here.

Kirsten: Yeah. So I found a press release about your research this last week and it just got me intrigued. And so, tell us why – I guess Rich, can you give us some details as to why you decided it would be a good idea to peer deeply into the brains of birds.

Richard: Well, I mean the real attraction is that they engage in this really beautiful form of vocal imitation. And it’s a form of motor learning. It has many features that are similar to speech learning in humans but it’s experimentally tractable.

Both at a behavioral level and at a cellular and even sub-cellular level which was a great tool for us in terms of imaging how the brain changes during initial stages of learning.

Kirsten: Nobody has ever gotten this close to the initial stages of learning before. I mean, can you tell us a little bit…laser beams looking at the brain. How did all this work?

Todd: Well, what we did was use a viral technique so that we can go in and label neurons in the songbird brain. And then we can put them under two-photon microscope. And this allows us to look pretty deeply into the brain about up to half a millimeter or so and with really high resolution.

And with this technique, we can then excite fluorescent proteins that we’ve made (us all express) and then visualize the points of synaptic contact in these neurons or on these neurons.

Kirsten: Okay. So basically you’ve infected, so to speak, infected the bird’s neurons with a fluorescent protein that gets excited when something happens?

Richard: Yeah. So, I mean, just to expound on that a little bit, I mean the real technical advances are the ability to get neurons to express this – what is originally a jellyfish protein, green fluorescent protein, that was awarded along with the discoverers and early characterizers of its use in other biological systems, the Nobel Prize in Physiology or Medicine a few years ago.

Kirsten: Yeah.

Richard: Getting neurons to express that, that’s one step and then the other and really I think equally or more critical is figuring out a way to use a light microscope to image what’s happening inside the living animal. And that’s on the – sort of the business end – a conventional light microscope with the one twist that the light source is a really high powered infrared laser.

And these have been developed for biological applications over the last decade or more but are really starting to find a more common use in neuroscience now, the image of a living brain.

And this is just something like, when I was a grad student, you know, as they say, what old men tend to say…

Kirsten: In my day.

Richard: But you couldn’t do – except for an affixed piece of brain tissue, a thinly cut slice of brain tissue. You might be able to get images of this resolution and what’s really amazing is now the technology exists to get high resolution images of nerve cells in an animal that’s alive and learning from a tutor, in this case.

Kirsten: Yeah. So you’re not killing any birds to be able to do this, for this process. And so the bird can actually behave and then you anesthetized it and then see what happens when the bird is kind of sleeping?

Todd: Yeah. So what we do is, we, you know, kept the birds on a reverse day-night cycle. And so, during their regular sleep cycle, we’d go in and briefly anesthetize them and put them under the two-photon microscope. And we would image changes in the brain by repeatedly imaging the same small structure of dendrite or the same small region on a neuron.

And looking at changes to the dendritic spines, these points of excitatory synaptic contact, and we would do this over the course of a couple of hours. And then we can return the bird to its cage. And it would wake up in the morning and we can put it in with a tutor and then it would have this auditory experience of a tutor.

And then the following night, we can do the exact same thing. And, you know, again put it under the microscope and find the exact same neurons and the same small structures of dendrite on those neurons and the same dendritic spines or some new dendritic spines on the same structures and quantify how stable or unstable these regions or these points of synaptic contact are before and after they first have this tutor experience.

Richard: So Kirsten, you really hit on a key point which is Todd and Katie were able to image and reimage in the same animal as it progressed along its learning axis over development.

And classically, I mean, I’m sure you and your listeners know, the approach is that you might examine one animal in a given condition. I mean compare its brain to another animal in the same covert later on in development or later on in the learning process and make inferences about what might have happened in any individual brain by making this cross individual comparisons.

Kirsten: Right.

Richard: That’s a really – statistically, you can make that work but it’s much less powerful. As we know from our own experience, learning is a highly individual process. We learn new skills at different rates, different times during our lives.

Kirsten: Yeah. And so how do you know exactly what’s happened if you’re having to look at different individuals. So that makes it really powerful here.

Richard: Exactly. You know, I mean there are a couple of things for this. I mean the techniques were around when Todd and Katie and Marguerita started working on this project. But nobody had really adapted these methods in songbirds. And they have this beautiful behavior. But unlike mice or zebra finch or fly, they don’t have the really powerful genetic tool kit…

Kirsten: Right.

Richard: …to label neuron. And no one had really gone in and looked at this kind of learning before in any system. And mice actually don’t exhibit…

Kirsten: This kind of behavior.

Richard: …this complex imitation. Right, yeah.

Justin: So my question is how do you do the labeling? I mean if you’re going in and doing the labeling ahead of the learning, you’re kind of having to pick where the changes are going to take place, right?

Todd: Well, what we do is inject a virus into the area that we want to image. And it will randomly label a subset of neurons, let’s say, you know, probably less than 1% of the total neurons in that area of the brain. And then, we can go back in.

We need to let the virus have time to express and for the expression of the green fluorescent protein to build up in the cells to a point where we can actually image these dendritic spines.

And so this takes about two weeks and then we can come back in and randomly sample under the microscope. You know, some subset of cells that are either close enough to the surface or well-labeled and then image those longitudinally.

Richard: Yeah. I mean to jump in here, Josh, I mean I think the – you’ve got it right, I mean we’re limited in where we can look in the brain to some extent.

Kirsten: Yeah.

Richard: Although, you might be able to – with fiber optics image in deeper structures the way the two-photon methods have been applied really successfully looking at surface structures like the cortical mantle in the mouse brain, for example.

Kirsten: With the bird brain, I mean you were looking at zebra finches. And zebra finches, they’ve got a brain the size of a garbanzo bean. And so if you’re imaging even a couple of millimeters like you said, into the surface of the brain, you’re getting a decent amount of cortical material there, right? Or of brain material.

Richard: Right, I mean and, you know, we have some insight into where to look in this system. It’s just by serendipity, HVC, the structure that we image just right on the dorsal surface of the forebrain making it optically accessible. And it turns out that that’s a really, really key place you’d want to look. We don’t mean to suggest in the study, this is the only place such changes are occurring.

Kirsten: Mm hmm.

Richard: But in fact, we were able to see very strong relationships between say, the turnover of dendritic spines and the capacity for imitation and rapid changes for those spines when an animal is exposed to an appropriate model. But it’s very likely that these reflect changes that are going on, you know, throughout many parts of circuitry that’s important to singing and song learning.

Kirsten: So what were the actual changes that you saw take place and were they different from what you expected?

Todd: Yes. So what we saw was that prior to being put in with the tutor,- these birds that were raised without exposure to a tutor had relatively high levels of spine dynamics that is…

Kirsten: And it’s good to note these birds learn their song from a tutor. And if they don’t have a tutor and if they don’t learn from someone who has a nice pretty song, their song ends up kind of screwed up.

Todd: Yeah. That’s very, very important to note. So these birds learn during a sensitive period. Usually they will acquire a memory of the tutor’s song between 45 and 60 days of age and then between – or 30 to 60 days of age.

And at around 60 days of age, the ability to acquire this memory starts to wane. And then they use auditory feedback where they’re practicing their own song and trying to match it to this memorized tutor song.

And they do that over an extended period of time. And they don’t really get a good match to the tutor song that they heard initially until they’re about 90 days of age. And what we saw was – we were looking at birds that were at 60 days of age. And they have been raised without exposure to a tutor. But they have been raised in relatively normal environments with siblings and female birds.

So they have lots of auditory experiences. They just didn’t have this one critical auditory experience and that is hearing that nice tutor song.

And what we saw was that at 60 days of age, these untutored birds have in general higher levels of spine turnover. And so their spines were more dynamic than we saw in controlled birds that were raised with exposure to a tutor.

And when these birds, right after they were exposed to a tutor, we saw that these spines rapidly stabilized within the first 24 hours or so. And this was really surprising to us because the song learning process takes a long time.

So within the first 24, 48 or 72 hours right after they are exposed to a tutor, these young birds, their song starts to change but it in no way resembles what the tutor or what their song will look like when they’re 90 days of age.

And so, it really doesn’t look like the tutor song. And the song learning process itself is a slow (interim) process where they’ll practice their song tens of thousands of times. And they’ll slowly build up until they finally have a good match for the tutor song.

And so we thought that what we might see was, you know, maybe an initial stage where the spines become more dynamic. And then they slowly stabilize over this period of sensory motor learning where they’re matching their own song to the memorized tutor song.

But instead what we saw was very rapid changes in the brain. Within the first 24, 48 hours, we saw that the spine’s rapidly stabilized, that the size of the spines got larger and that there is an increase in density of spines.

And particularly in terms of the stabilization, the amount of stabilization that we saw within the first 48 hours accounted for roughly 70% of the stabilization that we saw occur over the remainder of the sensory motor learning.

Justin: So, it’s almost as though the bird has learned the new song almost right away and then just has to practice at it?

Kirsten: Just make sure that those connections are right, right?

Justin: It has to learn from its own brain anyway, then.

Richard: This is really like – exactly. It’s sort of knowledge and trained. It’s as if the brain is catapulted forward by this really critical formative experience but it’s still going to have to work in the vocal apparatus and auditory system. We’re really going to have to work for a long time in concert to bring the behavior to perfection.

So, I think Todd really hit on it. We’re in a motor area or premotor area. One hypothesis we have at the outset was simply, well once you trigger learning, things will become more dynamic and the system will change its connections a lot for this prolonged learning phase.

But, in a way, we saw the opposite, the brain stabilized – at least at this part of the brain stabilized really rapidly even though the behavioral learning was going to evolve over many more weeks.

Justin: I’ve always thought my brain was smarter than me.

Richard: I think, you know, I think both of you, I’m sure your audience will appreciate the sensation. I mean, especially people who play a musical instrument know this sensation of, “Well, I know what I’m supposed to be doing. But I don’t know exactly where my fingers are supposed to go or how I am supposed to execute this.”

Kirsten: Right.

Richard: “But I have the sound in my head, how do I get it out?”

Justin: Yeah.

Kirsten: Huh.

Richard: I don’t know if anyone even has a memory of the challenge that they felt when they were trying to imitate their parent’s voice. But my guess is that a young child when he’s learning to speak has a pretty good idea of what it’s trying to sound like but is impeded by this output structure including its vocal apparatus that it has to train.

Kirsten: That it has to learn how to use, right?

Richard: Right, right.

Kirsten: Oh, that’s a really interesting idea. Did you see any – you talked about an increase in spine density and stabilization of the spines. One thing that a lot of people talk about during say, learning or this developmental period is the pruning of the dendritic branches.

And that the – so you have some branches and spines that stabilized and others that kind of get pruned away so that only the important ones remain. Did you see any evidence of that?

Todd: Well, we didn’t see any evidence of pruning at this early stage in development. We were able to compare birds that were able to learn from the tutor versus birds that didn’t learn from the tutor experience. And that’s primarily because we started training birds or gave birds exposure to a tutor when they were really at the – near the end of this sensitive period for being able to learn from their tutor.

And we only saw this increase in density in spines from the birds that did learn. And we didn’t see any change in the spines of the birds that did not learn. But that’s not to say that there isn’t going to be pruning of spines later in development, perhaps when the song becomes more crystallized.

And so, you know, one of the end stages of the song learning process is that the song becomes in a way more hard wired in the brain. Not that we’ve – this has been reported but, you know, just behaviorally the sound becomes much more stereotyped. And becomes – it’s harder to get the song to change even with – definitely as the animals become older. And so it could be that there is pruning at this later stages in development.

Richard: All right, I think one, you know, the other key feature that came out of these studies was what the naive brain was like in animals that were particularly good at learning.

Kirsten: Mm hmm.

Richard: And there was a more or less a continuum. There was in these naive birds at 60 days of age which is, as Todd noted, marks the end of the sensitive period for memorizing a tutor song.

There were birds with highly dynamic synapses, at least we inferred they had highly dynamics synapses because spines turned over a lot and other birds that looked like age match controls that had already been tutored. The birds that had highly dynamic spines went on to learn much more from their tutors than did the stable birds.

So, that tells us a couple of things. One of which is it suggests, when you got a really highly dynamic synaptic network, you’re better capable of learning. And it’s one way we think about it is that maybe under those conditions, experience can select certain synapses and augment them and maybe eliminate other synapses maybe some that aren’t associated with formative experience and learn from it. Whereas, if the network is too stable, essentially it cannot change in response to this experience.

Kirsten: And this could have implications for learning just in general and may have been an individual variation in ability to learn. Do you think this is something that could be looked for and could be hypothesized to be a process that would take place in mammals, in humans?

Richard: Oh, yeah. I think that these mechanisms are going to be highly conserved across vertebrates and probably across most animals. And it’s interesting (that worked) mostly from reduced systems without using hippocampal slice cultures and associated neuronal cultures. They’ve shown a very, very close length between spine turnover and relatively weak spine.

So apparently, spines that come and go much more rapidly reflects synapses that are functionally weaker. Under those conditions, synaptic networks are much more capable of sustaining this phenomenon known as long-term potentiation which is an activity-dependent increase in synaptic strength that’s thought to be a key step in formation of memory.

Kirsten: Yeah.

Richard: Those features are exactly similar to the features that we saw in the brains of birds that were really good learners. They had more dynamic and ultimately weaker synapses for which experience could act on. So I think yes, the implications are general.

Kirsten: Yeah.

Richard: And we’ve been very lucky to be funded both by the National Institutes of Health and particularly the Deafness and Communication Institute and also the National Science Foundation. And I think it’s really important to stress for your audience that this isn’t simply bird brains.

Kirsten: Yup, right.

Richard: It’s a really beautiful behavioral learning system that is in the laboratory setting really attractable. But we’re not trying to say this is something unique to birds, in fact quite the opposite. Our guess is that this is a generic phenomenon.

Kirsten: Right. And that this is something and the funding from the Institute for Deafness, it signifies the importance of this kind of a model system for understanding how hearing, how speech, how all these stuff works in humans and for therapeutic uses as well. I mean, all of this can potentially, down the road, have lots of influence in treatments for people who have hearing and speech deficits.

Richard: Yeah, and I was just at a symposium a couple of days ago that focus on cochlear implant technology.

Kirsten: Which is cool.

Richard: Really, really, you know, really powerful. And in cases of sensory neural hearing loss where the inner hair cell population is damaged, these implants can be very, very useful strategies.

But in children that are born without hearing, the issue still becomes, you know, whether or not their brains can interpret what are ultimately pretty abnormal patterns of activation of the auditory periphery as if it were normal auditory experience, probably not.

Kirsten: Right.

Richard: It would be really advantageous to know, you know, what portions of the brain have a limited like say, the auditory cortex – have a limited time window during which they require normal experience as has been shown for example on the developing visual cortex.

And in a system such as this, we can really start to explore when auditory experience is critical, how it transforms the brain and ultimately how to identify the molecular and cellular factors that regulate these sensitive periods with the hope of reopening them or lengthening them in cases where normal experience hasn’t occurred…

Kirsten: Yeah.

Richard: …because of say, a peripheral injury or insult.

Kirsten: Well, we are out of time and this has been great. Thank you so much for taking the time both of you, Rich and Todd, for taking the time to explain to us how you did your work with the significance of it. This is all, I mean this is peering into the brain with lasers and this is the future.

Richard: Future is now.

Kirsten: The future is now. So…

Richard: Thank you so much.

Todd: Yeah. Thanks for having us.

Justin: Absolutely.

Kirsten: Yeah, thank you so much. Have a great day. And good luck with the rest of your research.

Richard: Great.

Kirsten: Thanks. And this is This Week in Science. I have this cute – I want to play a little air.

Justin: I love that my personality is unknown to me, that my brain learns before it tells me what I’ve learned that it filters information – where? – in the brain – where am I?

Kirsten: Where am I?

Justin: When my brain is doing all of these things, I had no idea.

Kirsten: Are you having a philosophical moment here?

Justin: Yes. It’s this – it’s all this brain – my brain is now my teacher then.

Kirsten: Yeah.

Justin: I have to learn from my own brain. It’s filtering information. I’m trying to give it a personality but it’s denying me. It’s like, “No, that’s not your personality, it’s this. But I’ll let you have your little illusion.” (unintelligible)

Kirsten: All right. Well, we have to wrap it up. The TWIS Bookclub – this is in other news, TWIS Bookclub has a new book of the month. The book for March is, “Beyond Human: Living with Robots and Cyborgs.”

So, if you would like to take part in reading along with the TWIS Bookclub, go to How will advances in robotics, artificial intelligence and cybernetics affect the society over the coming decades? Will they change the nature of humanity itself? Find out what Gregory Benford and Elisabeth Malartre think in May’s book – March’s book and debate the issues.

Shoutouts to Rich Barton. He has a question to ask.

Justin: Great question of this week. We got to get all the minions to call and answer this one.

Kirsten: Can you smell things in your dreams?

Justin: Hit me on the Twitter at Jacksonfly if you can smell in your dreams.

Kirsten: If you – yeah, Jacksonfly wants to know. Can you smell in your dreams? Do we smell in our dreams? That’s the end.

Ali: Thanks everyone for listening. We hope you’ve enjoyed the show. TWIS is also available as a podcast. Go to our website, and click on Subscribe to the TWIS Science Podcast for more information on how to subscribe or just search for This Week in Science in iTunes.

Kirsten: And for more information on anything you’ve heard here today, show notes are going to be available on our website, We also want to hear from you, so email us at or

Ali: We love your feedback. If there’s a topic you would like us to cover or address or a suggestion for an interview, please let us know.

Kirsten: And we’re going to be back here on KDVS next Tuesday at 8:30 AM Pacific time. And we hope you’re going to join us again, plan on it for more science news.

Ali: And if you’ve learned anything from the show, remember…

Kirsten: It’s all in your head.

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