Faculty Spotlight: Dr. Samuel Sober

By Dr. Brian Bauss

Produced by Amielle Moreno

The Central Sulcus is proud to share its first podcast with you; an interview of the Emory Neuroscience Program’s Dr. Samuel Sober. Below is a link to the audio interview, and a transcript of the interview is located below. Enjoy!

-Amielle Moreno-

Brain Waves Podcast Transcript:

Hello! I’m Dr.Bryan Bauss, assistant associate professor of neocortical physics at the metropolitan university of Fruitville Florida. And this is Brain Waves! Every week on Brain Waves, we take a look at the fascinating world of Neuroscience and the implications of the latest research findings for health, law, medicine, health, and videogames. This week on Brain Waves we’ll be talking to Dr.Samuel Sober in the Biology Department at Emory University in Atlanta, Georgia about his work on sensorimotor learning using the songbird as a model system. I’m Dr. Bryan Bauss, and we now begin Brain Waves.

Dr. Bauss: Dr. Sober, first of all I’d like to thank you for taking the part in the Brain Waves podcast and I’m going to start with a question I always begin my interviews with; At what age did you first know you were interested in smoked meat products?

Dr. Sober: Hahaha! I came to smoked meat products relatively late in life. Some people think you have to start when you’re five or six years old to be a virtuoso but I was in graduate school when I first got into sausage and bacon.

Dr Bauss: I see. Now, to prepare for this interview I read your website and listened to a segment on National Public Radio about your work, and I understand that you work with birds. I want to pose you a question that was first asked by Dr. Violent Femmes; that is, ‘why do birds sing?’

Dr. Sober: They, the birds that we study and some of the other speicies basically sing for two reasons. First is to attract mates. In fact that’s probably mostly why the birds we study sing, also for territorial defense to mark off their territory.

Dr. Bouys: I see so to the two ‘F’s as I’ve heard them called: to flirt and to fight.

Dr. Sober: Yes

Dr. Bouys: I see. So going back to species for a second. I’ve often noticed that mockingbirds can sing an almost infinite number of songs and wondered how they can learn so much with their simple brains. Do you study mockingbirds and if not, what stupid lame species of birds do you study?

Dr. Sober: We do not study mockingbirds in the lab. Interestingly the field of songbird neurophysiology has chosen to focus on primarily Zebra finches and also Bengalese finches who have some of the smallest song repertoires of any bird, primarily for experimental reasons. If you’re going to study how different parts of the brain are active during different behaviors you want a bird that tends to do the same behavior over and over again. There are, of course, other species that have gigantic repertoires, including the brown thrasher, that happens to be the state bird of Georgia and also has the largest recorded repertoire. I think, it’s something like two or three thousand distinct syllables. There has been much less neurobiological work on those guys. From what I know the brain structure is not dramatically different then the species that we study. I would love to know what’s different about their brains that gives them those gigantic repertoires.

Dr. Bauss: Seems like you are really a ‘bird nerd.’

Dr. Sober: Yup.

Dr. Bauss: Speaking of ‘bird nerds’ and brains many times when we feel as though someone is not particularly intelligent, we might refer to them as a ‘bird brain.’ Is there any truth to the idea that bird’s brains are somehow less intelligent than our own? If I were a bird, how would my brain be different? Would I have a soul?

Dr. Sober: … Well, intelligence I believe strongly that there are many different definitions of intelligence. When it comes to learning songs, pecking for seeds and flying, birds far out preform humans. On certain videogames, chess, checkers, things like that people are obviously quite a bit better. So yeah, I get asked the bird brain question a lot and usually when that happens, I terminate the interview and make some sausage or bacon… But we can continue.

Dr. Bauss: I see. Here’s another question, sent in by Carol of Mr. Anderson’s third grade class: do birds have ears?

Dr. Sober: Birds do have ears! I get asked that question a lot. They actually have excellent hearing, which makes sense given how important the singing is. What birds don’t have is what we like to refer to as external pinnae, which are the little cartilaginous things that stick out the sides of our heads. In fact, the bird’s ear opening is covered in feathers and it’s just below and slightly behind the eye. They’re big, relative to their heads.

Dr. Bauss: I see. I had also read that you build tiny headphones for the birds. I guess now I understand why. Can you explain to the listeners of our podcast what kind of music you play through the headphones to the birds?

Dr. Sober: We actually do not play music through the head phones. In fact, the reason that we go to the ridiculous amount of trouble to build headphones for birds is to change how they hear themselves sing. So one thing that we’re very interested in our lab is how the brain learns from its mistakes. It turns out that songbirds are very, very good at this. The birds that we study learn how to sing through a process of vocal imitation where they memorize a song then learn how to create it themselves. The way they are able to achieve the song they want to produce is by learning from their mistakes. So to sum up, the reason we put headphones on songbirds is to give us control over the mistakes the birds experience while they’re singing.

Dr. Bauss: So, you can control the birds.

Dr. Sober: We can control what they hear.

Dr Bauss: I see. As I understand you had previously worked with a species, homo sapiens. And while working with this model system you told a well-known science reporter that we could never learn anything by studying songbirds. Why did you sell out? Is it because you were frustrated with your previous model system? Unable to control them, perhaps? Or is it just because of the sheer amount of money you can make in songbird research.

Dr. Sober: Purely for funding reasons; I followed the money. No, exactly the opposite. One of the first labs I ever worked in as an undergraduate was a very good songbird lab and at the time, I really enjoyed the lab but felt strongly that songbirds were not a good system to study any of the questions I was interested in. Ten years later I changed my mind and went back to studying songbirds, to look at some different questions. I did my doctoral work on how humans plan arm movements. Thinking about questions of how does the brain combine different sensory information and execute and learn accurate motor behaviors. But obviously in humans, we don’t have very much access to the patterns of neural activity that underlie these things. So after I finished my Ph.D. , I knew I wanted to work on a species where we could record and manipulate brain activity, which eventually lead me to work on songbirds. In terms of being able to control the species, one of the main frustrations of working on human subjects, the people don’t show up for their appointments. That is much less of a concern with songbirds. They tend to stay in the cage where you put them.

Dr. Bauss: You could also work with homing pigeons for the same reason.

Dr. Sober: (awkward forced laughter)

Dr. Bauss: And not only can you access their brains you can access their muscles. The same science reporter told me that your lab has designed a multi electrode array for recording from muscles, code named: Da Finchey Trode. Please explain what the trode does with the fincheys.

Dr. Sober: Sure! One of the many wonderful things that the brain does is control the body. This happens via muscles of course. So some neurons in the brain send their output to muscles and when those neurons are activated, those muscles contract. Those muscle contractions produce every behavior, essentially. So one of the things we’re very interested in is how the brain and the muscles work together to produce behaviors. So, we want to understand how, during learning, the brain changes the pattern of muscle activation that produces the behavior in order to make the behavior better. One of the ways that we and lots of other people explore how muscles function is to record the electrical activity from those muscles. So when a piece of muscle tissue contracts, it produces this characteristic electrical signal. One of the things that’s very challenging, especially in a very small animal like a songbird, is that these muscles are really really small and these muscles are made up of lots and lots of individual fibers that can become activated independently. So, we developed this type of electrode that allows us to record from these very small muscles with very high resolution. What this electrode is, is essentially an array of very very tiny gold contacts, very tiny gold particles embedded in a flexible substrate which we can then lay on top of the muscle and record these very nice signals. We had a contest, inside and outside the lab to come up with names for these. There were some interesting entries to the contest. We considered myo-flex before we decided that it sounded a little like an off brand exercise machine. Another one that we came up with was Flexible Electrode Mulit-Array, which is quite descriptive but unfortunately has the acronym ‘FEMA’. So we changed our mind on that one. Actually a friend of mine, who happens to be another science journalist came up with the name of ‘Da Finchey Trodes,’ which is horrendously awkward but has stuck, so the flexible electrodes are called Da Finchey Trodes.

Dr Bauss: I also discovered, during my extensive preparation for this interview, a comment on a blog on the internet that claimed that birdsong researchers fail to understand and properly apply information theory to the spiking activity of neurons. Can you explain what the hell that means, as is that true?

Dr. Sober: (defensively) It is not true. In fact, one of the recent publications from our lab uses a mathematical technique called information theory, which I’ll get to in a moment, to try to understand how the songbird brain tries controls vocal behavior. So to give some context, one of the things we’re interested in is how the activity of individual brain cells controls behavior and also changes during the process of learning. Without getting too technical, it’s one of the fundamental mysteries of neuroscience how electrical activity in parts of the brain corresponds to perception and behavior and things like that. Now there are lots and lots of different mathematical techniques that are available to us to understand the relationship between brain activity and behavior and information theory is a group of techniques that have been extensively applied to sensory processing, so how your brain hears and sees and touches and things like that. We had a paper at the end of last year where we used some similar techniques to try to understand how the brain controls behavior and the major finding there is that the timing of action potentials and the timing of electrical activities in the brain, turns out to be critically important for controlling vocal behavior.

Dr. Bauss: I see, so using these mathematical techniques, we can understand how the brain normally functions, but what about translational research? For instance, can a bird get Parkinson’s and if not why should we study them?

Dr. Sober: Very good question! So, ours is a basic research laboratory, so our goal is to find out some of the interesting things about the normal functioning of the brain. Of course we always do this research with an eye towards applications in humans and in human disease especially. One of the things we’ve been working on in the lab recently is trying to understand how a particular neurotransmitter called dopamine might be involved in vocal learning, which is to say the bird learning to change its song to improve it over time. So, one of the notable things about dopamine is that the dopamine system in the brain is one of the things that gets screwed up during Parkinson’s disease, so a lot the behavioral impairments that are very noticeable in Parkinson’s result directly or indirectly from a loss of dopamine. What we’re doing in this recent project in our lab is not to give songbirds Parkinson’s disease, although inevitably when I explain this project everyone’s like ‘oh, so you’re giving songbirds Parkinson’s disease.’ That’s not what we’re doing. What we are doing is damaging the dopamine system in songbirds and we’re doing that for this very particular reason; not to create a songbird Parkinson’s disease but to understand the contributions that dopamine makes to this particular form of vocal learning. So even though the bird doesn’t have Parkinson’s disease, this is relevant to Parkinson’s disease because Parkinson’s disease includes among many other symptoms these deficits in learning.

Dr. Bauss : I see. So, I guess studying dopamine isn’t just… for the birds.

Dr. Sober: (awkward pause)

Dr. Bauss: That concludes our interview with Dr. Samuel Sober from the Biology Department of Emory University. Thank you Dr. Sober.

Dr. Sober: You’re welcome. Thanks for having me.

We hope you’ve enjoyed this week’s special edition of Brain Waves. Join me next week for a round table discussion of the neuroethics of using deep brain stimulation to treat erectile disfunction. Executive director of Brain Waves is Amielle Moreno. Technical direction provided by Kyle Srivastava. Improv coach, Lukas Hoffmann. Human resources, Mackenzie Wyatt. Our staff physician is Dr. Conor Kelly. Coffee and pastries provided by Wood’s Bakeries. Brain Waves is a production of WMUF, the official radio station of the metropolitan area of Fruitville Florida. Once again I’m Dr. Bryan Bauss, assistant professor of Neocortical Physics, and this has been Brain Waves.


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