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From the College of Natural Sciences
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Office Hours: George Pollak's Big Idea

Office Hours: George Pollak's Big Idea

For more than 35 years, neurobiologist George Pollak has been using echolocating bats to study the mammalian auditory system, trying to understand how the auditory system processes communication signals and how animals are able to associate a sound with its location in space. He’s done groundbreaking work in, among other areas, decoding the meaning of complex “love songs” that male bats use to woo females.

I sat down with Pollak recently and asked him whether, over the course of his career, he’s developed any big-picture, unifying ideas that tie together his many individual discoveries about the auditory system.

George Pollak: The thinking that has emerged from my research at UT is that the wiring structure of the auditory system in bats—the system that makes echolocation possible—isn’t significantly different than the auditory system in other mammals. Things are bigger, more pronounced, but it’s basically mammalian.

That’s not where I started. When I came here and started working on the brain, I had every intention of understanding the super-specialized nature of the bat auditory system. I realized that the more things you find that correlate with, or explain, echolocation, the more papers you’re going to get in Science (and articles in Science do wonders for the advancement of one’s career). I tried, really tried, to find special adaptations, but I could not find them.

What I found, every time I looked in the bat’s auditory system, is that what I was seeing were the same things, the same structures and neuronal response features, that my colleagues see who study the auditory systems of cats, rats and other animals. I asked my colleagues who are comparative neuro-anatomists, who know the structures and connections of the auditory systems in primates and carnivores, whether they saw anything unique in bats. They all told me that the structures, wiring, neurochemistry and morphology of the bat’s auditory system are quintessentially mammalian; things are bigger, and more pronounced, in the bat’s auditory system, but the system is mammalian.

So I came to the conclusion about 20 years ago that I can’t understand echolocation as the product of a distinct system. It’s a mammalian auditory system. Whatever modifications in their auditory systems evolved that allow bats to “see the world with their ears” through echolocation have eluded me.  There must be something different in their auditory systems, but whatever it is, it is very subtle rather than a major restructuring.

Rather than try to find the underpinnings of echolocation, I exploit the pronounced features in the auditory systems of bats to evaluate basic mechanisms for processing acoustic information.  This is actually a time honored idea, first enunciated by August Krogh, who won the Nobel Prize in Medicine or Physiology in 1920.  The Krogh Principle states, “Organisms that exhibit extremes in adaptation may reveal principles not readily observable in less extreme species.”

It’s proven to be a very successful system for us.  We are deriving insights into the mechanisms that enable mammals to process and discriminate acoustic signals and the success we have had has proven to be both exciting and highly satisfying.

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Friday, 16 April 2021

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