Student Q&A: Eliza Jaeger

Driven by evolutionary questions, fifth-year PhD candidate Eliza Jaeger has done some adapting of her own.

Where did you grow up, how did you become interested in science?

I grew up in a lot of different places, since my parents are both professors and had various positions. We moved to Germany when I was 11, and I didn't speak German, but I joined a German school and learned by immersion. Part of what got me interested in the brain was this experience—I am this 11-year-old kid, and I didn't know German before, but somehow now I do. And I watched my brother, who is three years older than me, and my parents have a bit more difficulties absorbing the language. You have this critical period of language acquisition when you’re young that’s pretty plastic, but at some point, it does close. And so that got me thinking about brains and how human beings have evolved to have this amazing ability, and that's what made me want to be a neuroscience major.

What drew you to Columbia?

I went to Middlebury College, a small liberal arts school in Vermont, for undergrad, and I was ready to experience a bigger city, a bigger lab. And I knew that, before committing to a PhD, I wanted to make sure that full-time research was really my thing. I was looking primarily in the New York area, and found a job posting for a research technician position in Dr. Richard Axel’s lab at Columbia’s Zuckerman Institute. And I was like, Wow, that sounds exactly like what I want to do: I want to build a stronger skill and knowledge base in systems neuroscience. And I’m so happy I applied, and it worked out really well.

What kind of work did you do in the Axel lab?

Dr. Bianca Jones Marlin, who was a postdoc in the Axel lab but has since started her own research lab, had the idea to investigate whether traumatic experiences can be inherited through the male germline. We really wanted to understand what happens in the nervous system when you shock-condition a male mouse so that it expects something bad to happen when it smells a specific odor. Does just getting conditioned with an odor actually affect neurons in the olfactory epithelium, which is how the body processes chemical stimuli in the environment? Does it shift which neuron types actually get expressed?

And it turns out, it does. So you actually get more neurons in the main olfactory epithelium in a male mouse expressing receptors for the odor that he was conditioned for. The second part, which is still a work in progress, is understanding how that might affect his offspring’s ability to smell that odor. And when I was working there, we had some preliminary evidence that it actually increases the number of cells that respond to that odor in his offspring as well, even though they have never actually encountered that smell before.

How did you end up in the Dr. Maria Antonietta Tosches’s lab for your PhD?

I've always had this pull toward evolutionary questions. Why are things the way they are? What kind of evolutionary pressures have shaped animals to behave in certain ways to occupy different niches, to have brains that look the way they do? What Maria’s lab does fits what I'm interested in to a tee.

What we work on in the lab is trying to understand the evolutionary relationships between different vertebrate brains—specifically, their diverse neuron types. In her postdoctoral work, Maria compared neurons between reptiles and mammals and was able to find a few highly conserved cell types. But even though some types have been evolutionarily conserved since the divergence from reptiles, there are still plenty of novel cell types in mammals. And it’s possible these cells have something to do with why mammals are better at doing certain kinds of cognitive tasks. Now in the Tosches Lab, we've gone even further back and said, What about amphibians? What kind of cell types do amphibians, reptiles, and mammals share? And this is the meat of what we published in our Science paper: now we can say, across 350 million years of evolutionary time, that salamanders, reptiles, and mammals also have certain conserved cell types, so there's something possibly very essential about the function of these neurons that's been maintained across a long span of evolutionary time.

So that's kind of the groundwork, and then my main PhD work has been to contextualize those cell types in the context of behavior and function in the brain. We have a certain set of neurons that we're interested in—ones that we know are really important for learning and memory in mammals. What I'm trying to do is ask, are they also important for learning and memory in a salamander? So there's a few questions that then need to be addressed. First of all, can salamanders learn? How do we measure whether they're learning? And how do we measure neural activity in a learning salamander that has formed an associative memory? And that's what I'm working on now.