Episode 03: Sarah Pallas, PhD

The following interview was conducted in-class, during the Spring 2021 session of Hidden Figures: Brain Science through Diversity, taught by Dr. Adema Ribic at the University of Virginia. What follows is an edited transcript of the interview, transcribed and edited by Anushey Ahmed and Kate Jensen, who also drafted Dr. Pallas’ biography. The final editing was by Dr. Adema Ribic. The original recordings are available in Podcasts.

Dr. Sarah Pallas received her B.S. degree in Biology from the University of Minnesota and M.S. degree in Zoology from Iowa State University. For her Ph.D. she studied developmental plasticity in Dr. Ronald R. Hoy’s and in Dr. Barbara L. Finlay’s lab. Her postdoc was at the Massachusetts Institute of Technology in Dr. Mriganka Sur’s lab in the Brain and Cognitive Sciences department, for which she was awarded an NRSA fellowship from NIH/NEI. She started her own lab in 1992 at Baylor College of Medicine and moved to Georgia State University in 1997.  Dr. Pallas was promoted to Full Professor in 2006 and was appointed a Fellow of the American Association for the Advancement of Sciences (AAAS) in 2011. Dr. Pallas moved to the University of Massachusetts Amherst in 2019. Since the beginning of her career, Dr. Pallas has studied the mechanisms of neural development and plasticity in a variety of animal models. Her prior work includes cross-modal plasticity of visual and auditory inputs in ferrets, and among her recent discoveries was that vision during the critical period is not needed for receptive field maintenance into adulthood. In addition, Dr. Pallas has also worked on topographic map compression in the superior colliculus (SC). Her work led to a greater understanding of how the brain responds to injury. 

Can you tell us a bit about where you came from?

I was born in Minnesota to parents who grew up in Iowa. Like lots of people, I had a whole bunch of crap jobs. I worked my way through college, and I actually worked as a milkmaid. That was the only job I was ever fired from because I wanted to pet the cows instead of pushing them through the line. I started my degree in Colorado, but finished it in Minnesota and ended up going to Iowa State by accident. I had wanted to get into Ph.D. programs, and that didn’t work out because I didn’t really know how to apply for Ph.D. programs, or how to get good letters or anything like that. Because of that, I did my Master’s first and then was able to get into the Ph.D. program of my choice.

What model organisms have you worked with?

While I was in Colorado, I did an ecological study on a squirrel that you might never have seen, Abert’s squirrel. In Minnesota, I worked on deer mice, and then I made the switch to earthworms when I went to Iowa because I was really, really excited about working with this particular professor, who was the most wonderful mentor. I worked on the neural basis of that earthworm tail flattening process. That’s what they do to keep themselves in the borough when you’re trying to yank them out to go fishing. Then I worked for four years on the auditory system of crickets and then switched into the visual system of hamsters. Then I worked on ferrets with the cross-modal neuroplasticity experiments in Massachusetts. I am still working in different rodents and I’ve added Chilean Degu to the repertoire. This is a diurnal, very social, very visual rodent species.

What is your lab interested in?

We’re trying to understand this phenomenon of critical period plasticity in the visual system. Why are children able to learn language easily? We learn our native language when we are just two years old. We don’t have to do flashcards or take exams or anything like that, but if we tried to learn a second language later, that gets harder the older we are. Why is that? Wouldn’t it be nice if we could switch that plasticity on and off as needed for learning, or maybe for recovery from injury, for example? Another question that goes along with my work and my hobby is brain injury. You have heard of people who’ve had serious head injuries that go to the hospital and have skull fragments taken out of the brain. Their families are told to wait and see what happens. That’s a primitive way to treat a major injury and we should be able to do something better than that. In fact, the brain fixes itself, which is what we’re waiting for when the physician tells you “to wait and see”. Why don’t we learn how the brain does that so we can harness it for clinical purposes?

What is the hobby you mentioned, and how does that tie into your work?

I do equestrian sports. I’m on my third concussion. And I don’t remember it. That’s the beauty of having a concussion. I don’t remember any of the pain. Only the horse knows what happened. And yet I still keep doing it! This falls into the general nature versus nurture question. What’s pre-specified in the brain and what’s flexible and can be influenced by external information such as the way that you’re raised, experiences that you have, or just sensory information in general. 

Can you tell us more?

Evolution sets up brains so that we are ready to go to a certain extent when we are born. Different animals have different states of “ready-to-go” when they’re born. So for example, ungulates like horses, have got to be ready to run when they pop out. Humans have this prolonged period of very careful parental intervention, preventing them from hurting themselves, and we learn a lot as we’re growing up. Evolution takes this into consideration and makes the brain more or less flexible, and more or less ready to go, depending on what that evolutionary history is. But, since evolution can’t predict everything that’s going to happen, there’s a lot of flexibility that’s built into circuits. For example, we make at least twice as many neurons we need, thousands and thousands of more synapses than we need, and those are pruned back based on experience as time goes on and that experience includes sensory information. That’s what I find so fascinating about studying the sensory system compared to studying the motor system, this give and take between the environment and the circuitry. That really does predispose the brain to fix itself, so we’d like to be able to understand that. Some of the general questions we’re after are how the visual circuits in the brain get connected properly in the first place, how experience influences that, how do these circuits change in reaction to the experience, or to trauma, and how does age affect that.

Under what circumstances would you want to decrease synaptic plasticity?

If you had an injury in your brain, your brain could completely rewire itself to compensate in the wrong way. You might want to shut that off until things get back to normal. (After injury) you are having massive amounts of inflammation and cell death going on. That’s why they stick your head in an ice bucket or put you in a coma to slow everything down. But again, it's rather primitive.

Because you had such a long career, what would you say was your signature discovery?

I think the work that I will be the most known for is the cross-modal plasticity work, but I don't really consider that mine. What I think is really interesting is my work following up on that looking at how the auditory and visual inputs not only come to coexist (after rerouting visual inputs to the auditory cortex), but how they actually build a huge number of multimodal neurons in the cortex that's never supposed to have them. The map compression is, however, what I'm the most excited about. It is interesting because I started that work just so that I could finish my Ph.D. after being discriminated against in the previous lab. Who knows why we enjoy what we enjoy? I'm a person who really thinks topographic maps are fascinating and I cannot find my way out of a paper bag.

 I heard about this anecdote recently, where a lab full of male scientists was working with male mice only. Then a female scientist came into the lab and tried to verify their results with female mice. She found differences. Do you have any experiments or experiences that are similar to that where a different perspective changesd your conclusions?

Actually, yes. I find that each individual brings different perspectives. This is why it's important to have a lot of people, as many as you can afford. That’s why undergraduates who want to get some experience in the lab are so great because they come with no preconceived notions about how things would work. They ask what they often think is a dumb question, which turns out to be a brilliant question that the rest of us were just too blind to think of. I have had at times in my lab's history people from all over the world. There was a point in time where I had a student from every continent except Antarctica. We had so many different experiences and training backgrounds. I find working with the Chilean lab to be so refreshing because the training of STEM students in Chile is a lot more rigorous than it is here in terms of mathematics, computational sciences, and physics.

 Why is diversity important to you?

Having different kinds of training or having different perspectives is very important. Whether it's a male or female perspective or whether it's a perspective that differs along ethnic lines, training lines, or any different way of looking at a problem is just so helpful. It blows my mind that we have so many labs that are just so white-bred. Labs where everybody looks the same. I have found in faculty searches that oftentimes groups of scientists will want to get more people like themselves instead of bringing in people with new ideas, different perspectives, and different technical approaches.

What do you think is a good approach to fight this homogeneity in the science fields? What are you doing and what do you think is the way to go about it?

I'm not a subtle person. I always would be the first person to speak out if we're reviewing grad student applications or faculty applications.  You would find mysteriously that when you get to the Black candidate, the criteria have suddenly changed. Why is that? Maybe we should keep the criteria the same for everyone so that we get the best scientists instead of avoiding the scientist that we would like to discriminate against. We all have our unconscious biases, but if we're aware of them then we can work against them.  In Georgia where 38% of our students were black, it was frankly embarrassing that we had 1 or 2% of the faculty that were Black. We really had zero diversity there. You'd think that a place in Atlanta, the cradle of the civil rights movement would be a little more welcoming and wanting to work hard to attract Black scientists. When they did attract them, they tended to leave really quickly. Having talked to some that left, I know that they felt like they were never included. They never felt like they were going to be getting a fair chance. They're accustomed to being gaslighted.

Gaslighting in what sense?

Every person who is not white has gone through this crap: being subjected to white people who don't understand that it's really happening and white people who gaslight them and say, “​You must have misunderstood​”. Women in science have gone through that forever. You know that (male) professor that told you how you look cute today but “he didn't mean it like that”. That stuff is meant to put you in your place and to keep the hierarchy together. 

What advice would you give to people that are trying to get into the field in our part of marginalized communities? How to cope with the gaslighting? 

I think it's very important to have a support system. If you have friends and colleagues that are going through the same thing, it's healing to hear from each other “you could not believe what professor X said to me today”, and the other person says ”I know what you mean, he said that to me last week.” That way you know there's not some particular fault in you. Try to counteract the impostor syndrome that constantly tells you that you don't belong. You do belong or you would not have been admitted. Just keep that in your mind: you belong here. You have unique contributions to make. Find people that will uplift you. It doesn't have to be other people of the same ethnic background or field, but they do have to be allies. They do have to be reasonably ​woke​ so they understand what's going on in your life. People in Charlottesville certainly know that. So yes, stick it out. We need you.

Who were your mentors? Who had a big influence on you?

I think I had so many important mentors: people in my undergraduate education at Minnesota who gave me the opportunity to do undergraduate research, who supported me, and who taught me how to apply to graduate school so I could get accepted into a good program. One even brought me to a cocktail hour with visiting faculty members from one of the places that I was applying to. I thought that was really above and beyond. Then my master’s thesis advisor- the earthworm guy-was the most wonderful person I think I have ever met. He was so encouraging and so kind and persistent in teaching me, a woman who had never been allowed to do anything mechanical, to solder and build my own amplifiers. He would take all the wires off the rig and make me put them all back together again.  That was a tremendous education and I published two papers in two years from that lab. I have never had quite an experience since then. 

Did you have female mentors?

Yes, and Dr. Barbara Finley continues to be one of my best friends and was infinitely supportive to someone who had been essentially rejected from another lab. I was an unknown quantity (when I joined her lab). She was in the Psychology Department and I was in Neurobiology. She has supported me and kept me going at the lowest of times. Because of the things that people in my age cohort went through, it was really important to have female mentors. People that I didn't ever do any research with were so supportive of me. Dr. Martha Constantine-Paton was a very important mentor for me, as well as Dr. Carla Shatz who always made time for me at meetings and gave me advice. Dr. Vivian Casagrande, another one that we very sadly lost way before her time. The women really tended to support each other. 

This interview was conducted during the Spring Session of UVA’s Hidden Figures class in 2021. Class roster:

Addis, Lucas; Ahmed, Anushey; Akram, Amman; Alam, Maisha; Anderson, Sydney; Bhatia, Rhianna; Bonagiri, Paavan; Booth, Morgan; Clarke, Casey; Fisher, Grayson; Gandhi, Shreyal; Hossain, Mohammed; Rayan; Jensen, Kate; Kim, Michael; Lahham, Zina; Lea-Smith, Kori; Leffler, Schuyler; Leventhal, Emily; Mehfoud, Matthew; Morrisroe, Erin; Pham, Twindy; Sajonia, Isabelle; Sisk, Emma; Suram, Ananya; Wang, Jessica Beth; Webster, Tessa; Wilson, Gina. TA: McDonald, Amalia. Instructor: Ribic, Adema, PhD.