Journey into the Male & Female Brain: An Interview with Tracey Shors

This interview formerly appeared in Wild River Review as part of the Quark Park Column

By Kimberly Nagy

Nature or nurture? Learned or inborn? Good or bad?

Thankfully, most scientists (like poets) refuse to indulge the ardent cravings of absolutists. Perhaps the more one delves into the pluralistic intricacies of atoms or neurons (or for that matter, quarks) through experimentation and research, the more complicated the world around us grows. (Ever notice that after posing one question, another twenty quickly spring up?) A simple blade of grass becomes a towering mansion for microbes. Gentle streams connect us to fierce oceans. And perhaps nowhere are the complexities — and interconnected nature — of the universe more evident than in the study of learning and memory in the male and female brain.

In Vedic cosmology, male and female (Shiva/Shakti) energy figure differently, though interdependently, in the divine equation. So it is that Shiva (male energy) represents the sky, and Shakti (female energy), the earth. Shiva embodies the flames of the sun, and Shakti, light itself. Shiva, the ocean. Shakti, the sandy shore. And so on. And while these romantic metaphors may not be scientific, they point elliptically to the profound stylistic differences that mysteriously exist between males and females.

So I ask Tracey Shors, Professor of Psychology and prominent neuroscientist at the Center for Collaborative Neuroscience at Rutgers University, a woman with a bright gleam in her eye, and a formidable publication list, “Is nature or nurture even the right question?”

“I don’t think it is.” she quickly remarks. “Many people have shown that if animals learn something new their brain changes at an anatomical level as well as on a physiological level — so you can’t say what causes what. You have some structural differences that are probably genetic, while some are organized through hormones early in development. The presence of hormones in adulthood causes structural changes. And then, on top of that, you have structural changes that occur in response to experience — to living”

Shors and I stand, appropriately, in the middle of a walk-through hippocampus in Quark Park, or rather two hippocampi (one male and one female) — that part of the brain where learning and memory occur. The curving walls of her installation, two sets of interlocking Cs constructed of gigantic bamboo sticks, include decorations of actual microscopic portrayals of the hippocampus — a beautiful structure with three main sites where unique types of cells live.

Shors playfully admits that the subject of her exhibit “Learning in the Hippocampus” owes its inspiration to the 1966 Isaac Asimov movie, Fantastic Voyage. When brainstorming themes for Quark Park, Shors initially thought to herself, “Wouldn’t it be phenomenal if you could step inside the hippocampus and actually see what was going on”?

Within the figurative hippocampus, Tracey Shors spends much of her research time examining any of the following phenomena: how and why learning and memory occur; neurogenesis (the formation of new brain cells) and how learning helps the new cells survive; as well as how the male and the female hippocampi differ.

“Did you know,” she asks with a grin “that the female brain can exhibit very different responses than the male hippocampus?”

About such highly complicated (and controversial) questions, Shors exhibits the accomplished scientist’s ease in breaking down highly technical material into clear comprehensible English. But, true to her scientific training, Shors is highly cautious about making overly simplistic deductions about the incredibly elusive, ever dynamic brain.

WRR: Were you born in Princeton?

Oh no, I was born in Illinois but I lived all over the place. I also lived in Connecticut and Belgium, but spent most of my early years in Alabama. I went to high school and college there and then I moved to Los Angeles where I spent ten years. I received my PhD at the University of Southern California and stayed on for nearly five years of postdoctoral work. Then I came to the East Coast so I’ve been all over the place.

WRR: When did you first become interested in studying the human brain?

That’s a difficult question to answer because in retrospect it seems like I was always interested in it. I was always interested in why people do what they do and obviously that’s controlled by your brain.

WRR: Was there a moment of an epiphany?

No. I had a biology degree and a psychology degree and in those days you didn’t go to college and major in neuroscience. I would say it wasn’t until I did my postdoctoral work that I became passionate about it.

WRR: You study the differences between men’s and women’s brains…

Well, it’s really males and females…

WRR: Oh males and females…

Because, I study rats…

WRR: How does studying the brains of rats, help us understand ourselves, humans, more?

I guess one of the things that is, perhaps, surprising is that there are such profound differences in the brains, between the sexes, even in a rat. So, if they exist in a rat, presumably they exist in humans. It’s not only their brains, it’s their behavior, how they learn, how they respond to experience. We’ve shown really big differences in that — how they learn and how their brains respond to experience.

WRR: Can you talk a little about these differences?

Well, the main focus of my lab is learning. I’m interested in how memories are acquired and stored in the brain. That’s what I’d like to figure out. The hippocampus is a structure that’s used for learning, not necessarily for memory storage but more for learning, not necessarily for memory storage but more for learning. I’ve been doing work with processes involved in learning — plasticity in the hippocampus — for about twenty years.

About ten years ago, one of my graduate students and I decided to look at females, in part because females are rarely studied. I don’t think people appreciate that. And so, we decided to look and see how females respond to these experiences, and we found really huge differences — they can even respond in opposite ways to the same event.

I guess what I would say overall is that females are very dynamic. Females change over the course of their lifetime — before puberty, during puberty, after puberty, pregnancy, post- partum, menopause. We see differences in the way they learn and the way they respond to experiences at those different periods in their lives. We try to correlate those changes in behavior and learning with changes in the anatomy of their brain.

WRR: Can you talk about your work on memory and how basically, from what I’ve read, new cells are formed throughout our lifetime in the brain?

When I was in graduate school, and really until about ten years ago, it was assumed that the brain didn’t make new neurons. So you had a certain number of neurons when you were born and if you did not take good care of them, it was presumed that you would not get any more. And in general that’s true. I don’t mean to imply at all that the brain is like skin or something. But, the brain continues to make some new neurons. That discovery, or rediscovery, is in large part due to the work of Elizabeth Gould right here at Princeton in psychology — she’s a collaborator of mine and a friend.

A great number of these cells happen to be in the hippocampus — in this part of the hippocampus, the dentate gyrus. These cells are produced in the thousands and production varies depending on sex differences; another factor is exercise — a number of experiences can alter the production of the cells. One of the interesting properties of the new cells is that many die over a course of three or four weeks. But what we’ve shown is that if animals learn something that requires this part of the brain, then a significant number of those cells survive.

WRR: Is there a specific type of learning that’s more powerful than another since there are so many different types?

Yes. That is what we are trying to figure. “What it is about learning that rescues these cells from death?” I don’t want to be too adamant about it because I’m not sure we know the answer to that question. It seems as if tasks that require this part of the brain, the hippocampus, are effective. But it’s still pretty early to say anything definitive.

WRR: How did you meet Peter Soderman and become involved in Quark Park?

I met Peter about fifteen years ago at a bookstore, and we became friends. We’ve been friends ever since. He mentioned Quark Park to me a couple of years ago and asked me if I would be interested. I thought it would be a cool idea and it would be fun.

WRR: How do you feel science is perceived in this country in general?

I don’t know that the public is very interested in it, which is kind of sad actually. They seem to be more interested in what Britney Spears is doing (laughs). I think part of the problem with science or the reason why people aren’t interested in science is because they have a misconception about it.

It’s true that science is not always exciting. I mean counting thousands of cells, which people in my lab are doing right now, gets boring. But during the times that you make a discovery or something happens that you don’t think is going to happen more than makes up for any tedium.

I compare scientific experimentation to a rat pressing a bar. There’s this phenomenon called intermittent reinforcement. If you reinforce a rat every single time, he gets tired and bored and doesn’t press the bar as much. But if you just periodically reinforce him, he presses the bar like crazy. And so I think being a scientist is a little bit like that. Also, scientists are often portrayed as boring. Young people don’t say ‘Oh I’d like to be a scientist.’ They say, ‘I’d like to be a doctor,’ or ‘I’d like to be a lawyer,” something they’ve seen on TV which seems more glamorous.

WRR: Can artistic interpretation change that perception?

Yeah, well, I’d like to think so. But there is a fine line. If you popularize it too much then you trivialize it to some extent. But I suppose that if it gets young people interested in science or just teaches them something they didn’t know about before, then hopefully it’s useful.

WRR: What would you like a ten-year-old kid to learn?

Some people don’t even know what the hippocampus is, so that would be enough. And we’re going to have pictures of cells in each of the areas of the hippocampus. The structure is not uniform; each area has distinctive types of cells that reside there. So we’ll place the appropriate pictures of the cells in these different places. I’d also like for people to think about how we all learn. What does that mean? How does it occur? These are interesting questions.

WRR: Maybe also where it occurs?

Yes. We know that the hippocampus is involved, but that’s not the whole story. The hippocampus is intimately connected with most of the rest of the brain, so it’s not operating in isolation. Figuring out how information travels from one place to another and what it’s doing in each of these places places a big challenge. I’m not the only person interested in the hippocampus; it’s the most popular brain structure that there is. It’s fascinating to most people because of what it does, and for the way it looks.

WRR: How does the reality of your structure here in Quark Park match your original vision?

Well I think it’s much more interesting than I would have imagined, in part because it’s surrounded by all these other projects that are related. I initially saw it as being starker, you know, this bamboo thing in the middle of a field. When I first saw Quark Park it was just a vacant lot, so it was hard to imagine that it would look so complex and interconnected.

WRR: What scientist has influenced you most?

In my professional career it would be one of my mentors — Dick Thompson. He studies memory, too. I worked with him as a post doctorate and he taught me how to be a scientist. He understood that it’s fun to discover things.