Juraska Takes Brain Plasticity in New Directions

Janice Juraska has taken research into neuroplasticity in new directions by focusing on topics like hormonal influences and sex differences in the brain.

As a graduate student at the University of Illinois, Janice Juraska got interested in a topic that was gaining increased scrutiny in neuroscience circles: brain plasticity. Much of the interest in, as well as the validation of, the concept of brain plasticity was being led by researchers from Illinois.

Juraska wanted to take the work a step further so, after earning a Ph.D. at the University of Colorado, that meant a return to Illinois to work with one of the pioneers of brain plasticity and founding fathers of the Beckman Institute, William Greenough.

“I was working in plasticity here with Bill Greenough and then came back for a postdoc with Bill because I felt like I had left too soon,” Juraska said. “I realized – and this has been the theme that I have really pushed – that the fascinating work with neuroplasticity was all being done with male animals. And that the story might have some different twists in females.

“That, to some degree, has been the theme ever since. Not just sex differences and plasticity but also the effects of hormones. Everything came from that.”

“… the fascinating work with neuroplasticity was all being done with male animals. (I thought) that the story might have some different twists in females.”
– Janice Juraska

After stints as a postdoctoral researcher and later tenured faculty member at Indiana, Juraska returned for good to Illinois in 1986. She is now a full Professor in the Behavioral Neuroscience Division at the Department of Psychology, and member of Beckman’s NeuroTech group. Her research efforts are primarily focused on hormonal influences on the brain over the lifespan, particularly among adolescents and in aging populations.

“I’m interested in how hormones affect brain development and how they affect the brain the rest of your life,” Juraska said of her work. “And that has taken me in a couple of different directions.”

One of those directions involves studying questions such as whether there are sex differences in the brain, and how they might be influenced by the environment. The answer to both questions, Juraska says, is yes.

“There are sex differences in the brain, and that used to be a very unpopular thing to say,” she said. “Now people accept it. The environment affects the brain. How do hormones affect it? In working that out I am especially interested in parts of the brain that have something to do with cognition. There are a lot of people working on reproduction. They are doing very good work but I felt we already knew a lot about that. What we didn’t know was how hormones affect cognition.”

Juraska uses rats in her studies, looking at topics that are related to human health, and often for the first time in her field. A recent paper on the effects of hormone treatment was the first to use an aged animal model in investigating the effects of long-term treatment with estrogen and MPA on the number of synapses in the prefrontal cortex, an area of the brain known to lose mass with aging

The research found that the hormones, which are widely used as post-menopausal treatments by millions of women, increased levels of a protein marker of synapses in the prefrontal cortex.

“It came from wanting to know whether hormones were influencing how you used your brain as an adult,” Juraska said of the research. “With aging, you are losing some synapses and you may even be losing a few neurons. Women have taken estrogen and progesterone-like compounds  after menopause, so we gave hormones to female animals from middle age into early old age and showed that hormones do influence aging, and generally in a positive direction.

“The thing that helped the most was a combination of estrogen and MPA, which is an artificial progesterone, very commonly given to post-menopausal women and to young women for birth control. It ameliorates the loss of synapses during aging.”

Juraska is also heavily involved in research involving the other end of the lifespan, investigating topics such as brain development and sex differences in the adolescent brain.

“I realized that a lot of the hormones were actually influencing brain structure at puberty,” Juraska said. “I found that puberty was critical for cortical sex differences and that is one of my pursuits now.”

Juraska’s discovery of that fact in rats in the 1990s was validated a few years later by magnetic resonance imaging experiments. It’s an important topic for several reasons.

“Depression and schizophrenia can start in adolescence,” Juraska said. “After puberty, there  are developmental changes  that can get  perturbed in the brain.”

Juraska, in collaboration with Psychology colleague Josh Gulley, has also studied the effect high alcoholic consumption may have on adolescent brain development, including long-term effects.

“We have some preliminary data that yes alcohol does affect it,” she said. “It’s fairly subtle but we want to know more about it, whether synapses are actually lost.”

Their work was reported earlier this year in a paper that can be read here. They found, as they wrote, that glia cells in the prefrontal cortex are “particularly sensitive to binge-like exposure to ethanol during adolescence in male rats only, potentially due to a decrease in proliferation in males or protective mechanisms in females.”

Juraska said that the long-term effect of high alcohol consumption by adolescents is a topic worthy of further study for at least one important reason.

“Given that their brain is changing, it’s a particularly vulnerable time and there is evidence that these changes continue for a while,” she said. “In humans and to some degree in rats, the cortex is biggest around the time that puberty starts. Then it loses some mass and that’s because it’s pruning, it’s selecting what it needs. Well, what if it gets it wrong? The problem is even if you stop drinking alcohol, have you may have done something that is permanent.” 

Juraska and Gulley are also collaborating on a new research line funded by the Center for Nutrition, Learning, and Memory at the University of Illinois looking at the effect nutritional supplements may have on the aging brain in an animal model.

That research could lead to supplements that improve cognition in older adults. The research lines involving alcohol and brain development in adolescence and the study looking at the effects of hormone replacement treatments also have translational possibilities as intervention programs.

“I would like to see it all translate,” Juraska said. “The jump from the hormone study to the supplement is they are tied together as an intervention. The hormone study got me interested in interventions for aging.”

In addition to employing animal models in her research, Juraska also frequently uses the facilities at Beckman’s Microscopy Suite.

“The Beckman has been invaluable for us,” she said. “We use the Microscopy Suite all the time, and they have been very helpful for us. We’ve used the electron microscope, the confocal microscope, as well as the stereology scope, and are regular users of it.”

Juraska grew up near Chicago and later in Milwaukee, Wisconsin, attending undergraduate school at Lawrence University in Wisconsin. She began college as a chemistry major, but after taking a course in physiological psychology, switched majors. It was a move that is still reflected in her work today that combines trying to relate the physiological workings of the brain with its expressions in cognition.

“I liked physiological psychology immediately,” Juraska said. “I liked the combination of hard science and psychology. Had I known about biochemistry back then that might have been the direction I would have taken. But psychology has turned out to be more interesting.”