Research Roundup

Psychology graduate students are involved in a host of innovative research projects addressing many aspects of the human brain, body and behavior. Here are some brief profiles of student researchers--how they got started and where their research is going.

Social isolation delays exercise's benefits

Exercise provides many physical and mental benefits, including improved memory and related increases of new neurons, past research shows. However, a new study by Alexis Stranahan, a fourth-year Princeton neuroscience student, suggests that exercise may actually suppress the generation of new neurons in socially isolated rats.

"The combination of exercise, which puts additional stress on the body, and social isolation, which is primarily a psychological stressor, seems to decrease neurogenesis," she says.

Stranahan conducted the study as part of her master's thesis, and it was published last year in Nature Neuroscience (Vol. 9, No. 10, pages 526-533). In the first part of her study, Stranahan and her colleagues segregated 24 rats: Half of the animals lived in groups, and half lived alone. Additionally, half of the group-housed and half of the isolated animals lived in a cage with a running wheel; the others had no exercise equipment.

Every day for a week, the researchers injected the animals with BrdU, a chemical that marks new neurons by becoming part of their DNA. During that time, the animals in the cages with the wheels took advantage of the equipment, running up to four miles each day. The rats that were also housed in social groups spent the week playing with and grooming each other, while the isolated animals sat alone.

When researchers later studied the animals' brains, they found that the social animals with exercise equipment showed the most new cells in their hippocampi, an area of the brain involved in learning and memory. Tied for second in the brain-cell race were both groups of sedentary animals. The socially isolated exercisers grew the fewest new neurons during the experiment.

That's not to say that social isolation completely blocks the benefits of exercise, cautions Stranahan. In a companion study, she extended the experiment to 48 days and found that the exercise began paying off in the brains of even the socially isolated animals, though they didn't quite catch up with their social siblings.

Stranahan, who is completing her doctoral research through a fellowship at the National Institute on Aging, is now studying the effect of type 2 diabetes on the brain.

Dating and body image

Romantic partners may hold special sway over a woman's body image, according to preliminary findings by Kerstin Blomquist, a sixth-year clinical psychology student at Vanderbilt University.

Blomquist recruited 360 heterosexual women from Nashville, Tenn.-area universities, coffee shops and grocery stores to gather her data. Blomquist brought the women into her lab, took their pictures and asked them to fill out a questionnaire that asked, for example, "What is your favorite thing to do on a Friday night?" and, "How would you describe yourself?"

The participants believed that an unseen man in another room would be evaluating them on their looks and personality. Some were told he was determining their compatibility as a potential friend. Others thought he was considering them as a potential date.

After filling out the questionnaire, the women received the man's questionnaire, with his photo attached. The photos were of attractive men unaffiliated with the study; Blomquist composed their answers.

Some of the women learned that the man preferred women who are "thin and in shape" while others read that he liked women who are "honest, trustworthy and dependable." Then the participants received a rating of how compatible he thought they would be on a scale of one to nine.

At three points in the study--when the women first arrived, after they read the man's questionnaire and after they received his compatibility assessment--Blomquist asked the women to rank how happy they were with their body weight, shape and size, by indicating their level of satisfaction on unmarked number lines.

The women whose potential date wrote about body size and who rated the women as incompatible showed a dip in their body satisfaction over the course of the experiment. Those who were rated as compatible by that same man showed an increase, Blomquist found.

However, Blomquist was surprised to find that even when the man "considering" dates didn't bring up physical attractiveness he could boost or harm the participants' body satisfaction, unlike the man evaluating friendship.

"Because of the inherent physical component to romantic relationships...they could have a greater impact on a woman's body image," she says.

Blomquist hopes to continue this line of research and use her findings to help women develop sturdier positive attitudes about their bodies.

Slow and smart

As part of her dissertation research, Karen Davis trains turtles to knock over clear plastic bottles. It took weeks of painstaking work for Davis, a fourth-year experimental psychology student at the University of Tennessee, to entice nine Florida red bellies to leave their watery home and look for food on land--a foreign behavior, as they feed in the water in the wild. First she rewarded the turtles for stepping onto an experimental platform, then for turning in the direction of two bottles and finally for nosing them over. The prize? A piece of turtle brittle for the red bellies and a new way to measure turtle memory for Davis.

In the wild, red bellies' memory is key to their survival, she says. "Turtles return to nest sites....They go to the same food sources again and again," she explains. "They have better learning and memory abilities than you'd expect."

By studying turtle memory, Davis hopes to help keepers create richer environments for the animals in captivity.

She has been impressed with the cognitive capacity of the animals. After the turtles learned to expect rewards for knocking down either of the two bottles, the graduate student changed the rules of the game. She placed the turtle food underneath only one bottle, and the turtle got only one chance to find it. If it knocked down the wrong bottle, Davis placed the animal back into a holding tank with no food.

Most of the turtles were quick to catch on, changing their strategy after just a few trials. Previously they would charge toward a random bottle and knock it over. Under the new rules, they ambled up to a bottle, peered through the plastic and only nosed it over if they saw food.

What's more, six of the nine turtles remembered the strategy two months later, with no retraining necessary. An additional eight months later, eight of the turtles remembered the task.

The finding lays the foundation for future research by Davis. Shehas recently been spending time watching red bellies at the Chattanooga Aquarium, and she's noticed that particular individuals seem to choose others to interact with again and again. It's possible that the animals' memory abilities lay the foundation for social learning; they may even learn new behaviors through observation, she says.

-S. Dingfelder