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.

Does Ritalin prime teens for smoking?

Research from the National Institutes of Health suggests that children who take the commonly prescribed drug Ritalin may be more likely to start smoking cigarettes as teens. And Tom Wooters, a second-year behavioral neuroscience graduate student at the University of Kentucky, suspects that taking Ritalin may actually increase children's susceptibility to nicotine's addictive effects.

To test this theory, Wooters recently conducted a pilot study of Ritalin-exposure's effect on smoking with rats. He divided 18 rats into three groups-one that received daily saline injections, one that received injections of Ritalin and one that received nicotine injections. After ten days, Wooters gave each rat a nicotine injection.

The rats never before exposed to nicotine responded by becoming lethargic, while those who had been pretreated with Ritalin or nicotine became more active after receiving the nicotine injection. And increased activity usually means that the rats find a drug rewarding-as measured by other experiments where the animals have the opportunity to administer a drug to themselves, Wooters points out.

This finding suggests that exposure to Ritalin may make later exposure to nicotine more enjoyable, to rats and possibly to teens, he adds.

"That is just another reason why doctors might want to be a little more hesitant when they are putting young kids or teenagers on such powerful drugs," says Wooters.

As Wooters develops this line of research for his dissertation, he may investigate how this priming occurs in the rats' brains, he says.


Depression's pressure on memory

Can you remember what you had for breakfast? How about the color of your cereal bowl? People with depression may have particular difficulty answering the second question, says Laura Kong, a second-year clinical psychology student at the University of Arizona. Previous research suggests that depression can interfere with what is known as "source memory," or the context of an experience such as the color of a cereal bowl, she says.

Frontal-lobe function may underpin this deficit, says Kong. If this brain region-involved in executive function, problem solving and emotional control-takes primary responsibility for such deficits, future pharmacological interventions might target it specifically, she says.

To investigate this possibility, Kong will recruit 100 college students, half of whom meet criteria for depression. She will ask them to perform a variety of tasks that tap frontal-lobe functioning. In one such task-known as "backward digit span"-participants will reverse previously heard lists of numbers.

Kong will also evaluate participants' source memory by asking them to listen to one of eight male or female voices speaking sentences such as: "Stock prices fell in heavy trading today." Kong and her fellow researchers will then play them the same sentence and participants will judge whether the voice in the second version was the same one they heard before.

Kong expects to find that frontal-lobe function mediates the relationship between depression and source memory. If she is right, knowing that frontal-lobe dysfunction underpins depression could inform future pharmacological interventions by suggesting such medications target this area, she says.

"The next step may be to look at frontal-lobe functioning through [functional magnetic resonance imaging]," Kong says. With such technology, she may be able to pinpoint more exactly where the frontal-lobe functioning goes awry.


The double jeopardy of depression and aging

Aging and depression both result in cognitive decline, says Vonetta Dotson, a fifth-year graduate student in clinical and health psychology at the University of Florida. What's more, it's possible that an aging person with depression may be at particular risk for problems with attention and other areas of cognitive processing, she notes.

With a grant from the National Institute on Aging, Dotson will explore this possibility by observing the cognitive function of 50 young adults and 50 adults over the age of 65, using event related potentials-a measure of electrical activity in the brain. Dotson will also ask participants to complete the Beck Depression Inventory, as well as tests such as the Stroop task. In this well-known task, participants see a list of color words printed in different ink hues and name the color of words while ignoring the meaning of the word itself.

Dotson expects to find that depressed young adults show disturbances in brain waves in the dorsolateral prefrontal cortex-an area of the brain used in decision-making. Older adults may vary from the others by having changes in brain waves in the anterior cingulate cortex, involved in self-monitoring, she says. And adults who are both older and depressed may show a combination of these disturbances, Dotson notes.

"If we find out the people who are old and depressed have disproportional cognitive problems, they might have difficulty with everyday tasks-taking medication, driving, remembering appointments," says Dotson.

Discovering what underpins these problems might be a first step in developing treatments specific to depressed older adults, she notes.


The carrot versus the stick

The brain chemical dopamine may play a central role in the brain's ability to learn from mistakes, says Michael Frank, a fifth-year psychology and neuroscience graduate student at the University of Colorado at Boulder. A recent study by Frank, published in Science (Vol. 306, No. 5703), finds that when the brain cannot lower its levels of dopamine-as is the case with people with Parkinson's disease on dopamine-increasing medications-learning through negative experiences may be blocked.

People with Parkinson's disease sustain damage to the cells that produce dopamine in the brain, and many of their medications act to counteract this effect by raising dopamine levels. However, animal research has found that the brain responds to negative events by lowering dopamine levels. Parkinson's medications that artificially increase dopamine levels may prevent the brain from responding in this way, says Frank.

Frank tested this theory by asking both medicated and unmedicated people with Parkinson's disease, as well as a control group, to play a computer game in which they select one of two Japanese symbols.

The computer responded by noting the selection was "correct" or "incorrect." Over time, the participants began to make more correct selections, though they couldn't discern a clear pattern to the game.

By keeping track of the participant's choices, Frank and his colleagues inferred whether each participant learned to avoid "bad" characters or select "good" ones. For example, those who picked symbols with a large chance of being good over more neutral characters preferred to seek out positive results rather than avoid negative ones-the strategy patients with Parkinson's with high levels of dopamine took, Frank reports. However, patients with Parkinson's with low levels of dopamine tended to avoid the bad characters more then they choose the good ones, he says.

"In comparison, the control group learned equally from good and bad experiences," Frank notes.

These findings suggest that by lowering dopamine levels, the brain trains itself to avoid negative experiences, and by raising dopamine levels the brain learns to seek out positive ones-even in people without Parkinson's disease-says Frank.


Merging the results of delinquency studies

Michael Edwards, a fifth-year graduate student in quantitative psychology, has shouldered a difficult task: combining the results of three longitudinal studies of alcoholic parents and child delinquency.

"There are three really good studies but each one only covered part of the span we are interested in, from 3 to 30 [years old]," says Edwards, who attends the University of North Carolina at Chapel Hill. "What does that whole trajectory of delinquency look like? How do things like gender and parental alcoholism affect that trajectory?"

His tool of choice? A statistical technique known as item response theory (IRT). Using IRT, Edwards will create a common metric for the different measures used by the three studies. He will then patch together the results to build a larger picture than any of the three studies provides alone.

Edwards believes that the incorporation of IRT in longitudinal research could potentially change how researchers design studies. For example, instead of following one cohort of children for 15 years, it would be faster to study three cohorts for five years and then combine the results.

"These ideas are all out there in the literature. I think it's simply a question of demonstrating how these techniques work and showing researchers what the possible advantages are," states Edwards.

-S. DINGFELDER