Stress disrupts human thinking, but the brain can b...( A new neuroimaging study on stressed...)

A new neuroimaging study on stressed-out students suggests that male humans, like male rats, don't do their most agile thinking under stress. The findings, published this month in the Proceedings of the National Academy of Sciences, show that 20 male M.D. candidates in the middle of preparing for their board exams had a harder time shifting their attention from one task to another than other healthy young men who were not under the gun.

Previous experiments had found that stressed rats foraging for food had similar impairments and that those problems resulted from stress-induced changes in their brain anatomy. The new study, using functional magnetic resonance imaging (fMRI) to scan the stressed students' brains, is a robust example of how basic research in an animal model can lead to high-tech investigations of the human brain.

"It's a great translational story," says Bruce S. McEwen, head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at The Rockefeller University, who worked on the project with colleagues at Weill Cornell Medical College. "The research in the rats led to the imaging work on people, and the results matched up remarkably well."

The work holds good news too, for both rats and humans: Their brains recuperate quickly. Less than a month after the stress goes away, they are back to normal. "The message is that healthy brains are remarkably resilient and plastic," McEwen says.

To probe the effects of stress, the researchers scanned the brains of volunteers, some stressed and others relatively relaxed, performing two subtly different kinds of mental tasks, either an attention-shift or a response-reversal. Lying inside the scanner, the subjects looked at two discs: one red and one green, with one moving up and the other down. In a series of trials, they were prompted to choose a disc according to motion or color. By ordering when the subjects did which tasks, they challenged their
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