Ritalin helps people with attention-deficit hyperactivity disorder concentrate. But it stimulates the entire brain, causing side effects such as insomnia.

Earl K. Miller, associate director of the Picower Institute for Learning and Memory, and Timothy Buschman, a grad student in brain and cognitive sciences, hope that a better understanding of how attention works could lead to drugs targeting the brain regions where ADHD symptoms arise. They recently described their work, which suggests that two different brain regions control two different kinds of attention, in Science.

Miller and Buschman monitored electrical activity in the parietal and frontal cortices of monkeys performing visual tasks designed to elicit the two kinds of attention: automatic and willful. Monkeys watching a screen searched for a green rectangle. To test for automatic attention, the researchers put the green rectangle in a field of red rectangles, to make it pop out at the monkeys quickly. In images testing for willful attention, the green rectangle had to be distinguished more carefully from an array of multicolored rectangles.

Their results suggest that the frontal cortex is responsible for willful attention and the parietal cortex for automatic. Other researchers had looked at the cortices separately and found that both seemed to be involved with attention. The Picower researchers were the first to monitor both concurrently and to distinguish their roles in the two kinds of attention. They plan to test their findings in healthy people and those with ADHD.