Is this the way Bobby Fisher does it?

These computer-generated images of the brain illustrate how -- or actually, where -- chess players think. The brightly colored regions reveal that the various mental tasks of chess require the activation of different neural pathways, says Jordan Grafman, a neuropsychologist at the National Institute of Neurological Disorders and Stroke in Bethesda, Md.

He and his colleagues imaged the brains of 10 experienced, active chess players using positron emission tomography (PET). During the PET scans, these right-handed men answered questions about a chessboard displayed on a computer monitor.

The researchers designed the questions to examine increasingly complex problem solving. With each new task, they ignored areas activated by earlier, simpler tasks. In this way, they sought to identify parts of the brain used uniquely for a particular type of thinking.

Players first had to decide whether black or white pieces lay on the board. Then they noted the color of the piece closest to their own, which was marked with an X -- a test of spatial discrimination.

Next, they answered whether a particular piece, such as a pawn, could capture a nearby piece. The players had to both recognize the piece and remember how it moves. This so-called rule retrieval involved additional parts of the brain, including the hippocampus and other areas of the left temporal lobe, the researchers report in the May 19 NATURE.

Finally, the players decided whether one move remained to checkmate, based on the configuration of pieces on the computer screen. Only in that last task did they tap the prefrontal cortex, located in the front of the brain, Grafman notes. "We think that's because of its role in planning," he says.

This scheming also tapped an area toward the back of the brain not activated by the earlier tasks. The region seems to draw mental pictures of the chess-piece configurations being thought out by the prefrontal cortex, Grafman says.

These results bolster his contention that the prefrontal cortex is where the brain does its planning and processing of events or thoughts that must be considered as a unit instead of individually.