Finding the brain's autopilot.

• Position: Learning research

In grade school, most children struggle with learning multiplication tables. Yet, as every parent and teacher knows, frequent practice can make this difficult task seem automatic, even effortless. How this happens long has remained a mystery to scientists. Now, researchers at Washington University School of Medicine have found a circuit in the brain that automates non-motor tasks.

They found that the brain has two distinct circuits for completing a single task. When learning, a person uses a novel' circuit specifically designed for handling new information. After practice, though, there is a switch to a second circuit in a different location in the brain that handles learned tasks.

The research team used positron emission tomography (PET) to probe the brains of study subjects as they heard a list of nouns and responded with appropriate verbs--such as the stimulus "fork" and the response "eat." As a control, the volunteers were asked to repeat the noun they had just heard. PET scans taken during the experiment showed that the brain at first is taxed by the task and very specific areas of the brain are active.

As the routine is repeated, it becomes automatic, requiring less attention and little activity in the areas of the brain previously involved. Other parts become more active in the automatic state. After subjects are fed the list of nouns six or seven times, they begin to use the same area of the brain to respond that they used for simple word repetition.

This implies that, after practice, such a task requires very little thought or attention--it's as if the brain is on "autopilot," notes Marcus E. Raichle, professor...