Finding the brain's autopilot

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

"This study provides some insight into how the brain goes about efficiently learning to do things," says lead author Marcus E. Raichle, M.D., professor of neurology and radiology. The group found that the brain has two distinct circuits for completing a single task. When learning a task, for instance, a person uses a "novel" circuit specifically designed for handling new tasks. After practice though, there is a switch to a second circuit in a different location in the brain that handles learned tasks. The findings are presented in the January 1994 issue of Cerebral Cortex.

The research team used positron emission tomography (PET) to probe the brain 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 is at first taxed by the task, and very specific areas of the brain are active.

Surprisingly, as the task is repeated it becomes automatic, requiring less attention and little activity in the areas of the brain previously involved. Other areas of the brain become more active in the automatic state. After a person is 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 the task requires very little thought or attention--it's as if the brain is on "autopilot," says Raichle. Somewhere between the first attempt and "automaticness," the brain appears to shift gears, explains co-author, Steven E. Petersen, Ph.D., associate professor of neurology. When a person automates a task, he or she is using different brain circuitry than when first learning to do the task, he explains. In the study, the switch occurs after less than 15 minutes of practice.

Raichle and Petersen believe that their study shows how the brain might free itself from having to fret over mundane tasks--like shifting a car at the right time or walking--in order to devote energy to other endeavors. Why might this happen? It might be a way to conserve attention, a precious resource, Petersen says. At the broadest level, attention is a collection of mental states that together allow us to organize ourselves in the world, he says. People are constantly bombarded by huge amounts of information, and they also have many conflicting needs and desires. Our attention span manages information overload by helping people choose the information they take in. It also helps process that information and make decisions about how to respond so that needs and desires are fulfilled. The unconscious shift from the novel circuit to the autopilot might be mediated by attention.

Interestingly, automatic activities demand very little attention. Once a task is practiced long enough to become automatic it would be inappropriate for a person to use an attention-demanding strategy to complete the task. In real life this might happen when a star basketball player gets to the free-throw line in a tight game. If the player thinks too much about making the free-throw or the mechanics of the shot, the automaticness of the task may desert him, resulting in a 'choke.' "What you don't want in a crucial situation is for the attention-demanding circuit to interfere with the automatic circuitry," says Petersen, implying that the results could be disastrous.

The automatic circuit may also switch on at inopportune times during the day. Petersen explains with an anecdote: Traveling Highway 40 from his home to a St. Louis Cardinals game at Busch Stadium, there's a one-in-three chance that he will end up taking the exit that leads to the School of Medicine.

Because he travels the Highway 40 route to work each day, the act of driving there has been automated by his brain. When he leaves his house for the Cardinals game, he knows fully that his destination is Busch Stadium, but sometimes he cannot overcome the autopilot that directs him to turn right at the Kings Highway exit. In order to arrive downtown at the ballgame without a hitch, he must will himself to overcome the automatic tendency to take the exit that leads to his office. He must use a cognitive strategy that goes something like this: "You are going to the ballgame, go past here." Despite these sometimes comical situations, our experts hypothesize that the automatic circuit is a necessity for optimizing the ability to perform a great number of tasks and deeds during a lifetime.


By Jim Keeley

Jim Keeley is affiliated with Washington University School of Medicine, St Louis, MO.

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