Brain can adapt to changing situations

Washington, Aug 19 : As you are on the verge of leaving the office after the day's work is done, three things happen within a few minutes.

You wife calls to tell you to pick up some milk on the way home. Then within moments, she calls you again to buy some items from the hardware store.

Based on your knowledge of the area and rush-hour traffic, you decide to get the milk first and the toilet plunger second. But then your boss calls asking you stay back to complete pending work.

Modifying our behaviour to such changing circumstances enables us to achieve our goals. But how, exactly, do our brains switch so elegantly and quickly from one well-entrenched plan to a new one in reaction to a sudden change in circumstances?

In the milk-hardware-boss example, do we simply remember a list of streets and turns, or do we remember a more abstract set of "rules" governing the web of relationships between the items we want to buy, our driving route and our relationships with spouse and employer?

The answer is "both", according to researchers at the Johns Hopkins University, who have learned that two different areas of the brain are responsible for the way human beings handle complex sets of "if-then" rules.

The researchers, led by Susan Courtney, associate professor of psychological and brain sciences at the Zanvyl Krieger School of Arts and Sciences, learned that rules people must actively remember are controlled primarily through the prefrontal cortex, beneath the forehead.

"This discovery may eventually lead to enhanced understanding . . . schizophrenia, obsessive-compulsive disorder and attention deficit disorder, all conditions in which a person's ability to remember and change such rules is impaired," said Courtney.

Courtney and her team used mental math tasks and functional magnetic resonance imaging to investigate which areas of the brain are used for different functions.

What researchers surprisingly discovered was that the prefrontal cortex became more active when participants had to switch rules, and a different part of the brain - the parietal cortex, near the back of the head - became more active when the participants were asked to switch numbers.

"This indicates that different parts of our brains store different kinds of memories and information," Courtney said. That, she said, "provides clues about how the human brain accomplishes complex, goal-directed behaviours."

These findings have been published in Neuron.