You're about to leave work at the end of the day when your cell phone rings: it's your spouse, asking that you pick up a gallon of milk on the way home. Before you head out the door, though, your spouse calls again and asks you to stop by the hardware store too. Based on your knowledge of the area and rush-hour traffic, you decide to get the milk first and the toilet plunger second. But whoops! The phone rings again. This time, it's your boss, asking you to work late. That means another change of plans.
Adjusting our behavior 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 newer 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?
Susan Courtney
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 that people must actively remember (in other words, which are not part of their everyday habits) are controlled primarily through the prefrontal cortex, which is in the very front of the brain, beneath the forehead.
"This discovery may eventually lead to enhanced understanding of psychiatric diseases such as 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, lead author of a paper in a recent issue of Neuron.