Wednesday, August 19, 2009

Brain Is a Co-Conspirator in a Vicious Stress Loop

An interesting New York Times article today illustrates the relationships between chronic stress, brain function and how we behave. The classic "fight or flight" response can get thwarted into unproductive habits or passive inaction that likely brings more chronic stress.

Reporting earlier this summer in the journal Science, Nuno Sousa of the Life and Health Sciences Research Institute at the University of Minho in Portugal and his colleagues described experiments in which chronically stressed rats lost their elastic rat cunning and instead fell back on familiar routines and rote responses, like compulsively pressing a bar for food pellets they had no intention of eating.

Moreover, the rats’ behavioral perturbations were reflected by a pair of complementary changes in their underlying neural circuitry. On the one hand, regions of the brain associated with executive decision-making and goal-directed behaviors had shriveled, while, conversely, brain sectors linked to habit formation had bloomed.

In other words, the rodents were now cognitively predisposed to keep doing the same things over and over, to run laps in the same dead-ended rat race rather than seek a pipeline to greener sewers. “Behaviors become habitual faster in stressed animals than in the controls, and worse, the stressed animals can’t shift back to goal-directed behaviors when that would be the better approach,” Dr. Sousa said. “I call this a vicious circle.”

Robert Sapolsky, a neurobiologist who studies stress at Stanford University School of Medicine, said, “This is a great model for understanding why we end up in a rut, and then dig ourselves deeper and deeper into that rut.”

Makes one want to get out of the rat race. Hopefully those Portuguese rats are living stress-free these days. The article ends with sound advice for rodents and humans:

It’s still August. Time to relax, rewind and remodel the brain.