Source: www.nytimes.com
MINHO, PORTUGAL, August 17, 2009: Lab rats are known for their ingenious ability to navigate intricate mazes, pull different levers for food and other remarkable feats for such a small brain. But a report recently publish in the journal Science showed that chronically stressed rats lost their elastic rat cunning and creative problem-solving. Not only that, their neurological configuration changed.
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 described experiments in which stressed rats fell back on familiar routines and rote responses, like compulsively pressing a bar for food pellets they had no intention of eating. Their habits fell into a rut. 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.
Happily, the stress-induced changes in behavior and brain appear to be reversible. To rattle the rats to the point where their stress response remained demonstrably hyperactive, the researchers exposed the animals to four weeks of varying stressors: moderate electric shocks, being encaged with dominant rats, prolonged dunks in water. But with only four weeks’ vacation in a supportive setting free of bullies and Tasers, the formerly stressed rats looked just like the controls, able to innovate, discriminate and lay off the bar.