Animals' instincts not so different, study finds

The safe distance you keep between your face and the claws of a fractious cat or the jaws of a fearful dog isn't just a human instinct. Neuroscientists have found that animals are capable of making similar instinctive safety decisions. In a study published in the Proceedings of the National Academy of Sciences, researchers demonstrated that rats weigh their odds of safely retrieving food pellets placed at varying distances from a perceived predator.

But how do rats decide whether it's safe to leave the nest? Researchers found that the amygdala-an important brain area for perceiving and reacting to fear-was involved in the rats' decisions to risk their safety for food. In humans, impaired amygdala activity has been linked to risky decision-making, such as gambling. And an overactive amygdala could explain anxiety disorders, including posttraumatic stress disorder and phobias.

Researchers trained the male rats to retrieve a food pellet placed at varying distances from a safety zone or nest. The rats, hungry from a restricted food supply for several days, quickly learned to retrieve the food pellets. Researchers then introduced an alligator-shaped robot predator. With the robot in place, the rats began foraging as usual. When they neared the food, the Robogator quickly moved toward the rats and snapped its jaws. The rats scurried back to the safety of the nest and then momentarily froze-a typical fear response.

But the rats were still hungry and they paced back and forth in the nest areas, hidden from the Robogator. Slowly, they reemerged and cautiously approached the food, while the Robogator continued its aggressive movements whenever the rats neared the food pellet. After awhile, the rats learned that they could safely retrieve the food pellet placed closest, 10 inches, from their nest and not intersect the robot's path-they learned instinctively what was safe.