How animals handle fear to obtain food

WASHINGTON - Like humans, animals too are capable of making instinctive safety decisions and judge when is it safe to move out of their safety zones to get food, suggests a new study.

Jeansok Kim, of the University of Washington, has demonstrated that rats weigh their odds of safely retrieving food pellets placed at varying distances from a perceived predator.

“When animals go out to forage, they’re taking a risk. They’re leaving the safety of their nests, venturing out where there may be predators that could eat them,” said Kim.

Kim and co-author June-Seek Choi, of the Korea University, studied how the amygdala - known to be an important brain area for perceiving and reacting to fear - was involved in the rats’ decisions to risk their safety for food.

Kim and Choi trained 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.

The researchers introduced a “predator,” an alligator-shaped robot that was programmed to snap its jaws and surge at the rats. With a body made of gray Lego blocks and fangs of bright orange Legos, the Lego Mindstorms Robogator was about twice the size of the rats.

The researchers programmed the robot to lurch forward about 9 inches, open and shut its mouth and then return to its resting spot far away from the rats’ nest.

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.
till hungry, the rats paced back in forth in the nest areas, hidden from the Robogator. Slowly they re-emerged and cautiously approached the food, while the Robogator continued its aggressive movements whenever the rats neared the food pellet.

Most rats learned that they could safely retrieve the food pellet placed closest, 10 inches, from their nest and not intersect the robot’s path. None of the rats obtained the pellet nearer the Robogator, about 30 inches from the nest.

“Like when people cross the street, we just tend to automatically have a sense of what is safe. I think that most animals have that capability in their nervous system. Through our amygdala, we instinctively know what keeps us safe,” said Kim.

When Kim and Choi increased the amygdala activity, the rats showed greater fear. Even when the food was at a safe distance from the robot, rats treated with the drug bicuculline, which increases neural activity, were too afraid to venture out for the pellet.

“Because humans share many biological and behavioural features with animals, experimental studies with rats provide valuable information toward understanding the physiological as well as the psychological aspects of fear,” said Kim.

The study was published in the Proceedings of the National Academy of Sciences. (ANI)