How to scare a rat

I detest rodents. I dread the days when I return home only to find myself face to face with my whiskered nemesis, not an uncommon happening in rat-infested Baltimore by the way. I then usually spend hours of my time trying to rid my apartment of my furry friend and making sure he doesn’t return. But alas, he always finds a way back in. Which is why a study published in the Proceedings of the National Academy of Sciences this week drew my attention. Researchers June-Seek Choi and Jeansok Kim designed and performed experiments to scare rats. By doing so, they were trying to understand how our brains process fear and make risky decisions in situations where we are faced with predators.

The scientists created an artificial open field with a nest in which the rats lived. They placed pellets of food at increasing distances from the nest and noticed that the rats quickly learned to come out of their nest, grab the food pellet and return to their nest. To then determine how to rats would behave in the presence of a predator, the scientists placed a metallic robot called the Robogator at the opposite end of the open field. Each time a rat now tried to approach a food pellet, the robogator would surge forward and snap its metallic jaws at the rat and would then return to its original position. The Robogator never physically hurt the rats; it only gave them a good scare! When confronted with the Robogator the scientists noticed that the rats would flee back to their nests and freeze without getting the food pellet. After a while however, they would return, more cautiously, in order to get the food. However, the rats didn’t venture very far this time, and were only able to grab the food pellets closest to their nests. Therefore, the rats had a way of judging the risk of being attacked by the Robogator against the benefit of getting some food and therefore only went for the food pellets closest to them. To understand what part of the brain may be responsible for this response, the scientists interfered with the proper working of a region of the brain called the amygdala. Rats whose amygdalas were rendered inactive (turned off using chemicals or by making tiny lesions) showed a much decreased fear response. They were bolder and foraged food pellets placed farther away from their nests even in the presence of the Robogator. In fact, some of the rats were even curious about the metallic monster and spent a few seconds sniffing it. Conversely, when the amygdala of the rats were made to work overtime, the rats were petrified of the impending danger and took a much longer time to approach the food and were only able to forage at shorter distances from the nest. Thus the amygdala was integral to the rats’ fear response and risk assessment.

Studies like this can be important in understanding how the human brain may respond to fear and risks. In fact, the authors cite a recent study where humans with lesions in the amygdala (caused as a result of a disease) were much riskier gamblers than individuals with healthy amygdalas. As fascinating as this research is, however, I think the more important question here is- how do I get my hands on the Robogator? Furry friend, meet your new metallic adversary!

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