Male And Female Rats Have Very Different Ways Of Dealing With Fear

Female rats may deal with fear better than males, in the long run. photos2013/Shutterstock

When confronted with a threat, a decision has to be made: stand your ground, or escape? This response mechanism isn’t unique to humans, and a study examining it in rats has revealed something curious. Published in the journal eLife, this new research shows that male rats stand their ground and freeze, whereas female rats make a run for it – but it’s actually the female rats that control their fear better than the males.

It is conventionally thought that when rats are suddenly afraid of something they perceive to be a threat, they freeze and observe it. During a new study looking at how male and female rats react to threats, Rebecca Shansky – an assistant professor of psychology at Northeastern University – accidentally managed to upend this century-old assumption.

Shansky was originally investigating “fear conditioning,” wherein a creature is trained to be afraid of something that isn’t necessarily a threat. For example, the rats in this case were conditioned to fear a particular sound by giving them a small electric shock after a tone was played. Quickly, the rats began to fear the noise, even when the tone was played without the shock.

After a while, the rats began to realize that the tone would no longer be accompanied by a shock, and they lost their fear of it – this process is known as “extinction.” Shansky noted that most studies investigating fear responses and extinction used the males of the species, and in terms of rats, they almost always froze when encountering a threat. In this study, both males and females were used, and the way they dealt with fear was remarkably different from each other.

Female rats were four times more likely than males to dart across the room, chaotically and with considerable speed, when confronted with the fear-inducing noise. “They start running around like crazy,” Shansky said in a statement. “It looks like they're trying to escape.”

Does this study have any implications for how male and female humans deal with fear? hikrcn/Shutterstock

Male rats, as expected, preferred to just freeze, although some showed darting behavior. Either way, darting and freezing are both interpreted as learning behaviors: The males monitor the threat, while the females attempt to avoid encountering it.

During the extinction tests, when the tone was played without a shock, their behaviors diverged further. The darting rats became unafraid of the sound faster than the freezing males or females did, who remained on edge for far longer. The freezing rats appeared to take more time to understand that the sound was no longer going to be accompanied by an electric shock, which implies that females learned the new parameters more rapidly and dealt with the fear more efficiently.

The learning processes that underlie extinction form the basis of exposure therapy for people with post-traumatic stress disorder, wherein sufferers are shown the object of their fear without being put in danger. Over time, they experience extinction, and they come to no longer fear the object.

Women are twice as likely to be diagnosed with PTSD compared to men. Although the fear responses of rats and humans are quite different, this study raises the question of whether men and women cope with fear and PTSD in very different ways.

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