Research has shown that rats are often emotionally motivated to help other rats in distress and routinely free their trapped friends. However, the new findings show that rats who were given midazolam, an anti-anxiety medication, were less likely to free their trapped companions.
Midazolam did not affect the rats’ physical ability to open the restrainer door. In fact, rats on this medication routinely opened the door for a piece of chocolate but did not feel motivated enough to open the door for their stressed companions. The findings suggest that motivation to help others relies on emotional reactions, which are dampened by the anti-anxiety medication.
“The rats help each other because they care,” said Peggy Mason, Ph.D., professor of neurobiology at the University of Chicago. “They need to share the affect of the trapped rat in order to help, and that’s a fundamental finding that tells us something about how we operate, because we’re mammals like rats too.”
The researchers used a rat-helping test originally established in a 2011 study published in the journal Science by Mason, Inbal Ben-Ami Bartal, Ph.D., a post-doctoral scholar now at the University of California, Berkeley, and Jean Decety, Ph.D., Irving B. Harris Professor of Psychology and Psychiatry at the University of Chicago.
In those first experiments, one rat was kept in a restrainer — a closed tube with a door that can be nudged open only from the outside. The second rat roamed free in the cage around the restrainer, able to see and hear the trapped cage mate.
In that study, the free rats quickly figured out how to release their trapped cage mates, seen by the researchers as a sign of empathy for their companions in distress. In the latest research, rats injected with midazolam did not free their trapped companions, although they did open the same restrainer when that restrainer contained chocolate chips.
According to the study, stress — such as seeing and hearing a trapped companion — triggers the adrenal gland and sympathetic nervous system and causes physical symptoms such as increased heart rate and high blood pressure.
To determine whether the rats’ helping behavior was driven by these physical changes, the researchers conducted another set of experiments by giving the rats nadolol, a beta-blocker similar to those used to treat high blood pressure. Nadolol prevents the pounding heart and other bodily signs of a stress response. But even those rats who were given nadolol were just as likely to help their companions as those injected with saline or nothing at all.
“What that tells you is that they don’t have to be physiologically, peripherally aroused in order to help. They just have to care inside their brain,” Mason said.
Mason said that this study further confirms the previous research that rats, and by extension other mammals — including humans — are motivated to help others through empathy.
“Helping others could be your new drug. Go help some people and you’ll feel really good,” she said. “I think that’s a mammalian trait that has developed through evolution. Helping another is good for the species.”
The findings are published in the journal Frontiers in Psychology.