Rats care about their rat buddies — unless they’re on anti-anxiety medication, it would seem.

A 2011 study found that when a free rat came in contact with a rat trapped in a container, the free rat was empathically motivated to release the distressed rat from its cell. But a new study, published in Frontiers in Psychology, noted that a rat put in a similar scenario but given an anti-anxiety medication, was less likely to free its trapped peer.

Both studies were led in part by Peggy Mason, professor of neurobiology from the University of Chicago. In the most recent study, Mason discovered that rats given the anti-anxiety medication midazolam were less likely to free a fellow rat from a locked compartment, but would, however, open the same restrainer device when it contained chocolate instead. The drug dampened a test rat's emotional connection with a distressed peer, but did not limit its physical ability to open the container if it so chose to.

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Basically, the free rat acted like an self-centered, cocoa-fueled jerkwad. Or to put it politely, a medicated rat didn't feel rewarded helping a buddy, but was still plenty motivated by the almighty candy.

In a video explaining the study’s findings, Mason posits the larger implications of her team's research.

"In the context of today’s society," she says," which is a highly medicated society, lots of people are taking psychoactive drugs that might blunt their experience of negative affect. Our results would suggest that that would also blunt helping. If people’s ability to yolk to another’s distress is blunted, then their motivation to help that other individual is also blunted."

Mason’s team performed secondary experiments, and found that the rats weren’t motivated physiologically, as in an increased heart rate of blood pressure didn't inspire rats to free their peers. They simply, in Mason’s words, needed to "care inside their brain." I take much pleasure in knowing that if a rat ever chose to save my life, it would be because that rat cared about me.

The full study is available at Frontiers in Psychology, and The University of Chicago’s Science Life has a fascinating piece on the study, including insight from Mason herself.

Correction: The article originally referred to the medication as antidepressants. The study actually gave the rats anti-anxiety medication. The text and the headline have been corrected.

Evidence shows animals have empathy