March 20, 20254 min readMouse-to-Mouse Resuscitation: Rodents Try to Revive Unconscious BuddiesThree studies show that a mouse will try to rouse an unconscious companionBy Gennaro Tomma edited by Gary StixA mouse tries to pull out the tongue of an unconscious social partner, perhaps to clear its airway in an attempt to revive it. Wenjian Sun, Guangwei Zhang, et al.Mice in animated movies and shorts do the weirdest things, from cooking starred dishes to piloting steamboats. But sometimes real life exceeds the most feverish Disney-esque imaginings. Consider recent research highlighting a mouse version of CPR. This study found that when mice see an unconscious peer, they seem to perform first aid, apparently aimed at rescuing their companion, although not all experts are convinced.It all started from an accidental observation, says Li Zhang, a systems neuroscientist at the Keck School of Medicine of the University of Southern California (USC). While conducting laboratory experiments, Zhang and his colleagues noticed that when a mouse encountered an unconscious partner, it suddenly started to interact intensively with it.This caught our attention because this hasnt been reported before, how animals in general respond to unconscious conspecifics, Zhang says. While there are anecdotes of wild animals such as elephants, chimpanzees and dolphins trying to help others of their species in need, such rescuing behavior has never been carefully studied.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.To probe further, Zhang and his colleagues designed different experiments to analyze how a mouse behaved when it encountered another mouse that had been knocked out with anesthesia.Videos filmed with high-resolution cameras revealed that the first mouse performed a set of behaviors toward its unresponsive partner. First, it sniffed the unconscious mouses body and then started grooming the animal. Then it took more vigorous action: biting the mouth of its immobile partner and pulling its tongue out, clearing the airway opening. These actions resembled what humans do during first aid procedures, the team reports in a study published on February 21 in Science. When the researchers put an object in the mouth of the unresponsive mouse, the rescuer removed it most of the time.The team then designed additional experiments to rule out whether this behavior was motivated by a desire for social interaction with the unconscious mouse or curiosity about something new. The results were really a shock to us, Zhang says. We realized, Wow, this is a revival.The mice were more likely to administer this rescuelike behavior to familiar partners than to strangers, suggesting their actions were not motivated by aggressive impulses. For their part, the female rescuers sometimes went through this routine with strangers, suggesting they might have a higher level of empathy compared with males, the researchers say. The mice rescuers had no previous experience of interacting with an unconscious peer, suggesting the behavior is innate.While the recipients of the first aid behaviors revived more quickly from their unconscious states, the researchers remain cautious about whether such resuscitation attempts are intentional. It is possible that such rescuers actions arise from innate impulses that may have evolved because they enhance the chances of an animals survival, says study co-author Huizhong Tao, a professor of physiology and neuroscience at the Keck School of Medicine of USC.A closer look at the brains of these mice showed that neurons in the hypothalamus that release the hormone oxytocin play a key role in the expression of this first-aid-like behavior, Tao says.Another study investigating mouse first aid published in the same issue of Science produced similar results. The researchers found that a brain structure called the medial amygdala plays a part in the recognition of the unconscious animal and in regulating the rescuing behavior. These two different findings can complement each other, suggesting that both of the structures may be required for helpinglike behaviors toward unresponsive companions, Tao says.Yet another study, published on January 22 in Science Advances, reached similar conclusions while highlighting a different brain region that might be involved in this behavior.The behavior seems to be super surprising, says Inbal Ben-Ami Bartal, a neuroscientist at Tel Aviv University, who studies helping behavior in rats and was not involved in the new research. For a long time, we were trying to explain whether behaviors for others are something that is automatic or ... something that is more acquired. For example, in humans, Bartal says, so-called prosocial behaviors are thought by many to be culturally based, skills that are learned from others.But this result, Bartal says, points toward a different view proposed by some scientiststhat we also have an innate automatic circuit that is intended to act prosocially for others.I think its definitely relevant to humans, Bartal adds. I think it helps us to realize that there is something automatic about prosociality in us that is very evolutionarily ancient.But not all scientists are convinced. I completely disagree with the interpretation, says Peggy Mason, a professor of neurobiology at the University of Chicago, who also wasnt involved in the new research. While she agrees that the rescue behavior indicates that the mice are disturbed by their unresponsive peers, Mason believes they are not actually attempting to rescue the animals but are just curious about them and engaged in investigation. I think the behavior is fine, she says. I just think you got to name it differently.Overall, the findings raise new questions, and further studies could lead to a better understanding of the brain circuitry that controls these rescuelike behaviorsand the empathy toward other animals that underlies them. Once the brain pathways that control these behaviors become clear, the authors say, it could reveal the underlying causes of deficits for certain neurological disorders ranging from Alzheimers to autism.