Mice perform first-aid and save unconscious peers in emergencies

Humans instinctively attempt to revive unconscious individuals through first aid. A recent study suggests that mice display similar behaviors in an emergency.

Researchers from the Keck School of Medicine at USC observed that when a mouse became unresponsive, its companion reacted in ways that accelerated recovery.

For years, scientists have questioned whether animals exhibit emergency responses toward unconscious peers.

“But this study is the first time we’re seeing a first responder-like behavior in mice,” noted Li Zhang, the study’s principal investigator and a professor of physiology and neuroscience.

How mice act in an emergency

The study recorded how mice engaged with unconscious peers using a machine-learning-based analysis.

Their responses escalated from sniffing and grooming to more forceful actions such as biting the mouth or tongue and pulling it out. These behaviors resembled emergency actions seen in humans, such as clearing airways.

Wenjian Sun, the study’s first author and research associate at Keck School of Medicine’s Zilkha Neurogenetic Institute, said that he had never seen this behavior from mice before.

“The behavior was especially unique due to its similarity to how humans behave in emergency responses,” said Sun.

The discovery was made unexpectedly during an unrelated experiment. The pattern of escalating responses strongly suggested an instinctive effort to revive the unconscious peer.

Reviving actions and their impact

The emergency response shown by these “helper mice” had measurable effects.

Huizhong Tao, a professor of physiology and neuroscience and co-author of the study, noted that mice targeting the mouth and tongue of an unconscious peer often sped up recovery.

This behavior was not aggressive. The researchers found that once an unconscious mouse regained awareness, it displayed normal tongue function.

The study also showed that the behavior occurred primarily between familiar pairs and was rare when a mouse was simply sleeping.

Oxytocin drives the emergency response

Using neural imaging and optogenetics, researchers explored the brain activity linked to these responses.

Zhang and the team found that oxytocin neurons in the hypothalamic paraventricular nucleus showed increased activity when mice encountered an unconscious partner. Oxytocin, commonly associated with bonding, appeared to play a key role in triggering the emergency response.

Oxytocin neurons responded differently based on whether the partner was unconscious or active. Specific neurons activated during particular actions, such as tongue-pulling.

The study also demonstrated that stimulating oxytocin neurons increased reviving behaviors, while blocking oxytocin signaling reduced them.

A shared instinct across species

The findings suggest that reviving behaviors may be common among social species. The study showed that mice reacting to unconscious peers acted instinctively in an emergency situation rather than out of mere curiosity.

The behavioral sequence resembled emergency responses seen in other animals, including primates.

The researchers believe this behavior helps maintain group cohesion and increases survival chances in social species. Tao pointed out that future studies will investigate whether mice exhibit even more complex responses over longer periods.

This discovery sheds light on prosocial instincts in mammals, highlighting how emergency behaviors may have evolved to strengthen social bonds and improve survival.

Prosocial behavior in animals

The research team plans to conduct further studies to explore whether mice exhibit even more complex behaviors over extended periods.

Tao believes this discovery provides an exciting opportunity to investigate the biological foundations of empathy and social assistance in animals.

Future experiments will examine how these emergency responses develop, whether they vary between different strains of mice, and if similar behaviors occur in other rodent species.

Researchers also aim to explore whether these behaviors can be influenced by external factors, such as changes in social environment or hormonal manipulation.

Understanding the neural mechanisms behind prosocial behaviors in animals may have broader implications for human health.

Studying how oxytocin influences emergency responses could lead to insights into conditions where social behaviors are impaired, such as autism or social anxiety disorders.

In addition to Sun, Zhang, and Tao, the study included contributions from Guangwei Zhang, Junxiang J. Huang, Can Tao, and Michelle B. Seo of Keck School of Medicine.

The study is published in the journal Science.

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