Rat brains are wired to help their loved ones in times of crisis

Scientists have long known that a rat will try to help another rat in distress, but only if it belongs to the same ingroup. Now researchers at UC Berkeley have identified the brain regions that are active when rats experience empathy and when they decide whether to help or not.

For the study, the behavior and brain activity of unconstrained rats were monitored when they were in the presence of another rat trapped in a small, transparent cylinder. Brain imaging techniques such as photometry, immunohistochemistry and calcium imaging enabled researchers to conclude that all the rats experienced empathy in response to the distressed rat’s signals. 

During the rats’ experience of empathy, the brain’s sensory and orbitofrontal regions were activated, as well as the anterior insula. These regions are also active when humans and other animals experience empathy.

However, the experience of empathy only led to helping behaviour when the trapped rat was part of the same ingroup. Then an unconstrained rat would lean on, or butt its head against, the door to release the captive.  

The rats’ decision to help was associated with activity in the nucleus accumbens, a reward center in the brain, with neurotransmitters that include dopamine and serotonin. Similar neural networks are involved in empathic helping in humans. 

“Surprisingly, we found that the network associated with empathy is activated when you see a distressed peer, whether they are in the ingroup or not,” said Daniela Kaufer, study senior author and professor of neuroscience and integrative biology at UC Berkeley. “In contrast, the network associated with reward signaling was active only for ingroup members and correlated with helping behavior.”

“We have found that the group identity of the distressed rat dramatically influences the neural response and decision to help, revealing the biological mechanism of ingroup bias,” said Professor Kaufer.

The findings suggest that altruistic behavior in rodents, and probably in humans too, is influenced by social relationships and familiarity rather than purely by sympathy. 

This has bearing in the modern world where conflicts between different racial, religious, and ethnic groups are increasing, globally; this study suggests that social integration and fostering of a common group identity would be most effective in boosting cooperation between people in these circumstances.

The study is published in the journal eLife.

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By Alison Bosman, Earth.com Staff Writer