Acts of kindness: Social brains are wired to help

Why do some individuals rush to help, while others hesitate? A new study led by Dr. Inbal Bartal of Tel Aviv University digs deep into this question using rats. The findings highlight the strong influence of social experience and brain chemistry on prosocial behavior and willingness to help.

The team used a helping behavior task where rats could free a distressed peer trapped in a restrainer. Rats that had previous positive interactions were more likely to help.

These “helper rats” also showed more brain activity in areas linked to empathy and motivation compared to their less helpful counterparts.

Social bonds drive helping

Helper rats exhibited stronger activation in the anterior cingulate cortex, somatosensory cortex, and other empathy-related areas. This activity pattern suggests that not just feeling another’s distress, but having a social bond, is crucial for helping.

Interestingly, oxytocin – the hormone involved in bonding – played a key role. Rats that consistently helped had higher oxytocin receptor expression in the nucleus accumbens, a major reward center in the brain.

Blocking oxytocin signaling did not completely erase helping behavior but did reduce the rats’ social tendencies. According to the researchers, caring about others appears more important than simply sensing their distress.

“We appear to live in an increasingly polarized society where there is a gap in empathy towards others,” said Dr. Bartal, a faculty member in the Psychology Department and School of Neuroscience at Tel-Aviv University.

“This work helps us understand prosocial, or helpful, acts better. We see others in distress all the time but tend to help only certain individuals. The similarity between human and rat brains helps us understand the way our brain mediates prosocial decisions.”

Helpful rats socialize more

The study found that rats who became “helpers” showed greater social affiliation even before the helping task began. Before any rat was trapped, these rats spent more time interacting, lying together, and engaging in affiliative behaviors with their cagemates.

The frequency of social interactions predicted how quickly rats would later act to free a distressed peer. Rats that interacted more often on the first day were faster to help across testing days.

This link between early social behavior and later helping actions offers new insights into how prosocial tendencies develop.

Helpers had more oxytocin receptors

Gene expression studies revealed that helper rats had significantly higher oxytocin receptor (Oxtr) levels specifically in the nucleus accumbens. They also showed greater activity of genes related to social reward and emotional regulation.

Importantly, genes tied to stress responses were downregulated in helper rats. This suggests that lower stress reactivity could promote a readiness to help others. Brain-wide analyses also showed that helper rats had more active networks in sensory and empathy-related brain regions.

When the researchers blocked oxytocin signaling in the brain’s paraventricular nucleus, rats showed fewer social behaviors. This reduced sociality hints that oxytocin may strengthen social bonds in the brain, which in turn could drive helping actions.

Social brains are motivated to help

Helper rats demonstrated a widespread activation of the brain’s prosocial network. Critical areas included the anterior cingulate cortex, orbitofrontal cortex, nucleus accumbens, and insular cortex. Many of these regions overlap with known human empathy and reward circuits.

Moreover, the orbitofrontal cortex stood out as playing a major role. This area, known for evaluating rewards and decisions, showed the strongest difference between helpers and non-helpers.

Social interaction frequency correlated strongly with brain activity in these regions. Rats who were more socially engaged early on had higher brain activation related to empathy later, even days after initial testing.

Implications for human society

The research suggests that social connectedness and neurochemical factors together shape helping behavior. The results support the idea that empathy alone does not always lead to action – social bonds and emotional rewards are key motivators.

Understanding how oxytocin and social affiliation drive prosocial behavior could help us better support empathy in increasingly divided societies. Strengthening social bonds might be more effective than simply raising awareness about others’ distress.

Dr. Bartal and colleagues have illuminated the biological roots of kindness in a way that could one day inform how we nurture empathy in humans.

The study is published in the Journal of Neuroscience.

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