Rats prefer to help their own kind; humans may be similarly wired
Date:
July 13, 2021
Source:
University of California - Berkeley
Summary:
A decade after scientists discovered that lab rats will rescue a
fellow rat in distress, but not a rat they consider an outsider,
new research pinpoints the brain regions that drive rats to
prioritize their nearest and dearest in times of crisis. It also
suggests humans may share the same neural bias.
FULL STORY ==========================================================================
A decade after scientists discovered that lab rats will rescue a fellow
rat in distress, but not a rat they consider an outsider, new research
from the University of California, Berkeley, pinpoints the brain regions
that drive rats to prioritize their nearest and dearest in times of
crisis. It also suggests humans may share the same neural bias.
==========================================================================
The findings, published today, Tuesday, July 13, in the journal eLife,
suggest that altruism, whether in rodents or humans, is motivated by
social bonding and familiarity rather than sympathy or guilt.
"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 study senior
author Daniela Kaufer, a professor of neuroscience and integrative
biology at UC Berkeley.
With nativism and conflicts between religious, ethnic and racial groups
on the rise globally, the results suggest that social integration,
rather than segregation, may boost cooperation among humans.
"Priming a common group membership may be a more powerful driver for
inducing pro-social motivation than increasing empathy," said study lead
author Inbal Ben-Ami Bartal, an assistant professor of psychobiology at Tel-Aviv University in Israel.
Bartal launched the study in 2014 as a postdoctoral Miller fellow in
Kaufer's laboratory at UC Berkeley. Bartal, Kaufer and UC Berkeley
psychology professor Dacher Keltner led a research team that sought to
identify the brain networks activated in rats in response to empathy,
and whether they are mirrored in humans. The results suggest they are.
==========================================================================
"The finding of a similar neural network involved in empathic helping
in rats, as in humans, provides new evidence that caring for others is
based on a shared neurobiological mechanism across mammals," Bartal said.
Using fiber photometry, immunohistochemistry, calcium imaging and other diagnostic tools, researchers found that all the rats they studied
experienced empathy in response to another rat's signs of distress.
However, to act on that empathy, the helper rat's neural reward circuitry
had to be triggered, and that only occurred if the trapped rat was of
the same type as the helper rat, or member of its ingroup.
"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," Kaufer said. "In contrast, the network associated with
reward signaling was active only for ingroup members and correlated with helping behavior." Specifically, the rats' empathy correlated with the
brain's sensory and orbitofrontal regions, as well as with the anterior
insula. Meanwhile, the rodents' decision to help was linked to activity
in the nucleus accumbens, a reward center with neurotransmitters that
include dopamine and serotonin.
==========================================================================
For the study, more than 60 pairs of caged rats were monitored over
the course of two weeks. Some of the pairs were of the same strain or
genetic tribe while others were not.
In each trial, one rat would be trapped inside a transparent cylinder
while the other roamed free in a larger enclosure surrounding the
cylinder.
While unconstrained rats consistently signaled empathy in response to
the plight of trapped rats, they only worked to free those that were
part of their ingroup, in which case they would lean or butt their heads against the cage door to release the rat.
Indeed, in reviewing the results of multiple measures to understand the
neural roots of that bias, the research team found that while all the
rodents in the trials sensed their cage partner's distress, their brains' reward circuitry was only activated when they came to the rescue of a
member of their ingroup.
Moreover, humans and other mammals share virtually the same empathy and
reward regions in the brain, implying that we may have similar biases
toward our ingroup when it comes to helping others, Bartal noted.
"Overall, the findings suggest that empathy alone doesn't predict helping behavior, and that's really a crucial point," she said. "So, if you want
to motivate people to help others who are suffering, it may be that you
have to increase their feeling of belonging and group membership, and
work toward a common identity." "Encouragingly," she added, "we find
that this mechanism is very flexible and determined primarily by social experience. We will now try to understand how pro-social motivation
shifts when rats become friends, and how that is reflected in their
brain activity." Video:
https://www.youtube.com/watch?v=1pmrTLkz3ms&t=1s ========================================================================== Story Source: Materials provided by
University_of_California_-_Berkeley. Original written by Yasmin
Anwar. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Inbal Ben-Ami Bartal, Jocelyn M Breton, Huanjie Sheng, Kimberly
LP Long,
Stella Chen, Aline Halliday, Justin W Kenney, Anne L Wheeler,
Paul Frankland, Carrie Shilyansky, Karl Deisseroth, Dacher Keltner,
Daniela Kaufer. Neural correlates of ingroup bias for prosociality
in rats.
eLife, 2021; 10 DOI: 10.7554/eLife.65582 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2021/07/210713165303.htm
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