Newly discovered brain network offers clues to social cognition

May 18, 2017

Scientists call our ability to understand another person's thoughts—to intuit their desires, read their intentions, and predict their behavior—theory of mind. It's an essential human trait, one that is crucial to effective social interaction. But where did it come from?

Working with , researchers in Winrich Freiwald's Laboratory of Neural Systems at The Rockefeller University have discovered tantalizing clues about the origins of our ability to understand what other people are thinking. As reported in Science on May 18, Freiwald and postdoc Julia Sliwa have identified areas in the brains of these primates that are exclusively dedicated to analyzing social interactions. And they may have evolved into the neural circuitry that supports theory of mind in the .

The team used imaging (fMRI) to identify those parts of the monkeys' brains that become active when the animals watched different kinds of videos.

Some of those videos showed inanimate objects (i.e., monkey toys) colliding or otherwise interacting physically. Others showed macaques interacting with the same objects by playing with them. And others still showed macaques interacting socially with other macaques: grooming, playing, fighting, etc.

By analyzing the fMRI data, the researchers were able to determine precisely which portions of the monkeys' brains responded to physical or social interactions. And much of what they found came as a surprise.

The video will load shortly.
While showing monkeys videos of social interaction, scientists scanned their brains and tracked their gaze (red dot). Credit: C.J. Machado and D. Amaral

Monkey see, monkey analyze

For example, the team expected that areas containing specialized cells called mirror neurons, which fire when an animal performs an action such as grasping a stick or hitting a ball, or sees another animal performing the same action, would light up when the macaques watched other macaques playing with toys.

But the macaques' mirror neuron regions also showed activity when the animals watched their fellow monkeys interacting socially—and even when they watched objects colliding with other objects.

That, says Sliwa, suggests that the motor neuron system, which also exists in the human brain, could be more involved than previously thought in understanding a variety of both social and non-social interactions.

The scientists also expected those areas of the brain that respond selectively to specific visual shapes—namely, faces, bodies, or objects—would be activated when the monkeys watched videos featuring those shapes. And that did indeed happen.

Surprisingly, though, the body-selective areas of the ' brains got an extra boost when the animals watched videos of interacting with objects. And their face-selective areas perked up even more in response to videos of monkey-on-monkey social interactions. This suggests that the same parts of the brain that are responsible for analyzing visual shapes might also be partly responsible for analyzing both physical and social interactions.

An exclusive social network

Most intriguingly, the team discovered that additional areas of the brain, far removed from those face- and body-selective areas, also lit up in response to social interactions. Digging deeper, the researchers even identified a portion of the network that responded exclusively to social interactions, remaining nearly silent in their absence.

"That was both unexpected and mind-boggling," says Freiwald, who explains that no other study has shown evidence of a network in the brain going dark when denied its preferred input.

This socially sensitive network is located in the same areas of the brain that are associated with theory of mind in humans—areas that are similarly activated only when we reflect on the thoughts of others.

As a result, says Sliwa, it could represent an "evolutionary precursor" to the neural network that produces theory of mind in our own brains. And we humans, in turn, might not be quite as unique—or as far removed from our primate cousins—as we like to think.

Explore further: Facial motion activates a dedicated network within the brain, research shows

More information: J. Sliwa el al., "A dedicated network for social interaction processing in the primate brain," Science (2017). science.sciencemag.org/cgi/doi … 1126/science.aam6383

Related Stories

Facial motion activates a dedicated network within the brain, research shows

January 8, 2015
A face is more than a static collection of features. A shift in gaze, a tightening of the lips, a tilt of the head, these movements convey important clues to someone's state of mind. Scientists know that two particularly ...

Monkeys with larger friend networks have more gray matter

November 4, 2011
New research in the UK on rhesus macaque monkeys has found for the first time that if they live in larger groups they develop more gray matter in parts of the brain involved in processing information on social interactions.

Study shows differences in brain activity of humans and macaques engaged in the same task

July 14, 2015
(Phys.org)—A group of researchers with affiliations to several institutions in the U.S. has identified some of the ways the human brain differs in the way it focuses on a task as compared to macaques. In their paper published ...

Scientists reveal brain network for observed social threat interactions

September 30, 2015
Observing one person threatening another is a commonplace event. Now, in research published in eLife, scientists have used large-scale neural recording and big data analysis in monkeys to enable a first glimpse of the brain ...

Recommended for you

Brain activity buffers against worsening anxiety

November 17, 2017
Boosting activity in brain areas related to thinking and problem-solving may also buffer against worsening anxiety, suggests a new study by Duke University researchers.

Investigating patterns of degeneration in Alzheimer's disease

November 17, 2017
Alzheimer's disease (AD) is known to cause memory loss and cognitive decline, but other functions of the brain can remain intact. The reasons cells in some brain regions degenerate while others are protected is largely unknown. ...

Study may point to new treatment approach for ASD

November 17, 2017
Using sophisticated genome mining and gene manipulation techniques, researchers at Vanderbilt University Medical Center (VUMC) have solved a mystery that could lead to a new treatment approach for autism spectrum disorder ...

Neuroscientists find chronic stress skews decisions toward higher-risk options

November 16, 2017
Making decisions is not always easy, especially when choosing between two options that have both positive and negative elements, such as deciding between a job with a high salary but long hours, and a lower-paying job that ...

Paraplegic rats walk and regain feeling after stem cell treatment

November 16, 2017
Engineered tissue containing human stem cells has allowed paraplegic rats to walk independently and regain sensory perception. The implanted rats also show some degree of healing in their spinal cords. The research, published ...

Brain implant tested in human patients found to improve memory recall

November 15, 2017
(Medical Xpress)—A team of researchers with the University of Southern California and the Wake Forest School of Medicine has conducted experiments involving implanting electrodes into the brains of human volunteers to see ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.