Imaging the Social Brain

Group of friends socializing on rooftop deck on summer evening
Thomas Barwick/Getty Images

If you want to capture a baby’s attention, show it another baby.  From the earliest stages, we’re captivated by that which reminds us of, well, us.  Our brains are hardwired to interact with other humans.  Now scientists are using special neuroimaging techniques to study how the brain helps us to socialize.

Some studies have suggested that our social interactions are mediated in part by what have been called “mirror neurons,” a term which has fallen out of style in scientific circles   These groups of neurons were involved with performing an action, such as playing the piano, but were found to fire when seeing someone else play the piano as well.

  While mirror neurons have been posited to play a role in empathy, the story has become more nuanced.  For one, the empathic phenomena doesn’t result from any particular property of the nerve cells individually, but rather the network of interacting cells, which has been more recently deemed the action observation network, which includes areas such as the inferior frontal gyrus, medial temporal gyrus, and inferior parietal lobe. 

The action observation network has been said to be more active when watching a familiar action, rather than something unfamiliar.  For example, a recent study discussed at the Cognitive Neuroscience Society (CNS) annual meeting investigated this phenomenon in dancers.  While lying in a functional magnetic resonance imaging (fMRI) scanner, study participants were asked to either predict the dancer’s next posture, or to respond to some other unrelated question.  They participants were also asked to rate which movements were most familiar.

  As predicted, the AON was more active for more familiar gestures. 

While most functional MRI involves patients doing some task or other such as the example above, another technique only requires that patients lay still.  In so called resting-state functional connectivity MRI, the natural networks of the brain can be correlated with people’s character traits or performances on tasks outside the scanner.

  Functional connectivity MRI correlates fluctuations in blood oxygen level dependent signals in different regions of the brain.  Those regions whose rhythms are relatively synchronized often work closely together in everyday life.  This can be further supported by the use of a technique called diffusion tensor imaging (DTI), which can actually show the fiber tracks between different brain areas.  Using these kinds of techniques in combination can be an especially powerful way of studying the brain, and has allowed neuroscientists to comment on face selectivity of different brain areas, and also theory-of-mind, meaning the ability to consider another person’s thoughts and feelings.

One of the oldest ways of understanding the functions of different brain regions is to study diseases that damage one part of the brain more than another.  This approach has led to some of the most seminal moments in neurological understanding, such as the infamous accident of Phineas Gage, in which an explosion drove a thick tamping rod through the front part of his brain, damaging his medial prefrontal lobe.

The medial frontal lobe has been linked with a vast array of different behaviors, from action monitoring to complex social and emotional responses.  Lesley Fellows of the Montreal Neurological Institute discussed the use of voxel-based lesions symptom mapping (VLSM) to correlate different behaviors to different areas of the medial frontal lobe.  Her past work has focused on how this region of the frontal lobe is involved with making decisions in settings of uncertainty.  The medial frontal lobe has been found to be involved with self-monitoring as well—the way we know when we’ve messed up. 

Far from being a cold calculating machine, the medial frontal lobes are also involved with emotions.  Mauricio Delgado focused on how the ventromedial prefrontal cortex (part of the medial frontal lobe near the base of the brain) is involved with controlling emotional responses, and how this helps make better decisions.  As the brain is a massive network, the frontal lobe cooperates with other regions such as the basal ganglia to help us cope after life set-backs.

It's an exciting time in neuroscience, with new techniques shedding light on how the brain works, and also how it works well with others.


The Cognitive Neurology Society Annual Meeting, 2015, San Francisco, California.

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