Affiliative Experience Shows Unique Brain Signature

by Kayt Sukel

October 25, 2012

How closely linked are our social affiliations to our emotions?  Several neuropsychiatric disorders, including psychopathy, are characterized by a lack of remorse and an inability to socially connect with others—in fact, that emotional deficiency is believed to be at the heart of the problem.  But given the challenges of studying complex human emotions, past studies have failed to uncouple affiliative experiences, or our bonds with others, from their associated rewards and punishments.  Now, a new study from the D’Or Institute in Rio de Janeiro has uncovered a distinct neural signature of affiliative experience in the human brain—one that might change the way we understand and treat a variety of neuropsychiatric disorders.

Emotions and affiliations

Jorge Moll, a neuroscientist at the D’Or Institute, has been studying the neural basis of complex emotions for years.  His previous work focused on moral emotions—or those that provide a motivational basis for social behavior. 

“Emotions like guilt and compassion—these are there to help people interact with one another and you only feel them when you have an attachment to another person,” he says.  “And I wondered if there was some core component that might be common to all these complex social emotions.”

Roland Zahn, a researcher at the University of Manchester and Moll’s colleague, says the idea makes sense.  “Many of these moral emotions are exaggerated or missing in different disorders,” he says.  “Guilt, for example, is often exaggerated in depression.  But you won’t feel that guilt unless you have the ability to feel attachment towards another person.  So we were curious if we could see this attachment or affiliation represented separately in the brain, distinguished from other types of rewarding and punishing feelings.”

Different situations, different emotions

Moll, Zahn, and colleagues tested 27 people using functional magnetic resonance imaging (fMRI) as they evaluated 280 different social scenarios for emotion, pleasantness, and tenderness.  There were five different types of scenarios:  affiliative positive, affiliative negative, non-affiliative positive, non-affiliative negative, and neutral.  For example, an affiliative negative scenario might be “You were distracted and lost your small child in the park;” while a non-affiliative negative scenario would be “You were blamed for a problem that was not your fault and lost your job.”  The group hypothesized that affiliative scenarios, or those that included attachment to another person, would show activation in the sub-cortical regions of the brain.

“We believed it had to be a very primitive region in the brain,” says Moll.  “So we thought maybe the septal area of the hypothalamus would be activated as this region has been shown to be very important to attachment in animal models.  And we thought we would see activation whether the situation was negative or positive.”

That is exactly what the group found.  The results were published in the Sept. 5 issue of the Journal of Neuroscience.

“In studies that look at pair bonding in prairie voles, researchers like Larry Young and Thomas Insel have shown that this region is very important to the capacity to bond,” says Moll.  “We speculate that there is something very similar, with chemicals like oxytocin and vasopressin, happening in humans as well.”

Previous studies have suggested that the amygdala is also important to understanding the emotional salience, or emotional "weight," of social situations.  Moll and colleagues initially expected to see amygdala activation in affiliative scenarios—but it was only significantly active in negative affiliative scenarios, such as learning that one's father is dying of cancer.

“Any kind of threat is capable of activating the amygdala.  So it seems that amygdala activation is involved in affiliation but not specific to the affiliation,” says Moll.  “It may be that it is more important to the stress of learning someone you are attached to is suffering.  But it is something that we need to explore more.”

Prairie voles vs. humans

Larry Young, director of the Center for Translational Social Neuroscience at Emory University, says this study very elegantly disentangles the reward/punishment component of different situations from the affiliative components. 

“What [Moll et al.] call the septal hypothalamic area looks an awful lot like the paraventricular nucleus of the hypothalamus (PVN) to me,” he says.  “And that’s the area in prairie voles where oxytocin is made.”

Young says this study confirms much of the work that has been done in animals examining social bonds.  “The important takeaway here is that there is a core non-cortical area of the brain that regulates this very fundamental process of affiliation.  It is evolutionarily very ancient and it is very important,” he says.  “We think a lot of the things people do are very cortex-driven.  We have this huge cortex and that’s what regulates our behavior.  But we also need to recognize that we have these more ancient core systems that regulate things like affiliative behaviors that don’t require the cortex.”

Translating to neuropsychiatric disorders

Moll believes that, given the lack of affiliative emotion in disorders like psychopathy and post-partum depression, this work has implications for our understanding and treatment of the pathology underlying them.

“We speculate that the core prosocial circuitry is damaged in these disorders.  We may be able to use fMRI to identify and diagnose people with attachment disorders,” he says.  “And it is also possible that we may be able to train people using real-time fMRI and neurofeedback to achieve these specific emotional states.”

Young, however, cautions that there is still a lot to understand about affiliative emotion in the human brain before we can start creating therapies.

“This study is a good start,” says Young.  “I don’t think we know the path yet—how we go from recognizing that these brain areas are involved in affiliation to some kind of treatment.  But by understanding the circuits involved and how affiliation is involved, we may be able to one day find therapeutic approaches that specifically activate these brain areas and strengthen social behaviors.”