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The Lonely Social Brain

A new study finds differences in how lonelier people's brains represent others.

Matthew Henry / Unsplash
Source: Matthew Henry / Unsplash

Social connection is fundamental to our well-being. Feeling close to other people promotes well-being, whereas disconnection from others can compromise mental and physical health. Yet, how the brain reflects our subjective experience of attachment to people has remained unclear until recently. How does our brain represent interpersonal closeness and distance? And, how might our perception of our social connections be related to loneliness?

Researchers reasoned that insight into how the brain represents subjective social connection might come from a close examination of the medial prefrontal cortex (MPFC). While the MPFC is known to activate in response to thinking about the self, it exhibits similar activation when thinking about close others. And, these activation levels persist after controlling for one’s similarity to the close other. Activation is elicited more strongly by deeper characteristics of the person (e.g., their personality) than by superficial characteristics (e.g., their appearance). These results suggest that the MPFC may play a key role in representing the quality and quantity of our social connection to others.

In a new study published in the Journal of Neuroscience, researchers used functional magnetic resonance imaging (fMRI) to examine how people mapped or organized representations of others based on their perceived level of connection, and whether loneliness affected that organizational mapping in the brain. Before an fMRI procedure, 43 research participants wrote the names of five people with whom they had the “closest, deepest, most involved and most intimate relationships” and five acquaintances, such as classmates, colleagues, or neighbors, ranked in the order of how close they felt to each. They also completed the UCLA Loneliness Scale, which included items like, “How often do you feel close to people?” and “How often do you feel part of a group of friends?”

During the fMRI scan, research participants completed a self- and other-reflection task for the 16 targets: the self, five close others, five acquaintances, and five celebrities. The names of their closest people, acquaintances, and celebrity names (as a control) were used to elicit brain activation associated with thinking about others. Thinking about someone from each category corresponded with a different activity pattern in the medial prefrontal cortex, respectively, such that there were distinct patterns for the self; close others and acquaintances; and celebrities. The scans showed that the MPFC mirrored their network of social circles, based on perceived closeness.

Though the participants’ brains represented themselves as separate from others, the self-other distance was bridged by their perceptions of their closest friends as the most similar to themselves. That is, the social brain seems to stratify neural representations of people based on our subjective connection to them and separately cluster people who are and are not in our social network. And, the people we feel closest to are represented most closely to ourselves.

Interestingly, the lonely participants showed altered self-other mapping in these social brain regions. Most notably, in the MPFC, loneliness was associated with a reduced representational similarity between the self and others. In contrast, it was associated with increased representational similarity in another brain area, the posterior cingulate cortex (PCC), which is thought to track differences in power and affiliation between people. That finding, the researchers write, "may suggest a failure to distinguish the nuances between self and others in interpersonal space, which may contribute to and/or be a consequence of lonelier individuals’ difficulties navigating interpersonal interactions."

A closer look indicated that lonely people had “blurry social circles,” meaning they did not differentiate as clearly (in terms of neural representation) between close others, acquaintances, and celebrities. The expected differentiation between close others and acquaintances was less for lonely people. This blurring of social circles with lonely participants was even observed in the similarity between close others and celebrities.

The results suggest that a "lonelier" neural self-representation may mirror feelings of chronic social disconnection. The social brain appears to map our interpersonal ties, and the unique features of the maps of lonely individuals may help explain why they endorse statements such as "people are around me but not with me." Chronic loneliness may somehow suppress the perception of distinctiveness with which others are represented in the brain.

It’s unclear whether the brain structure leads to loneliness or loneliness leads to a distinct brain structure. But, these social brain maps are likely to have neuroplasticity.

Seeing similarities between ourselves and others is the foundation for empathy and maintaining and facilitating our social bonds. Even if the default for lonely people is to see themselves as separate from everyone else, they might deliberately challenge this perception by remembering shared experiences with others and seeing the value in the quality of their social connections. Reaching out to others can challenge perceptions of separateness, and lonely people may find that they are really not so different and distant after all.

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