Social connection is essential to one's well-being, but how the brain reflects a person's attachment to other people remains unclear. Now, a team of researchers has found that loneliness can alter the brain's social network, explaining how the brain represents relationships.
In this new study, published in The Journal of Neuroscience (JNeurosci), the researchers have found that the closer a person feels to people emotionally, the more he or she represents them in the brain. In comparison, those who feel socially disconnected from others appear to have a lonelier self-representation.
This explains why other people still feel lonely, even if they are surrounded by other people.
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A part of the brain called the medial prefrontal cortex (mPFC) maintains a structured map of a person's social network, based on how close he or she is to others. The mPFC is a premotor area that projects to the rostral ventrolateral medulla and is known to be involved in the adult social brain, particularly human social cognition and behavior.
The study looked at the social network of 43 college students, including people who were closest to them, such as close friends or family.
Examining brain activity
A team from the Dartmouth Social Neuroscience Laboratory used functional magnetic resonance imaging (fMRI) to evaluate the brain activity of the participants while they were thinking about themselves, close friends, family members, acquaintances, and celebrities. Thinking of a person from each category corresponded to a different activity in the mPFC region.
The participants were between the ages of 18 and 47 and were asked to name and rank five people whom they are closest to, and five acquaintances. During the scan, they were asked to make trait judgments about themselves, the people they are closest to, and their acquaintances, including five celebrities.
They ranked how much a trait described a person on a scale of 1 to 4, with the latter meaning "very much".
The brain appears to cluster representations of people into three factions – oneself, own social network, and celebrities or famous people. The closer participants felt to someone, the more similar their brain represented them throughout the social brain, including the mPFC. People who are closest to tended to elicit more powerful signals in the mPFC, which is are strikingly like the patterns of activity shown when people think about themselves.
However, brain patterns varied for lonely people. The researchers noticed that in lonely people, the activity related to thinking about others was more different. This means that loneliness can alter the brain's social network.
"If we had a stamp of neural activity that reflected your self-representation and one that reflected that of people whom you are close to, for most of us, our stamps of neural activity would look pretty similar. Yet, for lonelier people, the neural activity was differentiated from that of other people," Meghan Meyer, an assistant professor of psychological and brain sciences, and director of the Dartmouth Social Neuroscience Lab, explained.
Loneliness blurs social network
Lonelier people manifested less neural similarity between themselves and others in their mPFC regions. Further, the team found that the delineations between the three cliques or factions were blurrier in their neural activity. Put simply, the sadder or lonelier a person is, the less similar his or her brain looks when they think about themselves and others.
"Most notably, in MPFC, loneliness was associated with a reduced representational similarity between the self and others. The social brain maintains information about broad social categories as well as closeness to the self. Moreover, these results point to the possibility that feelings of chronic social disconnection may be mirrored by a 'lonelier' neural self-representation," the team wrote in the paper.
Finally, the team noted that lonelier individuals also appeared to have a "lonelier" neural self-representation in the mPFC.
The brain can map people's interpersonal ties, and alterations in this map may help explain why lonely people may feel that people are around them, but "not with them." This means that even if people are around others, they can still feel lonely. Loneliness is likely to have little to do with being alone and more to do with feeling alone, no matter what the situation is, even if surrounded by others.