A new study by researchers at MIT found that social isolation shares a neural basis with the food cravings when humans feel hungry.

The researchers found that after one day of total isolation, the sight of people having fun together activates the same brain region that lights up when someone who hasn't eaten all day sees a picture of food.

"People who are forced to be isolated crave social interactions similar to the way a hungry person craves food," says Rebecca Saxe, the John W. Jarve Professor of Brain and Cognitive Sciences at MIT, a member of MIT's McGovern Institute for Brain Research, and the senior author of the study.

She added: “Our finding fits the intuitive idea that positive social interactions are a basic human need, and acute loneliness is an aversive state that motivates people to repair what is lacking, similar to hunger.”

For the study, the research team collected the data between 2018 and 2019, a year before the coronavirus pandemic began.

Their new findings, published in Nature Neuroscience.

Methodology

For the study, the researchers shortlisted healthy volunteers, who were mainly college students, and confined them to a windowless room on MIT's campus for 10 hours.

The participants were not allowed to use their phones, but the room did have a computer that they could use to contact the researchers, if necessary.

Explaining the experiment, Saxe said: "There were a whole bunch of interventions we used to make sure that it would really feel strange and different and isolated. They had to let us know when they were going to the bathroom so we could make sure it was empty. We delivered food to the door and then texted them when it was there so they could go get it. They really were not allowed to see people."

After the 10-hour isolation, each participant was scanned in an MRI machine.

Each of the 40 participants also underwent 10 hours of fasting, on a different day. After the 10-hour period of isolation or fasting, the participants were scanned while looking at images of food, images of people interacting, and neutral images such as flowers.

Findings

The researchers observed a part of the brain called the substantia nigra, a tiny structure located in the midbrain. This has been linked with hunger cravings and drug cravings.

The study revealed that the amount of activation in the substantia nigra was correlated with how strongly the patients rated their feelings of craving either food or social interaction.

The researchers also found that the responses varied from people to people. People who were in chronic isolation before the experiment showed fewer cravings for social interaction than people who hoped for a richer social life.

"For people who reported that their lives were really full of satisfying social interactions, this intervention had a bigger effect on their brains and on their self-reports," Saxe added.

The researchers are now planning to examine the brain responses of the same participants after the lockdown was introduced due to the coronavirus pandemic.

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