神経科学：社会的隔離はヒトの脳内で渇望反応を引き起こす

After ten hours of mandatory social isolation, people tend to experience social craving and increased brain responses to images of social interactions, suggests a study published this week in Nature Neuroscience.

Social interactions are rewarding, and images associated with positive social interactions, like smiling faces, engage dopamine reward systems in the human brain. Previous research has shown that mice that underwent brief social isolation exhibit increased responses in the midbrain dopamine system during subsequent social interaction, which suggests that this region of the brain might contribute to a loneliness-like state after isolation. However, it is unclear whether humans experience a similar neural response after social isolation.

Livia Tomova and colleagues observed 40 people undergoing separate 10-hour sessions of isolation from in-person and online social interactions, as well as fasting. After each session, participants viewed images of social interactions, food or flowers while their brains were scanned, and they self-reported experiences of loneliness, food craving and social craving.

Participants reported increased social craving after isolation and increased food craving after fasting. Correspondingly, a midbrain region associated with reward and novelty responses consistent with dopaminergic activity showed greater responses to social images after isolation and to food images after fasting. The authors found that midbrain responses to food or social images after deprivation were more similar to each other than to responses to flower images, suggesting that acute social isolation can evoke social craving similarly to how fasting can lead to food craving.

The authors conclude that these findings shed light on how brief periods of social restriction or isolation can induce social craving and influence the brain’s responses to a deprived need, like social interaction.