Loneliness as a modulator of intersubject neural alignment across social and nonsocial contexts

Abstract

Loneliness is associated with cognitive biases that diverge from normative patterns of understanding and may be reflected in altered neural responses to the world. Here, we examined how loneliness modulates neural synchrony across individuals during the processing of social and nonsocial information. Using high-resolution movie-watching fMRI data (n = 178) from the Human Connectome Project, we applied intersubject correlation analyses to identify context-dependent neural signature of loneliness. Lonely individuals primarily showed more idiosyncratic responses in regions within the default mode network, visual association cortex, and amygdala during social contexts, and in reward-related circuitry during nonsocial contexts. This suggests less stereotyped processing of social information and reward in lonely individuals. In contrast, lonely individuals exhibited greater neural synchrony in the nucleus accumbens during social contexts and in somatomotor regions during nonsocial contexts. This potentially reflects shared experiences of social craving and engagement with a socially irrelevant physical environment. These effects were robust against demographic similarities, kinship, depression, and objective levels of social connection. Together, these findings identify loneliness as a modulator of intersubject neural alignment, which may contribute to shaping how individuals process and interpret different aspects of the world.