Investigating neural effects of social isolation

We live in an increasingly interconnected world new advances in technologies such as social media allow us to be connected with others at all times. Nevertheless, loneliness and social isolation are on the rise in modern society worldwide. This leads to severe negative consequences for mental and physical health and has been shown to drastically increase health care costs. However, the state of loneliness i.e., perceiving a gap between the social interactions we want, and those we experience - is not well understood. Particularly, the neural mechanisms underlying the desire to connect with others are unclear. In addition, it is unclear how social isolation affects experience of subsequent social interactions particularly the rewarding aspects of social contact. The proposed project aims to fill this gab in knowledge. First, we aim to identify the neural representation of social motivation in the human brain by building up on findings in the mouse model. Translating this research into human brain research, we will record functional magnetic resonance imaging (fMRI) signals from the human brain after short-term social isolation to identify the neural mechanisms underlying the experience of social isolation and the drive to re- engage in social interactions. We will test whether these neural representations are shared with other basic drives, such as food motivation, or, whether they are exclusively dedicated to social processes. Second, we aim to investigate how social isolation affects the experience of subsequent live social interactions and their underlying neural mechanisms. Particularly, we aim to investigate how neural mechanisms underlying social reward processing are affected during live social interactions following social isolation. This basic research aims to provide neural evidence on how social drives are represented in the human brain, how isolation affects motivation to engage with other people and whether the rewarding aspects of social interactions are modulated by social isolation. Thus, this project aims to advance a deeper understanding of loneliness and social isolation. Our work might lay the foundation for the development of clinical trials assessing how these neural mechanisms are altered in individuals suffering from chronic loneliness an ever-increasing health problem in modern societies.

When people are forced to be isolated from one another, do they crave social interactions? To address this question, we used functional magnetic resonance imaging (fMRI) to measure neural responses evoked by food and social cues after participants (n=40) experienced ten hours of mandated fasting or total social isolation. After isolation, people felt lonely and craved social interaction. Midbrain regions showed selective activation to food cues after fasting and to social cues after isolation; these responses were correlated with self-reported craving. By contrast, striatal and cortical regions differentiated between craving food versus social interaction. Across deprivation sessions, we find that deprivation narrows and focuses the brain's motivational responses to the deprived target. Our results support the intuitive idea that acute isolation causes social craving, similar to the way fasting causes hunger.