Social isolation affects how people behave as well as how their brains operate, according to a functional MRI (fMRI) study presented Feb. 15 at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago.
The research, conducted at the University of Chicago, is the first to use fMRI scans to study the connections between perceived social isolation (or loneliness) and activity in the brain. Combining fMRI scans with data relevant to social behavior is part of an emerging field examining brain mechanisms, according to the study's authors.
Scientists found that the ventral striatum--a region of the brain associated with rewards--is much more activated in non-lonely people than in the lonely when they view pictures of people in pleasant settings. In contrast, the temporoparietal junction--a region associated with taking the perspective of another person--is much less activated among lonely than in the non-lonely when viewing pictures of people in unpleasant settings.
"Given their feelings of social isolation, lonely individuals may be left to find relative comfort in non-social rewards," said John Cacioppo, PhD, the Tiffany and Margaret Blake Professor in Psychology at the University of Chicago, and co-author of the paper which was published in the January issue of the Journal of Cognitive Neuroscience.
In the study, researchers tested 23 female undergraduates to determine their level of loneliness. While in an fMRI scanner, the subjects were shown unpleasant pictures and human conflict as well as pleasant things such as money and happy people.
The subjects who rated as lonely were least likely to have strong activity in their ventral striata when shown pictures of people enjoying themselves.
Although loneliness may influence brain activity, the research also suggests that activity in the ventral striatum may prompt feelings of loneliness, according to co-author Jean Decety, PhD, the Irving B. Harris Professor in psychology and psychiatry at the institution.
In addition to differing responses in the ventral striatum, the subjects also recorded differing responses in other parts of the brain, which may indicate that loneliness plays a role in how their brain operates.
"The study raises the intriguing possibility that loneliness may result from reduced reward-related activity in the ventral striatum in response to social rewards," Decety said.