This is the first story in a new occasional article series we’re calling Slashback. We’ll be covering a topic that may not be breaking news, but is interesting to us. Today’s Slashback story features an article from Scientific American highlighting the profound effect of severe social isolation on the brain. From the report: The feeling of “wanting” something has repeatedly been shown to increase dopamine transmission in the brain reward circuit (see here and here). This circuit consists of the dopamingeric midbrain and the striatum. These areas are particularly active in response to images of food when hungry, to drug-related images for those who are addicted, and people with Internet Gaming Disorder who are deprived of gaming (see here, here, and here). What about social interactions? For social animals, it would make sense that social interactions would be a primary reward. However, so far such research has primarily been conducted on mice. In 2016, Gillian Matthews and colleagues published a paper showing that after 24 hours of social isolation, dopamine neurons in the midbrain were activated when mice sought social interaction. These dopamine neurons showed similar activation patterns to other cravings. It appears that the acute social isolation in these mice led to an aversive “loneliness-like” state that increased motivation for social engagement. Nevertheless, researchers have questioned whether these findings would apply to humans, especially since it’s not possible to assess whether a mouse subjectively feels lonely. Livia Tomova, a postdoctoral fellow in the Saxelab at MIT, was inspired by this earlier research on mice and pitched to Rebecca Saxe the idea of trying to replicate the findings in humans. […] What did the researchers find? After only ten hours of social isolation– and even despite people knowing exactly when their deprivation would end– people reported substantially more social craving, loneliness, discomfort, dislike of isolation, and decreased happiness than they did at baseline. Similarly, the same findings were seen after ten hours of food fasting. Critically, the researchers found similar midbrain activity in response to food cues after fasting and social cues after isolation. The response was variable across participants, and those who reported more social craving after the social isolation period showed a larger brain response to the social stimuli. Interestingly, the variability across participants was also partially explained by the variability in pre-existing chronic levels of loneliness. Participants with higher levels of chronic loneliness at baseline reported less craving for social contact after 10 hours of isolation in response to the social stimuli, and showed a muted response in their midbrain in response to the social cues after social isolation (they also showed reduced midbrain responses to food cues after fasting). This finding is consistent with prior research showing that chronic loneliness is associated with reduced motivation to engage socially with others. These results are exciting because they are consistent with the results from earlier research on mice and the “social homeostasis” hypothesis developed based on animal models. According to this hypothesis, since social connection is an innate need, animals evolved neural system to regulate “social homeostasis.” The current findings suggest that there is a similar mechanism underlying social craving in humans, and that people who are forced to be isolated crave social interactions in a similar way as a hungry person craves food. As the researchers note, these findings are also encouraging for translating mouse models of mental health disorders that affect social motivation, such as autism spectrum disorder, social anxiety disorder, or depression. While the article makes little to no mention of the coronavirus, it does make one ponder how the mandated period of isolation associated with it will affect us, especially as local governments around the country begin to lift restrictions and reopen. What happens when a person starved of food is suddenly presented with the ability to eat? They gorge themselves. What about when a person who has been socially isolated for weeks suddenly gets to socialize? Perhaps they’ll jump on the chance to surround themselves with others. We’re already starting to see more people booking local holidays… Read more of this story at Slashdot.