Kay Tye set out to answer a question that has taken on new resonance in the age of social distancing: When people feel lonely, do they crave social interactions in the same way a hungry person craves food? And could she and her colleagues detect and measure this “hunger” in the neural circuits of the brain?
[T]he researchers put some of the mice in solitary confinement for 24 hours and then reintroduced them to social groups. As one would expect, the animals sought out and spent an unusual amount of time interacting with other animals, as if they’d been “lonely.” Then Tye and [graduate student Gillian] Matthews isolated the same mice again, this time using optogenetics to silence the DRN neurons after the period in solitary. This time, the animals lost the desire for social contact.
Scientists have long known that the brain harbors the biological equivalent of a car’s fuel gauge—a complex homeostatic system that allows our gray matter to track the state of our basic biological needs, like those for food, water, and sleep. The purpose of the system is to drive us toward behaviors aimed at maintaining or restoring our natural state of balance.
Tye and Matthews seemed to have found the equivalent of a homeostatic regulator for the basic social-contact needs of rodents. The next question: What do these findings mean for people?