Scott Barry kaufman writes “mandatory social isolation triggers hunger-like neural cravings,” in the May 19 online issue of scientific American. If the need for relationships is really a basic need, the paper argues, then deprivation should show the same effect on the brain and behavior as other basic needs such as food and sleep deprivation. The article is edited as follows:
The need for relationships — to form and maintain at least a minimum number of positive, stable, and intimate relationships — is a fundamental need that affects our entire existence and permeates our entire mix of emotions, thoughts, and actions. Voluntary solitude can be a great source of creativity, and solitude does not necessarily mean loneliness, but what happens when people are forcibly isolated and seriously deprived of this basic human need?
Surprisingly, while there is plenty of evidence on the effects of loneliness on physical and mental health, there is little research on the consequences of severe enforced isolation. If the need for relationships is really a basic need, then deprivation should show the same effects on the brain and behavior as other basic needs such as food and sleep deprivation.
The feeling of “wanting” something has been shown time and again to increase dopamine transmission in the brain’s reward circuits. This circuit consists of the dopaminergic midbrain and striatum. These areas were particularly active when hungry people were shown pictures of food, when addicts were shown pictures of drugs, and when people with “online gaming disorder” were deprived of the opportunity to play games.
What about social interaction? It makes sense for social interactions to be a major reward for social animals. So far, however, such studies have been conducted mainly in mice. In 2016, gillian Matthews and colleagues published a paper showing that after 24 hours of social isolation, dopamine neurons in the brain were activated when mice sought social interaction. The firing patterns of these dopamine neurons are similar to those of other cravings. The severe social isolation these mice suffered seemed to lead to a negative “lonesome” state, increasing their incentive to socialize. However, the researchers questioned whether the findings would apply to humans, especially since they were unable to assess whether mice were subjectively lonely.
Livia tomova, a postdoctoral researcher at the Massachusetts institute of technology’s saxophone laboratory in the us, was inspired by the previous study in mice and came up with the idea for Rebecca sachs to replicate it in humans. However, researchers have many methodological challenges to overcome.
For example, a single day of social isolation isn’t that long for a person, and being alone doesn’t necessarily feel socially isolated. Being alone may also help with recovery. To meet this challenge, the researchers asked 40 healthy, socially connected adults to spend 10 hours alone (from 9 a.m. to 7 p.m.) without social networking or other social stimuli (like twitter, email or reading a novel).
Another methodological limitation is how to measure neural responses in the relevant dopaminergic midbrain regions. This is a major technical challenge. The area in question is tiny, right next to the sphenoid sinus, and prone to distortion and signal loss. To address this challenge, the researchers used an optimized imaging technique and a recently available midbrain atlas to identify the relevant regions in each participant’s brain.
Finally, the researchers aren’t sure if they can actually measure the signals involved in craving, especially considering that about 70 percent of the neurons in the substantia nigra part of the reward circuit are dopaminergic neurons. To meet this challenge, the researchers asked participants to look at pictures of their favorite social activities, favorite foods, and pleasant references to decipher the brain’s response to these different stimuli.