Loneliness is a social epidemic which has been amplified by the current Pandemic as humans have an inbuilt desire to be social and interact with each other. The lockdown and isolation due to Covid-19 is not helping things much in this sense. The amount of cases of clinical depression are going up world wide and psychologists world wide are concerned about the impact of this in the near future.
Humans have been talking about social isolation/loneliness for centuries but till date we haven’t really analyzed it from a neurological point of view; to say what does really happen when we are lonely? Does the desire for companionship light up a section of our brain similar to what happens when we are hungry and are craving food? Till recently there wasn’t much research done on the topic, infact till Kay Tye decided to do research on the the neuroscience of loneliness in 2016 there were no published papers that talked about loneliness & contained references to ‘cells’, ‘neurons’, or ‘brain’. So while working at the Stanford University lab of Karl Deisseroth, Tye decided to spend some time trying to isolate the neurons in rodent brains responsible for the need for social interaction. In addition to identifying the region in rodents she has also managed to manipulate the need by directly stimulating the neurons which is a fantastic break through.
Deisseroth had pioneered optogenetics, a technique in which genetically engineered, light-sensitive proteins are implanted into brain cells; researchers can then turn individual neurons on or off simply by shining lights on them though fiber-optic cables. Though the technique is far too invasive to use in people—as well as an injection into the brain to deliver the proteins, it requires threading the fiber-optic cable through the skull and directly into the brain—it allows researchers to tweak neurons in live, freely moving rodents and then observe their behavior.
Tye began using optogenetics in rodents to trace the neural circuits involved in emotion, motivation, and social behaviors. She found that by activating a neuron and then identifying the other parts of the brain that responded to the signal the neuron gave out, she could trace the discrete circuits of cells that work together to perform specific functions. Tye meticulously traced the connections out of the amygdala, an almond-shaped set of neurons thought to be the seat of fear and anxiety both in rodents and in humans.
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One of the first things Tye and Matthews noticed was that when they stimulated these neurons, the animals were more likely to seek social interaction with other mice. In a later experiment, they showed that animals, when given the choice, actively avoided areas of their cages that, when entered, triggered the activation of the neurons. This suggested that their quest for social interaction was driven more by a desire to avoid pain than to generate pleasure—an experience that mimicked the “aversive” experience of loneliness.
In a follow-up experiment, the 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 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. It was as if the social isolation had not been registered in their brains.
Since the experiment worked on Mice, the next step involved replicating the same thing with humans. Unfortunately they couldn’t use the same method to study the human behavior as no one sane would opt to have fiber-optic cable wired through their head just to participate in a study. So they fell back to a more imprecise method of using fMRI’s to scan the brains of the volunteers and she was able to identify a voxel (discrete population of several thousand neurons) that respond to the desire of wanting something like food/company. In fact they even managed to separate the two area’s responsible for desiring food and desiring company.
This is a fantastic first step because we have managed to identify the first part of the circuit that makes us social animals, obviously a lot more study is needed before this will have practical applications but we have taken the first steps towards the goal. It’s not hard to imagine a future where we have the ability to help suicidal people by simulating the area of their brain that enables them to extract joy from social connections. Or suppress the same in people who have to spend long duration’s of time alone, for example astronauts in interplanetary travel or deep sea researchers etc. The possibilities are endless.
Source: Why do you feel lonely? Neuroscience is starting to find answers.
– Suramya