An international team led by immunologist Sara Trabanelli at the University of Lausanne in Switzerland ran a series of experiments using virtual reality headsets. The experiments, which involved 248 healthy adults, found that our immune systems are remarkably sensitive to signs of illness.
When participants viewed a virtual avatar showing clear signs of illness (such as rashes associated with fever) at various distances, their brains activated rapidly and their immune systems shifted into a heightened state of readiness.
Conversely, when participants saw an avatar without any signs of illness, their brains did not show the same activation, and there was no immediate increase in immune markers in their blood.
Some of the immune markers measured were innate lymphoid cells (ILCs). The level of ILCs in the blood can surge dramatically during direct contact with a pathogen. However, it can also increase when a person sees or imagines a virtual infection, as reported by Science Alert.
“ILCs respond to infections not only when they are detected in the body but also when they are perceived as a potential threat,” the authors wrote in their report.
Using machine learning to analyze the data, the team found that brain activity tied to threat detection could largely explain the immune response.
The scientists observed that when the brain senses an impending threat, it reacts quickly by activating areas that then interact with the immune system (such as the hypothalamus). This gives the body time to mount a defense.
Sick avatars positioned at the greatest distance elicited a stronger response in the brain than avatars that were closer.
Some of these activated areas overlap with those stimulated after receiving a flu vaccine.
Thus, our brains are wired for resistance, even when it comes to the mere sight of a sick person rather than an actual threat of infection. The researchers suggested that this immune response may have evolved as a “fight or flight” reaction, although this theory requires further investigation.
“The results indicate that humans possess a complex neuroimmune response to the threat of infection, not just to physical contact,” the scientists concluded. So let’s give a nod to our brains for keeping our health in check.
The study was published in the journal Nature Neuroscience.
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