Recent research has found that the brain is highly sensitive to symptoms of various diseases and can quickly take various actions to protect itself. Merely seeing visual cues of a patient can activate the brain and body’s alarm system, even if they are far away and cannot infect you.
In a study led by immunologist Sara Trabanelli at the University of Lausanne in Switzerland, 248 healthy adults were brought in to participate in a series of experiments using virtual reality headsets to reveal how sensitive the brain is to disease symptoms.
The results showed that when these participants saw virtual characters at different distances displaying clear signs of illness, such as fever and rash, their brains suddenly activated the immune system, putting them on high alert.
On the other hand, when they saw healthy and normal virtual characters, their brains did not show the same activation pattern, and their immune markers in blood tests did not immediately increase.
Some of these immune markers are known as innate lymphoid cells. When the body comes into direct contact with pathogens, innate lymphoid cells increase in the bloodstream. However, in the experiment, participants’ innate lymphoid cells rapidly increased simply by seeing virtual infection scenarios and the possibility of exposure.
Trabanelli stated, “These data suggest that innate lymphoid cells respond not only when infections are detected internally but also when infections are perceived as potential threats close to the body.”
When researchers used machine learning to statistically analyze the experimental results, they found that threat detection activity in the brain largely explained immune responses.
Upon seeing sick virtual characters in the distance, participants’ brains activated in a unique pattern, and when the virtual characters’ expressions showed fear or neutrality, this pattern did not appear.
The brain responded most strongly to the furthest sick virtual characters. Interestingly, some of the activated brain regions overlapped with those that may be activated after receiving a flu vaccine.
This study demonstrates that when the brain perceives an imminent threat, it swiftly responds, triggering activities in areas like the hypothalamus, which then communicate with the immune system, giving the body time to mount a defense.
In one experiment, participants wearing virtual reality devices were asked to press a button when they felt their faces being touched. When they saw sick virtual characters in their virtual reality devices, they pressed the button faster than when they saw virtual characters with fearful or neutral expressions.
This indicates that their brains were prepared for seeing illness. The researchers concluded in their report, “These findings suggest that people generate an integrated neuroimmune response to infectious threats based on visual identification alone, not just after physical contact.”
Psychiatrist and behavioral scientist Michael Irwin from the University of California, Los Angeles, who was not involved in the study but reviewed it, told Science News that this research “uniquely demonstrates that the immune system can be triggered simply by visually identifying someone who appears sick. It is truly fascinating.”
The research findings were published on July 28 in the journal Nature Neuroscience.