Always on alert: The immune system even reacts to virtual threats

The human immune system is so alert that it reacts to the mere sight of a potential source of infection—even if this potential source of infection is only presented to human subjects in virtual reality. Scientists from the Universities of Lausanne and Geneva report this after an experiment published in the journal Nature Neuroscience .

The team, led by lead authors Camilla Jandus and Andrea Serino, showed nearly 250 participants moving avatars with human-like faces via a camera headset. Some of these digital people showed signs of infection, such as a rash or cough. While the participants viewed the avatars, the team examined their brain activity using methods including EEG and magnetic resonance imaging (fMRI). The researchers also analyzed the participants' blood samples.

The data from the brain scans showed that, on average, the participants reacted more sensitively to touch when the sick-looking avatars came very close to them in virtual reality. The team interprets the observation as indicating a state of alert in the organism. The participants' brains became particularly active in the regions involved in integrating sensory information and spatial perception when infectious avatars approached. However, when they encountered avatars with neutral or fearful faces in virtual reality, this brain activity did not occur.

The participants' blood samples also showed increased activity of some immune cells after virtual contact with infectious-looking avatars. This immune system reaction is similar to the response to a real infection or vaccination, according to a press release accompanying the article. The authors argue that the brain can orchestrate an early physiological response to a potential infection to prepare the immune system.

The group writes that the brain itself can trigger the body's early response to a potential infection. This happens even before pathogens enter the body. The result demonstrates how sensitive the immune system is to even signs of infectious diseases. However, the team also emphasizes that there have been no previous studies examining immune responses to virtual stimuli, so their study is of an "exploratory" nature. Nevertheless, the team emphasizes the central importance of a mechanism that helps identify potentially threatening encounters early on and, if necessary, protect oneself.