A Nature Neuroscience study found that observing signs of illness—like coughing or rashes—prompts the brain to anticipate infection risk and trigger immune defenses.
In an interview with Nature, he explained: “The findings highlight the brain’s ability to anticipate events and choose the right response to address them.”
To safely mimic an infectious threat, the team used Oculus Rift virtual reality headsets.
Virtual Avatars Simulating Illness Symptoms
Participants encountered virtual human avatars displaying flu-like symptoms—such as coughing or visible rashes—that entered their field of vision without making physical contact.
Meanwhile, a control group only received an actual flu vaccine, without exposure to avatars.
Researchers tracked participants’ brain and immune activity through electroencephalograms (EEG), functional MRI scans (fMRI), and blood analyses.
When sick avatars came near, brain regions tied to the “peripersonal space”—the area immediately surrounding the body—became active. This system acts as an early-warning mechanism for nearby threats.
Activation of the Salience Network and Stress Response Pathways
The response also engaged the salience network, which detects critical stimuli like danger. The hypothalamus then received signals and activated the hypothalamic-pituitary-adrenal (HPA) axis, which regulates stress and immune-related hormones.
Ultimately, this cascade boosted levels of innate lymphoid cells (ILCs), fast-acting immune cells that serve as the body’s frontline defense.
Volunteers who interacted with sick virtual avatars showed stronger activation of these immune cells compared to those who only received the vaccine.
Notably, the immune response occurred only when infection-related cues were present. Avatars displaying fear but lacking illness symptoms did not trigger the same brain or immune activity.
The researchers highlight that this “early brain alert” reveals a key, previously underexplored, connection between the central nervous system and the immune system—even without direct pathogen exposure.
Neural Anticipation Triggers Immune Responses Similar to Real Infections
“We demonstrate that potential contact with infectious avatars in the peripersonal space, within virtual reality, is anticipated by sensorimotor regions and activates the salience network. This forward-looking neural response alters the activity and frequency of innate lymphoid cells, closely resembling reactions to real infections,” they explained.
The study also supports the idea of a “behavioral immune system”—an evolutionary drive to avoid sick individuals to lower infection risk—something made especially evident during the COVID-19 pandemic.
However, the authors note that the research is preliminary and has limitations. Immune effects were tested with only one vaccine (FluarixTetra 2018–2019), and participants were healthy young adults (average age 26), restricting the findings’ generalizability across different age groups.
It remains unclear whether still images of sick people would provoke the same response as moving avatars. Emotional influences, such as disgust, may also play a role in shaping brain activity and warrant further study.
The researchers stress that the brain’s ability to detect infection cues—even in simulations—functions as a highly adaptive “early warning system,” much like a smoke detector: it is preferable to raise a false alarm than to miss a genuine threat.
Read the original article on: Cnn Brasil
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