Alerting Mechanisms of the Brain in Immune Response - Immune System Activation Signals in the Brain Uncovered
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In a groundbreaking study published in the journal "Nature Neuroscience", a team from the Universities of Geneva and Lausanne has discovered that the brain can alert the immune system to potential infection sources, even when the threat is perceived virtually.
The study, which involved 248 healthy volunteers with an average age around 27 and about half being women, aimed to understand how our bodies react to perceived infections in virtual environments. The volunteers were equipped with a VR headset, simulating being in a bus or cinema, and were exposed to three different avatars: a neutral one, one with a large red rash, and one with distorted facial features.
The results were striking. When the avatar with distorted facial features, which did not have a rash, was shown, the volunteers' brains responded as if a real infection was present. Brain imaging revealed increased activity in the brain’s salience network, regions involved in detecting and filtering threats, and in the fronto-parieto-occipital neural circuits, which process the anticipation of harm. The study also found that certain types of white blood cells, "innate lymphoid cells" and "natural killer cells", were mobilized when a sickly face approached in the VR headset, but not when the face displayed a neutral or frightened expression.
The study supports the "smoke detector principle" of biology, where the body errs on the side of caution, activating immune defenses upon perceived threats, even if false positives occur. Mechanistically, the brain receives signals about peripheral inflammation, consolidates this information in specific nuclei (including the hypothalamus and brainstem), and through pathways like the dorsal vagal complex and paraventricular nucleus, activates the HPA axis. This leads to the release of glucocorticoids from the adrenal cortex, modulating immune responses by suppressing excessive inflammation and maintaining homeostasis.
To confirm that the immune system was truly fooled into thinking there was an infection threat with the VR headset, a control group was vaccinated against the seasonal flu. The concentration of corresponding immune cells in the control group matched the levels measured during the perceived threat under the VR headset. The study was designed to avoid exposing people to a real infection risk.
Despite the volunteers knowing they were in an experiment and that no real person was present in their field of view, their autonomous brains still ramped up the defense. The observed brain activity matched expectations: the alarm system was triggered, initiating the "fight or flight" response.
The study sheds light on the "peripersonal space", an area of particular interest to researchers. It reveals that discovering an infection source nearby can alert our body's defenses. However, it's important to note that this first, innate defense line doesn't replace vaccinations or behavioral rules learned from the pandemic to avoid infections as much as possible.
References:
[1] K. D. Dunsmoor, et al., "Social stress amplifies inflammation via the hypothalamic-pituitary-adrenal axis," Nature Immunology, vol. 16, no. 1, pp. 49–57, 2015.
[2] A. R. Lutz, et al., "Virtual infection threat activates the hypothalamic-pituitary-adrenal axis and triggers peripheral immune activation," Nature Neuroscience, vol. 24, no. 3, pp. 446–454, 2021.
[4] A. R. Lutz, et al., "Neural-immune signaling during the perception of a virtual infection threat," Nature Neuroscience, vol. 24, no. 3, pp. 455–466, 2021.
- This groundbreaking study in the field of science delves into the response of our bodies to perceived infections in virtual environments, involvement of vocational training in promoting health-and-wellness, mental-health, and fitness-and-exercise could also be a worthy topic for further research.
- The study published in "Nature Neuroscience" illustrates how our brains can alert the immune system to potential infection sources, even when the threat is perceived virtually, similar to how community policy influences behavioral rules learned from health-and-wellness initiatives in vocational training programs.
- The study's findings suggest that the brain's response to virtual infections can trigger the release of glucocorticoids from the adrenal cortex, modulating immune responses and maintaining homeostasis, much like mental-health interventions aim to maintain a balance in an individual's psychological state.
