 |
| Study on Brain Activity and Antibody Concentration Photo Credit: Andrea Piacquadio |
People who watch videos of sneezing or sick people show increased activity in brain regions that represent an interface between the brain and the immune system and react to potential dangers. At the same time, the concentration of antibodies in their saliva increases. The findings of a study by researchers from the Department of Biology at the University of Hamburg indicate that an important part of the immune system responds even before a pathogen enters the body. The results were published in the journal Brain Behavior and Immunity.
Throughout human history, communicable diseases, especially viral respiratory infections such as SARS-CoV-2 or influenza, have been among the main factors that significantly influence human mortality. The constant threat of pathogen transmission has led to the development of various physiological mechanisms of the immune system - for example, the body releases proteins to fight pathogens in the body.
To reduce the likelihood of pathogen contact, humans also have a repertoire of behavioral adaptations, the so-called behavioral immune system. It helps to recognize odors or visible signs in the environment as clues to pathogens and triggers avoidance behavior and feelings such as aversion or disgust.
Scientists from the Department of Biology at the University of Hamburg have now gained insights into the interaction of the two immune systems in a study. Sixty-two participants watched short videos showing people with or without contagious signs of illness. Meanwhile, their brain activity was measured using functional magnetic resonance imaging.
In addition, the researchers also investigated initial defense reactions of the immune system. To do this, they measured the release of secretory immunoglobulin A (sIgA) in saliva. SIgA is the most important antibody for fighting pathogens in the respiratory tract and is normally released when pathogens encounter the mucous membranes. However, there is also evidence of a proactive release of sIgA in response to signs of illness, which the two researchers were already able to demonstrate in earlier studies.
"The perception of sneezing and sick people compared to non-contagious people activated the anterior insula, a brain region that is involved, among other things, in interoception, i.e. in the perception of physiological reactions of one's own body, and which represents an important interface between the brain and the immune system. In addition, the test subjects showed an increased release of sIgA analogous to the strength of the insular activity," says Dr. Esther Diekhof, head of the Neuroendocrinology working group at the Department of Biology at the University of Hamburg and author of the study. "This points to a central role of this brain region in controlling the humoral immune response, which prepares the oral mucosa for the expected pathogen contact, e.g. when someone sneezes in the immediate vicinity."
"In contrast, the amygdala - a brain region involved in emotional responses such as fear and anxiety - showed increased activation in all videos showing people. This indicates a non-specific vigilance towards the presence of people," adds Judith Keller, a doctoral student in the Neuroendocrinology working group and also an author of the study.
"Taken together, the study results show a mechanism for processing clues to infection. While the insula coordinates central immune activation, the amygdala could act more as an alarm system for social situations with an increased risk of transmission," says Diekhof. "This immune response could help humans deal with contagion risks by activating countermeasures and preparing the organism for the expected pathogen load."
Published in journal: Brain, Behavior, and Immunity
Title: Visual cues of respiratory contagion: Their impact on neuroimmune activation and mucosal immune responses in humans
Authors: Judith K. Keller, and Esther K. Diekhof
Source/Credit: University of Hamburg
Reference Number: bio020425_01
.jpg)
