Smelling: Why does strong fragrance make us sick?

Smelling: Why does strong fragrance make us sick?

We’ve added a new piece to our pool knowledge Olfactory system It includes hundreds of different receptors working simultaneously. Until now it was thought that the number of olfactory sensory neurons involved increased with increasing concentration of odor. Now, however, a team of researchers from the University of California, Santa Barbara (USA) has discovered that, above a certain threshold, neurons are silent and stop perceiving smell. “It’s a feature, not a glitch, of the system,” specifies Matthew Lewis, one of the study’s authors Published in Science Advances.

sucks a lot. Let’s think of jasmine: usually used as an aromatic perfume for its delicate floral scent, when we smell the concentrated essential oil, the scent becomes revolting and fermented. This happens because the predominant scent of the plant reaches levels so high that it “turns off” our olfactory neurons, which begin to perceive other notes of the “fragrance”: it so happens that the scent of jasmine also contains skatole, an organic substance that tastes like feces.

“The same scent can have different olfactory structures based on its different concentration,” Lewis explains. “This would explain why some fragrances are considered very distinct at low, medium, and high concentrations.”

Experience. To reach these conclusions, the researchers analyzed the behavior of some caterpillars fruit fliesand modifying them to leave only one olfactory neuron active and to place it at a certain distance from the source of the odor. Even with only one olfactory duct activated, the larvae moved toward the scent, but stopped at one point; By repeating the experiment with a less sensitive neuron, the larvae moved closer to the odor source before stopping.

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To understand more, the scientists then measured the activity of the flies’ sensory neurons, and discovered that the signal sent to the brain increased with increasing concentration (and proximity) of the scent. Instead of remaining constant once a certain threshold was crossed, the activity collapsed to zero: above a certain concentration, the odor was no longer perceived.

clearer picture. After, after pandemic Many studies have been done on the sense of smell, such an important and still largely unknown sense: the results of this experiment add to many others, and help us better understand how this complex system works.

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