Olfactory competition: two nostrils alternately handle two different smells

When the nose simultaneously encounters two different smells, the brain alternately processes them through each nostril.

The discovery made by researchers at Rice University in Houston is the first example of competition in the olfactory organ system. Details are published in the current Online Biology on August 20.

'Our findings open new perspectives in the discovery of the mechanism of action of the olfactory organ system and the sense of smell activity,' Denise Chen, research psychiatrist, co-author of the study. save, speak.

For the study, 12 volunteers tested the odors from two vials containing two different scents. A jar containing phenyl ethyl alcohol resemble rose scent, the other contains n-butanol that smells like a marker pen. Both vials have a mouth that fits snugly into the microscope's rotating nose size, making sure that volunteers can experience two smells simultaneously - each smells through one nostril.

Through 20 rounds of experimentation, all 12 volunteers said they felt alternating two smells - when it mainly smelled of roses, when they mainly smelled the line marker. Some people feel the smell transformation is more frequent and clearer, but among all volunteers, no one describes a specific smell-sensing model.

Chen said competition between the nostrils is like competition in other sensory organs.When the eyes simultaneously look at two different images, these two images will be observed alternately by the eyes, one eye at a time.

When the nose simultaneously encounters two different smells, the brain alternately processes them through each nostril. (Photo: iStockphoto)

In the laboratory, at the same time each nostril receives a different smell, but in fact volunteers are going through a "sense of deception", she said. 'Instead of recognizing a continuous mixture of both smells, they only noticed one of the two smells, the odor followed the other, alternately, as if the nostrils were competing with each other. Despite the fact that both smells are present at the same time, our brains only focus on one odor at a time. '

'Competition between the two sides of the nose is related to the adaptation of peripheral neurons and cortical neurons,' Chen said. 'Our work is the starting point for future follow-up studies on this phenomenon, from which we can learn more about the mechanisms of human odor recognition.'

In the competition between two nostrils, the overwhelming or concession of a specific smell exists only in the mind of the smoker, and the actual physical nature of the olfactory agent does not change, Chen insists. This makes people rarely separate the sense of smell from real physical stimulation.Therefore, competition between two nostrils can be the only door to understanding consciousness and awareness in both healthy and ill people.

Human smell is a very early field of research. Chen argues that understanding human mechanisms for processing olfactory information is not only important for basic science, but also in the long run to assess and treat olfactory disorders in patients. and the elderly.