Sense of smell

Main article: Human body

The sense of smell is a very "straightforward" feeling, since we actually inhale the smallest particles of the substance that we smell.

They end up on the olfactory epithelium, a mucous membrane in the nasal cavity that contains millions of olfactory receptors. These receptors interact with particles and transmit signals to the olfactory nerve, which sends them to the brain.

Why humans smell worse than other mammals

There are about 25 thousand genes in the human genome, that is, 25 thousand instructions for creating an active and thinking body.

Of these, 858 describe the process of creation of olfactory neurons - 3.5% of the chromosomal heritage is responsible for their creation. Of these, 468 are pseudogenes, their ancient functions are disabled as a result of a certain mutation that deprived them of the ability to synthesize proteins.

This explains why a person, despite the fact that smell and in his life plays a strategic role, feels smells not as acute as other mammals.

One smell everyone feels differently

We smell different ways. There are no two people in the world who feel smells absolutely the same. Why?

Each of us has aromatic zones of insensitivity in the olfactory apparatus, which includes those odors that we cannot recognize. This set is individual. The same perfume can smell like a rose for one and herbs for the other.

A person can smell their tongue

In June 2019, it became known that unexpected olfactory receptors on the tongue were discovered when studying the cellular structures of mice and humans. Cell activity imaging technology has proven that they respond to odors in exactly the same way as olfactory receptors in the nose.

The discovery raises many questions in relation to the human body - perhaps taste and olfactory receptors contribute to the brain in a completely different way, and not in the way previously thought.

While this phenomenon remains unexplored, work on this topic continues. Perhaps new discoveries will create new flavor enhancers based on odors. For example, they will be able to give food a sweet taste, while it will contain practically no sugar. This will reduce the number of diseases with diabetes mellitus and other problems related to nutrition.

Researches

2023

The first test in Russia to determine the level of smell has been released

Sechenov University has developed the first domestic test to assess smell. The press service of the university announced this at the end of August 2023. Read more here.

Sechenov University presented a simulator for returning smell to patients

In July 2023, Sechenov University presented a simulator for returning smell to patients. The technology relies on the use of neurointerface and trains new neural connections with essential oils. Read more here.

2022: A 3D image of a human olfactory bulb was autosegmented using neural networks

On August 8, 2022, Smart Engines announced that, together with colleagues from Russia, Italy and Germany, for the first time, they automatically segmented a 3D image of a human olfactory bulb using neural networks.

As reported, the human olfactory bulb is a small (about 0.5 cm) area of ​ ​ the brain that has a complex layered structure. Until recently, this and her similar brain microstructures were investigated either in low resolution by MRI, or with the destruction of the sample according to the results of histology. Now the team of scientists and artificial intelligence specialists managed to build a 3D model of the olfactory bulb in high resolution without destroying the sample. To do this, scientists conducted a multi-stage processing of phase contrast X-ray images obtained at a synchrotron source, said the co-author of the study, head of the department computed tomography by Smart Engines, Ph.D., Marina Chukalina. A non-living biological sample was used for the study. Phase contrast images were taken on the German synchrotron DESY PETRA III in Hamburg. The method of tomographic reconstruction created a digital 3D image of the human olfactory bulb in high resolution (4,000 sections). To build a 3D model, Smart Engines specialists together with other project participants created neural network models that provide recognition of individual layers of the olfactory bulb at each of the digital sections.

For the first time in the world, we have trained a neural network that automatically segments the image of the biological structure of the brain of such complexity on such a small scale. told Marina Chukalina

In their publication, the scientists described a single cycle of this study, involving the measurement of X-ray projections of the olfactory bulb, data processing, including tomographic reconstruction, bulb localization, and finally automatic segmentation of individual layers of this structure.

The results of the experiment will be in demand among biologists and doctors who study the causes of functional and morphological disorders of the olfactory bulb in people suffering from neurodegenerative disorders, as well as in people who have lost their sense of smell due to infection. COVID-19 supplemented by Marina Chukalina

Recent studies of the mechanisms of human olfactory bulb degeneration in aging, as well as in Alzheimer's disease and COVID-19 indicate the need to use proper images of the microstructural tissues of this area of ​ ​ the brain.

The results of the study are published in the journal Tomography^[1].