AFPpublished on Thursday 18 June 2020 at 23h06
In the United States, scientists have established for the first time an electronic signature that can be identified as an odor by the brain of mice, although it is totally synthetic.
The purpose of the study published in the journal Science on Thursday, is to analyze the way in which mammals perceive and distinguish the different smells.
Edmund Chong, a doctoral student at the school of medicine Grossman to NYU, who conducted these experiments, explained that there were a lot of things that scientists do not understand yet about the smell, and on its main features.
To explore this question, the researchers set up experiments with genetically modified mice so that their neurons could be activated by a light projected through an optical fiber, a technique called “optogenetics”.
The experiments focused on the olfactory bulb, a structure located behind the nose in animals and in man.
The molecules related to odor-activated receptor neurons in the nose, which pass the information in the form of electrical signal to the bundles of nerve fibers in the bulb, called glomerulus. The signals are finally sent to the neurons in the brain.
The team trained mice to recognize the signal of a synthetic smell that is created by using light to activate six nerve bundles in a particular order. The mice were rewarded with water when they were pushing a lever after having recognized “the smell”.
If they were pushing this lever to the activation of a combination of nerve bundles, they were not receiving water.
– The melody of smells –
With this experience, the scientists were able to change subtly the timing and combination of nerve fascicles activated to determine which ones were most important, that is to say, what aspect of a smell defines it in particular and differentiates it from a other fragrance.
The researchers have in particular realized that by changing the sequence of beams activated at the beginning of the sequence of a smell, this would reduce by 30% the recognition of the emanation.
Make changes later in the sequence, had a considerably smaller impact on the degree of identification of the smell.
Activating nerve was functioning as “the notes of a melody”, reported the scientists. As for recognize a song, the changes at the beginning of the sequence have a most significant impact on the identification of a smell, a change in the end of the sequence.
“Our results determine for the first time a code of how the brain transforms sensory information into a perception, in this case, smell”, notes one of the authors of the study, Dmitry Rinberg.
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