Mammals can identify smells in a fraction of a second

Researchers from NYU School of Medicine have discovered that mammals can identify scents much faster than previously realized. In less than one-tenth of a second, a mammal can distinguish between one odor and another, according to the new study.

By conducting tests on mice, researchers found that chemical particles which trigger the sense of smell known as odorants only need to reach a few signaling proteins on the inside lining of the nose for a familiar scent to be identified. The scientists also found that the mice could distinguish between odors regardless of how concentrated the scents were.

“Much like human brains only need a few musical notes to name a particular song once a memory of it is formed, our findings demonstrate that a mouse’s sense of smell needs only a few nerve signals to determine the kind of scent,” said senior researcher Dmitry Rinberg.

As soon as an odorant docks into its olfactory receptor protein on a nerve cell in the nose, the cell signals a region of the brain that assigns odor and the smell is identified, explained Rinberg.

The most important of the research team’s findings was that mice recognize a scent right after activation of the first few olfactory brain receptors, usually within the first 100 milliseconds of inhaling an odorant.

This was significant because earlier studies in animals had found that it takes as long as 600 milliseconds for the majority of olfactory brain receptors involved in smell to become fully activated. Previous experiments in mice showed that their smell receptors peaked after approximately 300 milliseconds because they have a faster sense of smell.

In addition, researchers had not described the role of concentration in the odor identification process prior to the current analysis. Earlier investigations had shown that more receptors were activated by highly concentrated scents, but Rinberg’s study revealed that mice could quickly differentiate between scents regardless of concentration.

Rinberg’s team plans to develop more animal experiments to link brain cell activity to smell identification. They will also examine how their findings can be applied to people.

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer