One-tenth of a second is the time it takes to distinguish one odor over another, according to recent research conducted on mice.
"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 study investigator and neurobiologist Dmitry Rinberg, Ph.D.
In a study published in the journal of Nature Communications, researchers at the NYU School of Medicine have found that mice only need odorants to reach a few signaling proteins to detect and distinguish a smell. Additionally, the researchers found that an animals’ ability to tell odors apart was the same no matter how strong the scent was.
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To test how quickly mammals smell, mice were trained to lick a straw to receive water if they smelt an odorant. Light-activated fibers were attached to each mouse’s nose, which allowed the researchers to trigger brain receptors or groups of receptors involved with olfaction. The mice were then challenged with different concentration of smells, while researchers controlled the receptors that were activated.
At the conclusion of the test, the team found that early interruptions in sensing smell (less than 50 milliseconds) reduced odor identification scores to near chance. However, reward scores greatly improved when the mouse’s sense of smell was interrupted at any point after 50 milliseconds but fell off after 100 milliseconds. Previous research had estimated that animals take as long as 600 milliseconds for all olfactory brain receptors to become fully activated.
"Our study lays the groundwork for a new theory about how mammals, including humans, smell: one that is more streamlined than previously thought," said Rinberg.
