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Sense of Smell Can Be Schooled; Experience in 1 Scent Teaches Brain About Similar Ones

WebMD Health News

Reviewed ByLouiseChang,MD
on Thursday, December 28, 2006

Dec. 29, 2006 -- How well you can smell isn't a given, Northwestern University researchers find.

The sense of smell may depend on the precise shape of a scent molecule triggering a reaction in the brain. But that's not all there is to it.

Researchers already have proven Shakespeare wrong: A rose by any other name does not smell as sweet. A person smelling a fresh cucumber will have a very different experience when told she's smelling mildew.

Now researchers in the lab of neurologist Jay Gottfried, MD, find that after smelling a floral scent for a few minutes, a person gains new ability to sense different floral scents.

"When you have prolonged sensory experience with one smell, you become an expert for smells that are part of that original category," Gottfried says in a news release.

In their study, Gottfried and colleagues misled volunteers into thinking they were rating the intensity of smells. The scientists then had them continuously smell one scent for three and a half minutes.

Sense of Smell Sharpened

Those who had experience with a floral smell became able to differentiate between a variety of different floral smells.

Those who experienced minty, alcohol-based, or ketone-based smells became experts in those categories.

Using functional magnetic resonance imaging (fMRI), the researchers found that this passive learning changed the way the scent centers of the brain responded to smells.

The conclusion: "Information about an odor is not static or fixed within these [brain] regions, but is highly malleable and can be rapidly updated" by smelling experience, says study researcher Wen Li, in the news release.

Li, Gottfried, and colleagues say learning to distinguish the smell of Bulgarian Rose from Rose Maroc would allow us to "appreciate the immense richness of aromas in everyday life."

How rich? Humans, the researchers note, "are able to recognize thousands, if not hundreds of thousands, of different smells."

Their study appears in the Dec. 21 issue of Neuron.

SOURCES: Li, W. Neuron, Dec. 21, 2006; vol 52: pp 1097-1108. News release, Northwestern University.

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