Can You Smell Through Your Mouth?

Yes, Scientists Show in Scent Study

From the WebMD Archives

Aug. 17, 2005 -- When it comes to the sense of smell, the nose may not have the market cornered. People may also sense an odor through their mouths, new research shows.

Scents sensed through the mouth are often labeled as tastes, write Dana Small, PhD, MSc, and colleagues in the journal Neuron.

"For example, we may say that we like the 'taste' of a wine because of its fruity or spicy notes," they write. But "fruity" and "spicy" aren't actually tastes -- which refer to sweet, sour, bitter, or salty. They're odor perceptions sensed through the mouth, according to the scientists.

Eating and drinking yield five taste sensations: sweet, sour, salty, savory, and bitter. Other "tastes" are actually odors sensed through the mouth, they write.

Scent Study

The theory was recently tested on 11 healthy people. They had small tubes inserted into their noses. One tube ended at the nostrils. The other tube ended at the back of the mouth.

The scientists wafted four scents, one by one, through the tubes. The odors were chocolate, lavender, and two smelly chemicals (butanol and farnesol). Meanwhile, the participants' brains were scanned.

Chocolate activated different brain regions, depending on whether the scent was piped into the nose or mouth, the study shows. Why the difference? The researchers suggest a few possibilities.

Brain Alert: Chocolate Nearby!

When sensed through the mouth, chocolate may have registered on the brain as a taste (without the fat, sugar, and calories of edible chocolate). When sniffed through the nose, chocolate may have delivered a different message to the brain.

If those messages used words, the mouth's version might be, "Yum, thanks!" or "More, please!" Instead, the nose may have told the brain, "Hey, wake up; there's chocolate nearby. Let's go find it."

Since people don't walk around with tubes funneling scents into their nose and mouth, the real-world meaning of such studies still need to be checked, writes Jay Gottfried, MD, PhD, in Neuron.

Gottfried didn't work on the study, but he previewed it for the journal. Gottfried works in the neurology department at Northwestern University's medical school in Chicago.

Show Sources

SOURCES: Small, D. Neuron, Aug. 18, 2005; vol 47: pp 593-605. Gottfried, J. Neuron, Aug. 18, 2005; vol 47: pp 473-476. News release, Cell Press.
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