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Study: It's not the nose, it's the nostril

By ASSOCIATED PRESS
Published December 18, 2006

NEW YORK - By studying blindfolded college students who crawled through grass to sniff out a chocolate-scented trail, scientists say they've found evidence of a human smelling ability that experts thought was impossible.

The study indicates that the human brain compares information it gets from each nostril to get clues about where a smell is coming from. And it suggests that dogs, mice and other mammals do the same thing, contrary to what most scientists have thought.

People compare signals from each ear to locate the source of a noise. But the prevailing notion has been that mammals can't follow the same strategy for smells, because their nostrils are too close together to get distinct signals.

"We debunked that," said Noam Sobel of the University of California at Berkeley, who reported the new results Sunday with graduate student Jess Porter and others on the Web site of the journal Nature Neuroscience. The work will appear in the journal's January issue.

The report isn't the first to suggest the two-nostril idea. But Sobel and colleagues have now "opened the doors for full consideration of it," said an expert familiar with the work, neuroscientist Charles Wysocki of the Monell Chemical Senses Center in Philadelphia.

One of five experiments used in the study showed that two-thirds of 32 participants could use just their noses to follow a 30-foot-long trail of chocolate-scented twine, which traced a dogleg course through the grass.

Another experiment, with 14 participants, found that the volunteers did better if they used two nostrils than if one nostril was taped shut. They succeeded 66 percent of the time with two nostrils, versus 36 percent with one nostril.

[Last modified December 18, 2006, 00:16:34]