They say their study, published in the April issue of Nature Neuroscience, should raise firm doubts about the validity of "vibration theory," which states that molecules in each substance generate a specific vibration frequency that the nose can interpret as distinct smells.

The reigning theory of smell, which also is as yet unproven, is that the shape of a chemical determines how it smells - much the same way as taste works.

However, at present there is no way to look at a chemical and predict what it will smell like. This is different from other sensory stimuli that are defined by simple physical properties. Color, for example, is defined by the wavelength of light.

While experiments conducted in this study were not designed to confirm the "shape theory," the results support the theory favored by most scientists, that shape of the odor molecule is the most important determinant of its smell.

"We didn't disprove the vibration theory. We just didn't find anything to support it," says assistant professor Leslie B. Vosshall, Ph.D., head of the Laboratory of Neurogenetics and Behavior. "All of our data are consistent with the shape theory, but don't prove the shape theory."

The findings are important in the sometimes contentious field of smell research because it is the first time vibration theory has actually been put to the rigor of a controlled and double-blind human test, the Rockefeller researchers say.

Andreas Keller, Ph.D., a postdoctoral fellow in Vosshall's lab, conducted a series of experiments that the principle proponent of vibration theory, the biophysicist Luca Turin, Ph.D., said would prove that his theory is correct.

Turin himself proposed the experiments in a theoretical paper but never undertook them, Keller says. Since Turin's theory was based s
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Contact: Joseph Bonner
bonnerj@rockefeller.edu
212-327-8998
Rockefeller University
21-Mar-2004