Scott Spicer Festival of Science 2001 Poster Presentation

Scott Spicer

Advisor: Dr. David Hornung

SLU Festival of Science 2001 Poster Presentation

THE IMPACT OF MUCOSAL SOLUBILITY ON CHANGES IN ODORANT PERCEPTUAL INTENSITY

Scott M Spicer^1,2, David E. Hornung^1,2, Daniel B. Kurtz², Jason W. Newlon²

1.St. Lawrence University, Canton, NY,2.Upstate Medical University, Syracuse, NY

Using psychophysical and gas chromatographic techniques, this study examined the impact that mucosal solubility has on changes in odorant perceptual intensity.Psychophysics:15 normosmic subjects (UPSIT score greater than 35) rated the perceptual intensity of 9 odorants (propionic acid, butyric acid, isopropanol, hexanol, trans-cinnamaldehyde, heptanoic acid, octanol, hexanoic acid, pentanol) at 2 concentrations in 3 randomized test blocks using the Green Scale(Chemical Senses 18:683-702, 1993). Normosmic, nondilated controls rated the lower concentration of each odorant at a perceptual intensity of 20 and the higher concentration at an intensity of 40. There were two conditions, with and without a nasal dilator, with the order counterbalanced. As expected, when wearing a nasal dilator, subjects rated all the odorants as being more intense, however not all odorants showed the same increase in perceptual intensity. The odorants were ranked based on the relative increases in perceptual intensity.

Gas chromatography: to determine the relative mucosal solubility of the 9 odorants, 4 normosmic subjects, while performing velopharyngeal closure, had a continuous stream of odorant injected in one nostril.Molecules exiting the nasal passageways were collected from the contralateral nostril and the airstream sent to a photoionization detector.At equilibrium, the ratio of the number of molecules exiting the nose to the total number of molecules injected served as a means of ranking the relative mucosal solubilities of the 9 odorants.

The ranking of intensity increases and odorant mucosal solubilities were highly correlated.That is, the three odorants that showed the least enhancement in intensity were also the three odorants that had the lowest ratio of molecules sorbed by the mucosa.There was a similar correlation between the odorants which showed the greatest enhancement in intensity and had the highest ratios.Although the perceptual intensity of an odorant is due to many factors, these data support the hypothesis that mucosal solubility, in part, determines how perceptual intensity will change as nasal anatomy changes.