1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

221 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalMEASURES OF CONFUSION AND SIMILARITY BETWEENBITTER TASTE AND BURNING SENSATIONLim J. 1 , Green B. 1 1 The John B. Pierce Laboratory, New Haven, CTAlthough it has long been studied as a pure irritant, capsaicin can alsoevoke and desensitize bitter taste. This suggests that bitter taste andburning sensation might be closely related perceptually. The currentstudy investigated the psychophysical relationship between bitternessand burning using two different approaches. In Exp. 1, spatialdiscrimination of four basic tastes was measured in the presence orabsence of capsaicin. Subjects reported which of three swabs spaced 1cm apart and presented to the tongue tip contained a taste stimulus when(1) water was presented on the other two swabs, or (2) when 10 µMcapsaicin was presented on all three swabs. The presence of capsaicindid not change performance on the 3-AFC task for sweet, sour and saltystimuli, while the localization error for 1.8-mM QSO 4 significantlyincreased (p = 0.03). In Exp. 2, the overall similarity/dissimilarity oftaste stimuli and capsaicin was measured directly. All combinations offour taste stimuli and capsaicin were applied in pairs to opposite sidesof the tongue tip on swabs separated by 2 cm. Multidimensional scalinganalyses applied to the similarity ratings showed that capsaicin fellnearer to QSO 4 than to any other taste stimuli. Cluster analysiscorroborated this finding: capsaicin was closely linked with QSO 4 , andthe capsaicin-QSO 4 group was separated from the other taste stimuli.The results also indicated that bitterness was more similar to burningthan to the other basic taste qualities. These findings imply thatbitterness and burn may be functionally related as sensory signals ofpotentially dangerous stimuli. Supported in part by NIH grantDC005002.222 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalGUSTATORY–OLFACTORY MIXTURES: A CONFUSIONMATRIX STUDYMunoz D.M. 1 , Frank M.E. 1 , Gent J.F. 2 , Hettinger T.P. 1 1 Oral Health &Diagnostic Sciences, UCONN Health Center, Farmington, CT;2 Epidemiology & Public Health, Yale University, New Haven, CTGustation may dominate olfaction in taste-odor mixtures (Laing etal., 2002). We measured identification of odors and tastes in binarymixtures after water or chlorhexidine rinses with a 10-stimuluschemosensory confusion matrix (CCM): 100 mM NaCl, 300 mMsucrose, 100 µM phenethyl alcohol, 30 µM vanillin, 4 taste-odormixtures, 1 odor-odor mixture and water. The odorant concentrationsused did not linger and were reliably identified retronasally. Stimuliwere presented to 10 subjects twice in separate sessions with differenttreatment rinses: 1.34 mM chlorhexidine, an oral antiseptic that reducessalty taste intensity (Frank et al., 2001), or deionized water, in a crossover design. Percent correct identification and two measures derivedfrom information theory: T10 and T2 (Hettinger et al., 1999), werecalculated and analyzed with ANOVA and post hoc t-tests. In taste-odormixtures, tastants were identified more frequently (92% correct) thanodorants (60% correct) [t(7) = 5.2, p = 0.001]. Response consistency(T10) was lower after chlorhexidine (1.96 ± 0.12 bits) than after water(2.36 ± 0.16 bits) [t(9) = 4.92, p = 0.0008] and chlorhexidine rinsedecreased discriminability (T2) of NaCl solutions [F(23,207) = 5.1, p =