ODORANT-SPECIFIC SPATIAL PATTERNS IN MUCOSAL ACTIVITY PREDICT PERCEPTUAL DIFFERENCES AMONG ODORANTS

1. Using operant techniques, rats were trained to differentially repor t (i.e., identify) the odorants propanol, carvone, citral, propyl acet ate, and ethylacetoacetate. After acquisition training, the animals we re tested using a 5 x 5 confusion matrix design. The results of the be havioral tests were used to measure the degree of perceptual dissimila rity between any pair of odorants. These dissimilarity measures were t hen subjected to multidimensional scaling analysis to establish a two- dimensional perceptual odor space for each rat. 2. At the completion o f behavioral testing, the fluorescence changes in the dye di-4-ANEPPS were monitored on the rat's nasal septum and medial surface of the tur binates in response to the same odorants. For each mucosal surface a 6 .0 x 6.0 mm area was sampled at 100 contiguous sites with a 10 x 10 ph otodiode array. 3. Formal statistical analysis indicated a highly sign ificant predictive relationship between the relative position of an od orant's mucosal loci of maximal activity or ''hot spot'' and the relat ive position of the same odorant in a psychophysically determined perc eptual odor space (F = 15.6, P < 0.001). 4. The results of this study suggest for the first time that odorant-induced mucosal activity patte rns serve as the substrate for the perception of odorant quality.