Four studies, all emphasizing how the response of the olfactory mucosa relates to the stimulation features with which the odorant molecules access the mucosa, are proposed. 1) We will investigate electrophysiologically in bullfrog whether the chromatographic-like sorption process, which differentially distributes the molecules of different odorants across the mucosa, and the regional sensitivity differences across the muscosa to different odorants interplay to give composite odorant-specific mucosal activity patterns. We will compare the relative contribution of these two mechanisms in generating these mucosal activity patterns, nothing whether it differs among odorants in accordance with how strongly they are sorbed by the mucosa. We will also test the tiger salamander because by having a simpler flow path than the bullfrog it may display different relative contributions for the two mechanisms. This comparison is relevant to vertebrates, including humans, where the complexity of the flow path becomes more exaggerated. 2) We will pursue electrophysiologically our theoretical and experimental indication that the effect of sniff flow rate upon the response can be either positive or negative depending upon an interaction between the flow rate level and how strongly the odorant is sorbed by the mucosa. Since flow rate is a basic feature of the olfactory stimulus, it is important to know whether its effect varies both in magnitude and sign not only from one level to another but also from one odorant to another. 3) Using a new technique, voltage- sensitive dyes, we will scan the odorant-induced responses simultaneously generated at 100 points on the mucosal surface, giving an unprecdentedly fine matrix for analyzing mucosal activity patterns in regards to the stimulus features possibly affecting them. This technique will be tried in two new applications: a) studying, in terms of mucosal activity patterns, the effect of odorant mixtures, and b) testing for mucosal activity patterns in a mammal. 4) We will analyze the olfactory process at the mucosal level in accordance with the engineering principles of fluid mechanics and mass transfer. The mass transfer coefficients required in the development of an overall theoretical model will be provided by experimental measurements in a scaled up constructed model of the olfactory cavity. In showing how different stimulus features affect the mucosal response all these studies point out where and how, at this level, the system may malfunction thereby giving further insight into how the olfactory patient might be tested and otherwise approached.
