Maxwell M. Mozell - US grants

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.

The purpose of the SUNY Upstate Clinical Smell Research Center is to quantitatively assess a number of clinical conditions possibly underlying olfactory dysfunctions. There is one basis for olfactory perception about which there can be no doubt. That is, if odorant molecules cannot reach the olfactory receptors, there can be no olfactory perception, and the degree to which the airflow towards the olfactory mucosa is compromised, olfactory perception is likely also to be compromised. Similarly, if alteration in airflow reduces the number of odorant molecules which would normally reach the chemoreceptors of the nasal mucosa, the trigeminal component of olfactory experience would be compromised as well. The overall result would be a marked reduction of smell-related information being transmitted centrally via the principle chemoreceptive pathways which originate in the nose. Thus, all of the projects in this proposal investigate olfaction in regards to the availability of the stimulus to the various chemoreceptive inputs in the nose. Central to normal airflow through the nose is the sniff itself. We will quantitatively investigate the effect that different olfactory tasks have on sniffing strategies and the effect that these strategies have on olfactory ability. The olfactory ability of patients with altered nasal airflow including laryngectomized patients will be assessed, and using an anatomically correct model of the nose we will describe the relationship between nasal anatomy and the pattern of nasal airflow. Intubated infants represent and interesting group in which early odorant deprivation may show olfactory deficits later in life. These research efforts require a precise definition of olfactory dysfunction and to this end we have developed a psychophysical approach previously not used in olfaction. Our specific objectives are to: 1): Further refine and analyze the current clinical description of olfactory patients; 2) Continue to describe sniffing behavior and examine how odorant molecules are normally distributed to the receptors; 3) Describe olfactory maturation during childhood and identify children at risk for olfactory deficits; 4) Anatomically document which nasal airway deformaties and obstructions effect olfactory ability; 5) Pursue the possibility that lack of nasal airflow contributes differentially to the hyposmia of laryngectomy depending on the odorant and neural input; 6) Describe the relationship between nasal anatomy and the pattern of airflow through the nose; 7) Determine the physiological and anatomical characteristics of the trigeminal contribution to olfactory experiences using electrophysiological methods.

The purpose of the SUNY Upstate Clinical Smell Research Center is to quantitatively assess a number of clinical conditions possibly underlying olfactory dysfunctions. There is one basis for olfactory perception about which there can be no doubt. That is, if odorant molecules cannot reach the olfactory receptors, there can be no olfactory perception, and the degree to which the airflow towards the olfactory mucosa is compromised, olfactory perception is likely also to be compromised. Similarly, if alteration in airflow reduces the number of odorant molecules which would normally reach the chemoreceptors of the nasal mucosa, the trigeminal component of olfactory experience would be compromised as well. The overall result would be a marked reduction of smell-related information being transmitted centrally via the principle chemoreceptive pathways which originate in the nose. Thus, all of the projects in this proposal investigate olfaction in regards to the availability of the stimulus to the various chemoreceptive inputs in the nose. Central to normal airflow through the nose is the sniff itself. We will quantitatively investigate the effect that different olfactory tasks have on sniffing strategies and the effect that these strategies have on olfactory ability. The olfactory ability of patients with altered nasal airflow including laryngectomized patients will be assessed, and using an anatomically correct model of the nose we will describe the relationship between nasal anatomy and the pattern of nasal airflow. Intubated infants represent and interesting group in which early odorant deprivation may show olfactory deficits later in life. These research efforts require a precise definition of olfactory dysfunction and to this end we have developed a psychophysical approach previously not used in olfaction. Our specific objectives are to: 1): Further refine and analyze the current clinical description of olfactory patients; 2) Continue to describe sniffing behavior and examine how odorant molecules are normally distributed to the receptors; 3) Describe olfactory maturation during childhood and identify children at risk for olfactory deficits; 4) Anatomically document which nasal airway deformaties and obstructions effect olfactory ability; 5) Pursue the possibility that lack of nasal airflow contributes differentially to the hyposmia of laryngectomy depending on the odorant and neural input; 6) Describe the relationship between nasal anatomy and the pattern of airflow through the nose; 7) Determine the physiological and anatomical characteristics of the trigeminal contribution to olfactory experiences using electrophysiological methods.

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.