A Numerical Model of Nasal Odorant Transport for the Analysis of Human Olfaction

Keyhani, Keyvan; Scherer, Peter; Mozell, Maxwell M.

doi:10.1006/jtbi.1996.0347

Cited by 177 publications

(128 citation statements)

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“…This is low enough for the flow to be laminar, as discussed in [40], and verified for this model by in vitro experiment using an anatomically accurate replica [41]. This volume flux of 12 l/min (6 l/min through each nostril) is equivalent to quiet restful breathing [4,42]. At a flow rate of 115 ml/s , slightly above that chosen, the first evidence of unsteadiness appears for this geometry, as demonstrated by experimental studies, [41], where also the effects of higher flow rates (170 ml/s) on transport are revealed by dye visualisation.…”

Section: Flow Conditions and Methodologymentioning

confidence: 59%

Modelling nasal airflow using a Fourier descriptor representation of geometry

Gambaruto

Taylor

Doorly

2008

Numerical Methods in Fluids

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. SUMMARYProcedures capable of providing both compact representations and rational simplifications of complex anatomical flow conduits are essential to explore how form and function are related in the respiratory, cardiovascular and other physiological flow systems. This work focuses on flow in the human nasal cavity. Methods to derive the cavity wall boundary from medical images are first outlined. Anisotropic smoothing of the boundary surface is shown to provide less geometric distortion in regions of high curvature, such as at the ends of the narrow nasal passages. A reversible decomposition of the surface into a stack of planar contours is then effected using an implicit function formulation. Fourier descriptors provide a continuous representation of each contour as a modal expansion, and permit simplification of the geometry by retaining only dominant modes via filtering.Computations of the steady inspiratory flow field are performed for replica and reduced geometries, where the reduced geometry is derived by retaining only the first fifteen modes in the expansion of each slice contour. The overall pressure drop and integrated wall shear are shown to be virtually unaffected by simplification. More sensitive measures, such as the Lagrangian particle trajectories and residence time distributions show slight changes as discussed.Comparison of the Fourier descriptor method applied to three different patient data sets indicate the potential of the technique as a means to characterise complex flow conduit geometry, and the scope for further work is outlined.

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Section: Flow Conditions and Methodologymentioning

confidence: 59%

Modelling nasal airflow using a Fourier descriptor representation of geometry

Gambaruto

Taylor

Doorly

2008

Numerical Methods in Fluids

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“…Though the velocity of air moving through the nasal passages is in fact time-varying, we assumed steady-state flow to match most previous work on the subject (e.g. [4][5][6][7][8][9][10]) and because good agreement exists between patterns of flow between steady and unsteady regimes [33].…”

Section: Methodsmentioning

confidence: 99%

“…dogs [3,5]; rats [6][7][8]), and those with a small olfactory region and poorly developed sense of smell on the other (e.g. humans [9,10]). To date, no study has attempted to use a group of closely related species to more precisely link differences in their apparent reliance on olfaction with differences in airway morphology and patterns of airflow.…”

Section: Introductionmentioning

confidence: 99%

How much does nasal cavity morphology matter? Patterns and rates of olfactory airflow in phyllostomid bats

2015

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The morphology of the nasal cavity in mammals with a good sense of smell includes features that are thought to improve olfactory airflow, such as a dorsal conduit that delivers odours quickly to the olfactory mucosa, an enlarged olfactory recess at the back of the airway, and a clear separation of the olfactory and respiratory regions of the nose. The link between these features and having a good sense of smell has been established by functional examinations of a handful of distantly related mammalian species. In this paper, we provide the first detailed examination of olfactory airflow in a group of closely related species that nevertheless vary in their sense of smell. We study six species of phyllostomid bats that have different airway morphologies and foraging ecologies, which have been linked to differences in olfactory ability or reliance. We hypothesize that differences in morphology correlate with differences in the patterns and rates of airflow, which in turn are consistent with dietary differences. To compare species, we make qualitative and quantitative comparisons of the patterns and rates of airflow through the olfactory region during both inhalation and exhalation across the six species. Contrary to our expectations, we find no clear differences among species in either the patterns of airflow through the airway or in rates of flow through the olfactory region. By and large, olfactory airflow seems to be conserved across species, suggesting that morphological differences appear to be driven by other mechanical demands on the snout, such as breathing and feeding. Olfactory ability may depend on other aspects of the system, such as the neurobiological processing of odours that work within the existing morphology imposed by other functional demands on the nasal cavity.

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“…Mozell and colleagues (Mozell, 1964(Mozell, , 1970Mozell and Jagodowicz, 1973;Hornung and Mozell, 1977;Mozell et al, 1987;Hahn et al, 1994;Kent et al, 1996;Keyhani et al, 1997) have demonstrated that smaller and more hydrophilic odorants are absorbed rapidly by the aqueous mucosa upon entry into the nasal epithelium, and therefore are likely to have limited access only to the dorsal central channels towards the entrance of the nasal cavity (Schoenfeld and Knott, 2004). On the other hand, larger and more hydrophobic odorants, including octane, were found to be able to disperse more freely throughout the olfactory epithelium than the hydrophilic ones.…”

Section: Glomerular Response Patterns May Emerge From a Combination Omentioning

confidence: 99%

Long hydrocarbon chains serve as unique molecular features recognized by ventral glomeruli of the rat olfactory bulb

Johnson

Leon

2006

J of Comparative Neurology

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In an effort to understand mammalian olfactory processing, we have been describing the responses to systematically different odorants in the glomerular layer of the main olfactory bulb of rats. To understand the processing of pure hydrocarbon structures in this system, we used the [ 14 C]2-deoxyglucose method to determine glomerular responses to a homologous series of alkanes (from six to sixteen carbons) that are straight-chained hydrocarbons without functional groups. We found two rostral regions of activity evoked by these odorants, one lateral and one medial, that were observed to shift ventrally with increasing alkane carbon chain length. Furthermore, we successfully predicted that the longest alkanes with carbon chain length greater than our previous odorant selections would stimulate extremely ventral glomerular regions where no activation had been observed with the hundreds of odorants that we had previously studied. Overlaps in response profiles were observed in the patterns evoked by alkanes and by other aliphatic odorants of corresponding carbon chain length despite possessing different oxygen-containing functional groups, which demonstrated that hydrocarbon chains could serve as molecular features in the combinatorial coding of odorant information. We found a close and predictable relationship among the molecular properties of odorants, their induced neural activity, and their perceptual similarities. Keywordsalkanes; chemotopic organization; combinatorial coding; odor similarity; glomeruli; deoxyglucose; habituation Studies by a number of laboratories using odorants that differ systematically in molecular structures continue to support a combinatorial model of olfactory processing initially proposed by Polak (1973), in which molecular features of an odorant are recognized and encoded by the system (Kauer and Cinelli, 1993; Korsching, 1997, 1998;Joerges et al., 1997;Johnson et al., 1998Johnson et al., , 1999Johnson et al., , 2002Johnson et al., , 2004Johnson et al., , 2005aMalnic et al., 1999;Rubin and Katz, 1999;Sachse et al., 1999; Johnson and Leon, 2000a, b;Uchida et al., 2000;Belluscio and Katz, 2001;Fuss and Korsching, 2001;Meister and Bonhoeffer, 2001;Igarashi and Mori, 2005). According to this model, odorants that share a molecular feature should be recognized by the same type of olfactory receptors to produce overlapping neural activity. To test this prediction, and to understand how the olfactory system responds to various molecular features, our laboratory has been studying responses to hundreds of odorants in the glomerular layer of the rat main olfactory bulb (Johnson et al., 1998(Johnson et al., , 1999(Johnson et al., , 2002(Johnson et al., , 2004(Johnson et al., , 2005a Johnson and Leon, 2000a, b;Linster et al., 2001a). In an effort to understand the processing of pure hydrocarbon structures in this system, we determined in this study the response to a series of alkanes, which are straight-chained hydrocarbons without functional groups.Corresponding author: Sabrina L. Ho, Unive...

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A Numerical Model of Nasal Odorant Transport for the Analysis of Human Olfaction

Cited by 177 publications

References 0 publications

Modelling nasal airflow using a Fourier descriptor representation of geometry

Modelling nasal airflow using a Fourier descriptor representation of geometry

How much does nasal cavity morphology matter? Patterns and rates of olfactory airflow in phyllostomid bats

Long hydrocarbon chains serve as unique molecular features recognized by ventral glomeruli of the rat olfactory bulb

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