Peripheral adaptive filtering in human olfaction? Three studies on prevalence and effects of olfactory training in specific anosmia in more than 1600 participants

Croy, Ilona; Olgun, Selda; Mueller, L.; Schmidt, Anna; Muench, M.; Hummel, Cornélia; Gisselmann, Guenter; Hatt, Hanns; Hummel, Thomas

doi:10.1016/j.cortex.2015.08.018

Cited by 57 publications

(71 citation statements)

References 21 publications

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“…Using a mixture of odorants as stimuli in olfactory threshold testing seems to be favorable for the participants but foremost appears to increase test–retest reliability of the tool. This finding supports the notion that the individual expression of olfactory receptors across the population has a significant impact on olfactory experience and smell abilities (Croy et al, ; Gilbert & Kemp, ; Keller et al, ). Using molecularly varied stimuli makes olfactory threshold assessments relatively independent from an individual variability in sensitivity to specific odorants (Hsieh, Keller, Wong, Jiang, & Vosshall, ; Oleszkiewicz, Pellegrino, Pusch, Margot, & Hummel, ).…”

Section: Discussionsupporting

confidence: 85%

Molecularly diverse odors advance olfactory threshold testing

Oleszkiewicz

Würfel

Han

et al. 2018

Journal of Sensory Studies

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Multiple‐compound mixtures of odorants are likely to produce significantly more reliable and favorable results of olfactory sensitivity testing. Within the current study, we aimed to investigate this hypothesis and determine the optimal number of odor compounds within a testing stimulus. One‐hundred individuals volunteered to participate in the study procedure wherein their olfactory threshold was measured with stimuli varying in the number of compounds during two sessions. We found that molecularly varied stimuli made olfactory threshold assessments relatively independent from an individual variability in sensitivity to specific odorants. Nevertheless, this was only true in certain conditions—depending on the number of components and quality of the odorants. On this basis, we outline future directions for studies aimed to advance assessments of the olfactory threshold by discussing the relationships between the chemical and physical properties of odorants and results of the threshold assessment they produce. Practical applications This study provides empirical evidence that olfactory threshold testing becomes more favorable and reliable when an odor stimulus contains ~10 types of molecules. This is assumed due to an efficient activation of olfactory receptors. These findings advance the current state of knowledge in the field of biology by presenting behavioral responses to the augmented potential for binding molecules through olfactory receptors. Results presented in this manuscript constitute a significant improvement in the methods of olfactory function assessments and should be of interest to both scientific and clinical audience in the fields of neuroscience, chemosensory research, chemistry, and biology. These results are likely to translate to a more accurate assessment of olfactory abilities in commercial settings, that is, perfumes, or wine experts.

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Section: Discussionsupporting

confidence: 85%

Molecularly diverse odors advance olfactory threshold testing

Oleszkiewicz

Würfel

Han

et al. 2018

Journal of Sensory Studies

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“…The first objective of this work was to eliminate the problems inherent in olfactory sensitivity tests that rely on a single molecule. Although it is well known that specific insensitivity to individual odorant molecules is common in normal human subjects (28), commercial threshold tests use monomolecular stimuli such as butanol or phenylethyl alcohol to test olfactory sensitivity (23,29). Our data suggest that this approach confounds specific and general olfactory sensitivity.…”

Section: Discussionmentioning

confidence: 83%

“…Six self-identified as Hispanic. In the Taiwanese group, the mean age was 26 (range: [19][20][21][22][23][24][25][26][27][28][29][30]) and 26 of 36 subjects were female. Although we recruited subjects with a selfreported normal sense of smell, two of the North American subjects had UPSIT and SMELL-R (v2) scores below the cut-off for olfactory dysfunction (Fig.…”

Section: Experiments 3 Designmentioning

confidence: 99%

SMELL-S and SMELL-R: olfactory tests not influenced by odor-specific insensitivity or prior olfactory experience

Hsieh

Keller

Wong

et al. 2017

Preprint

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Smell dysfunction is a common and underdiagnosed medical condition that can have serious consequences. It is also an early biomarker of Alzheimer's disease that precedes detectable memory loss. Clinical tests that evaluate the sense of smell face two major challenges. First, human sensitivity to individual odorants varies significantly, leading to potential misdiagnosis of people with an otherwise normal sense of smell but insensitivity to the test odorant. Second, prior familiarity with odor stimuli can bias smell test performance. We have developed new nonsemantic tests for olfactory sensitivity (SMELL-S) and olfactory resolution (SMELL-R) that overcome these challenges by using mixtures of odorants that have unfamiliar smells. The tests can be self-administered with minimal training and showed high test-retest reliability. Because SMELL-S uses odor mixtures rather than a single molecule, odor-specific insensitivity is averaged out. Indeed, SMELL-S accurately distinguished people with normal and dysfunctional smell. SMELL-R is a discrimination test in which the difference between two stimulus mixtures can be altered stepwise. This is an advance over current discrimination tests, which ask subjects to discriminate monomolecular odorants whose difference cannot be objectively calculated. SMELL-R showed significantly less bias in scores between North American and Taiwanese subjects than conventional semantically-based smell tests that need to be adapted and translated to different populations. We predict that SMELL-S and SMELL-R will be broadly effective in diagnosing smell dysfunction, including that associated with the earliest signs of memory loss in Alzheimer's disease.

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“…This is interesting as results from these measurements – despite of relatively large variation – correlate with the overall chemosensory sensitivity of the tested person although it can be assumed, that the single substance only activates a certain portion of olfactory receptors. In this context it is important to know that humans differ in the expression of olfactory receptors67. Thus, it would appear to be logical to investigate thresholds for several odors or mixtures of odors.…”

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confidence: 99%

Chemical complexity of odors increases reliability of olfactory threshold testing

Oleszkiewicz

Pellegrino

Pusch

et al. 2017

Sci Rep

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Assessment of odor thresholds is a widely recognized method of measuring olfactory abilities in humans. To date no attempts have been made to assess whether chemical complexity of odors used can produce more reliable results. To this end, we performed two studies of repeated measures design with 121 healthy volunteers (age 19–62 years). In Study 1, we compared thresholds obtained from tests based on one odor presented in a pen-like odor dispensing device with three odors and six odors mixtures presented in glass containers. In study 2 we compared stimuli of one and three odors, both presented in glass containers. In both studies measurements were performed twice, separated by at least three days. Results indicate that the multiple odor mixtures produced more reliable threshold scores, as compared to thresholds based on a single substance.

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Peripheral adaptive filtering in human olfaction? Three studies on prevalence and effects of olfactory training in specific anosmia in more than 1600 participants

Cited by 57 publications

References 21 publications

Molecularly diverse odors advance olfactory threshold testing

Molecularly diverse odors advance olfactory threshold testing

SMELL-S and SMELL-R: olfactory tests not influenced by odor-specific insensitivity or prior olfactory experience

Chemical complexity of odors increases reliability of olfactory threshold testing

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