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Hintschich CA, Ma C, Hähner A, Hummel T. Pronounced Olfactory Habituation with Age. Laryngoscope 2024. [PMID: 38597777 DOI: 10.1002/lary.31442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 03/05/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
OBJECTIVES Olfactory habituation is a transient decrease in olfactory sensitivity caused by prolonged odor exposure, aiding in the discernment of new olfactory stimuli against the background. We explored the impact of subclinical olfactory impairment on odor habituation using age as a proxy. METHODS Before the actual experiment, the individual olfactory threshold for the rose-like odorant phenylethyl alcohol (PEA) was assessed separately for the left and right nostril using the "Sniffin' Sticks" test, and ratings for odor intensity and pleasantness were collected. After applying a nasal clip continuously delivering PEA odor to one nostril for 10 min and 2 h, respectively, threshold, intensity, and pleasantness were reassessed immediately after clip removal. RESULTS In the group of 80 participants (younger adults-mean age 27.7 ± 4.5 years; older adults-mean age 61.5 ± 4.7 years), olfactory thresholds were already significantly elevated after just 10 min, and this habituation was even more pronounced after 2 h. This effect could be observed bilaterally even though significantly more distinct on the exposed side. Older participants generally exhibited a more pronounced habituation on the exposed side after 2 h compared to the younger participants. CONCLUSION The results indicate that older people experience more notable habituation after extended exposure to odors. This is most likely due to the compromised olfactory function in age. Although older and younger subjects scored in the normosmic range when tested with standardized olfactory tests, the stress on the system after exposure to an odor clearly revealed the lower functionality of the aging sense of smell. LEVEL OF EVIDENCE 3 Laryngoscope, 2024.
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Affiliation(s)
- Constantin A Hintschich
- Department of Otorhinolaryngology, Smell and Taste Clinic, TU Dresden, Dresden, Germany
- Department of Otorhinolaryngology, Regensburg University Hospital, Regensburg, Germany
| | - Cindy Ma
- Department of Otorhinolaryngology, Smell and Taste Clinic, TU Dresden, Dresden, Germany
| | - Antje Hähner
- Department of Otorhinolaryngology, Smell and Taste Clinic, TU Dresden, Dresden, Germany
| | - Thomas Hummel
- Department of Otorhinolaryngology, Smell and Taste Clinic, TU Dresden, Dresden, Germany
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Ye Y, Wang Y, Zhuang Y, Tan H, Zuo Z, Yun H, Yuan K, Zhou W. Decomposition of an odorant in olfactory perception and neural representation. Nat Hum Behav 2024:10.1038/s41562-024-01849-0. [PMID: 38499771 DOI: 10.1038/s41562-024-01849-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 02/19/2024] [Indexed: 03/20/2024]
Abstract
Molecules-the elementary units of substances-are commonly considered the units of processing in olfactory perception, giving rise to undifferentiated odour objects invariant to environmental variations. By selectively perturbing the processing of chemical substructures with adaptation ('the psychologist's microelectrode') in a series of psychophysical and neuroimaging experiments (458 participants), we show that two perceptually distinct odorants sharing part of their structural features become significantly less discernible following adaptation to a third odorant containing their non-shared structural features, in manners independent of olfactory intensity, valence, quality or general olfactory adaptation. The effect is accompanied by reorganizations of ensemble activity patterns in the posterior piriform cortex that parallel subjective odour quality changes, in addition to substructure-based neural adaptations in the anterior piriform cortex and amygdala. Central representations of odour quality and the perceptual outcome thus embed submolecular structural information and are malleable by recent olfactory encounters.
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Affiliation(s)
- Yuting Ye
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
- Institute of Psychology, School of Public Affairs, Xiamen University, Xiamen, China
| | - Yanqing Wang
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
- School of Psychology, Northwest Normal University, Lanzhou, China
| | - Yuan Zhuang
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Huibang Tan
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Zhentao Zuo
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China
- Sino-Dannish College, University of Chinese Academy of Sciences, Beijing, China
| | - Hanqi Yun
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Kaiqi Yuan
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Wen Zhou
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China.
- Chinese Institute for Brain Research, Beijing, China.
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Arrestin-mediated desensitization enables intraneuronal olfactory discrimination in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2022; 119:e2116957119. [PMID: 35878038 PMCID: PMC9351366 DOI: 10.1073/pnas.2116957119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In the mammalian olfactory system, cross-talk between olfactory signals is minimized through physical isolation: individual neurons express one or few olfactory receptors among those encoded in the genome. Physical isolation allows for segregation of stimuli during signal transduction; however, in the nematode worm Caenorhabditis elegans, ∼1,300 olfactory receptors are primarily expressed in only 32 neurons, precluding this strategy. Here, we report genetic and behavioral evidence that β-arrestin-mediated desensitization of olfactory receptors, working downstream of the kinase GRK-1, enables discrimination between intraneuronal olfactory stimuli. Our findings suggest that C. elegans exploits β-arrestin desensitization to maximize responsiveness to novel odors, allowing for behaviorally appropriate responses to olfactory stimuli despite the large number of olfactory receptors signaling in single cells. This represents a fundamentally different solution to the problem of olfactory discrimination than that which evolved in mammals, allowing for economical use of a limited number of sensory neurons.
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The impact of learning on perceptual decisions and its implication for speed-accuracy tradeoffs. Nat Commun 2020; 11:2757. [PMID: 32488065 PMCID: PMC7265464 DOI: 10.1038/s41467-020-16196-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 04/01/2020] [Indexed: 11/16/2022] Open
Abstract
In standard models of perceptual decision-making, noisy sensory evidence is considered to be the primary source of choice errors and the accumulation of evidence needed to overcome this noise gives rise to speed-accuracy tradeoffs. Here, we investigated how the history of recent choices and their outcomes interact with these processes using a combination of theory and experiment. We found that the speed and accuracy of performance of rats on olfactory decision tasks could be best explained by a Bayesian model that combines reinforcement-based learning with accumulation of uncertain sensory evidence. This model predicted the specific pattern of trial history effects that were found in the data. The results suggest that learning is a critical factor contributing to speed-accuracy tradeoffs in decision-making, and that task history effects are not simply biases but rather the signatures of an optimal learning strategy. Here, the authors show that rats’ performance on olfactory decision tasks is best explained by a Bayesian model that combines reinforcement-based learning with accumulation of uncertain sensory evidence. The results suggest that learning is a critical factor contributing to speed-accuracy tradeoffs.
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Oleszkiewicz A, Rambacher L, Whitcroft KL, Hummel T. The confounding effect of background odors on olfactory sensitivity testing. J Neurosci Methods 2018; 306:88-91. [PMID: 29782885 DOI: 10.1016/j.jneumeth.2018.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/17/2018] [Accepted: 05/17/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Human olfactory sensitivity is known to vary significantly across subjects. Furthermore, environmental factors such as background noise and odor are known to affect target odor threshold scores but have not yet been fully delineated. We aimed to determine whether congruent and non-congruent background odor impaired target odor threshold scores. NEW METHOD We performed odor threshold testing in 103 normosmic adults, using phenylethylalcohol (PEA) or linalool as target odors, under three conditions: (a) congruent target and background odors (e.g., PEA in the test and PEA in the background), (b) non-congruent target and background odors (e.g. PEA in the test and Linalool in the background) and (c) no background odor. Background odor was applied to the investigator's glove and testing was performed in an otherwise odorless room. RESULTS We found that congruent background odors significantly impaired target odor threshold scores. Non-congruent background odors also impaired target odor threshold, but significantly more so with PEA as target and Linalool as background odor. The best threshold scores were obtained with no background odor. Comparison with Existing Method(s). At present, many testing environments may be contaminated with ambient background odors. We have shown that this may negatively affect odor threshold scores, particularly where background and target odors are congruent. CONCLUSIONS We suggest that investigators performing odor threshold testing do so in well ventilated, odor free environments.
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Affiliation(s)
- A Oleszkiewicz
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Germany; University of Wroclaw, Institute of Psychology, Wroclaw, Poland.
| | - L Rambacher
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Germany
| | - K L Whitcroft
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Germany; UCL Ear Institute, University College London, London, UK; Centre for the Study of the Senses, Institute of Philosophy, School of Advanced Study, London, UK; Royal National Throat Nose and Ear Hospital, University College London Hospitals, London, UK
| | - T Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Germany
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Pellegrino R, Sinding C, de Wijk R, Hummel T. Habituation and adaptation to odors in humans. Physiol Behav 2017; 177:13-19. [DOI: 10.1016/j.physbeh.2017.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 03/28/2017] [Accepted: 04/08/2017] [Indexed: 10/19/2022]
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Walliczek-Dworschak U, Pellegrino R, Lee S, Hummel C, Hähner A, Hummel T. Olfactory Performance Can Be Influenced by the Presentation Order, Background Noise, and Positive Concurrent Feedback. Chem Senses 2016; 41:697-701. [PMID: 27432834 DOI: 10.1093/chemse/bjw079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sniffin' Sticks have become a popular procedure to measure overall olfactory functionality with 3 subtest: phenyl ethyl alcohol threshold test (T), discrimination (D), and identification (I). However, several procedural components specified by the original paper have not been tested nor has the impact of deviations been measured. The aim of the present work was to measure olfactory performance under modified testing procedures. First, the reverse order of subtests (IDT) was compared with more standard practices (TDI). Next, the possible impact of background noise and positive concurrent feedback were assessed. A total of 120 individuals participated in the study where the 3 conditional experiments, each involving 40 participants, were completed. Testing procedures that reversed the presentation order of subtests (I->D->T) scored a significantly lower overall TDI score than standard testing order with the threshold subtest being the most influenced. Additionally, nonverbal background noise lowered overall olfactory performance while concurrent feedback modulated threshold performance. These results emphasize the importance of testing parameters where olfactory perception and tasks may be modulated by adaptation and attentional distraction, respectively. This study helped furthermore to demonstrate that the investigated 3 deviations from the standard procedure revealed a significant impact on the performance outcome in olfactory assessment using the Sniffin' Sticks.
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Affiliation(s)
- Ute Walliczek-Dworschak
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and Department of Otorhinolaryngology, Philipps-University, Marburg, Germany
| | - Robert Pellegrino
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and
| | - Shangwa Lee
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and
| | - Cornelia Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and
| | - Antje Hähner
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and
| | - Thomas Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, "Technische Universität Dresden", Dresden, Germany and
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Prokop-Prigge KA, Greene K, Varallo L, Wysocki CJ, Preti G. The Effect of Ethnicity on Human Axillary Odorant Production. J Chem Ecol 2016; 42:33-9. [PMID: 26634572 PMCID: PMC4724538 DOI: 10.1007/s10886-015-0657-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 11/17/2015] [Accepted: 11/20/2015] [Indexed: 11/29/2022]
Abstract
Previous findings from our laboratory highlighted marked ethnic differences in volatile organic compounds (VOCs) from cerumen among individuals of Caucasian, East Asian, and African-American descent, based, in part, on genetic differences in a gene that codes for a transport protein, which is a member of the ATP-binding cassette transporter, sub-family C, member 11 (ABCC11). In the current work, we hypothesized that axillary odorants produced by East Asians would differ markedly from those obtained from individuals of European or African descent based on the pattern of ethnic diversity that exists in ABCC11. Using gas chromatography/mass spectrometry (GC/MS) we examined differences in axillary odorant VOCs among 30 individuals of African-American, Caucasian, and East Asian descent with respect to their ABCC11 genotype. While no qualitative differences in the type of axillary odorants were observed across ethnic groups, we found that characteristic axillary odorants varied quantitatively with respect to ethnic origin. We propose that ABCC11 is not solely responsible for predicting the relative amounts of volatiles found in axillary secretions and that other biochemical pathways must be involved.
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Affiliation(s)
| | - Kathryn Greene
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Lauren Varallo
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Charles J Wysocki
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - George Preti
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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9
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Stuck BA, Fadel V, Hummel T, Sommer JU. Subjective Olfactory Desensitization and Recovery in Humans. Chem Senses 2013; 39:151-7. [DOI: 10.1093/chemse/bjt064] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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10
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Kaeppler K, Mueller F. Odor Classification: A Review of Factors Influencing Perception-Based Odor Arrangements. Chem Senses 2013; 38:189-209. [DOI: 10.1093/chemse/bjs141] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Takeuchi K, Yabuki M, Hasegawa Y. Review of odorants in human axillary odour and laundry malodour: The importance of branched C7 chain analogues in malodours perceived by humans. FLAVOUR FRAG J 2012. [DOI: 10.1002/ffj.3130] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kohei Takeuchi
- Perfumery Development Research Labs.; Kao Corporation, 2-1-3; Bunka Sumida-ku; Tokyo; 131-8501; Japan
| | - Masayuki Yabuki
- Perfumery Development Research Labs.; Kao Corporation, 2-1-3; Bunka Sumida-ku; Tokyo; 131-8501; Japan
| | - Yoshihiro Hasegawa
- Perfumery Development Research Labs.; Kao Corporation, 2-1-3; Bunka Sumida-ku; Tokyo; 131-8501; Japan
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Increased JNK1 activity contributes to the upregulation of ApoD in the apocrine secretory gland cells from axillary osmidrosis. Mol Cell Biochem 2011; 354:311-6. [PMID: 21526344 DOI: 10.1007/s11010-011-0830-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 04/15/2011] [Indexed: 01/04/2023]
Abstract
Axillary osmidrosis is a benign disorder that causes functional and emotional problems in Asian patients. Recently, ApoD has been identified as an axillary odorant binding protein. The present study was designed to compare the expression of ApoD in normal and osmidrosis subjects. Compared with the normal subjects, osmidrosis subjects had a higher expression of AR and ApoD in the apocrine samples, both at mRNA and protein level. Further study showed that, consistent with the increased ApoD and AR, phosphorylated JNK1 was higher in apocrine samples from axillary osmidrosis subjects, while with no obvious differences of the total expression of JNK1. In the cultured apocrine epithelial cells from normal subjects, 5α-dihydrotestosterone (5α-DHT) increased the expression of ApoD in a dose dependent manner, which can be inhibited by the JNK1 inhibitor. In contrast, in the cultured apocrine epithelial cells from axillary osmidrosis subjects, inhibition of JNK1 significantly reduced the expression of ApoD. Taken together, our study here revealed that increased JNK1 activation in the apocrine cells from axillary osmidrosis contributes to the increased ApoD expression, which in turn involved in the process of axillary osmidrosis.
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Wysocki CJ, Louie J, Leyden JJ, Blank D, Gill M, Smith L, McDermott K, Preti G. Cross-adaptation of a model human stress-related odour with fragrance chemicals and ethyl esters of axillary odorants: gender-specific effects. FLAVOUR FRAG J 2009. [DOI: 10.1002/ffj.1927] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Wise PM, Miyazawa T, Gallagher M, Preti G. Human Odor Detection of Homologous Carboxylic Acids and Their Binary Mixtures. Chem Senses 2007; 32:475-82. [PMID: 17488748 DOI: 10.1093/chemse/bjm016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Does structural similarity of odorants influence detectability of their mixtures? To address this question, psychometric (probability of correct detection vs. concentration) functions were measured for aliphatic carboxylic acids and selected binary mixtures thereof. Unmixed stimuli included acetic (C2), butyric (C4), hexanoic (C6), and octanoic (C8) acids. Mixtures included C2 + C4, C2 + C6, and C2 + C8. Vapor-phase concentrations of individual compounds, as measured by a combination of solid-phase micro extraction and gas chromatography/mass spectrometry, were always the same, whether presented singly or in a binary mixture. Additivity of detectability was assessed with respect to response addition (independent processing of mixture components). For C2 + C6, for which the mixture components differed by 4 methylene units, and C2 + C8, which differed by 6 methylene units, response addition provided a reasonably good description of detection at all levels of performance. In contrast, for C2 + C4, which differed by only 2 methylene units, detection showed a tendency to exceed additivity at low concentrations but fell below additivity at higher concentrations. These results suggest that interaction among odors in binary mixtures does depend on structural similarity, at least for detection of carboxylic acids. Future studies can determine if this result is particular to carboxylic acids.
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Affiliation(s)
- Paul M Wise
- Monell Chemical Senses Center, Philadelphia, PA 19104-3308, USA.
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Wilson DA, Stevenson RJ. Olfactory perceptual learning: the critical role of memory in odor discrimination. Neurosci Biobehav Rev 2003; 27:307-28. [PMID: 12946684 DOI: 10.1016/s0149-7634(03)00050-2] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The major problem in olfactory neuroscience is to determine how the brain discriminates one odorant from another. The traditional approach involves identifying how particular features of a chemical stimulus are represented in the olfactory system. However, this perspective is at odds with a growing body of evidence, from both neurobiology and psychology, which places primary emphasis on synthetic processing and experiential factors--perceptual learning--rather than on the structural features of the stimulus as critical for odor discrimination. In the present review of both psychological and sensory physiological data, we argue that the initial odorant feature extraction/analytical processing is not behaviorally/consciously accessible, but rather is a first necessary stage for subsequent cortical synthetic processing which in turn drives olfactory behavior. Cortical synthetic coding reflects an experience-dependent process that allows synthesis of novel co-occurring features, similar to processes used for visual object coding. Thus, we propose that experience and cortical plasticity are not only important for traditional associative olfactory memory (e.g. fear conditioning, maze learning, and delayed-match-to-sample paradigms), but also play a critical, defining role in odor discrimination.
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Affiliation(s)
- Donald A Wilson
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA.
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Abstract
The psychological basis of odor quality is poorly understood. For pragmatic reason, descriptions of odor quality generally rely on profiling odors in terms of what odorants they bring to mind. It is argued here that this reliance on profiling reflects a basic property of odor perception, namely that odor quality depends on the implicit memories that an odorant elicits. This is supported by evidence indicating that odor quality as well as one's ability to discriminate odors is affected by experience. Developmental studies and cross-cultural research also point to this conclusion. In this article, these findings are reviewed and a model that attempts to account for them is proposed. Finally, the model's consistency with both neurophysiological and neuropsychological data is examined.
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Abstract
We previously found that exposure-induced increase in odor sensitivity involves, at least in part, the olfactory epithelium. We did this by exposing mice to 5 alpha-androst-16-en-3-one (androstenone) and measuring changes in the epithelium. Past research showed that sensitivity to androstenone also could be induced by exposing individuals to 4-(4',4'-dimethylcyclohexyl)-2-methylcyclohexanone (DMCMC), a structural and functional analog of androstenone. What remained unknown is whether structural and/or functional odorant analogs share peripheral components. In the current work, we used a well-established model to disconnect the olfactory epithelium from the olfactory bulbs (BNX) to disrupt mechanisms underlying olfactory coding (when the afferents reinnervate the bulb, they do not synapse in their original glomeruli), and to examine the effects of disruption and restoration on exposure-induced odor sensitivity. In this study, we determined whether analogs of androstenone, viz., 5 alpha-androstan-3-one (androstanone) and DMCMC, could induce sensitivity to androstenone after BNX. Results demonstrate that exposure to either androstanone or DMCMC can induce sensitivity to androstenone in control mice. Different results were observed in mice that had recovered from bilateral BNX. Exposure to androstanone for 10 days immediately after surgery increased sensitivity to androstenone; however, exposure to DMCMC did not. These results suggest that androstanone and DMCMC, although apparent perceptual analogs of androstenone, may be using different pathways of olfaction within the central nervous system (CNS).
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Affiliation(s)
- Karen K Yee
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104-3308, USA.
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