The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Thomas Hummel - One of the best experts on this subject based on the ideXlab platform.
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The Presentation of Olfactory–Trigeminal Mixed Stimuli Increases the Response to Subsequent Olfactory Stimuli
Journal of agricultural and food chemistry, 2017Co-Authors: Ute Walliczek-dworschak, Johan Poncelet, Daniel Baum, Ramona Baki, Charlotte Sinding, Jonathan Warr, Thomas HummelAbstract:The aim of this study was to evaluate the effect of (1) the addition of trigeminal stimuli to an Olfactory Stimulus and (2) the congruence in the odorous mixture after repeated odor presentation. Twenty-five normosmic volunteers were enrolled and presented stimulation blocks, consisting of three habituation stimuli (H) (orange odor), one dishabituation (DH) (control condition, orange odor; congruent condition, orange odor + CO2; incongruent condition, orange odor + l-isopulegol), and one dishabituated Stimulus (D) (orange odor). Olfactory event-related potentials were analyzed. Response amplitudes differed significantly in the incongruent condition (N1P2 between H3 and D; peak to peak N1P2 at electrode positions Cz, Fz, and Pz; response amplitudes between H3 and DH). The addition of CO2 modified the perception of orange odor, pronouncing a fruity note, whereas the addition of l-isopulegol as a DH pronounced the l-isopulegol note. This study provides evidence that incongruent trigeminal-Olfactory stimulants increase the response to subsequent Olfactory Stimulus.
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The presentation of Olfactory-trigeminal mixed stimuli increases the response to subsequent Olfactory stimuli
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Ute Walliczek-dworschak, Johan Poncelet, Daniel Baum, Ramona Baki, Charlotte Sinding, Jonathan Warr, Thomas HummelAbstract:The aim of this study was to evaluate the effect of 1) the addition of trigeminal stimuli to an Olfactory Stimulus and 2) the congruence in the odourous mixture after repeated odor presentation. 25 normosmic volunteers were enrolled and presented stimulation blocks, consisting of three habituation stimuli (H) (orange odor), one dishabituation (DH) (control condition: orange odor; congruent condition: orange odor + CO2; incongruent condition: orange odor + L-isopulegol) and one dishabituated Stimulus (D) (orange odor). Olfactory event-related potentials were analyzed. Response amplitudes differed significantly in the incongruent condition (N1P2 between H3 and D ; peak to peak N1P2 at electrode positions Cz, Fz and Pz; response amplitudes between H3 and DH) . The added DH modified perception of orange odor-pronouncing a fruity note by addition of CO2 respectively L-isopulegol note by addition of L-isopulegol. This study provides evidence that incongruent trigeminal-Olfactory stimulants increase the response to following Olfactory Stimulus.
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Localization of Odors Can Be Learned
Chemical senses, 2013Co-Authors: Simona Negoias, Oxana Aszmann, Ilona Croy, Thomas HummelAbstract:Chemicals selectively stimulating the Olfactory nerve typically cannot be localized in a lateralization task. Purpose of this study was to investigate whether the ability of subjects to localize an Olfactory Stimulus delivered passively to 1 of the 2 nostrils would improve under training. Fifty-two young, normosmic women divided in 2 groups participated. One group performed Olfactory lateralization training, whereas the other group performed cognitive tasks. Results showed that only subjects performing lateralization training significantly improved in their ability to lateralize Olfactory stimuli compared with subjects who did not undergo such training.
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Recording Odor-Evoked Response Potentials at the Human Olfactory Epithelium
Chemical senses, 2012Co-Authors: Hadas Lapid, Thomas HummelAbstract:Electro-olfactogram (EOG) represents the sum of generator potentials of Olfactory receptor neurons in response to an Olfactory Stimulus. Although this measurement technique has been used extensively in animal research, its use in human olfaction research has been relatively limited. To understand the promises and limitations of this technique, this review provides an overview of the Olfactory epithelium structure and function, and summarizes EOG characteristics and conventions. It describes methodological pitfalls and their possible solutions, artifacts, and questions of debate in the field. In summary, EOG measurements provide a rare opportunity of recording neuronal input from the peripheral Olfactory system, while simultaneously obtaining psychophysical responses in awake humans.
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Loss of trigeminal sensitivity reduces Olfactory function.
The Laryngoscope, 2006Co-Authors: Alexander Husner, Johannes Frasnelli, Antje Welge-lüssen, Gilfe Reiss, Thomas Zahnert, Thomas HummelAbstract:The trigeminal and Olfactory nerves share overlapping innervation areas in the nasal cavity and seem to work in an interactive way. Loss of Olfactory function leads to a decreased trigeminal sensitivity, as shown in anosmic subjects. To report the impact of disturbed trigeminal sensitivity on the Olfactory function, we present a patient with unilateral loss of trigeminal function resulting from a meningeoma. Thresholds to a selective Olfactory Stimulus were elevated by a factor of 64 on the affected side. Recordings of event-related potentials in response to Olfactory stimuli showed a significantly reduced response on the affected side. This report indicates that loss of trigeminal function may affect the sense of smell.
Fiona Carr - One of the best experts on this subject based on the ideXlab platform.
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Unpredictable turns in the worm
Nature Reviews Neuroscience, 2015Co-Authors: Fiona CarrAbstract:The probabilistic behaviour of Caenorhabditis elegans in response to a fixed Olfactory Stimulus arises owing to variability in the activity state of the neural circuit that receives the sensory input.
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Neural circuits: Unpredictable turns in the worm.
Nature reviews. Neuroscience, 2015Co-Authors: Fiona CarrAbstract:The probabilistic behaviour of Caenorhabditis elegans in response to a fixed Olfactory Stimulus arises owing to variability in the activity state of the neural circuit that receives the sensory input.
Richard L Doty - One of the best experts on this subject based on the ideXlab platform.
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Physiologic impairment of Olfactory Stimulus processing in schizophrenia.
Biological Psychiatry, 2003Co-Authors: Bruce I. Turetsky, Paul J. Moberg, Kiana Owzar, Sarah C. Johnson, Richard L DotyAbstract:Abstract Background Behavioral studies of olfaction have demonstrated impairments in the ability to detect and identify odors in patients with schizophrenia. These deficits appear to be independent of either symptom severity or other cognitive impairment. Only limited efforts have been made to investigate the neurophysiologic substrate of these Olfactory abnormalities. This article reports the first examination of Olfactory electrophysiologic responses in patients with schizophrenia. Methods Olfactory event-related potential responses to three different concentrations of hydrogen sulfide were recorded in a sample of 21 patients and 20 healthy control subjects. Odors were presented via an olfactometer to ensure there was no associated trigeminal nerve stimulation. Results Patients exhibited abnormalities in the amplitudes of the N1 and P2 components of the Olfactory evoked potential, and delayed latency of the P2. The N1 abnormality, which denotes primary Olfactory cortex activity, was related to impaired odor detection threshold sensitivity; the P2 abnormality was related to impaired odor identification. Conclusions These data indicate the presence of a primary physiologic impairment in the Olfactory cortex underlying behavioral Olfactory deficits seen in patients with schizophrenia. This is consistent with postmortem and in vitro studies suggesting abnormalities in Olfactory receptor neurons. Understanding the nature of these physiologic Olfactory impairments could offer clues to the basic neuropathology of this disorder.
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Physiologic impairment of Olfactory Stimulus processing in schizophrenia.
Biological psychiatry, 2003Co-Authors: Bruce I. Turetsky, Paul J. Moberg, Kiana Owzar, Sarah C. Johnson, Richard L Doty, Raquel E. GurAbstract:Behavioral studies of olfaction have demonstrated impairments in the ability to detect and identify odors in patients with schizophrenia. These deficits appear to be independent of either symptom severity or other cognitive impairment. Only limited efforts have been made to investigate the neurophysiologic substrate of these Olfactory abnormalities. This article reports the first examination of Olfactory electrophysiologic responses in patients with schizophrenia. Olfactory event-related potential responses to three different concentrations of hydrogen sulfide were recorded in a sample of 21 patients and 20 healthy control subjects. Odors were presented via an olfactometer to ensure there was no associated trigeminal nerve stimulation. Patients exhibited abnormalities in the amplitudes of the N1 and P2 components of the Olfactory evoked potential, and delayed latency of the P2. The N1 abnormality, which denotes primary Olfactory cortex activity, was related to impaired odor detection threshold sensitivity; the P2 abnormality was related to impaired odor identification. These data indicate the presence of a primary physiologic impairment in the Olfactory cortex underlying behavioral Olfactory deficits seen in patients with schizophrenia. This is consistent with postmortem and in vitro studies suggesting abnormalities in Olfactory receptor neurons. Understanding the nature of these physiologic Olfactory impairments could offer clues to the basic neuropathology of this disorder.
Benjamin Auffarth - One of the best experts on this subject based on the ideXlab platform.
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Understanding the Odour Spaces: A Step towards Solving Olfactory Stimulus-Percept Problem
PloS one, 2015Co-Authors: Ritesh Kumar, Benjamin Auffarth, Rishemjit Kaur, Amol P. BhondekarAbstract:Odours are highly complex, relying on hundreds of receptors, and people are known to disagree in their linguistic descriptions of smells. It is partly due to these facts that, it is very hard to map the domain of odour molecules or their structure to that of perceptual representations, a problem that has been referred to as the Structure-Odour-Relationship. We collected a number of diverse open domain databases of odour molecules having unorganised perceptual descriptors, and developed a graphical method to find the similarity between perceptual descriptors; which is intuitive and can be used to identify perceptual classes. We then separately projected the physico-chemical and perceptual features of these molecules in a non-linear dimension and clustered the similar molecules. We found a significant overlap between the spatial positioning of the clustered molecules in the physico-chemical and perceptual spaces. We also developed a statistical method of predicting the perceptual qualities of a novel molecule using its physico-chemical properties with high receiver operating characteristics(ROC).
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Understanding smell--the Olfactory Stimulus problem.
Neuroscience and biobehavioral reviews, 2013Co-Authors: Benjamin AuffarthAbstract:The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing Stimulus statistics and perception. The core questions in olfaction are hence the so-called Stimulus problem, which refers to the understanding of the Stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to Olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the Stimulus, biology, physiology, and behavior and perception can provide new insights into Olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in Olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception.
Bruce I. Turetsky - One of the best experts on this subject based on the ideXlab platform.
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Physiologic impairment of Olfactory Stimulus processing in schizophrenia.
Biological Psychiatry, 2003Co-Authors: Bruce I. Turetsky, Paul J. Moberg, Kiana Owzar, Sarah C. Johnson, Richard L DotyAbstract:Abstract Background Behavioral studies of olfaction have demonstrated impairments in the ability to detect and identify odors in patients with schizophrenia. These deficits appear to be independent of either symptom severity or other cognitive impairment. Only limited efforts have been made to investigate the neurophysiologic substrate of these Olfactory abnormalities. This article reports the first examination of Olfactory electrophysiologic responses in patients with schizophrenia. Methods Olfactory event-related potential responses to three different concentrations of hydrogen sulfide were recorded in a sample of 21 patients and 20 healthy control subjects. Odors were presented via an olfactometer to ensure there was no associated trigeminal nerve stimulation. Results Patients exhibited abnormalities in the amplitudes of the N1 and P2 components of the Olfactory evoked potential, and delayed latency of the P2. The N1 abnormality, which denotes primary Olfactory cortex activity, was related to impaired odor detection threshold sensitivity; the P2 abnormality was related to impaired odor identification. Conclusions These data indicate the presence of a primary physiologic impairment in the Olfactory cortex underlying behavioral Olfactory deficits seen in patients with schizophrenia. This is consistent with postmortem and in vitro studies suggesting abnormalities in Olfactory receptor neurons. Understanding the nature of these physiologic Olfactory impairments could offer clues to the basic neuropathology of this disorder.
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Physiologic impairment of Olfactory Stimulus processing in schizophrenia.
Biological psychiatry, 2003Co-Authors: Bruce I. Turetsky, Paul J. Moberg, Kiana Owzar, Sarah C. Johnson, Richard L Doty, Raquel E. GurAbstract:Behavioral studies of olfaction have demonstrated impairments in the ability to detect and identify odors in patients with schizophrenia. These deficits appear to be independent of either symptom severity or other cognitive impairment. Only limited efforts have been made to investigate the neurophysiologic substrate of these Olfactory abnormalities. This article reports the first examination of Olfactory electrophysiologic responses in patients with schizophrenia. Olfactory event-related potential responses to three different concentrations of hydrogen sulfide were recorded in a sample of 21 patients and 20 healthy control subjects. Odors were presented via an olfactometer to ensure there was no associated trigeminal nerve stimulation. Patients exhibited abnormalities in the amplitudes of the N1 and P2 components of the Olfactory evoked potential, and delayed latency of the P2. The N1 abnormality, which denotes primary Olfactory cortex activity, was related to impaired odor detection threshold sensitivity; the P2 abnormality was related to impaired odor identification. These data indicate the presence of a primary physiologic impairment in the Olfactory cortex underlying behavioral Olfactory deficits seen in patients with schizophrenia. This is consistent with postmortem and in vitro studies suggesting abnormalities in Olfactory receptor neurons. Understanding the nature of these physiologic Olfactory impairments could offer clues to the basic neuropathology of this disorder.
