Understanding the Dynamics of Odor to Aid in Odor Detection

Canines ◽  
2021 ◽  
pp. 217-273
Author(s):  
Lauryn E. DeGreeff ◽  
Michele Maughan
Keyword(s):  
Odor Detection

Olfactory Modulation of Steady- State Visual Evoked Potential Topography in Comparison with Differences in Odor Sensitivity

2002 ◽  
Vol 16 (2) ◽  
pp. 71-81 ◽  
Author(s):  
Caroline M. Owen ◽  
John Patterson ◽  
Richard B. Silberstein
Keyword(s):  
Steady State ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Behavioral Responses ◽  
Simultaneous Recording ◽  
Odor Concentration ◽  
Odor Detection ◽  
Detection Response ◽  
Response Groups ◽  
Visual Evoked

Summary Research was undertaken to determine whether olfactory stimulation can alter steady-state visual evoked potential (SSVEP) topography. Odor-air and air-only stimuli were used to determine whether the SSVEP would be altered when odor was present. Comparisons were also made of the topographic activation associated with air and odor stimulation, with the view toward determining whether the revealed topographic activity would differentiate levels of olfactory sensitivity by clearly identifying supra- and subthreshold odor responses. Using a continuous respiration olfactometer (CRO) to precisely deliver an odor or air stimulus synchronously with the natural respiration, air or odor (n-butanol) was randomly delivered into the inspiratory airstream during the simultaneous recording of SSVEPs and subjective behavioral responses. Subjects were placed in groups based on subjective odor detection response: “yes” and “no” detection groups. In comparison to air, SSVEP topography revealed cortical changes in response to odor stimulation for both response groups, with topographic changes evident for those unable to perceive the odor, showing the presence of a subconscious physiological odor detection response. Differences in regional SSVEP topography were shown for those who reported smelling the odor compared with those who remained unaware of the odor. These changes revealed olfactory modulation of SSVEP topography related to odor awareness and sensitivity and therefore odor concentration relative to thresholds.

scholarly journals A Behavioral and Electrophysiological Investigation of Effects of Visual Congruence on Olfactory Sensitivity During Habituation to Prolonged Odors

2020 ◽  
Vol 45 (9) ◽  
pp. 845-854
Author(s):  
Nicholas Fallon ◽  
Timo Giesbrecht ◽  
Anna Thomas ◽  
Andrej Stancak
Keyword(s):  
Cognitive Processing ◽  
Visual Cues ◽  
Reaction Times ◽  
Event Related Potential ◽  
Detection Sensitivity ◽  
Moderate Intensity ◽  
Odor Perception ◽  
Potential Analysis ◽  
Odor Detection ◽  
Central Processing

Abstract Congruent visual cues augment sensitivity to brief olfactory presentations and habituation of odor perception is modulated by central-cognitive processing including context. However, it is not known whether habituation to odors could interact with cross-modal congruent stimuli. The present research investigated the effect of visual congruence on odor detection sensitivity during continuous odor exposures. We utilized a multimethod approach, including subjective behavioral responses and reaction times (RTs; study 1) and electroencephalography (EEG, study 2). Study 1: 25 participants received 2-min presentations of moderate-intensity floral odor delivered via olfactometer with congruent (flower) and incongruent (object) image presentations. Participants indicated odor perception after each image. Detection sensitivity and RTs were analyzed in epochs covering the period of habituation. Study 2: 25 new participants underwent EEG recordings during 145-s blocks of odor presentations with congruent or incongruent images. Participants passively observed images and intermittently rated the perceived intensity of odor. Event-related potential analysis was utilized to evaluate brain processing related to odor–visual pairs across the period of habituation. Odor detection sensitivity and RTs were improved by congruent visual cues. Results highlighted a diminishing influence of visual congruence on odor detection sensitivity as habituation occurred. Event-related potential analysis revealed an effect of congruency on electrophysiological processing in the N400 component. This was only evident in early periods of odor exposure when perception was strong. For the first time, this demonstrates the modulation of central processing of odor–visual pairs by habituation. Frontal negativity (N400) responses encode the aspects of cross-modal congruence for odor–vision cross-modal tasks.

scholarly journals Preliminary accuracy of COVID-19 odor detection by canines and HS-SPME-GC-MS using exhaled breath samples

2021 ◽  
pp. 100155
Author(s):  
Julian Mendel ◽  
Kelvin Frank ◽  
Lourdes Edlin ◽  
Kelley Hall ◽  
Denise Webb ◽  
...  
Keyword(s):  
Exhaled Breath ◽  
Odor Detection

The Brief Odor Detection Test (B-ODT) for Very Early Diagnosis of Cognitive Decline: A Preliminary Study

2017 ◽  
Vol 18 (2) ◽  
pp. 197-210
Author(s):  
Dimitra Savvoulidou ◽  
Efthymia Totikidou ◽  
Chariklia Varvesiotou ◽  
Magda Iakovidou ◽  
Ourania Sfakianaki ◽  
...  
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Adult Population ◽  
Detection Threshold ◽  
Community Dwelling ◽  
Odor Detection ◽  
Olfactory Impairment ◽  
Older Adult Population ◽  
Community Dwelling Older Adults

Olfactory impairment in older adults is associated with cognitive decline. This study describes the development of a Brief Odor Detection Test (B-ODT), and its pilot administration in community-dwelling older adults. The study aimed at examining whether the test could differentiate older adults with very mild cognitive impairment from their cognitively healthy counterparts. The sample consisted of 34 older adults (22 women), aged from 65 to 87 years. Participants were divided into two groups according to their general cognitive functioning. Odor detection was measured via vanillin solutions at the following concentrations: 150 mg/L, 30 mg/L, 15 mg/L, 3 mg/L, and .03 mg/L. The first condition of the test involved a scale administration of vanillin solutions. The second condition examined the change in air odour and it required vanillin solution of 30 mg/L and a metric ruler of 30 cm. The examiner had to place the solution at a specific distance point from each nostril. Odour identification sensitivity was secondarily measured. The results showed statistically significant differences in odour detection threshold between the two groups. In the unirhinal testing, left nostril differences of the two groups were definite. Hence, the B-ODT seems a promising instrument for very early cognitive impairment screening in older adult population.

Neural correlates of memory for odor detection conditioning in adult rats

1993 ◽  
Vol 163 (1) ◽  
pp. 36-40 ◽  
Author(s):  
William D. Hamrick ◽  
Donald A. Wilson ◽  
Regina M. Sullivan
Keyword(s):  
Neural Correlates ◽  
Adult Rats ◽  
Odor Detection

scholarly journals Functional Near Infrared Spectroscopy (fNIRS) based Odor Detection and Classification using Functional Data Analysis

2021 ◽  
Author(s):  
Faezeh Moradi ◽  
Shima T. Moein ◽  
Issa Zakeri ◽  
Kambiz Pourrezaei
Keyword(s):  
Infrared Spectroscopy ◽  
Data Analysis ◽  
Near Infrared Spectroscopy ◽  
Functional Data Analysis ◽  
Functional Data ◽  
Near Infrared ◽  
Stimulus Condition ◽  
Functional Near Infrared Spectroscopy ◽  
Odor Detection ◽  
The Brain

AbstractAn objective approach for odor detection is to analyze the brain activity using imaging techniques during the odor stimulation. In this study, Functional Near Infrared Spectroscopy (fNIRS) is used to record hemodynamic response from the frontal region of the brain by using a 4-channel fNIRS system. The fNIRs data is collected during the odor detection task in which the subjects were asked to press a button when they detect the given odor. Functional Data Analysis (FDA) was applied on fNIRs data to convert discrete measured samples of data to continuous smooth curves. The FDA method enables us to use the bases coefficients of fNIRS smoothed curves for features that represent the shape of the raw fNIRS signal. With the learning algorithm that we proposed, these features were used to train the support vector machine classifier. We evaluated the odor detection problem, in two binary classification cases: odorant vs. non-odorant and odorant vs. fingertapping. The model achieved a classification accuracy of 94.12% and 97.06% over the stimulus condition in the two cases, respectively. Moreover to find the actual predictors we used the extracted defined features (slope, standard deviation, and delta) to train our classifier. We achieved an average accuracy of 91.18 % on classifying odorant vs. non-odorant and an accuracy of 94.12% for odorant vs. fingertapping on the stimulus condition. The results determined that fNIRs signals of odorant and non-odorant are distinguishable without being affected by the motor activity during the experiment.These findings suggest that fNIRs measurement on the forehead could be potentially used for objective and comparably inexpensive assessment of odor detection in cases that the subjective report is unreliable.

Relationship between the Differences of Odor Detection Threshold Values Measured by Different Methods and some of the Physicochemical Properties

2013 ◽  
Vol 807-809 ◽  
pp. 451-455 ◽  
Author(s):  
Di Fang ◽  
Jie Min Liu ◽  
Qin Yi
Keyword(s):  
Physicochemical Properties ◽  
Functional Group ◽  
Saturated Vapor ◽  
Detection Threshold ◽  
Threshold Values ◽  
Odor Detection ◽  
Linear Relationships ◽  
Odor Detection Threshold ◽  
The Difference ◽  
The Relationship

The amount of sample can enter the nasal cavity depends on the physiochemical characteristics such as distribution, volatility and solubility. It can be suspected that the difference of odor detection threshold (ODT) measured by different methods is related to the physicochemical properties of compounds. To investigate the relationship between ODT differences and the physicochemical properties of compounds, ODT values of four series of organic compounds were measured by triangle odor bag method and gas chromatography and olfactometry method; the results were compared and the absolute differences were calculated. Relationship between ODT differences and the type of functional group and some of the physicochemical properties of compounds was analyzed. The results showed the type of functional group had significant effect on the differences. Certain linear relationships between the logarithmic value of differences and the logarithmic values of saturated vapor pressure and molecular weight were observed.

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