Journal articles on the topic 'Odor signal'
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Xu, Han, Chi Geng, Xinzhong Hua, Penglai Liu, Jinshan Xu, and Anan Li. "Distinct Characteristics of Odor-evoked Calcium and Electrophysiological Signals in Mitral/Tufted Cells in the Mouse Olfactory Bulb." Neuroscience Bulletin 37, no. 7 (April 15, 2021): 959–72. http://dx.doi.org/10.1007/s12264-021-00680-1.
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AbstractFiber photometry is a recently-developed method that indirectly measures neural activity by monitoring Ca2+ signals in genetically-identified neuronal populations. Although fiber photometry is widely used in neuroscience research, the relationship between the recorded Ca2+ signals and direct electrophysiological measurements of neural activity remains elusive. Here, we simultaneously recorded odor-evoked Ca2+ and electrophysiological signals [single-unit spikes and local field potentials (LFPs)] from mitral/tufted cells in the olfactory bulb of awake, head-fixed mice. Odors evoked responses in all types of signal but the response characteristics (e.g., type of response and time course) differed. The Ca2+ signal was correlated most closely with power in the β-band of the LFP. The Ca2+ signal performed slightly better at odor classification than high-γ oscillations, worse than single-unit spikes, and similarly to β oscillations. These results provide new information to help researchers select an appropriate method for monitoring neural activity under specific conditions.
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Muezzinoglu, Mehmet K., Ramon Huerta, Henry D. I. Abarbanel, Margaret A. Ryan, and Mikhail I. Rabinovich. "Chemosensor-Driven Artificial Antennal Lobe Transient Dynamics Enable Fast Recognition and Working Memory." Neural Computation 21, no. 4 (April 2009): 1018–37. http://dx.doi.org/10.1162/neco.2008.05-08-780.
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The speed and accuracy of odor recognition in insects can hardly be resolved by the raw descriptors provided by olfactory receptors alone due to their slow time constant and high variability. The animal overcomes these barriers by means of the antennal lobe (AL) dynamics, which consolidates the classificatory information in receptor signal with a spatiotemporal code that is enriched in odor sensitivity, particularly in its transient. Inspired by this fact, we propose an easily implementable AL-like network and show that it significantly expedites and enhances the identification of odors from slow and noisy artificial polymer sensor responses. The device owes its efficiency to two intrinsic mechanisms: inhibition (which triggers a competition) and integration (due to the dynamical nature of the network). The former functions as a sharpening filter extracting the features of receptor signal that favor odor separation, whereas the latter implements a working memory by accumulating the extracted features in trajectories. This cooperation boosts the odor specificity during the receptor transient, which is essential for fast odor recognition.
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Meng, John Hongyu, and Hermann Riecke. "Structural spine plasticity: Learning and forgetting of odor-specific subnetworks in the olfactory bulb." PLOS Computational Biology 18, no. 10 (October 24, 2022): e1010338. http://dx.doi.org/10.1371/journal.pcbi.1010338.
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Learning to discriminate between different sensory stimuli is essential for survival. In rodents, the olfactory bulb, which contributes to odor discrimination via pattern separation, exhibits extensive structural synaptic plasticity involving the formation and removal of synaptic spines, even in adult animals. The network connectivity resulting from this plasticity is still poorly understood. To gain insight into this connectivity we present here a computational model for the structural plasticity of the reciprocal synapses between the dominant population of excitatory principal neurons and inhibitory interneurons. It incorporates the observed modulation of spine stability by odor exposure. The model captures the striking experimental observation that the exposure to odors does not always enhance their discriminability: while training with similar odors enhanced their discriminability, training with dissimilar odors actually reduced the discriminability of the training stimuli. Strikingly, this differential learning does not require the activity-dependence of the spine stability and occurs also in a model with purely random spine dynamics in which the spine density is changed homogeneously, e.g., due to a global signal. However, the experimentally observed odor-specific reduction in the response of principal cells as a result of extended odor exposure and the concurrent disinhibition of a subset of principal cells arise only in the activity-dependent model. Moreover, this model predicts the experimentally testable recovery of odor response through weak but not through strong odor re-exposure and the forgetting of odors via exposure to interfering odors. Combined with the experimental observations, the computational model provides strong support for the prediction that odor exposure leads to the formation of odor-specific subnetworks in the olfactory bulb.
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Renou, Michel, Virginie Party, Angéla Rouyar, and Sylvia Anton. "Olfactory signal coding in an odor background." Biosystems 136 (October 2015): 35–45. http://dx.doi.org/10.1016/j.biosystems.2015.06.001.
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Guo, Weiqing, Haohui Kong, Junzhang Wu, and Feng Gan. "Odor Discrimination by Similarity Measures of Abstract Odor Factor Maps from Electronic Noses." Sensors 18, no. 8 (August 13, 2018): 2658. http://dx.doi.org/10.3390/s18082658.
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The aim of this study is to improve the discrimination performance of electronic noses by introducing a new method for measuring the similarity of the signals obtained from the electronic nose. We constructed abstract odor factor maps (AOFMs) as the characteristic maps of odor samples by decomposition of three-way signal data array of an electronic nose. A similarity measure for two-way data was introduced to evaluate the similarities and differences of AOFMs from different samples. The method was assessed by three types of pipe and powder tobacco samples. Comparisons were made with other techniques based on PCA, SIMCA, PARAFAC and PARAFAC2. The results showed that our method had significant advantages in discriminating odor samples with similar flavors or with high VOCs release.
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Iskandarani, Mahmoud Zaki. "Detection of Unwanted Odors using Unmasking Odor Algorithm (UOA)." International Journal of Circuits, Systems and Signal Processing 15 (November 10, 2021): 1643–49. http://dx.doi.org/10.46300/9106.2021.15.177.
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A new approach to detection of the existence of unwanted odors after spraying the smart home and vehicular environment with perfumes is considered in the work. The approach is based on registering the response curve of an array of sensors to perfumes and to odors such as herbs, then using the proposed intersection algorithm to uncover the ability of the perfume to mask specific odors. Three odors (herbs) and three perfumes are tried and resulted in the ability of perfumes to mask two of the herbs, one deeper than the other. The response curve intersection technique (RCIT) provides the ability to unmask unwanted odor existence, thus forms the heart of the unmasking odor algorithms (UOA). Mathematical equations are used to prove the concept with digital logic is further used to support the presented algorithm. The research found that using the proposed technique, an odor masked by spraying of perfumes can be unmasked using the RCIT as the case in herb 3 presented in the work. The work also showed the unique curve shape for both perfumes and herbs and the fact that some herbs can be easily masked and hidden within the response of perfumes. In addition, it is shown that the perfumes response is much more complex compared to herbs
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Lebovich, Lior, Michael Yunerman, Viviana Scaiewicz, Yonatan Loewenstein, and Dan Rokni. "Paradoxical relationship between speed and accuracy in olfactory figure-background segregation." PLOS Computational Biology 17, no. 12 (December 6, 2021): e1009674. http://dx.doi.org/10.1371/journal.pcbi.1009674.
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In natural settings, many stimuli impinge on our sensory organs simultaneously. Parsing these sensory stimuli into perceptual objects is a fundamental task faced by all sensory systems. Similar to other sensory modalities, increased odor backgrounds decrease the detectability of target odors by the olfactory system. The mechanisms by which background odors interfere with the detection and identification of target odors are unknown. Here we utilized the framework of the Drift Diffusion Model (DDM) to consider possible interference mechanisms in an odor detection task. We first considered pure effects of background odors on either signal or noise in the decision-making dynamics and showed that these produce different predictions about decision accuracy and speed. To test these predictions, we trained mice to detect target odors that are embedded in random background mixtures in a two-alternative choice task. In this task, the inter-trial interval was independent of behavioral reaction times to avoid motivating rapid responses. We found that increased backgrounds reduce mouse performance but paradoxically also decrease reaction times, suggesting that noise in the decision making process is increased by backgrounds. We further assessed the contributions of background effects on both noise and signal by fitting the DDM to the behavioral data. The models showed that background odors affect both the signal and the noise, but that the paradoxical relationship between trial difficulty and reaction time is caused by the added noise.
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Dobrzyniewski, Dominik, Bartosz Szulczyński, and Jacek Gębicki. "Determination of Odor Air Quality Index (OAQII) Using Gas Sensor Matrix." Molecules 27, no. 13 (June 29, 2022): 4180. http://dx.doi.org/10.3390/molecules27134180.
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This article presents a new way to determine odor nuisance based on the proposed odor air quality index (OAQII), using an instrumental method. This indicator relates the most important odor features, such as intensity, hedonic tone and odor concentration. The research was conducted at the compost screening yard of the municipal treatment plant in Central Poland, on which a self-constructed gas sensor array was placed. It consisted of five commercially available gas sensors: three metal oxide semiconductor (MOS) chemical sensors and two electrochemical ones. To calibrate and validate the matrix, odor concentrations were determined within the composting yard using the field olfactometry technique. Five mathematical models (e.g., multiple linear regression and principal component regression) were used as calibration methods. Two methods were used to extract signals from the matrix: maximum signal values from individual sensors and the logarithm of the ratio of the maximum signal to the sensor baseline. The developed models were used to determine the predicted odor concentrations. The selection of the optimal model was based on the compatibility with olfactometric measurements, taking the mean square error as a criterion and their accordance with the proposed OAQII. For the first method of extracting signals from the matrix, the best model was characterized by RMSE equal to 8.092 and consistency in indices at the level of 0.85. In the case of the logarithmic approach, these values were 4.220 and 0.98, respectively. The obtained results allow to conclude that gas sensor arrays can be successfully used for air quality monitoring; however, the key issues are data processing and the selection of an appropriate mathematical model.
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Klailova, Michelle, and Phyllis C. Lee. "Wild Western Lowland Gorillas Signal Selectively Using Odor." PLoS ONE 9, no. 7 (July 9, 2014): e99554. http://dx.doi.org/10.1371/journal.pone.0099554.
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Batsell, W. Robert, H. Wayne Ludvigson, and Paul M. Kunko. "Odor from rats tasting a signal of illness." Journal of Experimental Psychology: Animal Behavior Processes 16, no. 2 (1990): 193–99. http://dx.doi.org/10.1037/0097-7403.16.2.193.
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Kjelvik, Grete, Hallvard R. Evensmoen, Veronika Brezova, and Asta K. Håberg. "The human brain representation of odor identification." Journal of Neurophysiology 108, no. 2 (July 15, 2012): 645–57. http://dx.doi.org/10.1152/jn.01036.2010.
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Odor identification (OI) tests are increasingly used clinically as biomarkers for Alzheimer's disease and schizophrenia. The aim of this study was to directly compare the neuronal correlates to identified odors vs. nonidentified odors. Seventeen females with normal olfactory function underwent a functional magnetic resonance imaging (fMRI) experiment with postscanning assessment of spontaneous uncued OI. An event-related analysis was performed to compare within-subject activity to spontaneously identified vs. nonidentified odors at the whole brain level, and in anatomic and functional regions of interest (ROIs) in the medial temporal lobe (MTL). Parameter estimate values and blood oxygenated level—dependent (BOLD) signal curves for correctly identified and nonidentified odors were derived from functional ROIs in hippocampus, entorhinal, piriform, and orbitofrontal cortices. Number of activated voxels and max parameter estimate values were obtained from anatomic ROIs in the hippocampus and the entorhinal cortex. At the whole brain level the correct OI gave rise to increased activity in the left entorhinal cortex and secondary olfactory structures, including the orbitofrontal cortex. Increased activation was also observed in fusiform, primary visual, and auditory cortices, inferior frontal plus inferior temporal gyri. The anatomic MTL ROI analysis showed increased activation in the left entorhinal cortex, right hippocampus, and posterior parahippocampal gyri in correct OI. In the entorhinal cortex and hippocampus the BOLD signal increased specifically in response to identified odors and decreased for nonidentified odors. In orbitofrontal and piriform cortices both identified and nonidentified odors gave rise to an increased BOLD signal, but the response to identified odors was significantly greater than that for nonidentified odors. These results support a specific role for entorhinal cortex and hippocampus in OI, whereas piriform and orbitofrontal cortices are active in both smelling and OI. Moreover, episodic as well as semantic memory systems appeared to support OI.
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Croijmans, Ilja, Daniel Beetsma, Henk Aarts, Ilse Gortemaker, and Monique Smeets. "The role of fragrance and self-esteem in perception of body odors and impressions of others." PLOS ONE 16, no. 11 (November 15, 2021): e0258773. http://dx.doi.org/10.1371/journal.pone.0258773.
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Human sweat odor serves as social communication signal for a person’s traits and emotional states. This study explored whether body odors can also communicate information about one’s self-esteem, and the role of applied fragrance in this relationship. Female participants were asked to rate self-esteem and attractiveness of different male contestants of a dating show, while being exposed to male participant’s body odors differing in self-esteem. High self-esteem sweat was rated more pleasant and less intense than low self-esteem sweat. However, there was no difference in perceived self-esteem and attractiveness of male contestants in videos, hence explicit differences in body odor did not transfer to judgments of related person characteristics. When the body odor was fragranced using a fragranced body spray, male contestants were rated as having higher self-esteem and being more attractive. The finding that body odors from male participants differing in self-esteem are rated differently and can be discriminated suggests self-esteem has distinct perceivable olfactory features, but the remaining findings imply that only fragrance affect the psychological impression someone makes. These findings are discussed in the context of the role of body odor and fragrance in human perception and social communication.
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Kawadiya, Siddharth, Claire Welling, Sonia Grego, and Marc A. Deshusses. "Fecal Malodor Detection Using Low-Cost Electrochemical Sensors." Sensors 20, no. 10 (May 20, 2020): 2888. http://dx.doi.org/10.3390/s20102888.
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Technology innovation in sanitation is needed for the 4.2 billion people worldwide, lacking safely managed sanitation services. A major requirement for the adoption of these technologies is the management of malodor around toilet and treatment systems. There is an unmet need for a low-cost instrumented technology for detecting the onset of sanitation malodor and triggering corrective actions. This study combines sensory data with low-cost gas sensor data on malodor emanating from feces. The response of 10 commercial electrochemical gas sensors was collected alongside olfactometric measurements. Odor from fecal specimens at different relevant dilution as well as specimens with pleasant odors as a control were evaluated for a total of 64 responses. Several of the sensors responded positively to the fecal odor, with the formaldehyde, hydrogen sulfide, and ammonia sensors featuring the highest signal to noise ratio. A positive trend was observed between the sensors’ responses and the concentration of the odorant and with odor intensity, but no clear correspondence with dilution to threshold (D/T) values was found. Selected sensors were responsive both above and below the intensity values used as the cutoff for offensive odor, suggesting the possibility of using those sensors to differentiate odor offensiveness based just on the magnitude of their response. The specificity of the sensors suggested that discrimination between the selected non-fecal and fecal odors was possible. This study demonstrates that some of the evaluated sensors could be used to assemble a low-cost malodor warning system.
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Weissburg, Marc J., and David B. Dusenbery. "Behavioral observations and computer simulations of blue crab movement to a chemical source in a controlled turbulent flow." Journal of Experimental Biology 205, no. 21 (November 1, 2002): 3387–98. http://dx.doi.org/10.1242/jeb.205.21.3387.
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SUMMARYThe behavior of crabs tracking odor in turbulent chemical plumes was compared to the performance of computer simulations of search behavior operating in similar chemical signal environments. The movement of blue crabs(Callinectes sapidus) towards a source of food odor was studied in controlled flow conditions in a flume. The evolving chemical stimulus field of a similar chemical source in an equivalent flow environment was captured by recording concentration patterns of a fluorescent tracer. Hypotheses about the sensory mechanisms employed by the crabs were tested by computer simulation using the recorded fluorescence as the stimulus. The results demonstrate that a simple model combining chemotropotaxis (simultaneous, spatial comparisons of chemical signals) and odor-stimulated upstream movement (rheotaxis) is sufficient to explain the efficient movements towards the source displayed by foraging crabs. Spatial integration around each sensor improves performance significantly, but the number of sensors does not have a large impact on performance. The weighting of information from chemical versus flow signals can substantially change simulation performance, resulting in more or less congruence between the behavior of simulations and that of crabs, which suggests the general importance of both sources of information for successful odor-guided navigation.
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R Mohamed, Rajina, Razali Yaacob, Mohamad A Mohamed, Tengku Azahar Tengku Dir, and F. A Rahim. "Food Freshness Using Electronic Nose and Its Classification Method: A Review." International Journal of Engineering & Technology 7, no. 3.28 (August 17, 2018): 49. http://dx.doi.org/10.14419/ijet.v7i3.28.20964.
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Generally, E-nose mimics human olfactory sense to detect and distinguish an odor or gasses or volatile organic compound from a few objects such as food, chemicals, explosive etc. Thus, E-nose can be used to measure gas emitted from food due to its ability to measure gas and odor. Principally, the E-nose operates by using a number of sensors to response to the odorant molecules (aroma). Each sensor will respond to their specific gas respectively. These sensors are a major part of the electronic nose to detect gas or odor contained in a volatile component. Information about the gas detected by sensors will be recorded and transmitted to the signal processing unit to perform the analysis of volatile organic compound (VOC) pattern and stored in the database classification, in order to determine the type of odor. Classification is a way to distinguish a mixture odor/aroma obtained from gas sensors in an electric signal form. In this paper, we discussed briefly about electronic nose, it’s principle of work and classification method and in order to classify food freshness.
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Chen, Cheng-Hsuan, Kuo-Kai Shyu, Cheng-Kai Lu, Chi-Wen Jao, and Po-Lei Lee. "Classification of Prefrontal Cortex Activity Based on Functional Near-Infrared Spectroscopy Data upon Olfactory Stimulation." Brain Sciences 11, no. 6 (May 26, 2021): 701. http://dx.doi.org/10.3390/brainsci11060701.
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The sense of smell is one of the most important organs in humans, and olfactory imaging can detect signals in the anterior orbital frontal lobe. This study assessed olfactory stimuli using support vector machines (SVMs) with signals from functional near-infrared spectroscopy (fNIRS) data obtained from the prefrontal cortex. These data included odor stimuli and air state, which triggered the hemodynamic response function (HRF), determined from variations in oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) levels; photoplethysmography (PPG) of two wavelengths (raw optical red and near-infrared data); and the ratios of data from two optical datasets. We adopted three SVM kernel functions (i.e., linear, quadratic, and cubic) to analyze signals and compare their performance with the HRF and PPG signals. The results revealed that oxyHb yielded the most efficient single-signal data with a quadratic kernel function, and a combination of HRF and PPG signals yielded the most efficient multi-signal data with the cubic function. Our results revealed superior SVM analysis of HRFs for classifying odor and air status using fNIRS data during olfaction in humans. Furthermore, the olfactory stimulation can be accurately classified by using quadratic and cubic kernel functions in SVM, even for an individual participant data set.
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Manabe, Hiroyuki, and Kensaku Mori. "Sniff rhythm-paced fast and slow gamma-oscillations in the olfactory bulb: relation to tufted and mitral cells and behavioral states." Journal of Neurophysiology 110, no. 7 (October 1, 2013): 1593–99. http://dx.doi.org/10.1152/jn.00379.2013.
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Odor signals are conveyed from the olfactory bulb (OB) to the olfactory cortex by two types of projection neurons, tufted cells and mitral cells, which differ in signal timing and firing frequency in response to odor inhalation. Whereas tufted cells respond with early-onset high-frequency burst discharges starting at the middle of the inhalation phase of sniff, mitral cells show odor responses with later-onset lower-frequency burst discharges. Since odor inhalation induces prominent gamma-oscillations of local field potentials (LFPs) in the OB during the transition period from inhalation to exhalation that accompany synchronized spike discharges of tufted cells and mitral cells, we addressed the question of whether the odor-induced gamma-oscillations encompass two distinct gamma-oscillatory sources, tufted cell and mitral cell subsystems, by simultaneously recording the sniff rhythms and LFPs in the OB of freely behaving rats. We observed that individual sniffs induced nested gamma-oscillations with two distinct parts during the inhalation-exhalation transition period: early-onset fast gamma-oscillations followed by later-onset slow gamma-oscillations. These results suggest that tufted cells carry odor signals with early-onset fast gamma-synchronization at the early phase of sniff, whereas mitral cells send them with later-onset slow gamma-synchronization. We also observed that each sniff typically induced both fast and slow gamma-oscillations during awake, whereas respiration during slow-wave sleep and rapid-eye-movement sleep failed to induce these oscillations. These results suggest that behavioral states regulate the generation of sniff rhythm-paced fast and slow gamma-oscillations in the OB.
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Yan, Fenxia, Zilong Gao, Pin Chen, Li Huang, Dangui Wang, Na Chen, Ruixiang Wu, et al. "Coordinated Plasticity between Barrel Cortical Glutamatergic and GABAergic Neurons during Associative Memory." Neural Plasticity 2016 (2016): 1–20. http://dx.doi.org/10.1155/2016/5648390.
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Neural plasticity is associated with memory formation. The coordinated refinement and interaction between cortical glutamatergic and GABAergic neurons remain elusive in associative memory, which we examine in a mouse model of associative learning. In the mice that show odorant-induced whisker motion after pairing whisker and odor stimulations, the barrel cortical glutamatergic and GABAergic neurons are recruited to encode the newly learnt odor signal alongside the innate whisker signal. These glutamatergic neurons are functionally upregulated, and GABAergic neurons are refined in a homeostatic manner. The mutual innervations between these glutamatergic and GABAergic neurons are upregulated. The analyses by high throughput sequencing show that certain microRNAs related to regulating synapses and neurons are involved in this cross-modal reflex. Thus, the coactivation of the sensory cortices through epigenetic processes recruits their glutamatergic and GABAergic neurons to be the associative memory cells as well as drive their coordinated refinements toward the optimal state for the storage of the associated signals.
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Kay, Leslie M., and Jennifer Beshel. "A Beta Oscillation Network in the Rat Olfactory System During a 2-Alternative Choice Odor Discrimination Task." Journal of Neurophysiology 104, no. 2 (August 2010): 829–39. http://dx.doi.org/10.1152/jn.00166.2010.
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We previously showed that in a two-alternative choice (2AC) task, olfactory bulb (OB) gamma oscillations (∼70 Hz in rats) were enhanced during discrimination of structurally similar odorants (fine discrimination) versus discrimination of dissimilar odorants (coarse discrimination). In other studies (mostly employing go/no-go tasks) in multiple labs, beta oscillations (15–35 Hz) dominate the local field potential (LFP) signal in olfactory areas during odor sampling. Here we analyzed the beta frequency band power and pairwise coherence in the 2AC task. We show that in a task dominated by gamma in the OB, beta oscillations are also present in three interconnected olfactory areas (OB and anterior and posterior pyriform cortex). Only the beta band showed consistently elevated coherence during odor sniffing across all odor pairs, classes (alcohols and ketones), and discrimination types (fine and coarse), with stronger effects in first than in final criterion sessions (>70% correct). In the first sessions for fine discrimination odor pairs, beta power for incorrect trials was the same as that for correct trials for the other odor in the pair. This pattern was not repeated in coarse discrimination, in which beta power was elevated for correct relative to incorrect trials. This difference between fine and coarse odor discriminations may relate to different behavioral strategies for learning to differentiate similar versus dissimilar odors. Phase analysis showed that the OB led both pyriform areas in the beta frequency band during odor sniffing. We conclude that the beta band may be the means by which information is transmitted from the OB to higher order areas, even though task specifics modify dominance of one frequency band over another within the OB.
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Xue, Jingyi, Jinqin Wang, Shiang Hu, Ning Bi, and Zhao Lv. "OVPD: Odor-Video Elicited Physiological Signal Database for Emotion Recognition." IEEE Transactions on Instrumentation and Measurement 71 (2022): 1–12. http://dx.doi.org/10.1109/tim.2022.3149116.
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Zufall, Frank, Trese Leinders-Zufall, and Charles A. Greer. "Amplification of Odor-Induced Ca2+ Transients by Store-Operated Ca2+ Release and Its Role in Olfactory Signal Transduction." Journal of Neurophysiology 83, no. 1 (January 1, 2000): 501–12. http://dx.doi.org/10.1152/jn.2000.83.1.501.
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A critical role of Ca2+ in vertebrate olfactory receptor neurons (ORNs) is to couple odor-induced excitation to intracellular feedback pathways that are responsible for the regulation of the sensitivity of the sense of smell, but the role of intracellular Ca2+ stores in this process remains unclear. Using confocal Ca2+ imaging and perforated patch recording, we show that salamander ORNs contain a releasable pool of Ca2+ that can be discharged at rest by the SERCA inhibitor thapsigargin and the ryanodine receptor agonist caffeine. The Ca2+ stores are spatially restricted; emptying produces compartmentalized Ca2+ release and capacitative-like Ca2+ entry in the dendrite and soma but not in the cilia, the site of odor transduction. We deplete the stores to show that odor stimulation causes store-dependent Ca2+ mobilization. This odor-induced Ca2+ release does not seem to be necessary for generation of an immediate electrophysiological response, nor does it contribute significantly to the Ca2+ transients in the olfactory cilia. Rather, it is important for amplifying the magnitude and duration of Ca2+ transients in the dendrite and soma and is thus necessary for the spread of an odor-induced Ca2+ wave from the cilia to the soma. We show that this amplification process depends on Ca2+-induced Ca2+ release. The results indicate that stimulation of ORNs with odorants can produce Ca2+ mobilization from intracellular stores without an immediate effect on the receptor potential. Odor-induced, store-dependent Ca2+ mobilization may be part of a feedback pathway by which information is transferred from the distal dendrite of an ORN to its soma.
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Chen, Li Wei, Jian Hua Yang, and Zhong Lin Tang. "Experimental Study on Odor Compass System Based on Gas Sensor Array and DSP Technology." Advanced Materials Research 317-319 (August 2011): 1102–6. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.1102.
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Abstract. Based on metal oxide gas sensors and DSP technology an odor compass is designed in this paper. Odor compass estimates direction of point odor source by analyzing responses of sensors which are placed on different concentration gradient. Main structure consists of distributed metal oxide gas sensors and plexiglas material. Signal sampling and processing are accomplished by DSP system. The directivity of whole system is tested in uniform wind field. Experimental result shows that the responses for the odor sources with 30°disparity have obvious difference. Ratio of resistance response is selected as characteristic quantity. In this way, influence which is generated from individual difference of sensors is effectively eliminated.
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Wiesel, Eric, Sabine Kaltofen, Bill S. Hansson, and Dieter Wicher. "Homeostasis of Mitochondrial Ca2+ Stores Is Critical for Signal Amplification in Drosophila melanogaster Olfactory Sensory Neurons." Insects 13, no. 3 (March 9, 2022): 270. http://dx.doi.org/10.3390/insects13030270.
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Insects detect volatile chemosignals with olfactory sensory neurons (OSNs) that express olfactory receptors. Among them, the most sensitive receptors are the odorant receptors (ORs), which form cation channels passing Ca2+. OSNs expressing different groups of ORs show varying optimal odor concentration ranges according to environmental needs. Certain types of OSNs, usually attuned to high odor concentrations, allow for the detection of even low signals through the process of sensitization. By increasing the sensitivity of OSNs upon repetitive subthreshold odor stimulation, Drosophila melanogaster can detect even faint and turbulent odor traces during flight. While the influx of extracellular Ca2+ has been previously shown to be a cue for sensitization, our study investigates the importance of intracellular Ca2+ management. Using an open antenna preparation that allows observation and pharmacological manipulation of OSNs, we performed Ca2+ imaging to determine the role of Ca2+ storage in mitochondria. By disturbing the mitochondrial resting potential and induction of the mitochondrial permeability transition pore (mPTP), we show that effective storage of Ca2+ in the mitochondria is vital for sensitization to occur, and release of Ca2+ from the mitochondria to the cytoplasm promptly abolishes sensitization. Our study shows the importance of cellular Ca2+ management for sensitization in an effort to better understand the underlying mechanics of OSN modulation.
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Chang, Zhi Yong, Dong Hui Chen, Zhi Hong Zhang, Yue Ying Tong, Jin Tong, and Lu Dai. "Design of a Bionic Olfactory, Tactile Integrated System and its Application in Chicken Meat Quality Inspection." Applied Mechanics and Materials 461 (November 2013): 814–21. http://dx.doi.org/10.4028/www.scientific.net/amm.461.814.
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This study is aiming at the practical problem of meat freshness evaluation. Since meat putrefaction is a complex process that is influenced by many factors, it is necessary to have a comprehensive investigation of the various indicators to determine the freshness of meat. This research integrated information from a multisensory system to reduce uncertainty of evaluation. According to the odor mechanism model of rotten chicken, six types of sensors were chosen, which were combined as array for olfactory experiments. WDW-20 electronic universal testing machine (UTM) was adopted as tactile sensing device. As a bionic tactile test part, the UTM head is to obtain pressure characteristic curves of the meat. According to the odor model and elastic mechanics parameters of the chicken, the mechanical parameters were analyzed under the condition of cold storage, as well as time-varying results of fingerprint odor signal and salt base nitrogen volatile signal. Then, established the meat odor, elastic mechanics and freshness parameters, which were integrated into a fusion system and combined with the data through the experimental test. Eventually, established the mathematical model among meat odor, elastic mechanics parameters and meat freshness. This study provides theory reference for the evaluation of meat freshness, and delivers new thought and method for the design of multiphase bionic intelligent electrical measuring equipment.
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Watson, Susan B. "AQUATIC TASTE AND ODOR: A PRIMARY SIGNAL OF DRINKING-WATER INTEGRITY." Journal of Toxicology and Environmental Health, Part A 67, no. 20-22 (October 2004): 1779–95. http://dx.doi.org/10.1080/15287390490492377.
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Milinski, Manfred. "A Review of Suggested Mechanisms of MHC Odor Signaling." Biology 11, no. 8 (August 7, 2022): 1187. http://dx.doi.org/10.3390/biology11081187.
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Although an individual’s mix of MHC immune genes determines its resistance, finding MHC-dependent mate choice occurred by accident in inbred mice. Inbred mice prefer MHC dissimilar mates, even when the choice was restricted to urine. It took decades to find the info-chemicals, which have to be as polymorphic as the MHC. Microbiota were suggested repeatedly as the origin of the odor signal though germ-free mice maintained normal preference. Different versions of the ‘carrier hypothesis’ suggested MHC molecules carry volatiles after the bound peptide is released. Theory predicted an optimal individual MHC diversity to maximize resistance. The optimally complementary mate should be and is preferred as several studies show. Thus, the odor signal needs to transmit the exact information of the sender’s MHC alleles, as do MHC ligand peptides but not microbiota. The ‘MHC peptide hypothesis’ assumes that olfactory perception of the peptide ligand provides information about the MHC protein in a key-lock fashion. Olfactory neurons react only to the anchors of synthesized MHC peptides, which reflect the binding MHC molecule’s identity. Synthesized peptides supplemented to a male’s signal affect choice in the predicted way, however, not when anchors are mutated. Also, the human brain detects smelled synthesized self-peptides as such. After mate choice, the lottery of meiosis of randomly paired oocyte and sperm haplotypes would often produce MHC non-optimal offspring. In sticklebacks, eggs select MHC-compatible sperm, thus prefer the best combination close to the population optimum.
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Zhang, Peng, Chun Yang, and Rona J. Delay. "Odors activate dual pathways, a TRPC2 and a AA-dependent pathway, in mouse vomeronasal neurons." American Journal of Physiology-Cell Physiology 298, no. 5 (May 2010): C1253—C1264. http://dx.doi.org/10.1152/ajpcell.00271.2009.
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Located at the anterior portion of the nose, the paired vomeronasal organs (VNO) detect odors and pheromones. In vomeronasal sensory neurons (VSNs) odor responses are mainly mediated by phospholipase C (PLC), stimulation of which elevates diacylglycerol (DAG). DAG activates a transient receptor potential channel (TRPC2) leading to cell depolarization. In this study, we used a natural stimulus, urine, to elicit odor responses in VSNs and found urine responses persisted in TRPC2−/− mice, suggesting the existence of a TRPC2-independent signal transduction pathway. Using perforated patch-clamp recordings on isolated VSNs from wild-type (WT) and TRPC2−/− mice, we found a PLC inhibitor blocked urine responses from all VSNs. Furthermore, urine responses were reduced by blocking DAG lipase, an enzyme that produces arachidonic acid (AA), in WT mice and abolished in TRPC2−/− mice. Consistently, direct stimulation with AA activated an inward current that was independent of TRPC2 channels but required bath Ca2+ and was blocked by Cd2+. With the use of inside-out patches from TRPC2−/− VSNs, we show that AA activated a channel that also required Ca2+. Together, these data from WT and TRPC2−/− mice suggest that both DAG and its metabolite, AA, mediate excitatory odor responses in VSNs, by activating two types of channels, a TRPC2 and a separate Ca2+-permeable channel.
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Tonacci, Alessandro, Jessica Di Monte, Maria Beatrice Meucci, Francesco Sansone, Anna Paola Pala, Lucia Billeci, and Raffaele Conte. "Wearable Sensors to Characterize the Autonomic Nervous System Correlates of Food-Like Odors Perception: A Pilot Study." Electronics 8, no. 12 (December 4, 2019): 1481. http://dx.doi.org/10.3390/electronics8121481.
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Background: The sense of smell has been recently recognized as one of the most important sensory features in the human being, representing a reliable biomarker for a number of clinical conditions. The relationship between olfactory function and the person’s attitude towards food has frequently been investigated, often using questionnaires. The administration of minimally invasive methods for characterizing autonomic nervous system (ANS) functionality could help in objectivizing such measurements. Methods: The present study assessed ANS activation through the analysis of the electrocardiogram (ECG) and galvanic skin response (GSR) signals, in response to olfactory stimuli using non-invasive wearable devices. The ANS activation was also studied with respect to the odor familiarity, as well as with other olfactory and food dimensions (e.g., odor identification, odor pleasantness, food neophobia). Results: We demonstrated a significant activation of the ANS, in particular of its sympathetic branch, during the olfactory stimulation, with the ECG signal seen as more sensitive to detect ANS response to moderate olfactory stimuli rather than the GSR. Conclusions: When applied to a greater number of subjects, or to specific groups of patients, this methodology could represent a promising, reliable addition to diagnostic methods currently used in clinical settings.
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Pellegrino, R., A. Hahner, V. Bojanowski, C. Hummel, J. Gerber, and T. Hummel. "Olfactory function in patients with hyposmia compared to healthy subjects - An fMRI study." Rhinology journal 54, no. 4 (December 1, 2016): 374–81. http://dx.doi.org/10.4193/rhino16.098.
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Background: Individuals with hyposmia, or the partial loss of smell, represent a large sector (15 %) of the population that is likely to grow with the current aging population; however, our understanding to how hyposmics centrally process odors is still not clear. One popular non-invasive tool for in vivo imaging of biological activity among human brains has been function magnetic resonance imaging (fMRI) which uses blood-oxygenation level dependent (BOLD) signal as an indirect measurement. Therefore, the aim of this study was to understand differences in olfaction processing between patients with hyposmia and healthy controls using functional magnetic resonance imaging (fMRI). Methodology: Eleven hyposmic and 12 healthy, normosmic subjects were exposed to two different food-related odors (coffee and peach) during a block-designed fMRI session. Additionally, odor perception qualities were rated for each odor throughout the scanning session. Results: The activations of the normosmic group were localized in typical olfactory areas (insula, orbitofrontal cortex [OFC], limbic system and amygdala). The hyposmic group showed similar regions of activation (insula, OFC, limbic system), however, less activation was found in the amygdala, left anterior cingulate and right OFC, but higher activation was shown in the right parahippocampal and both the left and right posterior cingulate gyrus which are assumed to play an important role in the processing and remembrance of memories. Conclusions: These results indicate similar central olfactory processing among groups, yet subjects with partial loss may attempt to compensate smell impairment with odor memory or higher motivation to smell.
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Chen, Wen-Hsuan, Anthony Bain, Sheng-Yang Wang, Yi-Chiao Ho, and Hsy-Yu Tzeng. "Mediation of a Mutualistic Conflict for Pollination via Fig Phenology and Odor Recognition between Ficus and Fig Wasp." Plants 11, no. 19 (October 3, 2022): 2603. http://dx.doi.org/10.3390/plants11192603.
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The vegetative and reproductive growth of plants provide the basic tempo for an ecosystem, and when species are interdependent, phenology becomes crucial to regulating the quantity and quality of the interactions. In plant–insect interactions, the plants signal the beginning of their reproductive period with visual and chemical cues; however, in the case of Ficus mutualism, the cues are strictly chemical. The volatile organic compounds emitted by a fig species are a unique, specific blend that provides a signal to mutualistic wasps that the figs are receptive for pollination. In this study, we studied both the phenological pattern of Ficus septica in Central Taiwan and its emissions of volatile compounds at receptivity. This dioecious fig species displays a pattern of continuous vegetative and reproductive production all through the year with a decrease in winter. In parallel, the odor blends emitted by male and female trees are similar but with seasonal variations; these are minimal during winter and increase with the size of the wasp population during the favorable season. In addition, the pollinating females cannot distinguish between the male and female summer odor blends. The link between odor similarity, pollinators and intersexual conflict is discussed.
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Fletcher, Max L., Arjun V. Masurkar, Junling Xing, Fumiaki Imamura, Wenhui Xiong, Shin Nagayama, Hiroki Mutoh, Charles A. Greer, Thomas Knöpfel, and Wei R. Chen. "Optical Imaging of Postsynaptic Odor Representation in the Glomerular Layer of the Mouse Olfactory Bulb." Journal of Neurophysiology 102, no. 2 (August 2009): 817–30. http://dx.doi.org/10.1152/jn.00020.2009.
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Olfactory glomeruli are the loci where the first odor-representation map emerges. The glomerular layer comprises exquisite local synaptic circuits for the processing of olfactory coding patterns immediately after their emergence. To understand how an odor map is transferred from afferent terminals to postsynaptic dendrites, it is essential to directly monitor the odor-evoked glomerular postsynaptic activity patterns. Here we report the use of a transgenic mouse expressing a Ca2+-sensitive green fluorescence protein (GCaMP2) under a Kv3.1 potassium-channel promoter. Immunostaining revealed that GCaMP2 was specifically expressed in mitral and tufted cells and a subpopulation of juxtaglomerular cells but not in olfactory nerve terminals. Both in vitro and in vivo imaging combined with glutamate receptor pharmacology confirmed that odor maps reported by GCaMP2 were of a postsynaptic origin. These mice thus provided an unprecedented opportunity to analyze the spatial activity pattern reflecting purely postsynaptic olfactory codes. The odor-evoked GCaMP2 signal had both focal and diffuse spatial components. The focalized hot spots corresponded to individually activated glomeruli. In GCaMP2-reported postsynaptic odor maps, different odorants activated distinct but overlapping sets of glomeruli. Increasing odor concentration increased both individual glomerular response amplitude and the total number of activated glomeruli. Furthermore, the GCaMP2 response displayed a fast time course that enabled us to analyze the temporal dynamics of odor maps over consecutive sniff cycles. In summary, with cell-specific targeting of a genetically encoded Ca2+ indicator, we have successfully isolated and characterized an intermediate level of odor representation between olfactory nerve input and principal mitral/tufted cell output.
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Reisert, J., and D. Restrepo. "Molecular Tuning of Odorant Receptors and Its Implication for Odor Signal Processing." Chemical Senses 34, no. 7 (June 12, 2009): 535–45. http://dx.doi.org/10.1093/chemse/bjp028.
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Doty, R. L., and M. Ferguson-Segall. "Odor detection performance of rats followingd-amphetamine treatment: a signal detection analysis." Psychopharmacology 93, no. 1 (September 1987): 87–93. http://dx.doi.org/10.1007/bf02439592.
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KAY, LESLIE M., LARRY R. LANCASTER, and WALTER J. FREEMAN. "REAFFERENCE AND ATTRACTORS IN THE OLFACTORY SYSTEM DURING ODOR RECOGNITION." International Journal of Neural Systems 07, no. 04 (September 1996): 489–95. http://dx.doi.org/10.1142/s0129065796000476.
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Olfactory bulb activity has been postulated to be chaotic, as measured in the EEG, and to be subject to an attractor with many “wings” enabling classification of different learned odor classes. Two parallel questions are thus addressed by the work presented here: (1) what is the evidence for attractors in the olfactory system, which can mediate learned odor classes? and (2) how does the olfactory system enter a specific attractor or attractor wing associated with the learned odor during the classification process? Both of these questions address the wider notion of endogenous activity preparing the system for an expected stimulus, which is at the basis of the reafference principle. By viewing the brain as a distributed complex dynamical system with global attractors, these questions can be answered together. Rats were implanted with bipolar macroelectrodes in the Olfactory Bulb (OB), Prepyriform Cortex (PPC), Entorhinal Cortex (EC), and Dentate Gyrus (DG), and then trained in an operant paradigm to press a bar for a reward in the presence of one odor and to receive no reward in the presence of another odor. Local Field Potentials (LFP) were recorded simultaneously from the structures during the operant task. We present evidence for three endogenous events: (1) preafference, which is manifested both by the EC entering an attractor and a mid-range signal (15–30 Hz) which appears to be passed from the EC to the OB just before the OB enters an attractor; (2) afference, where the OB enters an attractor during the odor recognition period of the experiment and the LFP recordings indicate that the OB drives the other structures in all frequency bands, especially the high gamma band (65–100 Hz) associated with the OB burst frequency; and (3) reafference or post-afference, which is accompanied by a lower frequency gamma band signal (40–60 Hz) originating in the PPC and passed to both the OB and the EC just before the onset of the motor response to the odor. We use a new method, NECTAR (Nonparametric Exact Contingency Table Association Routine), related to mutual information, to verify what is seen with coherence and phase estimates, the apparent driving of each structure at different times in the odor trials, and to display evidence for non-periodic attractors governing both individual physiological structures and the system of structures. This is the first evidence of an endogenous, limbic event associated with sensory perceptual tuning in a mammal. These results are also the first experimental confirmation that the attractors governing olfactory activity involve multiple sites in the olfactory/limbic system and implement the process of attention.
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Filla, Ina, and Randolf Menzel. "Mushroom body extrinsic neurons in the honeybee (Apis mellifera) brain integrate context and cue values upon attentional stimulus selection." Journal of Neurophysiology 114, no. 3 (September 2015): 2005–14. http://dx.doi.org/10.1152/jn.00776.2014.
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Multimodal GABA-immunoreactive feedback neurons in the honeybee brain connecting the output region of the mushroom body with its input are expected to tune the input to the mushroom body in an experience-dependent way. These neurons are known to change their rate responses to learned olfactory stimuli. In this work we ask whether these neurons also transmit learned attentional effects during multisensory integration. We find that a visual context and an olfactory cue change the rate responses of these neurons after learning according to the associated values of both context and cue. The learned visual context promotes attentional response selection by enhancing olfactory stimulus valuation at both the behavioral and the neural level. During a rewarded visual context, bees reacted faster and more reliably to a rewarded odor. We interpreted this as the result of the observed enhanced neural discharge toward the odor. An unrewarded context reduced already low rate responses to the unrewarded odor. In addition to stimulus valuation, these feedback neurons generate a neural error signal after an incorrect behavioral response. This might act as a learning signal in feedback neurons. All of these effects were exclusively found in trials in which the animal prepares for a motor response that happens during attentional stimulus selection. We discuss possible implications of the results for the feedback connections of the mushroom body.
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Yamagata, Nobuhiro, Toshiharu Ichinose, Yoshinori Aso, Pierre-Yves Plaçais, Anja B. Friedrich, Richard J. Sima, Thomas Preat, Gerald M. Rubin, and Hiromu Tanimoto. "Distinct dopamine neurons mediate reward signals for short- and long-term memories." Proceedings of the National Academy of Sciences 112, no. 2 (December 29, 2014): 578–83. http://dx.doi.org/10.1073/pnas.1421930112.
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Drosophila melanogaster can acquire a stable appetitive olfactory memory when the presentation of a sugar reward and an odor are paired. However, the neuronal mechanisms by which a single training induces long-term memory are poorly understood. Here we show that two distinct subsets of dopamine neurons in the fly brain signal reward for short-term (STM) and long-term memories (LTM). One subset induces memory that decays within several hours, whereas the other induces memory that gradually develops after training. They convey reward signals to spatially segregated synaptic domains of the mushroom body (MB), a potential site for convergence. Furthermore, we identified a single type of dopamine neuron that conveys the reward signal to restricted subdomains of the mushroom body lobes and induces long-term memory. Constant appetitive memory retention after a single training session thus comprises two memory components triggered by distinct dopamine neurons.
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Somboon, Pakpum, Bartosz Wyszynski, and Takamichi Nakamoto. "Odor Recorder Capable of Wide Dynamic Recordable Range Based on Higher Order Sensing and Signal Extraction Technique for Small Signal." IEEE Sensors Journal 9, no. 2 (February 2009): 93–102. http://dx.doi.org/10.1109/jsen.2008.2011072.
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Ruiz-May, Eliel, Alma Altúzar-Molina, José M. Elizalde-Contreras, Jiovanny Arellano-de los Santos, Juan Monribot-Villanueva, Larissa Guillén, Mirna Vázquez-Rosas-Landa, et al. "A First Glimpse of the Mexican Fruit Fly Anastrepha ludens (Diptera: Tephritidae) Antenna Morphology and Proteome in Response to a Proteinaceous Attractant." International Journal of Molecular Sciences 21, no. 21 (October 29, 2020): 8086. http://dx.doi.org/10.3390/ijms21218086.
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Anastrepha ludens is a key pest of mangoes and citrus from Texas to Costa Rica but the mechanisms of odorant perception in this species are poorly understood. Detection of volatiles in insects occurs mainly in the antenna, where molecules penetrate sensillum pores and link to soluble proteins in the hemolymph until reaching specific odor receptors that trigger signal transduction and lead to behavioral responses. Scrutinizing the molecular foundation of odorant perception in A. ludens is necessary to improve biorational management strategies against this pest. After exposing adults of three maturity stages to a proteinaceous attractant, we studied antennal morphology and comparative proteomic profiles using nano-LC-MS/MS with tandem mass tags combined with synchronous precursor selection (SPS)-MS3. Antennas from newly emerged flies exhibited dense agglomerations of olfactory sensory neurons. We discovered 4618 unique proteins in the antennas of A. ludens and identified some associated with odor signaling, including odorant-binding and calcium signaling related proteins, the odorant receptor co-receptor (Orco), and putative odorant-degrading enzymes. Antennas of sexually immature flies exhibited the most upregulation of odor perception proteins compared to mature flies exposed to the attractant. This is the first report where critical molecular players are linked to the odor perception mechanism of A. ludens.
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Yang, Chun, and Rona J. Delay. "Calcium-activated chloride current amplifies the response to urine in mouse vomeronasal sensory neurons." Journal of General Physiology 135, no. 1 (December 28, 2009): 3–13. http://dx.doi.org/10.1085/jgp.200910265.
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The vomeronasal organ (VNO) is an odor detection system that mediates many pheromone-sensitive behaviors. Vomeronasal sensory neurons (VSNs), located in the VNO, are the initial site of interaction with odors/pheromones. However, how an individual VSN transduces chemical signals into electrical signals is still unresolved. Here, we show that a Ca2+-activated Cl− current contributes ∼80% of the response to urine in mouse VSNs. Using perforated patch clamp recordings with gramicidin, which leaves intracellular chloride undisrupted, we found that the urine-induced inward current (Vhold = −80 mV) was decreased in the presence of chloride channel blockers. This was confirmed using whole cell recordings and altering extracellular chloride to shift the reversal potential. Further, the urine-induced currents were eliminated when both extracellular Ca2+ and Na+ were removed. Using inside-out patches from dendritic tips, we recorded Ca2+-activated Cl− channel activity. Several candidates for this Ca2+-activated Cl− channel were detected in VNO by reverse transcription–polymerase chain reaction. In addition, a chloride cotransporter, Na+-K+-2Cl− isoform 1, was detected and found to mediate much of the chloride accumulation in VSNs. Collectively, our data demonstrate that chloride acts as a major amplifier for signal transduction in mouse VSNs. This amplification would increase the responsiveness to pheromones or odorants.
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Roppel, Thaddeus, and Denise M. Wilson. "Biologically-inspired pattern recognition for odor detection." Pattern Recognition Letters 21, no. 3 (March 2000): 213–19. http://dx.doi.org/10.1016/s0167-8655(99)00150-6.
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Menco, Bert Ph M. "Ultrastructural aspects of olfactory signal transduction and its development." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 142–43. http://dx.doi.org/10.1017/s042482010016844x.
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Vertebrate olfactory receptor cells are specialized neurons that have numerous long tapering cilia. The distal parts of these cilia line the interface between the external odorous environment and the luminal surface of the olfactory epithelium. The length and number of these cilia results in a large surface area that presumably increases the chance that an odor molecule will meet a receptor cell. Advanced methods of cryoprepration and immuno-gold labeling were particularly useful to preserve the delicate ultrastructural and immunocytochemical features of olfactory cilia required for localization of molecules involved in olfactory signal-transduction. We subjected olfactory tissues to freeze-substitution in acetone (unfixed tissues) or methanol (fixed tissues) followed by low temperature embedding in Lowicryl K11M for that purpose. Tissue sections were immunoreacted with several antibodies against proteins that are presumably important in olfactory signal-transduction.
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Heba, Stefanie, Matthias Sczesny-Kaiser, Kirsten Sucker, Jürgen Bünger, Thomas Brüning, Martin Tegenthoff, and Tobias Schmidt-Wilcke. "Pain Perception, Brain Connectivity, and Neurochemistry in Healthy, Capsaicin-Sensitive Subjects." Neural Plasticity 2020 (October 28, 2020): 1–11. http://dx.doi.org/10.1155/2020/9125913.
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Most of the occupational exposure limits (OELs) are based on local irritants. However, exposure to much lower concentrations of irritant substances can also lead to health complaints from workers. Exposure to irritants is often accompanied by strong unpleasant odors, and strong odors might have distracting effects and hence pose a safety risk. The findings obtained in human exposure studies with chemically sensitive, stressed, or anxious persons suggest that their ability to direct attention away from the odorous exposure and to focus on a cognitive task is reduced. In addition, after repeated odor exposure, these persons show signs of sensitization, i.e., difficulties in ignoring or getting used to the exposure. The question arises as to whether certain health conditions are accompanied by a change in sensitivity to odors and irritants, so that these persons are potentially more distracted by odors and irritants and therefore more challenged in working memory tasks than nonsusceptible persons. In our study, susceptible persons with sensory airway hyperreactivity (“capsaicin-sensitive”) respond more strongly to mechanical skin stimuli than controls and show altered network connectivity. Capsaicin-sensitive subjects have a lower pain threshold and thus are more sensitive to mechanical skin stimuli. The intrinsic functional connectivity of their saliency network is higher, and the lower the GABAergic tone of the thalamus, the higher their pain sensitivity to mechanical stimuli. It seems that the increased communication between resting-state networks promotes a stronger perception of the sensory input signal. The results can be used to inform about actual risks (i.e., attention diversion and increased risk of accidents) and “pseudo” risks such as odor perception without a negative impact on one’s well-being. This way, uncertainties that still prevail in the health assessment of odorous and sensory irritating chemicals could be reduced.
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Reidt, Ulrich, Andreas Helwig, Gerhard Müller, Lutz Plobner, Veronika Lugmayr, Sergey Kharin, Yuri Smirnov, et al. "Detection of Microorganisms Onboard the International Space Station Using an Electronic Nose." Gravitational and Space Research 5, no. 2 (July 21, 2020): 89–111. http://dx.doi.org/10.2478/gsr-2017-0013.
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AbstractWe report on the detection of microorganisms onboard the International Space Station (ISS) using an electronic nose we named the E-Nose. The E-Nose, containing an array of ten different metal oxide gas sensors, was trained on Earth to detect the four most abundant microorganisms that are known to exist onboard the ISS. To assess its performance in space, the E-Nose was brought to the ISS and three measurement campaigns were carried out in three different locations inside the ISS during a 5-month mission. At the end of this mission, all investigated locations were wiped with swabs, and the swabs and odor sensor signal data were sent back to Earth for an in-depth analysis in earthbound laboratories. The in-space measurements were compared with an odor database containing four organisms, but a consensus odor could not be identified. Microbiological results could not provide clues to the smell that was measured. The yeast Rhodotorula mucilaginosa was identified in the literature as the most probable candidate for the unknown odor. Further investigations showed that the smell of Rhodotorula mucilaginosa matches very well with the data obtained inside the ISS. Finally, Rhodotorula mucilaginosa DNA was identified in swabs taken from the sleeping cabin of the astronaut, which confirms the assumption that the yeast Rhodotorula mucilaginosa was actually measured in space by the E-Nose.
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Del-Claro, Kleber, and Paulo S. M. Pacheco. "Nestmate Recognition in the Amazonian Myrmecophyte Ant Pseudomyrmex concolor Smith (Hymenoptera, Formicidae)." Sociobiology 62, no. 3 (September 30, 2015): 356. http://dx.doi.org/10.13102/sociobiology.v62i3.746.
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Nestmate recognition is fundamental to colonial cohesion in social insects, since it allows altruistic behavior towards relatives, recognition of intruders, territorial monopoly and resources defense. In ants, olfactory cues is a key factor in this process. Pseudomyrmex concolor is a highly aggressive ant that defends their host plant Tachigali myrmecophila against herbivores. However, this defense depends on the ant ability to discriminate in order to treat differentially between members of their own colony and intruders . In this study we investigated “whether” and “how” P. concolor recognizes nestmates from non-nestmates. We hypothesized that P. concolor is skillful in recognizing nestmates and tested it in field with experiments using nestmates and non-nestmates. Additionally, to test the efficiency of resident ants against intraspecific competition during colony foundation, we simulate the plant occupation by a competitor queen, introducing non-nestmates queens in plants previously occupied by P. concolor. For the issue of the "how", we hypothesized that the main cue used by this ant in nestmate recognition is olfactory signal. Thus, we tested adaptive threshold model, which predicts that, if the individual odor and colony’s internal template are discrepant enough, the resident nestmate will behave aggressively towards incoming individuals. In this case, we confined nestmates with non-nestmates odors, and then, we reintroduced them in its host plants. In each experiment the frequency of aggressive behaviors were recorded and compared. Results showed that P. concolor recognize and discriminate nestmates from non-nestmates workers (biting and stinging them) and exclude potential competitors queens. Workers reintroduced in their own colony after impregnated with non-familiar odor were treated as non-nestmates. The adaptive threshold hypothesis was confirmed, the main cue used by this ant species in nestmate recognition is olfactory signals.
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Fuscà, Debora, and Peter Kloppenburg. "Odor processing in the cockroach antennal lobe—the network components." Cell and Tissue Research 383, no. 1 (January 2021): 59–73. http://dx.doi.org/10.1007/s00441-020-03387-3.
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AbstractHighly interconnected neural networks perform olfactory signal processing in the central nervous system. In insects, the first synaptic processing of the olfactory input from the antennae occurs in the antennal lobe, the functional equivalent of the olfactory bulb in vertebrates. Key components of the olfactory network in the antennal lobe are two main types of neurons: the local interneurons and the projection (output) neurons. Both neuron types have different physiological tasks during olfactory processing, which accordingly require specialized functional phenotypes. This review gives an overview of important cell type-specific functional properties of the different types of projection neurons and local interneurons in the antennal lobe of the cockroach Periplaneta americana, which is an experimental system that has elucidated many important biophysical and cellular bases of intrinsic physiological properties of these neurons.
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Fleischer, Joerg, Pablo Pregitzer, Heinz Breer, and Jürgen Krieger. "Access to the odor world: olfactory receptors and their role for signal transduction in insects." Cellular and Molecular Life Sciences 75, no. 3 (August 21, 2017): 485–508. http://dx.doi.org/10.1007/s00018-017-2627-5.
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Qi, Guangyu, Fangfang Qu, Lu Zhang, Shihao Chen, Mengyuan Bai, Mengjiao Hu, Xinyan Lv, Jinglei Zhang, Zhenhe Wang, and Wei Chen. "Nanoporous Graphene Oxide-Based Quartz Crystal Microbalance Gas Sensor with Dual-Signal Responses for Trimethylamine Detection." Sensors 22, no. 24 (December 16, 2022): 9939. http://dx.doi.org/10.3390/s22249939.
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This paper presents a straightforward method to develop a nanoporous graphene oxide (NGO)-functionalized quartz crystal microbalance (QCM) gas sensor for the detection of trimethylamine (TMA), aiming to form a reliable monitoring mechanism strategy for low-concentration TMA that can still cause serious odor nuisance. The synthesized NGO material was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its structure and morphology. Compared with the bare and GO-based QCM sensors, the NGO-based QCM sensor exhibited ultra-high sensitivity (65.23 Hz/μL), excellent linearity (R2 = 0.98), high response/recovery capability (3 s/20 s) and excellent repeatability (RSD = 0.02, n = 3) toward TMA with frequency shift and resistance. Furthermore, the selectivity of the proposed NGO-based sensor to TMA was verified by analysis of the dual-signal responses. It is also proved that increasing the conductivity did not improve the resistance signal. This work confirms that the proposed NGO-based sensor with dual signals provides a new avenue for TMA sensing, and the sensor is expected to become a potential candidate for gas detection.
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Zhang, Wen Na, Guo Jun Qin, and Niao Qing Hu. "Parallel Factor Analysis for Gas Sensor Array Signals." Applied Mechanics and Materials 494-495 (February 2014): 955–59. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.955.
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Data from sensor array are often arranged in three-dimension as sample × time × sensor. Traditional methods are mainly used for two-dimension data. When such methods are applied, some time-profile information will lost. To acquire the information of samples, sensors and times more exactly, parallel factor analysis (PARAFAC) is investigated to deal with three-way data array. Through the analysis and classification of three kinds of oil odor samples, the performance of PARAFAC in gas sensor array signal analysis is verified and validated.
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Zhou, Mingmin, Nannan Chen, Jingsong Tian, Jianzhi Zeng, Yunpeng Zhang, Xiaofan Zhang, Jing Guo, et al. "Suppression of GABAergic neurons through D2-like receptor secures efficient conditioning in Drosophila aversive olfactory learning." Proceedings of the National Academy of Sciences 116, no. 11 (February 22, 2019): 5118–25. http://dx.doi.org/10.1073/pnas.1812342116.
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The GABAergic system serves as a vital negative modulator in cognitive functions, such as learning and memory, while the mechanisms governing this inhibitory system remain to be elucidated. In Drosophila, the GABAergic anterior paired lateral (APL) neurons mediate a negative feedback essential for odor discrimination; however, their activity is suppressed by learning via unknown mechanisms. In aversive olfactory learning, a group of dopaminergic (DA) neurons is activated on electric shock (ES) and modulates the Kenyon cells (KCs) in the mushroom body, the center of olfactory learning. Here we find that the same group of DA neurons also form functional synaptic connections with the APL neurons, thereby emitting a suppressive signal to the latter through Drosophila dopamine 2-like receptor (DD2R). Knockdown of either DD2R or its downstream molecules in the APL neurons results in impaired olfactory learning at the behavioral level. Results obtained from in vivo functional imaging experiments indicate that this DD2R-dependent DA-to-APL suppression occurs during odor-ES conditioning and discharges the GABAergic inhibition on the KCs specific to the conditioned odor. Moreover, the decrease in odor response of the APL neurons persists to the postconditioning phase, and this change is also absent in DD2R knockdown flies. Taken together, our findings show that DA-to-GABA suppression is essential for restraining the GABAergic inhibition during conditioning, as well as for inducing synaptic modification in this learning circuit. Such circuit mechanisms may play conserved roles in associative learning across species.
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Abraçado, L. G. "Multiple Orientation Circuits Converging on the Pd7 Cells in Tritonia diomedea." ISRN Biophysics 2012 (June 13, 2012): 1–4. http://dx.doi.org/10.5402/2012/839040.
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Magnetoreception is a sophisticated orientation mechanism, involving a magnetoreceptor connected to the nervous system with signal amplification. The mollusk Tritonia diomedea is a good model to investigate the behavioral and neural responses to the magnetic field. The mollusk inhibits all unnecessary activities and focuses on an available cue during orientation. Although Pd7 cells are inhibited by magnetic pathway, it was excited by another stimulus, water streams plus food odor. Two sensory pathways connected to Pd7 through the same or different circuits were tested. The action potential activity through Pd7 was compared in these different stimulations. The changes in Pd7 activity indicate a response of enhanced electrical activity to water streams plus food odor stimulus, and Pd7 activity can be excited by at least one of these stimuli. These results indicate an inverse relationship between magnetic orientation and feeding.