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Chemical Senses

Preet Bano Singh, Alix Young, Synnøve Lind, Marie Cathinka Leegaard, Alessandra Capuozzo, Valentina Parma
Despite the fact that human body odors can transfer anxiety-related signals, the impact of such signals in real-life situations is scant. In this study, the effects of anxiety chemosignals on the performance of dental students operating on simulation units, wearing t-shirts imbued with human sweat and masked with eugenol were tested. Twenty-four 4th year dental students (17F) donated their body odors in two sessions (Anxiety and Rest). Twenty-four normosmic, sex- and age-matched test subjects who were3rd year dental students performed three dental procedures while smelling masked anxiety body odors, masked rest body odors or masker alone...
May 15, 2018: Chemical Senses
Charalampos Georgiopoulos, Suzanne T Witt, Sven Haller, Nil Dizdar, Helene Zachrisson, Maria Engström, Elna-Marie Larsson
Studying olfaction with functional Magnetic Resonance imaging (fMRI) poses various methodological challenges. This study aimed to investigate the effects of stimulation length and repetition time (TR) on the activation pattern of four olfactory brain regions: the anterior and the posterior piriform cortex, the orbitofrontal cortex and the insula. 22 healthy participants with normal olfaction were examined with fMRI, with two stimulation lengths (6 seconds and 15 seconds) and two TRs (0.901 seconds and 1.34 seconds)...
May 3, 2018: Chemical Senses
Adam B Schroer, Joshua D Gross, Shane W Kaski, Kim Wix, David P Siderovski, Aurelie Vandenbeuch, Vincent Setola
The mammalian tastes of sweet, umami, and bitter are initiated by activation of G protein-coupled receptors (GPCRs) of the T1R and T2R families on taste receptor cells. GPCRs signal via nucleotide exchange and hydrolysis, the latter hastened by GTPase-accelerating proteins (GAPs) that include the Regulators of G protein Signaling (RGS) protein family. We previously reported that RGS21, uniquely expressed in Type II taste receptor cells, decreases the potency of bitter-stimulated T2R signaling in cultured cells, consistent with its in vitro GAP activity...
April 26, 2018: Chemical Senses
Ruina Zhang, Yi Pan, Lucky Ahmed, Eric Block, Yuetian Zhang, Victor S Batista, Hanyi Zhuang
Metal-coordinating compounds are generally known to have strong smells, a phenomenon that can be attributed to the fact that odorant receptors for intense-smelling compounds, such as those containing sulfur, may be metalloproteins. We previously identified a mouse OR, Olfr1509, that requires copper ions for sensitive detection of a series of metal-coordinating odorants, including (methylthio)methanethiol (MTMT), a strong-smelling component of male mouse urine that attracts female mice. By combining mutagenesis and QM/MM modeling, we identified candidate binding sites in Olfr1509 that may bind to the copper-MTMT complex...
April 6, 2018: Chemical Senses
Jacqueline Ferreira, Valentina Parma, Laura Alho, Carlos F Silva, Sandra C Soares
Many studies have indicated that the chemical cues from body odors (BOs) of donors experiencing negative emotions can influence the psychophysiological and behavioral response of the observers. However, these olfactory cues have been used mainly as contextual information for processing visual stimuli. Here, for the first time, we evaluate how emotional BO affects the emotional tone of a subsequent BO message. Axillary sweat samples were taken from 20 donors in three separate sessions while they watched fear, disgust or neutral videos...
March 30, 2018: Chemical Senses
Paul Szyszka, C Giovanni Galizia
In a recent paper, Joseph and colleagues (Joseph et al., 2017) have characterized an IR60b receptor-expressing neuron in Drosophila. They showed that it responds to sucrose and serves to limit sucrose consumption, and proposed that it may thereby act to prevent overfeeding. Here, we propose an alternative hypothesis for the functional role of sucrose feeding control, and for how this limitation of sucrose uptake is accomplished. Adult fruit flies feed by excreting saliva onto the food, and imbibing the predigested liquefied food, or by filling the crop, where the food is predigested...
March 13, 2018: Chemical Senses
A Fjaeldstad, A Niklassen, H Fernandes
The sense of taste holds a key integrate role in assessing the flavour of food before swallowing is initiated. If the expectations for taste are not met, palatability and pleasure of the food can decrease. In patients suffering from taste disorders, this may impair appetite and nutritional state. Testing gustatory function can be important for diagnostics and assessment of treatment effects. However, the gustatory tests applied are required to be both sensitive and reliable.In this study, we investigate the re-test validity of popular Taste Strips gustatory test for gustatory screening...
March 12, 2018: Chemical Senses
Sherlley Amsellem, Richard Höchenberger, Kathrin Ohla
Odors are inherently ambiguous and therefore susceptible to redundant sensory as well as context information. The identification of an odor object relies largely on visual input. Thus far, it is unclear whether visual and olfactory stimuli are indeed integrated at an early perceptual stage and which role the congruence between the visual and olfactory inputs plays. Previous studies on visual-olfactory interaction used either congruent or incongruent information, leaving it open whether nuances of visual-olfactory congruence shape perception differently...
March 8, 2018: Chemical Senses
Maria Piochi, Caterina Dinnella, John Prescott, Erminio Monteleone
Fungiform papillae on human tongue are the proxy structures designated to oral stimuli detection and transduction. However, the role of their density (fungiform papillae/cm2) in explaining oral sensitivity is still controversial. While early studies generally found that the responsiveness to oral stimuli increased as the number of papillae increased, recent large-scale studies failed to confirm this finding.The present paper reviews relevant studies dealing with the relationship between fungiform papillae density and responsiveness to oral sensations including: fundamental tastes, 6-n-propyl-2-thiouracil (PROP) and sensations from trigeminal stimulation...
February 27, 2018: Chemical Senses
David M Coppola, Burton Slotnick
In the course of our ongoing studies of odor-cued taste avoidance (OCTA) to measure olfactory capabilities in animals, we observed that mice could rapidly learn to use the vapor of the classical bitterant quinine hydrochloride to avoid contact with the tastant. Here we expand on this observation to determine which among several compounds generally classed as bitter could be detected at a distance. Since mice were initially naïve we were able to assess whether the vapors of the bitter compounds tested were innately aversive as are their tastes...
April 23, 2018: Chemical Senses
Edward J Szczygiel, Sungeun Cho, Robin M Tucker
Little is known about the relationship between sleep and chemosensation. The purpose of this study was to characterize the relationship between chemosensory function and sleep duration, quality, and architecture. A total of 56 nonobese (body mass index <30 kg/m2) female participants who denied having diagnosed sleep disorders completed testing. Sleep was measured for two nights using a single-channel (A1-A2) electroencephalogram (Zmachine). Sweet taste threshold and preference as well as olfactory threshold, recognition ability, and pleasantness ratings were evaluated...
April 23, 2018: Chemical Senses
Koji Sato, Peter W Sorensen
Although it is well established that the olfactory epithelium of teleost fish detects at least 6 classes of biologically relevant odorants using 5 types of olfactory sensory neurons (OSNs), little is understood about the specificity of individual OSNs and thus how they encode identity of natural odors. In this study, we used in vivo extracellular single-unit recording to examine the odor responsiveness and physiological characteristics of 109 individual OSNs in mature male goldfish to a broad range of biological odorants including feeding stimuli (amino acids, polyamines, nucleotides), sex pheromones (sex steroids, prostaglandins [PGs]), and a putative social cue (bile acids)...
April 23, 2018: Chemical Senses
Jonas Töle, Antje Stolzenburg, Susan M Tyree, Frauke Stähler, Wolfgang Meyerhof
Despite long and intense research, some fundamental questions regarding representation of taste information in the brain still remain unanswered. This might in part be due to shortcomings of the established methods that limit the researcher either to thorough characterization of few elements or to analyze the response of the entirety of neurons to only one stimulus. To overcome these restrictions, we evaluate the use of the immediate early gene Arc as a neuronal activity marker in the early neural structures of the taste pathway, the nodose/petrosal ganglion (NPG) and the nucleus of the solitary tract (NTS)...
April 23, 2018: Chemical Senses
Chengyu Li, Jianbo Jiang, Kanghyun Kim, Bradley A Otto, Alexander A Farag, Beverly J Cowart, Edmund A Pribitkin, Pamela Dalton, Kai Zhao
Nasal airflow that effectively transports ambient odors to the olfactory receptors is important for human olfaction. Yet, the impact of nasal anatomical variations on airflow pattern and olfactory function is not fully understood. In this study, 22 healthy volunteers were recruited and underwent computed tomographic scans for computational simulations of nasal airflow patterns. Unilateral odor detection thresholds (ODT) to l-carvone, phenylethyl alcohol (PEA) and d-limonene were also obtained for all participants...
April 23, 2018: Chemical Senses
Sangzin Ahn, Mooseok Choi, Hyunju Kim, Eun-Jeong Yang, Usman Mahmood, Seong-Il Kang, Hyun-Woo Shin, Dae Woo Kim, Hye-Sun Kim
Olfactory loss is known to affect both mood and quality of life. Transient anosmia was induced in mice to study the resulting changes in mood, behavior, and on a molecular level. Transient anosmia was induced by a single intranasal instillation of ZnSO4 in BALB/c mice. Hematoxylin and eosin (HE) staining, and potato chip finding test were performed to confirm olfactory loss. Tail suspension, forced swim, and splash tests were performed to evaluate depression-related behavior; while the open field, and elevated plus maze tests were used to evaluate anxiety-related behavior...
April 23, 2018: Chemical Senses
Alex M Pierce, Christopher T Simons
Odorants are perceived orthonasally (nostrils) or retronasally (oral cavity). Prior research indicates route of delivery impacts odorant perception, pleasantness, and directed behaviors thus suggesting differential processing of olfactory information. Adaptation is a form of neural processing resulting in decreased perceived intensity of a stimulus following prolonged and continuous exposure. The present study objective was to determine whether route of delivery differentially impacts olfactory adaptation and whether cross-adaptation occurs between orthonasal and retronasal pathways...
February 26, 2018: Chemical Senses
Yada Treesukosol, Timothy H Moran
The orosensory characteristics of a diet play a role in its acceptance and rejection. The current study was designed to investigate the gustatory components that contribute to the intake of a palatable, high-energy diet (HE; 45% calories from fat, 17% calories from sucrose). Here, rats were conditioned to avoid HE diet by pairings with i.p. injections of LiCl to induce visceral malaise. Subsequently, the degree of generalization was tested to an array of taste compounds using a brief-access lick procedure (10-s trials, 30-min sessions)...
February 26, 2018: Chemical Senses
Amir Banner, Idan Frumin, Simone G Shamay-Tsoory
A growing body of evidence suggests that humans can communicate socially relevant information, such as aggression, dominance, and readiness for competition, through chemosensory signals. Androstadienone (androsta-4,16,-dien-3-one), a testosterone-derived compound found in men's axillary sweat, is a main candidate for a human pheromone that may convey such information. The current study aimed to investigate whether androstadienone serves as a chemosignaling threat cue to men, thus triggering avoidance behavior during competitive interaction with another man...
February 26, 2018: Chemical Senses
Soleil E Worthy, German L Rojas, Charles J Taylor, Elizabeth E Glater
Animals have evolved specialized pathways to detect appropriate food sources and avoid harmful ones. Caenorhabditis elegans can distinguish among the odors of various species of bacteria, its major food source, but little is known about what specific chemical cue or combination of chemical cues C. elegans uses to detect and recognize different microbes. Here, we examine the strong innate attraction of C. elegans for the odor of the pathogenic bacterium, Serratia marcescens. This initial attraction likely facilitates ingestion and infection of the C...
February 26, 2018: Chemical Senses
Takuya Onuma, Hiroaki Maruyama, Nobuyuki Sakai
Previous studies have reported that the umami taste of monosodium l-glutamate (MSG) and salty-smelling odors (e.g., soy sauce, bacon, sardines) enhance the perception of saltiness. This study aimed to investigate the neural basis of the enhancement of saltiness in human participants using functional near-infrared spectroscopy (fNIRS). University students who had passed a taste panel test participated in this study. Sodium chloride solutions were presented with or without either 0.10% MSG or the odor of soy sauce...
February 26, 2018: Chemical Senses
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