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Odor Discrimination (odor + discrimination)

Distribution by Scientific Domains
Medical Sciences60%
Life Sciences40%

Selected Abstracts

Odor discrimination by G protein-coupled olfactory receptors

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002
Kazushige Touhara
Abstract The vertebrate olfactory system possesses a remarkable capacity to recognize and discriminate a variety of odorants by sending the coding information from peripheral olfactory sensory neurons in the olfactory epithelium to the olfactory bulb of the brain. The recognition of odorants appear to be mediated by a G protein-coupled receptor superfamily that consists of ,1% of total genes in vertebrates. Since the first discovery of the olfactory receptor gene superfamily in the rat, similar chemosensory receptors have been found in various species across different phyla. The functions of these receptors, however, had been uncharacterized until the recently successful functional expression and ligand screening of some olfactory receptors in various cell expression systems. The functional cloning of odorant receptors from single olfactory neurons allowed for the identification of multiple receptors that recognized a particular odorant of interest. Reconstitution of the odorant responses demonstrated that odorant receptors recognized various structurally-related odorant molecules with a specific molecular receptive range, and that odor discrimination is established based on a combinatorial receptor code model in which the identities of different odorants are encoded by a combination of odorant receptors. The receptor code for an odorant changes at different odorant concentrations, consistent with our experience that perceived quality of an odorant changes at different concentrations. The molecular bases of odor discrimination at the level of olfactory receptors appear to correlate well with the receptive field in the olfactory bulb where the input signal is further processed to create the specific odor maps. Microsc. Res. Tech. 58:135,141, 2002. © 2002 Wiley-Liss, Inc. [source]

Neuronal cell adhesion molecule deletion induces a cognitive and behavioral phenotype reflective of impulsivity

GENES, BRAIN AND BEHAVIOR, Issue 4 2008
L. D. Matzel
Cell adhesion molecules, such as neuronal cell adhesion molecule (Nr-CAM), mediate cell,cell interactions in both the developing and mature nervous system. Neuronal cell adhesion molecule is believed to play a critical role in cell adhesion and migration, axonal growth, guidance, target recognition and synapse formation. Here, wild-type, heterozygous and Nr-CAM null mice were assessed on a battery of five learning tasks (Lashley maze, odor discrimination, passive avoidance, spatial water maze and fear conditioning) previously developed to characterize the general learning abilities of laboratory mice. Additionally, all animals were tested on 10 measures of sensory/motor function, emotionality and stress reactivity. We report that the Nr-CAM deletion had no impact on four of the learning tasks (fear conditioning, spatial water maze, Lashley maze and odor discrimination). However, Nr-CAM null mice exhibited impaired performance on a task that required animals to suppress movement (passive avoidance). Although Nr-CAM mutants expressed normal levels of general activity and body weights, they did exhibit an increased propensity to enter stressful areas of novel environments (the center of an open field and the lighted side of a dark/light box), exhibited higher sensitivity to pain (hot plate) and were more sensitive to the aversive effects of foot shock (shock-induced freezing). This behavioral phenotype suggests that Nr-CAM does not play a central role in the regulation of general cognitive abilities but may have a critical function in regulating impulsivity and possibly an animal's susceptibility to drug abuse and addiction. [source]

Blockage of voltage-gated calcium signaling impairs migration of glial cells in vivo

GLIA, Issue 3 2005
Christian Lohr
Abstract Migration of glial cells is an essential step in the development of the antennal lobe, the primary olfactory center of insects, to establish well-defined borders between olfactory glomeruli required for odor discrimination. In the present study, we used two-photon microscopy to visualize calcium signaling in developing antennal lobe glial cells of the sphinx moth Manduca sexta. We found a correlation between the upregulation of functional voltage-gated calcium channels and the onset of glial cell migration. In addition, glial cells migrating into the center of the antennal lobe express larger voltage-gated calcium transients than glial cells that remain at the periphery. Migration behavior and calcium signaling of glial cells in vivo were manipulated either by deafferentation, by injection of the calcium channel blockers diltiazem, verapamil, and flunarizine, or by injection of the calcium chelators BAPTA-AM and Fluo-4-AM. In deafferented antennal lobes, glial cells failed to express functional voltage-gated calcium channels and did not migrate. Calcium channel blockage or reducing glial calcium signals by calcium chelators prevented glial cell migration and resulted in antennal lobes lacking glial borders around glomeruli, indicating that voltage-gated calcium signaling is required for the migration of antennal lobe glial cells and the development of mature olfactory glomeruli. © 2005 Wiley-Liss, Inc. [source]

Odor discrimination by G protein-coupled olfactory receptors

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002
Kazushige Touhara
Abstract The vertebrate olfactory system possesses a remarkable capacity to recognize and discriminate a variety of odorants by sending the coding information from peripheral olfactory sensory neurons in the olfactory epithelium to the olfactory bulb of the brain. The recognition of odorants appear to be mediated by a G protein-coupled receptor superfamily that consists of ,1% of total genes in vertebrates. Since the first discovery of the olfactory receptor gene superfamily in the rat, similar chemosensory receptors have been found in various species across different phyla. The functions of these receptors, however, had been uncharacterized until the recently successful functional expression and ligand screening of some olfactory receptors in various cell expression systems. The functional cloning of odorant receptors from single olfactory neurons allowed for the identification of multiple receptors that recognized a particular odorant of interest. Reconstitution of the odorant responses demonstrated that odorant receptors recognized various structurally-related odorant molecules with a specific molecular receptive range, and that odor discrimination is established based on a combinatorial receptor code model in which the identities of different odorants are encoded by a combination of odorant receptors. The receptor code for an odorant changes at different odorant concentrations, consistent with our experience that perceived quality of an odorant changes at different concentrations. The molecular bases of odor discrimination at the level of olfactory receptors appear to correlate well with the receptive field in the olfactory bulb where the input signal is further processed to create the specific odor maps. Microsc. Res. Tech. 58:135,141, 2002. © 2002 Wiley-Liss, Inc. [source]

Smell and taste disorders in polyneuropathy: a prospective study of chemosensory disorders

ACTA NEUROLOGICA SCANDINAVICA, Issue 4 2009
J. G. Heckmann
Objective,,, The aim of the study was to assess the occurrence and the frequency of chemosensory dysfunction in patients with polyneuropathy (PNP). Methods,,, We performed a prospective observational study. Olfactory function was assessed using the standardized ,Sniffin' Sticks' test to measure odor threshold for phenyl ethyl alcohol, odor discrimination, and odor identification. Gustatory function was assessed using the standardized ,taste strips' test. In addition, we assessed etiology, neurophysiology, and severity of the PNP, and the patients' comorbidities and medication. Results,,, A total of 53 consecutive patients were enroled (15 women, 38 men; mean age 61 years); 27 of them (51%) exhibited olfactory dysfunction and 23 of them (43%) gustatory dysfunction. Patients with diabetic PNP had significantly lower taste scores than patients with inflammatory, genetic, or idiopathic PNP. In addition, odor identification was negatively correlated with PNP severity. Conclusion,,, The applied bedside tests are useful to detect chemosensory dysfunction in patients with PNP. Chemosensory dysfunction is quite frequent in these patients. [source]