Introduction: Processing odor information by the olfactory system depends greatly on the odor concentration. In order to use an odorant in a smell identification test (SIT), the minimum identification concentration (MIC) needs to be determined.  Materials and Methods: This study was conducted in 60 healthy native individuals aged 20 to 60 years, selected from patients’ companions in a tertiary...

Early olfactory experience with a specific odorant enhances the subsequent response of the glomerular layer of the rat olfactory bulb to that same odorant. Because different odorants activate different glomerular layer regions, it seemed plausible that experience with a large number of odorants might result in enhanced glomerular activation during subsequent exposure to both the previously expe...

BACKGROUND The honeybee has to detect, process and learn numerous complex odours from her natural environment on a daily basis. Most of these odours are floral scents, which are mixtures of dozens of different odorants. To date, it is still unclear how the bee brain unravels the complex information contained in scent mixtures. METHODOLOGY/PRINCIPAL FINDINGS This study investigates learning of...

Identifications (IDs) of paired retronasal and orthonasal odorants were studied, with stimuli limited to air phase. Odorants were liquid extracts of plant materials, sold as food flavorings, matched by each subject both for retronasal-only and orthonasal-only air phase intensities and then learned to 100% correct veridical name retronasal-only and orthonasal-only IDs. Subjects were tested for I...

Although many studies have reported that odorants can elicit inhibitory responses as well as excitatory responses in vertebrate olfactory receptor neurons, the cellular mechanisms that underlie this inhibition are unclear. Here we examine the inhibitory effect of odorants on newt olfactory receptor neurons using whole cell patch clamp recording. At high concentrations, odorant stimulation decre...

Responses of the rat olfactory epithelium were assessed with the electroolfactogram while odorants were presented to the external nares with an artificial sniff or to the internal nares by positive pressure. A series of seven odorants that varied from very polar, hydrophilic odorants to very nonpolar, hydrophobic odorants were used. Although the polar odorants activated the dorsal olfactory epi...

Using primary olfactory neuronal cultures, we have demonstrated rapid, potent increases in cAMP levels and adenylate cyclase [AC; ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity in response to odorants. Isobutyl-methoxypyrazine is active at 1 nM. Odorant enhancement is dependent on Ca2+ concentration with maximal effects at 10-100 microM. Biphasic temporal and concentration-related ef...

Abstract Noses are extremely sophisticated chemical detectors allowing animals to use scents interpret and navigate their environments. Odor detection starts with the activation of odorant receptors (ORs), expressed in mature olfactory sensory neurons (OSNs) populating mucosa. Different odorants, or different concentrations same odorant, activate unique ensembles ORs. This mechanism combinatori...

For reliable stimulus identification, sensory codes have to be robust by including redundancy to combat noise, but redundancy sacrifices coding efficiency. To address how experience affects the balance between the robustness and efficiency of sensory codes, we probed odor representations in the mouse olfactory bulb during learning over a week, using longitudinal two-photon calcium imaging. When...

An odor-stimulated adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] is thought to mediate olfactory transduction in vertebrates. However, it is not known whether the adenylate cyclase serves this function for all odorants or for only certain classes of odorants. To investigate this question, we have compared the abilities of 35 odorants to stimulate the adenylate cyclase and ...