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Results for “Olfactory Perception”

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PubMed2005

Crossmodal interactions between olfactory and visual learning in Drosophila.

Different modalities of sensation interact in a synergistic or antagonistic manner during sensory perception, but whether there is also interaction during memory acquisition is largely unknown. In Drosophila reinforcement learning, we found that conditioning with concurrent visual and olfactory cues reduced the threshold for unimodal memory retrieval. Furthermore, bimodal preconditioning followed by unimodal conditioning with either a visual or olfactory cue led to crossmodal memory transfer. Crossmodal memory acquisition in Drosophila may contribute significantly to learning in a natural environment.

Animals↗

PubMed2000

Activation of olfactory cortex in newborn infants after odor stimulation: a functional near-infrared spectroscopy study.

In mammals, perception of smells during the first hours of life is an essential prerequisite for adaptation of the newborn to the new extrauterine world. Functional magnetic resonance studies have shown that olfactory impression is processed in the lateral and anterior orbito-frontal gyri of the frontal lobe. Near-infrared spectroscopy (NIRS) can detect changes in oxygenated [Hb O2], and deoxygenated [Hb H] Hb during cortical activation. The aim of this study was to assess by NIRS olfactory cortex activity in newborn infants receiving olfactory stimuli. Twelve males and 11 females were studied when awake at 6 h to 8 d after birth. NIRS monitoring was carried out using two optodes placed above the left anterior orbito-frontal gyri. Each newborn was exposed for 30 s to two different smell stimuli-mother's colostrum and vanilla-and to a negative control, distilled water. Changes in Hb concentration were measured over the orbitofrontal region. During exposure to vanilla, [Hb O2] increased significantly over the left orbito-frontal area in all babies. The magnitude of the [Hb O2] increase over the illuminated region during colostrum exposure was inversely related to postnatal age. We conclude that monitoring Hb changes by NIRS can be valuable in assessing olfactory responsiveness in infants.

Aging↗

PubMed1990

Fish-odor syndrome presenting as dysosmia.

We describe a patient who had perceived an unpleasant odor or taste for at least 20 years. Several other physicians had unsuccessfully treated her for infections, mucus membrane dryness and inflammation, chronic tonsillitis, and psychiatric disorders. Her workup at the State University of New York Health Science Center at Syracuse Olfactory Referral Center included a thorough history, examinations (including endoscopic studies of her nose, pharynx, and lungs), roentgenograms, taste testing, olfactory testing, and selective anesthesia of her chemosensory areas. The perception occurred only during exhalation, and appeared to be binasal. These findings, together with her morning mucus sample having a strong fishlike odor, prompted us to suspect a metabolic problem. Further testing at the Monell-Jefferson Chemosensory Clinical Research Center, Philadelphia, Pa, confirmed that she had trimethylaminuria. It is important to consider this and other treatable conditions when evaluating individuals with olfactory complaints.

Adult↗

PubMed1992

Vomeronasal and/or olfactory mediation of ultrasonic calling and scent marking by female golden hamsters.

The role of the olfactory and vomeronasal systems in mediating odor-stimulated ultrasonic calling, flank marking, and vaginal marking by female hamsters was investigated by selective lesions of either system. Removal of the vomeronasal organ resulted in reduced frequencies of ultrasonic calling by estrous and nonestrous females in response to conspecific odors but it had no influence on either scent marking behavior during the same tests. When tested immediately after separation from a male, ultrasonic calling was not reduced by vomeronasal removal, indicating that such surgery does not cause deficits in calling ability and that the vomeronasal organ specifically mediates odor-stimulated calling. Zinc sulfate treatment of the olfactory mucosa led to reduction in the frequency of ultrasonic calling, flank marking, and vaginal marking in response to conspecific odors. Females' ability to discover buried food was also impaired by this treatment. Thus, the stimulation of both scent marking behaviors due to the perception of conspecific odors appears to be mediated primarily by the olfactory system, whereas stimulation of ultrasonic calling is mediated by both olfactory and vomeronasal systems.

Animals↗

PubMed1999

[Olfactory lateralization in humans: a review of the literature].

In the field of human perception, the chemical senses (taste and smell) have received little attention from neuroscience research when compared with auditory, visual and tactile senses. In the case of olfaction, it would appear that the publications over the last few years have been trying to overcome this lack of research. Many investigations have been carried out on lateralization, mainly in relation to specific pathologies (i.e., epilepsy, split-brain, lobotomy, etc.), while there have been few studies of healthy subjects. The results are often contradictory due particularly to special features of the olfactory system. However, consensus is emerging concerning, first, the fact that if both hemispheres are involved in the olfactory process, it is probable that one is more dominant than the other (many studies have revealed a greater impact on the right hemisphere in the treatment of olfactory information, but the dominance has not been clearly established). Second, the simple detection process would appear not to be lateralized whereas the higher-order olfactory tasks which involve memory processes and lexical aspects could be. The exact conditions governing lateralization still require more clarification by systematically taking into consideration the characteristics of the individual subjects, as well as those of the odorant stimuli and the test conditions. Finally, currently available techniques used in neurosciences and particularly cerebral imagery will contribute to a better understanding of the complexity of cerebral asymmetry in olfaction.

Functional Laterality↗

PubMed2006

Ventromedial hypothalamic nucleus lesions disrupt olfactory mate recognition and receptivity in female ferrets.

Previous research showed that ferrets of both sexes rely on the perception of conspecifics' body odors to identify and motivate approach towards opposite-sex mating partners, and exposure to male body odors stimulated Fos expression in an olfactory projection circuit of female, but not male, ferrets that terminates in the ventromedial hypothalamic nucleus (VMH). We asked whether the female-typical preference of ferrets to approach male as opposed to female body odors in Y-maze tests would be disrupted by VMH lesions. Sexually experienced female ferrets were ovo-hysterectomized prior to receiving bilateral electrolytic lesions of the VMH, the preoptic area/anterior hypothalamus (POA/AH) or a sham operation. Subsequently, while receiving estradiol benzoate, females that received either complete or partial bilateral lesions of the VMH approached volatile odors from an anesthetized male on significantly fewer trials than females given POA/AH lesions or a sham operation. Both groups of ferrets with VMH lesion damage reliably discriminated between volatile anal scents as well as urinary odors from the 2 sexes in home cage habituation/dishabituation tests, suggesting that their odor-based sex discrimination remained intact. Females with complete bilateral VMH lesions showed significantly lower acceptance of neck gripping from a stimulus male (receptivity) and more aggression towards the male than all other groups of female subjects. Estrogen-sensitive neurons in the VMH appear to play a central role in female-typical neural processing of odor inputs leading to a preference to seek out a male sex partner, in addition to facilitating females' sexual receptivity.

Animals↗

PubMed1994

Individual differences in the perceived intensity and quality of specific odors following self- and cross-adaptation.

Adaptation techniques have traditionally been employed in sensory physiology and psychology to characterize afferent pathways and to dissect the quantitative and, to a lesser degree, the qualitative aspects of perception. We continue to explore the individual differences in olfactory capabilities among subjects initially classified by their ability to detect and identify the diastereoisomeric ketone, cis-4-(4'-t-butylcyclohexyl)-4-methyl-2-pentanone (pemenone) which shares with 5 alpha-androst-16-en-3-one (androstenone) a pronounced urine-sweaty odor. Our previous studies of these and other compounds for which specific anosmias were said to exist revealed significant relationships between intensity scores and a corresponding clustering of the odor quality descriptors used to characterize these materials by subjects judged to be specifically anosmic for the urinous note. Here, we attempt to dissect the web of interactions which give rise to individual differences in perceived odor quality by evaluating the effects of self- and cross-adaptation on the intensity and quality reports elicited by pemenone, androstenone and four other odors in 18 human subjects including both pemenone-osmic and non-osmic (n = 6) individuals. Intensity and quality ratings for the six compounds were obtained before and after an adaptation sequence in which subjects sniffed a test odorant, pemenone or the diluent. For each odorant, intensity ratings under the different adapting conditions were compared by ANOVA. Self-adaptation was universal but cross-adaptation by pemenone was only found in the intensity ratings of androstenone. The intensity ratings of isovaleric acid, which shares the urinous note with pemenone and androstenone, were unaffected by pemenone adaptation. Most of the subjects judged to be osmic still reported a urinous odor quality for androstenone and isovaleric acid following pemenone adaptation. Except for shifts to the no-odor category, adaptation did not significantly alter the odor quality reports of osmic or non-osmic individuals. This suggests that the odor quality reports engendered by these substances are multidimensional and that compounds which share the same odor quality label may interact with different perceptual channels.

Adaptation, Physiological↗

PubMed1987

Citric acid aerosol as a potential smoking cessation aid.

We tested the ability of a citric acid aerosol to simulate the tracheal sensations produced by cigarette smoke and to satisfy smokers' desire for cigarettes. Fifteen smokers rated puffs from their own brand of cigarette, citric acid aerosol, a low tar and nicotine cigarette, and air. To focus on tracheal perceptions and pharmacologic effects of nicotine, we equated visual, olfactory and taste cues across conditions. Subjects rated the citric acid aerosol more similar to their own brand, more desirable, and more satisfying (after a block of puffs) than control puffs of air. It was also rated equal to or better than the low tar and nicotine cigarette. Subjects' own brands were rated best, although puffs of citric acid aerosol were of comparable strength and harshness. The results suggest that a nebulizer delivering citric acid in a fine mist might reduce craving for cigarettes in smokers attempting to quit and may thereby increase cessation rates.

Adult↗

PubMed1997

Biology of chromosome 6.

The major histocompatibility (HLA) complex on the short arm of human chromosome 6 has attracted many scientists over the last three decades. It is the purpose of this brief review to point out that the remaining large regions of chromosome 6 contain genes involved in several interesting biological phenomena as well. Focus will be particularly on genes affecting behavioural features and sensory perception. The likely involvement of HLA and closely linked olfactory receptor loci in mate selection and their possible role in favouring heterozygosity among the offspring will also be discussed.

Animals↗

PubMed2002

A divergent gene family encoding candidate olfactory receptors of the moth Heliothis virescens.

The antennae of moths have been an invaluable model for studying the principles of odour perception. In spite of the enormous progress in understanding olfaction on the molecular level, for the moth one of the key elements in olfactory signalling, the odourant receptors, are still elusive. We have assessed a genome database of a heliothine moth (Heliothis virescens, Noctuidae) and employed exon-specific probes to screen an antennal cDNA library of this species. Analysis of isolated cDNA-clones led to the discovery of a divergent gene family encoding putative seven-transmembrane domain proteins. The notion that they may encode candidate olfactory receptors of the moth, was supported by a tissue-specific expression; several of the subtypes were exclusively expressed in antennae. By means of double-labelling in situ hybridization studies it was demonstrated that the receptors are indeed expressed in antennal sensory neurons; moreover, each receptor subtype appears to be expressed in a distinct population of sensory cells. The results strongly suggest that the newly discovered gene family indeed encodes olfactory receptors of moth.

Amino Acid Sequence↗

PubMed2004

The potion's magic.

During remembering, a perception of the past is constructed that includes sensory details of the original episode. In this issue of Neuron, Gottfried and colleagues provide evidence for selective piriform activation during recognition of visual cues previously paired with scents. These data provide evidence of sensory-specific reactivation of olfactory cortex during remembering.

Auditory Cortex↗

PubMed2005

Behavioral correlates of olfactory and trigeminal gaseous stimulation in chickens, Gallus domesticus.

Despite growing evidence of avian olfactory abilities, there are few reports of behavioral correlates of chemosensory stimulation in birds. The present study aimed to determine how the behavioral responses of hens to selected gases might be affected by input from different chemosensory systems. We also hoped to relate electrophysiological thresholds previously measured in our laboratory to behavioral evidence of perception. Immediate behavioral responses to ascending series of short (7 s) pulses of olfactory (hydrogen sulphide), trigeminal (carbon dioxide) and combining (ammonia) gaseous stimulants were measured in 12 partially restrained adult hens (Gallus domesticus) using a purpose built gas delivery system. The concentration ranges applied matched those used in our previous electrophysiological studies of olfactory bulb responses. Consistent and specific behavioral responses were observed in response to stimulation with each gas. While significant increases in mandibulation (a distinctive rapid bout of bill movements), interruption of ongoing behavior, orientation to the end of the stimulus, and struggling were seen during stimulation with all three gases, orientation towards the stimulus occurred only in response to the olfactory stimulants, ammonia and hydrogen sulphide. The only gas to elicit significant avoidance was hydrogen sulphide, while gasping and headshaking were elevated in response to stimulation with carbon dioxide. Approximate threshold values for some types of behavior related reasonably well to receptor thresholds determined electrophysiologically, but perception may have occurred at lower concentrations without overt behavioral consequences. The diversity of the behavioral responses observed supports the notion that the gases selectively stimulated different sensory pathways.

Ammonia↗

PubMed1975

Bilateral sensory neglect following midsagittal reticular formation lesions in cats.

We have observed that midsagittal reticular formation lesions in cats produce bilateral deficits in attention to and localization of various sensory modalities. To correlate these changes with previously reported changes following lesions in other areas of the brain, we propose the existence of two interdependent inhibitory pathways which originate in the frontal lobes.

Animals↗

PubMed1987

Odour mixture suppression: evidence for a peripheral mechanism in human and rat.

Rarely do we encounter a single odorant in our environment. Perception of odours, therefore, usually depends on the reception and neural processing of many components. However, little is known about how and where odour mixtures are processed. Evidence is presented here that suppression of one odour by another, a common result of mixing odours, is primarily a peripheral event. Having demonstrated with human subjects that perception of one or both odorants in two-component mixtures is dependent on the polarity and perceived intensity of the odorants, the same mixtures were presented to rats that had been injected with a metabolic marker, [3H]2-deoxyglucose (2-DG). By measuring the metabolic activity in the glomeruli of the rat olfactory bulb, where the axons of the receptor cells terminate, it was found that in a mixture where humans had perceived only one odour, there is a dramatic reduction in metabolic activity of glomeruli specific to the suppressed odour. In mixtures where both odorants were perceived, metabolic activity characteristic of both components was observed. These findings indicate that similar mechanisms underlie the perception of odour mixtures in the two species. Since metabolic activity revealed by 2-DG in glomeruli occurs predominantly in presynaptic receptor axons, the reduced activity seen after stimulation with odour mixtures indicates that a mechanism for mixture suppression begins at the receptor cells. Therefore, the ability of one odorant to suppress another in a mixture is probably determined by their relative chemical polarities, which effects access to and competition for membrane receptor sites in the olfactory epithelium.

Adult↗

PubMed2006

Olfactory receptor gene repertoires in mammals.

In mammals, olfaction is mediated by two distinct organs that are located in the nasal cavity: the main olfactory epithelium (MOE) that binds volatile odorants is responsible for the conscious perception of odors, and the vomeronasal organ (VNO) that binds pheromones is responsible for various behavioral and neuroendocrine responses between individuals of a same species. Odorants and pheromones bind to seven transmembrane domain G-protein-coupled receptors that permit signal transduction. These receptors are encoded by large multigene families that evolved in mammal species in function of specific olfactory needs.

Animals↗

PubMed2003

Identification of plant odours activating receptor neurones in the weevil Pissodes notatus F. (Coleoptera, Curculionidae).

Plants release complex mixtures of volatiles important in the interaction with insects and other organisms. In the search for compounds that contribute to the perception of odour quality in the weevil Pissodes notatus, single olfactory receptor neurones on the antennae were screened for sensitivity to naturally produced plant volatiles by the use of gas chromatography linked to single cell recordings. We here present 60 olfactory neurones responding to 25 of the numerous compounds released by host and non-host plants. All the neurones show high selectivity and are classified into 12 distinct types. The two most abundant types respond to alpha-pinene, beta-pinene, and 3-carene ( n=17), and to isopinocamphone and pinocamphone ( n=17), respectively. Other neurone types respond to limonene ( n=9), beta-phellandrene ( n=3), and fenchone ( n=4). Responses to beta-caryophyllene ( n=1) and to ethanol ( n=4) are also shown. Except for two pairs, the neurone types do not show overlap of the molecular receptive range. The active compounds are present in the host, Pinus pinaster, as well as in non-hosts, supporting the idea that plant odour quality is mediated by the ratio of the compounds rather than specific odorants.

Animals↗

PubMed2006

Olfactory learning and behaviour are 'insulated' against visual processing in larval Drosophila.

We investigate the organization of behaviour across sensory modalities, using larval Drosophila melanogaster. We ask whether olfactory learning and behaviour are affected by visual processing. We find that: (1) Visual choice does not affect concomitant odour choice. (2) Visual context does not influence odour learning, nor do changes of visual context between training and test affect retrieval of odour memory. (3) Larvae cannot solve a biconditional discrimination task, despite generally permissive conditions. In this task, larvae are required to establish conditional associations: in light, one odour is rewarded and the other one is not, whereas in dark the opposite contingency is established. After such training, choice between the two odours is equal under light and dark testing conditions, suggesting that larvae do not establish odour memories specifically for one visual context only. Together, these data suggest that, in larval Drosophila, olfactory learning and behaviour are 'insulated' against visual processing.

Animals↗

PubMed1998

An olfactory recognition model based on spatio-temporal encoding of odor quality in the olfactory bulb.

In order to study the problem how the olfactory neural system processes the odorant molecular information for constructing the olfactory image of each object, we present a dynamic model of the olfactory bulb constructed on the basis of well-established experimental and theoretical results. The information relevant to a single odor, i.e. its constituent odorant molecules and their mixing ratios, are encoded into a spatio-temporal pattern of neural activity in the olfactory bulb, where the activity pattern corresponds to a limit cycle attractor in the mitral cell network. The spatio-temporal pattern consists of a temporal sequence of spatial firing patterns: each constituent molecule is encoded into a single spatial pattern, and the order of magnitude of the mixing ratio is encoded into the temporal sequence. The formation of a limit cycle attractor under the application of a novel odor is carried out based on the intensity-to-time-delay encoding scheme. The dynamic state of the olfactory bulb, which has learned many odors, becomes a randomly itinerant state in which the current firing state of the bulb itinerates randomly among limit cycle attractors corresponding to the learned odors. The recognition of an odor is generated by the dynamic transition in the network from the randomly itinerant state to a limit cycle attractor state relevant to the odor, where the transition is induced by the short-term synaptic changes made according to the Hebbian rule under the application of the odor stimulus.

Animals↗