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Results for “Olfactory Perception”

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PubMed2002

Pheromone detection by mammalian vomeronasal neurons.

The vomeronasal organ (VNO) of mammals plays an essential role in the perception of chemical stimuli of social nature including pheromone-like signals but direct evidence for the transduction of pheromones by vomeronasal sensory neurons has been lacking. The recent development of electrophysiological and optical imaging methods using confocal microscopy has enabled researchers to systematically analyze sensory responses in large populations of mouse vomeronasal neurons. These experiments revealed that vomeronasal neurons are surprisingly sensitive and highly discriminative detectors of volatile, urinary metabolites that have pheromonal activity in recipient mice. Functional mapping studies of pheromone receptor activation have uncovered the basic principles of sensory processing by vomeronasal neurons and revealed striking differences in the neural mechanisms by which chemosensory information is detected by receptor neurons in the VNO and the main olfactory epithelium. These advances offer the opportunity to decipher the logic of mammalian pheromonal communication.

Animals↗

PubMed2006

Supraspinal anesthesia: behavioral and electroencephalographic effects of intracerebroventricularly infused pentobarbital, propofol, fentanyl, and midazolam.

BACKGROUND: Anesthetic endpoints of unconsciousness and immobility result from agent effects on both brain and spinal cord that are difficult to separate during systemic administration. To investigate cerebral mechanism of anesthetic-induced unconsciousness, the authors studied behavioral and electrophysiologic effects of four anesthetics infused intracerebroventricularly to conscious rats. The authors aimed to produce progressively increasing anesthetic depths, indicated by electro-encephalographic synchronization and behavioral change. METHODS: During anesthesia, rats were equipped with intracerebroventricular infusion catheters, hind-paw stimulation, and epidural electrodes to record the electroencephalogram from the somatosensory cortex. Silicone bolus was injected into the fourth ventricle to minimize drug distribution to the spinal cord. 60 min later, 50-min infusion of pentobarbital (6.0 mg/h), fentanyl (0.75 microg/h), propofol (3.0 mg/h), or midazolam (0.24 mg/h) was initiated. Vibrissal, olfactory, corneal, and tail-pinch responses were tested every 10 min. RESULTS: All agents depressed vibrissal, olfactory, and corneal responses; propofol and pentobarbital produced the strongest effect. All agents except propofol depressed tail-pinch response; fentanyl and pentobarbital produced the strongest effect. All agents except midazolam increased delta power. Pentobarbital enhanced theta power. All agents except fentanyl enhanced alpha and beta power. Pentobarbital and midazolam slightly increased, whereas fentanyl decreased, gamma power. Pentobarbital increased and midazolam decreased somatosensory evoked potential; these changes were small and apparently unrelated to behavior. CONCLUSIONS: Alpha and beta power increase may reflect sedative component of anesthesia. Simultaneous delta, alpha, and beta power increase may correlate with loss of consciousness. Theta and delta power increase may reflect surgical anesthesia. Opioid-induced gamma power decrease may reflect suppression of pain perception. Pentobarbital-, fentanyl-, and midazolam-induced immobility to noxious stimulation may be mediated supraspinally.

Anesthetics, Intravenous↗

PubMed2000

Behavioral and mesocorticolimbic dopamine responses to non aggressive social interactions depend on previous social experiences and on the opponent's sex.

In these experiments we evaluated the relationship between behavioral and brain dopamine (DA) responses to social interactions. Subjects were group housed male mice confronted with a non aggressive male or female conspecific following either repeated defeat (defeated) or repeated non aggressive experiences (social). Defeated mice showed more defensive/submissive reactions then mice of the social group regardless of the opponent sex. However, mice defeated by females showed reduced social exploration without significant differences in non social exploration whilst the opposite was true for mice defeated by male opponents. Non aggressive social interactions enhanced dopamine metabolism in the prefrontal cortex (pFC) of DEFEATED mice regardless of opponent sex. However, only mice defeated by females showed enhanced dopamine metabolism and release in the nucleus accumbens septi (NAS) and olfactory tubercle (OT) following interaction with the non aggressive opponent. Finally, correlation between central and behavioral responses evidenced that 3,4-dihydroxiphenilacetic acid levels in the pFC were positively correlated with defensive behaviors and negatively correlated with non social exploration in mice confronted with male opponents but not in those confronted with females. The latter, showed a significant positive correlation between 3-methoxytyramine (3-MT) levels in the OT and defensive responses and significant negative correlation between social investigation and 3-MT levels in the OT and in the NAS. These results indicate a strict relationship between mesocorticolimbic dopamine transmission and behavior responses to social cues. Moreover, they strongly support the view that mesocorticolimbic DA modulates social behavior by affecting perceptive processing.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2004

Evolution of bitter taste receptors in humans and apes.

Bitter taste perception is crucial for the survival of organisms because it enables them to avoid the ingestion of potentially harmful substances. Bitter taste receptors are encoded by a gene family that in humans has been shown to contain 25 putatively functional genes and 8 pseudogenes and in mouse 33 putatively functional genes and 3 pseudogenes. Lineage-specific expansions of bitter taste receptors have taken place in both mouse and human, but very little is known about the evolution of these receptors in primates. We report the analysis of the almost complete repertoires of bitter taste receptor genes in human, great apes, and two Old World monkeys. As a group, these genes seem to be under little selective constraint compared with olfactory receptors and other genes in the studied species. However, in contrast to the olfactory receptor gene repertoire, where humans have a higher proportion of pseudogenes than apes, there is no evidence that the rate of loss of bitter taste receptor genes varies among humans and apes.

Animals↗

PubMed2005

Nasal airflow and olfactory function after the repair of cleft palate (with and without cleft lip).

OBJECTIVE: The objective of this study was to examine nasal airflow and olfactory functions in patients with repaired cleft palate compared with matching normal controls. STUDY DESIGN: The all-cleft group consisted of 25 patients with hard palate cleft comprising 15 patients with unilateral cleft palate and lip (UCLP); 2 with CP but no cleft lip (UCLP subgroup) and 8 patients with bilateral cleft lip and palate (BCLP subgroup). All had had surgical correction of the palate in infancy. The control group consisted of 20 nonaffected orthodontic patients. The median age of both groups was 14 years. The tests included the following: (1) nasal airflow measured by anterior rhinomanometry, (2) smell threshold for isoamyl-acetate determined using a 3-way forced choice method, (3) a self-administered questionnaire regarding the subjective perception of smell sense function, and (4) orthonasal and retronasal smell identification (correct/incorrect) and hedonics using visual analog scale (VAS). RESULTS: The respective test results follow. (1) When compared with the control group, the total airflow in the UCLP subgroup was significantly lower especially on the affected side; while in the BCLP subgroup it was lower than in the control group bilaterally. No significant difference was found between the cleft side of UCLP and BCLP subgroups. (2) The smell threshold of the UCLP subgroup was significantly higher than that of the control group and BCLP subgroup. No significant differences were found between right and left nostrils within the BCLP patients and between them and the control group. (3) No difference was found between the groups regarding the subjective perception of smell. (4) No significant differences were found between the UCLP and BCLP subgroups and between the all-cleft group and the control group, except for one item, regarding orthonasal and retronasal smell identification and hedonics. CONCLUSION: Although nasal airflow is significantly lower and the smell threshold higher on the cleft side, the day-to-day function of the sense of smell of cleft patients is similar to that of normal controls.

Adolescent↗

PubMed2005

Dissociation of emotional processes in response to visual and olfactory stimuli following frontotemporal damage.

Contemporary neuropsychological studies have stressed the widely distributed and multicomponential nature of human affective processes. Here, we examined facial electromyographic (EMG) (zygomaticus and corrugator muscle activity), autonomic (skin conductance and heart rate) and subjective measures of affective valence and arousal in patient TG, a 30 year-old man with left anterior mediotemporal and left orbitofrontal lesions resulting from a traumatic brain injury. Both TG and a normal control group were exposed to hedonically valenced visual and olfactory stimuli. In contrast with control subjects, facial EMG and electrodermal activity in TG did not differentiate among pleasant, unpleasant and neutral pictures. In addition, the controls reacted spontaneously with larger corrugator EMG activity and higher skin conductance to unpleasant odors. By contrast, the subjective feeling states (pleasure and arousal ratings) remained preserved in TG. The covariation between facial and self-report measures of negative valence was also a function of the nature of the olfactory task in the patient only. Taken together, the data suggest a functional dissociation between brain substrates supporting generation of emotion and those supporting representation of emotion.

Accidents, Traffic↗

PubMed1979

Continuities in the olfactory deficits of chronic alcoholics and alcoholics with the Korsakoff syndrome.

Olfactory dysfunction, a finding prevalent among alcoholic Korsakoff patients, was investigated in long-term alcoholics with Korsakoff's Syndrome. The results demonstrate that alcoholics are impaired on odor quality discrimination but performed normally on complex hue discriminations. These findings support the hypothesis that chronic alcoholics and alcoholic Korsakoff patients represent two points on a single continuum of cognitive deterioration associated with alcohol abuse.

Alcohol Amnestic Disorder↗

PubMed2001

[Taste impairment in Alzheimer's disease].

We conducted a study of Alzheimer's disease focusing on taste impairment to determine at which step of gustatory information processing (discriminative or perceptive, gnosic or associative, gustatory-verbal) possible perturbations might be located. We used various foods found in a normal diet. Twenty patients and a matched control group participated in this study. The patients were divided into two subgroups according to disease severity (mild, moderate or severe). The study showed that patients with Alzheimer's disease exhibited an impairment at all three levels of gustatory information processing. Impairment of discriminative and gustatory-verbal stages was more obvious in the group of patients with severe Alzheimer's disease. Our study also showed that the gustatory deficiency can be described as an associative agnosia in the mild stage of Alzheimer's disease. This concept is in line with the notion of a dissociation between preservation of olfactory and gustatory thresholds and an alteration in odor identification in patients with mild stage Alzheimer's disease, suggesting that the alteration is central rather than peripheral. Our findings suggest that an alteration of the associative level of gustatory information processing can be found in Alzheimer's disease early stage.

Aged↗

PubMedDate not supplied

Association of visual objects and olfactory cues in Drosophila.

Context-dependent preferences in a choice between an upper and a lower visual object of otherwise identical appearance were recorded during stationary flight of the fruitfly, Drosophila melanogaster, in a flight simulator. The test animal was held in a fixed orientation at the center of a wing-beat processor that converts attempted turns into counter-rotations of a surrounding cylindrical panorama. This allowed the fly to maneuver the preferred object into the actual direction of flight. Single flies were trained to avoid a course toward the visual object that had been associated with the aversive odor benzaldehyde (BAL). Conditioned object avoidance was investigated in different treatment groups by collective evaluation of the scores from 80 long-lasting flights (> 1 hr). In addition to a significant cross-modal association, we found a striking long-term effect of transient exposure to BAL both in the embryonic and larval states. The preimaginal experience significantly increased the indifference to BAL in the adult flies. Disturbed vision does not account for this effect: Neither the perception nor the discrimination of the visual objects was significantly impaired in the investigated flies. Disturbed olfaction could explain the present results. Recently, however, preimaginal BAL uptake has been found to interfere directly with the retention of heat-shock-conditioned object avoidance.

Animals↗

PubMed2005

Local effects in the respiratory tract: relevance of subjectively measured irritation for setting occupational exposure limits.

OBJECTIVES: Chemosensory effects of stimulation by a chemical can either be irritating (trigeminal stimulation) or odorous (olfactory stimulation) or both. For odorous irritants, a clear-cut distinction between odour and irritation is difficult to make. The differences in the lowest concentration found to be irritating to the respiratory tract in humans when compared to experimental animals has brought much debate in the process of setting occupational exposure limits (OELs) for such chemicals. In this paper it will be discussed as to how far subjectively measured sensory irritation threshold levels can be used to establish OELs. METHODS: Data on respiratory irritation of four odorous irritants were retrieved from public literature and discussed, viz. acetone, formaldehyde, furfural and sulphur dioxide. RESULTS: Objective measures of irritation yielded results that differed from subjective evaluations. Important factors modulating the reported levels of irritation and health symptoms include the perception of odour intensity, exposure history and the individual's bias to report irritation on the basis of his/her prejudice or knowledge of the compound. CONCLUSIONS: Subjective measures alone are less appropriate for establishing sensory irritation thresholds of odorous irritants and are, therefore, less suitable to establish OELs without supporting evidence. Objectively measured irritation in humans, the Alarie assay (an experimental animal test assessing the concentration that results in a 50% reduction of the breathing frequency) and repeated exposure studies in animals may be of help to study objective irritation. If subjective measurements are used to study sensory irritation, the study design should at least include: measurement of both incidence and severity determined at several concentrations, an appropriate (0 ppm) control condition, preferably a non-irritant odorant control exposure, validated questionnaires and correct concentration measurements.

Air Pollutants, Occupational↗

PubMed2005

The Cardiff Anomalous Perceptions Scale (CAPS): a new validated measure of anomalous perceptual experience.

The study describes the Cardiff Anomalous Perceptions Scale (CAPS), a new validated measure of perceptual anomalies. The 32-item CAPS measure is a reliable, self-report scale, which uses neutral language, demonstrates high content validity, and includes subscales that measure distress, intrusiveness, and frequency of anomalous experience. The CAPS was completed by a general population sample of 336 participants and 20 psychotic inpatients. Approximately 11% of the general population sample scored above the mean of the psychotic patient sample, although, as a group, psychotic inpatients scored significantly more than the general population on all CAPS subscales. A principal components analysis of the general population data revealed 3 components: "clinical psychosis" (largely Schneiderian first-rank symptoms), "temporal lobe disturbance" (largely related to temporal lobe epilepsy and related seizure-like disturbances) and "chemosensation" (largely olfactory and gustatory experiences), suggesting that there are multiple contributory factors underlying anomalous perceptual experience and the "psychosis continuum."

Adolescent↗

PubMed2005

New evidence that the MHC influences odor perception in humans: a study with 58 Southern Brazilian students.

Increasing evidence suggests a correlation between mate choice, odor preference, and genetic similarity at the Major Histocompatibility Complex (MHC) in a variety of animals, including our species. The MHC is a highly polymorphic group of genes that play an important role in the immunological self/nonself recognition. Its products have been reported to take part on the variety of compounds and reactions that together build an individual's body odor. It has been suggested, therefore, that animals use body odor as a guide to identify possible mates as MHC-similar or MHC-dissimilar from their own genotype. Preference for a MHC-dissimilar partner enhances MHC heterozygosity of an individual's offspring. The possible adaptive advantages are clear: it is a mechanism of avoiding inbreeding and MHC-heterozygous offspring may have enhanced immunocompetence. The aim of this study was to search, in our species, new evidence on the correlation between specificities at HLA-A and HLA-B and assessments of pleasantness regarding specific body odors. HLA is the name for the human MHC. Four olfactory sessions were performed with 58 young Southern Brazilian students, in order to investigate whether assessments of pleasantness of body odors from individuals correlate to a person's HLA phenotype. Body odors were collected via sweat and urine from all participants. Women smelled and scored all male odor samples and men did the same with all female samples. We found a significant correlation only when female smellers evaluated male sweat odors.

Adolescent↗

PubMed2004

Nature as a model for technical sensors.

Nature has developed a stunning diversity of sensory systems. Humans and many animals mainly rely on visual information. In addition, they may use acoustic, olfactory, and tactile cues for object detection and spatial orientation. Beyond these sensory systems a large variety of highly specialized sensors have evolved. For instance, some buprestid beetles use infrared organs for the detection of forest fires. The infrared sensors of boid and crotalid snakes are used for prey detection at night. For object detection and spatial orientation many species of nocturnal fish employ active electrolocation. This review describes certain aspects of the detection and processing of infrared and electrosensory information. We show that the study of natural exotic sensory systems can lead to discoveries that are useful for the construction of technical sensors and artificial control systems. Comparative studies of animal sensory systems have the power to uncover at least a small fraction of the gigantic untapped reservoir of natural solutions for perceptive problems.

Animals↗

PubMed2002

Seeing and not seeing.

Recent studies revealed that although subterranean mammals inhabit a dark underground environment, they can still perceive light stimuli and use this to entrain their circadian activity rhythm. Regarding spatial orientation, olfactory and tactile cues are employed for short-distance; whereas for long-distance, subterranean mammals employ the earth's magnetic field and self-generated (vestibular and kinestatic) cues. We suggest that seismic signals, utilized for long-distance communication, might also be used as an echolocation mechanism to determine digging depth and presence of obstacles ahead. Taken together, these mechanisms provide an equally efficient means of overall orientation and communication as those found in sighted mammals.

Animals↗

PubMed1997

A genetic screen for mutations that disrupt an auditory response in Drosophila melanogaster.

Hearing is one of the last sensory modalities to be subjected to genetic analysis in Drosophila melanogaster. We describe a behavioral assay for auditory function involving courtship among groups of males triggered by the pulse component of the courtship song. In a mutagenesis screen for mutations that disrupt the auditory response, we have recovered 15 mutations that either reduce or abolish this response. Mutant audiograms indicate that seven mutants reduced the amplitude of the response at all intensities. Another seven abolished the response altogether. The other mutant, 5L3, responded only at high sound intensities, indicating that the threshold was shifted in this mutant. Six mutants were characterized in greater detail. 5L3 had a general courtship defect; courtship of females by 5L3 males also was affected strongly. 5P1 males courted females normally but had reduced success at copulation. 5P1 and 5N18 showed a significant decrement in olfactory response, indicating that the defects in these mutations are not specific to the auditory pathway. Two other mutants, 5M8 and 5N30, produced amotile sperm although in 5N30 this phenotype was genetically separable from the auditory phenotype. Finally, a new adult circling behavior phenotype, the pirouette phenotype, associated with massive neurodegeneration in the brain, was discovered in two mutants, 5G10 and 5N18. This study provides the basis for a genetic and molecular dissection of auditory mechanosensation and auditory behavior.

Animals↗

PubMed2004

Cross-modal self-recognition: the role of visual, auditory, and olfactory primes.

Three priming experiments were conducted to determine how information about the self from different sensory modalities/cognitive domains affects self-face recognition. Being exposed to your body odor, seeing your name, and hearing your name all facilitated self-face recognition in a reaction time task. No similar cross-modal facilitation was found among stimuli from familiar or novel individuals. The finding of a left-hand advantage for self-face recognition was replicated when no primes were presented. These data, along with other recent results suggest the brain processes/represents information about the self in highly integrated ways.

Adult↗

PubMed1989

A chart review study of late-onset and early-onset schizophrenia.

This chart review study compared 54 schizophrenic patients with onset of illness after age 45 years to 54 young and 22 elderly patients with early-onset schizophrenia (before age 45). The index group was more likely to have visual, tactile, and olfactory hallucinations; a greater number of different types of hallucinations; persecutory delusions; and premorbid schizoid personality traits, and was less likely to have thought disorder and affective flattening, than was either comparison group. Among the two elderly groups, index patients had more auditory and visual sensory impairment. Nearly half (48.1%) of the index patients responded to neuroleptic treatment with complete remission.

Adolescent↗

PubMed2004

Relaxation of selective constraint and loss of function in the evolution of human bitter taste receptor genes.

Bitter taste perception prevents mammals from ingesting poisonous substances because many toxins taste bitter and cause aversion. We hypothesize that human bitter taste receptor (TAS2R) genes might be relaxed from selective constraints because of the change in diet, use of fire and reliance on other means of toxin avoidance that emerged in human evolution. Here, we examine the intra-specific variations of all 25 genes of the human TAS2R repertoire. Our data show hallmarks of neutral evolution, including similar rates of synonymous (d(S)) and non-synonymous (d(N)) nucleotide changes among rare polymorphisms, common polymorphisms and substitutions; no variation in d(N)/d(S) among functional domains; segregation of pseudogene alleles within species and fixation of loss-of-function mutations. These results, together with previous findings of large numbers of loss-of-function mutations in olfactory, pheromonal and visual sensory genes in humans, suggest surprisingly reduced sensory capabilities of humans in comparison with many other mammals.

Africa↗