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Results for “Olfactory Perception”

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PubMed2006

Estrogen and performance in recognition memory for olfactory and visual stimuli in females diagnosed with Alzheimer's disease.

Patients with Alzheimer's disease (AD) exhibit a deficit in episodic recognition memory for odors. It is hypothesized that the higher rate of AD in women may be due to estrogen-deprivation in postmenopausal women. Research suggests that estrogen may help to minimize cognitive decline in AD as well as postmenopausal olfactory loss. The current study examined the effects of estrogen replacement therapy (ERT) on performance of a recognition memory task for olfactory and visual stimuli in women AD patients. Participants included 24 women AD patients who were ERT users and 77 women AD patients who never used ERT. Compared with the ERT non-users, the ERT users committed significantly less false-positive memory errors for olfactory stimuli, whereas performance for visual stimuli did not differentiate between ERT users and non-users. The results suggest benefits of ERT could help ameliorate the earliest symptoms of AD, olfactory dysfunction, and memory impairment.

Aged↗

PubMed2003

Convergent and divergent effects of odors and emotions in depression.

The aim of the present study was to investigate the similarities and differences in the olfactory and visual processing of emotional stimuli in healthy subjects and in patients with major depressive disorder (MDD). Twenty-five inpatients were investigated after admission to the psychiatric clinic. Fifteen of them participated a second time, shortly before their discharge from the hospital. A group of healthy subjects, matched according to age and sex, served as a control. Chemsosensory event-related potentials (CSERPs) were recorded using the constant flow method. In addition, event-related potentials (ERPs), in response to colors and emotional slides, were obtained to control modality and emotion-specific effects. The subjects' task was to discriminate the colors (red/yellow) and odors (phenyl-ethylalcohol = rose/ isobutyraldehyde = rotten butter) according to their quality and to judge the valence of the emotional slides (IAPS slides). The EEG was recorded from 32 scalp locations. At the beginning of the therapy, visual stimulus processing was attenuated in depressive subjects at a relatively late processing level (reduced amplitudes of the P3 and pSW in response to colors and emotional slides), whereas olfactory stimulus processing had already been affected at an early level (reduced amplitudes of the P2 and P3-1 peaks in MDD patients). However, after successful medical treatment, ERPs did not differentiate between depressive patients and healthy controls. We discuss whether functional deviations within the primary olfactory cortex are responsible for the lower olfactory sensitivity, as well as for the altered emotional stimulus processing in MDD patients.

Adult↗

PubMed2000

Rehabilitation of olfaction after laryngectomy by means of a nasal airflow-inducing maneuver: the "polite yawning" technique.

OBJECTIVE: To develop a nasal airflow-inducing maneuver and apply it in the olfactory rehabilitation of patients who have undergone laryngectomy. DESIGN: Intervention study; before-and-after trial. SETTING: National cancer center. PATIENTS: Forty-four patients who underwent laryngectomy; 34 men and 10 women; mean age, 64 years (range, 42-80 years); mean time since surgery, 6 years (range, 8 months to 18 years). INTERVENTION: In a prospective clinical intervention study, we assessed the effectiveness of a nasal airflow-inducing maneuver ("polite yawning," ie, yawning with closed lips). Speech therapists trained the patients in the maneuver, and its effectiveness in inducing nasal airflow was checked with digital and water manometers. MAIN OUTCOME MEASURES: Olfactory acuity was assessed before and after the intervention by means of an odor detection test and a structured questionnaire concerning olfaction, taste, and appetite. Patients were categorized as "smellers" and "nonsmellers" on the basis of the results of the odor detection test and the present odor perception scale derived from the questionnaire. RESULTS: The nasal airflow-inducing maneuver could be taught to all patients, mostly in only one 30-minute therapy session. Fifteen of the 33 patients in the pretreatment nonsmeller category converted to smellers, for a success rate of 46% (P<.001). CONCLUSION: The nasal airflow-inducing maneuver (the "polite yawning" technique) allowed almost half of the patients to recover their sense of smell.

Adult↗

PubMed2005

Type 4 phosphodiesterase inhibition impairs detection of low odor concentrations in mice.

The cAMP-specific phosphodiesterase PDE4A is abundant in the dendrites, soma and axons of olfactory receptor neurons of the mouse, but it is not present in the cilia, where olfactory transduction initiates. Although the function of PDE4A in mammalian olfaction is unknown, patch clamp studies on deciliated olfactory receptor cells in the newt have shown that adrenaline or cAMP analogs can increase the contrast sensitivity to current injection. We used mice to ask whether increasing the levels of cAMP in sensory neurons by inhibiting PDE4A activity with rolipram could lead to changes in the perception of odorants that correspond to the in vitro cellular responses seen in newts. In an automated olfactometer, rolipram treatment (1mg/kg, i.p.) significantly impaired the detection accuracy of 1-propanol at relatively high dilutions but did not affect detection at lower dilutions. Meanwhile, the ability to discriminate amyl acetate alone from a mixture of amyl acetate+citronellal was not affected by rolipram at any odor dilution. In a different task in which mice were trained to discriminate between cups of scented versus unscented sand, rolipram treatment resulted in poorer discrimination at high and better discrimination at low, odor dilutions. In sum, PDE4 inhibition resulted in a consistent decrement in the ability of mice to detect low concentrations of odorants, but the effects of rolipram on detection of higher concentrations were task-dependent.

1-Propanol↗

PubMed1988

Sensory assessment of fat content in fluid dairy products.

It is unclear what stimulus properties and sensory systems contribute to the discrimination of fat content in foods. Fluid dairy products containing 0.5 to 36% fat were rated on category scales for "fat content", "creaminess", and "pleasantness" under various conditions. In the first experiment, perceived fat content of the stimuli was not changed from normal conditions when visual and olfactory inputs were removed. In a second experiment, the stimuli were altered by the addition of a textural agent, such that their viscosities were all approximately equivalent. Elimination of olfactory input again had no effect on ratings of "fat content". Addition of a textural agent greatly enhanced the apparent "fat content" of the lower fat samples, though it did not fully compensate for the perceived differences amongst the stimuli. These experiments strongly support the concept that perceptions of "fat content" in these products is largely attributable to textural properties, such as viscosity, sensed within the oral cavity.

Adult↗

PubMed2003

Differential involvement of dopamine in the anterior and posterior parts of the dorsal striatum in latent inhibition.

The involvement of mesostriatal dopaminergic neurons in cognitive operations is not well understood, and needs to be further clarified. The use of latent inhibition paradigms is a means of investigating cognitive processes. In this study, we investigated the involvement in latent inhibition of dopaminergic inputs in the anterior part and posterior part of the dorsal striatum. The latent inhibition phenomenon was observed in a conditioned olfactory aversion paradigm. Changes in extracellular dopamine levels induced by the conditioned olfactory stimulus (banana odor) were monitored in the two parts of the dorsal striatum in the left hemisphere after pre-exposure to the olfactory stimulus using in vivo voltammetry in freely moving rats. During the conditioning session animals received either an i.p. injection of NaCl (0.9%) (control groups) or an i.p. injection of LiCl (0.15 M) (conditioned groups). Dopamine variations and place preference or aversion toward the stimulus were analyzed simultaneously in pre-exposed and non-pre-exposed animals. Data collected during the retention (test) session were as follows. Where the anterior part of the striatum was concerned, similar enhancements in dopamine levels (+100%) were obtained in pre-exposed and non-pre-exposed control animals, as well as in the pre-exposed experimental animals. In contrast, dopamine levels in the non-pre-exposed experimental group (conditioned animals) remained fairly consistently close to the baseline after the presentation of the olfactory stimulus. Where the posterior part of the striatum was concerned, increases in extracellular dopamine levels were similar (+50%) for the different groups. The present results suggested that dopaminergic neurons reaching the anterior part of the dorsal striatum are implicated in the latent inhibition phenomenon and affective perception, whereas dopaminergic terminals in the posterior part of the dorsal striatum appeared to be involved neither in latent inhibition nor in affective perception of the stimulus, seeming only to be affected by the intrinsic properties of the stimulus. Cognitive as well as affective deficits have been reported in patients with schizophrenia. Thus the present data may be considered in the context of the pathophysiology of schizophrenic psychoses.

Affect↗

PubMed2005

Differential neural responses evoked by orthonasal versus retronasal odorant perception in humans.

Odors perceived through the mouth (retronasally) as flavor are referred to the oral cavity, whereas odors perceived through the nose (orthonasally) are referred to the external world. We delivered vaporized odorants via the orthonasal and retronasal routes and measured brain response with fMRI. Comparison of retronasal versus orthonasal delivery produced preferential activity in the mouth area at the base of the central sulcus, possibly reflecting olfactory referral to the mouth, associated with retronasal olfaction. Routes of delivery produced differential activation in the insula/operculum, thalamus, hippocampus, amygdala, and caudolateral orbitofrontal cortex in orthonasal > retronasal and in the perigenual cingulate and medial orbitofrontal cortex in retronasal > orthonasal in response to chocolate, but not lavender, butanol, or farnesol, so that an interaction of route and odorant may be inferred. These findings demonstrate differential neural recruitment depending upon the route of odorant administration and suggest that its effect is influenced by whether an odorant represents a food.

Appetite↗

PubMed2001

The color of odors.

The interaction between the vision of colors and odor determination is investigated through lexical analysis of experts' wine tasting comments. The analysis shows that the odors of a wine are, for the most part, represented by objects that have the color of the wine. The assumption of the existence of a perceptual illusion between odor and color is confirmed by a psychophysical experiment. A white wine artificially colored red with an odorless dye was olfactory described as a red wine by a panel of 54 tasters. Hence, because of the visual information, the tasters discounted the olfactory information. Together with recent psychophysical and neuroimaging data, our results suggest that the above perceptual illusion occurs during the verbalization phase of odor determination.

Color Perception↗

PubMed2004

The nose knows who's who: chemosensory individuality and mate recognition in mice.

Individual recognition is an important component of behaviors, such as mate choice and maternal bonding that are vital for reproductive success. This article highlights recent developments in our understanding of the chemosensory cues and the neural pathways involved in individuality discrimination in rodents. There appear to be several types of chemosensory signal of individuality that are influenced by the highly polymorphic families of major histocompatibility complex (MHC) proteins or major urinary proteins (MUPs). Both have the capability of binding small molecules and may influence the individual profile of these chemosignals in biological fluids such as urine, skin secretions, or saliva. Moreover, these proteins, or peptides associated with them, can be taken up into the vomeronasal organ (VNO) where they can potentially interact directly with the vomeronasal receptors. This is particularly interesting given the expression of major histocompatibility complex Ib proteins by the V2R class of vomeronasal receptor and the highly selective responses of accessory olfactory bulb (AOB) mitral cells to strain identity. These findings are consistent with the role of the vomeronasal system in mediating individual discrimination that allows mate recognition in the context of the pregnancy block effect. This is hypothesized to involve a selective increase in the inhibitory control of mitral cells in the accessory olfactory bulb at the first level of processing of the vomeronasal stimulus.

Animals↗

PubMedDate not supplied

Sensitivity to androstenone in female subjects is associated with an altered brain response to male body odor.

Androstenone is a boar pheromone. and has also been found within different human body fluids. However, it is still unclear whether it carries pheromonal information in humans and whether it contributes significantly to the complex human body odor at all. Some humans fail to perceive the odor of androstenone, but most of these anosmics can achieve sensitivity by daily sniffing. The following study was designed to investigate whether sensitivity to androstenone influences the perception of body odors. Four females osmic to and four females anosmic to androstenone attended two EEG sessions. Anosmics were successfully sensitized to androstenone between sessions. CSERPs (chemosensory event-related potentials) were obtained while subjects perceived their own body odor and a male body odor within an olfactory oddball paradigm. The CSERPs showed a general decrease in amplitude from the first to the second session except for the sensitized anosmics in response to male body odor. The results indicate that the sensitivity to androstenone in females is associated with a stronger brain response to male body odor.

Adult↗

PubMed1985

Brain and liver insulin binding is decreased in Zucker rats carrying the 'fa' gene.

Insulin binding was measured in membrane particles prepared from the liver and several brain regions of 4-month-old female Zucker fa/fa (obese), Fa/fa (heterozygous), and Fa/Fa (lean) rats. High affinity insulin binding was decreased in the olfactory bulb of fatty (0.23 pmol bound/mg protein) and heterozygous (0.16 pmol/mg) rats compared with that in the lean controls (0.64 pmol/mg). Total binding was not changed in the cerebral cortex or hypothalamus. High affinity insulin binding was also decreased in the liver of both fatty (0.44 +/- 0.22 pmol/mg; P less than 0.01) and heterozygous (0.75 +/- 0.35 pmol/mg) animals compared with that in the lean rats (2.10 +/- 1.55 pmol/mg). This decreased binding is probably not due to down-regulation of receptors in the heterozygous rats, as they do not exhibit the hyperinsulinemia observed in the fatty rats. Rather, our findings suggest that there is a gene-related alteration in insulin binding in the Zucker rat, as low binding was observed in rats carrying either one (Fa/fa) or two (fa/fa) doses of the gene. We postulate that this central defect in insulin binding may contribute to inadequate perception of a central insulin feedback signal and to the hyperphagia observed in the obese rats.

Animals↗

PubMed1989

Ability to perceive androstenone can be acquired by ostensibly anosmic people.

Nearly half the adult human population does not perceive an odor when sniffing androstenone (5 alpha-androst-16-en-3-one), a volatile steroid found in human perspiration, boar saliva, some pork products (e.g., bacon), truffles, and celery. This variation in ability to perceive androstenone has a significant heritable component, suggesting that androstenone insensitivity is in part determined genetically. We now report that the ability to perceive androstenone was induced in 10 of 20 initially insensitive subjects who were systematically exposed to androstenone. Since olfactory neurons of the olfactory epithelium undergo periodic replacement from differentiating basal cells, and assuming the induction of sensitivity to be peripheral, we propose that a portion of the apparently anosmic human population does in fact possess olfactory neurons with specific receptors for androstenone. Such neurons may undergo clonal expansion, or selection of lineages with more receptors or receptors of higher affinity, in response to androstenone stimulation, much in the manner of lymphocytes responding to antigenic stimulation, thus raising odor stimulation to the level of conscious perception. As a guide to further study of the genetics and mechanism of variation of androstenone perception, we provisionally envisage three categories of human subjects, the truly anosmic, the inducible, and those subjects who either are constitutionally sensitive or have already experienced incidental induction.

Androstenes↗

PubMed1979

Parotid and whole-mouth secretion in response to viewing, handling, and sniffing food.

There was no significant change in flow rates of parotid saliva in nineteen of twenty subjects while they viewed photographs of lemons, or in fourteen of twenty subjects while they cut lemons in a glove box. Neither parotid nor whole-mouth secretion changed from baseline when subjects viewed fresh lemons and lemonade presented in a plastic box. Further, no significant changes in whole-mouth secretion rates were observed when subjects viewed photographs of two appetizing foods, or of fresh doughnuts in a plastic box, even though subjects knew they could eat the doughnuts after the experiment. In most cases, sniffing of the lemons or of the doughnuts resulted in increased flow rates. Subjects demonstrated large differences in their patterns of affective responses to full-strength and diluted lemon juice, which were independent of salivary flow. In the absence of olfactory or tactile stimulations, few subjects altered parotid or whole-mouth secretion rates in response to viewing food or photographs of food. A reevaluation of findings on 'psychic' stimulation of saliva may be in order to ascertain the role of olfactory, tactile, and even trigeminal clues in salivary response to food stimuli.

Citrates↗

PubMed1998

Mushroom bodies of the cockroach: activity and identities of neurons recorded in freely moving animals.

This article describes novel attributes of the mushroom bodies of cockroaches revealed by recording from neurons in freely moving insects. The results suggest several hitherto unrecognized functions of the mushroom bodies: extrinsic neurons that discriminate between imposed and self-generated sensory stimulation, extrinsic neurons that monitor motor actions, and a third class of extrinsic neurons that predict episodes of locomotion and modulate their activity depending on the turning direction. Electrophysiological units have been correlated with neurons that were partially stained by uptake of copper ions and silver intensification. Neurons so revealed correspond to Golgi-impregnated or Lucifer yellow-filled neurons and demonstrate that their processes generally ascend to other areas of the protocerebrum. The present results support the idea of multiple roles for the mushroom bodies. These include sensory discrimination, the integration of sensory perception with motor actions, and, as described in the companion article, a role in place memory.

Animals↗

PubMed2002

Rats can track odors, other rats, and themselves: implications for the study of spatial behavior.

In order to demonstrate that rats solve dead reckoning (path integration) tasks in which they return to a starting location using self-movement (idiothetic) cues, it is necessary to remove external (allothetic) cues. Odor cues, especially those generated by a rat on a single passage, are difficult to control and they can potentially serve as a cue to guide a homeward trip. Because it is presently unknown whether rats can track the cues that they themselves leave, as opposed to the odor trails left by other rats, we investigated this question in the present study. A tracking task was used in which rats: (1) followed a scented string from a refuge to obtain a food pellet located on a large circular table; (2) followed odors left on the table; (3) followed odors left by the passage of another rat; or (4) followed odors left by themselves. Groups of rats were presented with strings scented with either the rat's own odor (Group Own), a conspecific's odor (Group Other), or another scent, vanilla (Group Vanilla). After training, a series of discrimination tests were given to determine the nature of the stimulus that controls scent tracking. The results indicated that Own, Other, and Vanilla groups were equally proficient in discriminating and following their respective odors. The rats were also able to follow odor trails on the table surface as well as a trail left by the single passage of another rat or their own passage. This is the first study to demonstrate that rats can discriminate between conspecific odors and their own odor left during a single passage. The results are discussed in relation to their implications for experimental methodology and olfactory contributions to spatial navigation in general and dead reckoning in particular.

Animals↗

PubMed1980

Sensory determinants of suckling behavior in weanling rats.

Exteroceptive determinants of nipple attachment in albino rat pups were studied by altering maternal sensory features. Rats 15, 20, 25, and 30 days of age were permitted to locate and attach to the nipples of their anesthetized mother after she had received one of the following treatments: (a) thermalnipple and peripheral skin temperatures were lowered to either 31 or 28 degrees C, (b) tactile--the mother's ventrum was shaved clean; (c) thermotactile--the mother was shaved, and her peripheral temperature was lowered to 31 degrees C; and (d) olfactory--all nipples were thoroughly cleaned with methylene chloride and ethanol solvents. Only the nipple-wash treatment consistently affected nipple attachment. Washing the nipple disrupted suckling; returning a vacuum distillate of the wash extract or of pup saliva reinstated attachment to normal levels. Thus, in sighted weanling rats, as in younger rat pups, olfactory stimuli remain the major determinants of nipple attachment.

Animals↗

PubMed2002

The limited capacity of humans to identify the components of taste mixtures and taste-odour mixtures.

The capacity of humans to identify the components of taste mixtures and odour-taste mixtures was investigated in two experiments. Subjects were trained to identify the components presented alone and to use a 'yes/no' procedure to identify them in mixtures. All stimuli were presented with a retronasal (by mouth) technique. A maximum of three tastants were identified in both types of mixtures, only one tastant was identified in five-component taste mixtures, and no component was identified in four-component odour-taste mixtures. Importantly, in no instance was the olfactory stimulus identified in any mixture with tastes, including binary mixtures. Loss of identity of the odorant in binary and ternary mixtures may have been due to suppression as a consequence of temporal processing, or to the absence of an association between the odorant and tastants that had established an identifiable percept. In contrast, poor identification of the components of the quaternary odour-taste mixture and quinternary taste mixture is attributed to the limited capacity of working memory. Overall, the poorer ability to identify components in odour-taste mixtures than in taste mixtures indicates that interactions occurred between the two senses, challenging the proposal that odours and tastes are processed independently when present in complex chemosensory stimuli.

Adult↗

PubMed1997

Olfactory cues from an oxytocin-injected male rat can reduce energy loss in its cagemates.

Rats can recognize the odor of a stressed conspecific and react with stress themselves. Stress mobilizes energy, causing increased core temperatures and energy loss by radiation from the naked tail. Oxytocin administered in high doses (1 mg/kg, s.c.) reduces a rat's tail skin temperature and thereby the radiated energy loss. While administration of this high dose of oxytocin induces sedation low doses induce anxiolysis. This study demonstrates that the cagemates of an oxytocin-treated (1 mg/kg s.c.) rat, which themselves have not received any oxytocin-treatment, show energy conservation, apparent as reduced tail skin temperature. This effect was blocked by olfactory impairment. The temperature reduction in the cagemates probably reflects an oxytocin-mediated olfactorily activated stress inhibitory mechanism.

Animals↗