SEARCH · PubMed Health

Results for “Olfactory Perception”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

PubMed2000

Specificity of amygdalostriatal interactions in the involvement of mesencephalic dopaminergic neurons in affective perception.

We have recently shown that dopaminergic responses to an attractive or an aversive stimulus were respectively increased and decreased in the core part of the nucleus accumbens and the ventromedial dorsal striatum. By contrast, increases in dopaminergic responses were obtained in the shell part of the nucleus accumbens with stimuli of both affective values. In addition, the involvement of the basolateral amygdala in affective processes has been reported by several authors. Anatomo-functional relationships between the basolateral amygdala and striatal structures have also been described. Thus, in the present work we studied the regulation by the basolateral amygdala of affective dopaminergic responses in the two parts of the nucleus accumbens (core and shell) and the ventromedial dorsal striatum. More precisely, variations in extracellular levels of dopamine induced by an attractive or an aversive olfactory stimulus were studied using in vivo voltammetry in freely moving rats. Changes in dopamine levels in the three left striatal regions were measured after functional blockade of the ipsilateral basolateral amygdala with tetrodotoxin. Changes in place attraction or aversion toward the stimulus were studied in parallel to dopamine variations. The results obtained suggest a specific regulation of affective dopaminergic responses in the two parts of the nucleus accumbens by the basolateral amygdala and a lack of influence of the basolateral amygdala on the ventromedial dorsal striatum. The results suggest that attraction or aversion toward a stimulus are correlated with dopamine variations in the core of the nucleus accumbens and that the basolateral amygdala controls affective behavioural responses. These data may provide new insights into the pathophysiology of schizophrenic psychoses.

Affect↗

PubMed1979

Evolution of olfactory receptor in oriental fruit fly Dacus dorsalis.

Male oriental fruit flies (Dacus dorsalis) from colonies in Taiwan and Hawaii were evaluated for limit of response to various analogues of methyl eugenol. The results are interpreted in terms of the geometry and allosteric requirements of the antennal receptor that triggers the characteristic methyl eugenol reflex. This receptor has evolved for complementarity to all portions of the methyl eugenol molecule and responds only to ortho-substituted benzenes with adjacent oxygen atoms or isoelectronic equivalents. Substantial differences in responses of Taiwan and Hawaiian D. dorsalis suggest that perceptible evolution of the receptor protein has occurred during the past 50 years. A plausible scheme for the coevolution of dacini flies with plants containing phenylpropionoid essential oils is outlined.

Journal Article↗

PubMed2002

Olfactory acuity and cognitive function converge in older adulthood: support for the common cause hypothesis.

Visual and auditory thresholds and cognitive variables have shown converging losses in old age, which might exist because standard cognitive tests rely on these modalities for assessment. The present study investigated the common cause hypothesis in another sensory modality. Structural equation modeling tested the fit of a model representing the common cause hypothesis for olfactory acuity and cognitive function data from 98 nondemented older adults and 103 younger adults. The model fit better the data from the older adults, consistent with the common cause hypothesis. In addition, unique influences of age beyond those shared between cognitive and sensory variables were also demonstrated. The results suggest that olfactory functioning may be a valid indicator of the integrity of the aging brain in older adults.

Adolescent↗

PubMedDate not supplied

Odogenic change of blood coagulation in humans.

The blood coagulation time as an integral sign of human homeostasis is revealed to be influenced by conscious or unconscious olfactory stimuli through autonomic mechanisms. The hemostasis of subjects with predominance of sympathetic activity is more sensitive to the olfactory stimuli than that of subjects with vagal prevalence. The effects of the olfactory stimuli upon hemostasis in humans support the viewpoint that simultaneous information and physico-chemical processes act together in parallel to play and important role in life activities of human organism (Simonov, 1981; Sudakov, 1995). Emotions, therefore, are essential in the transfer of information from the environment (Anokhin, 1966; Miltner et al., 1994). It is not excluded that even very weak stimuli which are subthreshold for conscious perception might be informational for the organism as those engaging emotional response.

Adult↗

PubMed1984

Brain reward circuitry: a case for separate systems.

Anatomical, lesion and pharmacological data pertaining to intracranial self-stimulation are reviewed in the context of multiple independent substrates of brain-stimulation reward. Subsystems related to chemosensitive pathways, motor control and mood are identified. Forebrain dopamine pathways are recognized to be important components of two separate subsystems of reward. Nigrostriatal DA neurons are linked to an extrapyramidal circuit with reinforcement derived from response initiation and it is conjectured that the meso-limbic DA pathway is related to the control and perception of positive affect. Other candidate systems include a trigeminal system in the hind brain that may function independently from forebrain substrates of reward.

Amygdala↗

PubMed1998

Effects of olfactory stimulation on the vigilance performance of individuals with brain injury.

Observers with brain injury and control participants performed a vigilance task during which they received periodic whiffs of unscented air or air scented with peppermint. Under both fragrance conditions, controls reduced the frequency of commissive errors (false alarms) over the course of the vigil, an adaptive strategy given the low probability of signals employed (0.04). The false alarm rate of observers with brain injury increased precipitously toward the end of the vigil in the unscented air condition. However, exposure to the scent of peppermint rendered the false alarm scores of observers with brain injury similar to that of controls, a result which is consistent with evidence that olfactory stimulation activates brain areas vital for planning and judgment.

Adolescent↗

PubMed1987

Visual dominance in olfactory memory.

The object of the present study was to verify the emergence of a 'visual dominance' effect in memory tests involving different sensory modes (sight and smell), brought about the preattentive mechanisms which select the visual sensory mode regardless of the recall task.

Adult↗

PubMed2001

Functional expression and characterization of a Drosophila odorant receptor in a heterologous cell system.

Odorant receptors (ORs) constitute the molecular basis for the detection of volatile odorous molecules and the perception of smell. Our understanding of chemical senses has been greatly expanded by the discovery of the OR gene families in vertebrates and in the nematode Caenorhabditis elegans. Recently, candidate Drosophila OR genes have been identified. The putative ORs do not possess any primary sequence identity with known vertebrate or C. elegans receptors, but belong to the family of G protein-coupled receptors according to their predicted seven transmembrane topology. To prove olfactory function of these proteins, we expressed a member of the putative Drosophila OR gene family, Or43a, in Xenopus laevis oocytes. Using two-electrode voltage-clamp recording we identified four odors (cyclohexanone, cyclohexanol, benzaldehyde, and benzyl alcohol) that activated the receptor at low micromolar concentration and structurally related substances that did not. This report shows the function and specificity of a member of the recently identified family of Drosophila ORs expressed in a heterologous system.

Animals↗

PubMed1990

Identification of a specialized adenylyl cyclase that may mediate odorant detection.

The mammalian olfactory system may transduce odorant information via a G protein-mediated adenosine 3',5'-monophosphate (cAMP) cascade. A newly discovered adenylyl cyclase, termed type III, has been cloned, and its expression was localized to olfactory neurons. The type III protein resides in the sensory neuronal cilia, which project into the nasal lumen and are accessible to airborne odorants. The enzymatic activity of the type III adenylyl cyclase appears to differ from nonsensory cyclases. The large difference seen between basal and stimulated activity for the type III enzyme could allow considerable modulation of the intracellular cAMP concentration. This property may represent one mechanism of achieving sensitivity in odorant perception.

Adenylyl Cyclases↗

PubMed1999

Comparative study of visual, auditory, and olfactory function in Usher syndrome.

BACKGROUND: Usher syndrome is a genotypically and phenotypically heterogeneous group of autosomal recessive diseases featuring retinitis pigmentosa (RP) and sensorineural hearing loss. A general ciliary dysfunction has been suspected following reports of a mutated cytoskeletal protein (myosin VIIA) in type IB, and preliminary data has suggested an olfactory deficit. The purpose of this study was to quantitatively assess olfactory function in Usher syndrome patients and to search for a correlation between the degree of impairment of the three sensory systems as indication of an underlying ciliary defect. METHODS: 39 patients with Usher syndrome (8 type I, 31 type II) were examined. The ophthalmologic protocol included patient history, visual acuity, eye morphology, Goldmann perimetry, and electroretinography. The ENT protocol included a thorough examination, speech-recognition test, pure-tone audiometry and an olfactory function test. RESULTS: In both groups, visual acuity was typically 20/40, the remaining visual field area was small, and the ERG responses were low to non-detectable. Average hearing loss was 100% in type I and 40% in type II. Olfactory thresholds were normal [median 9.7 (I) and 8.5 (II) vs. 8.5 in the control group]. There were multiple significant correlations between parameters of the same organ, but no relationship between parameters of different sensory systems. CONCLUSION: Almost all Usher syndrome patients in this study had an advanced form of RP. In contrast, auditory function differed considerably between type I and type II. An impairment of the olfactory system could not be detected, and there was no correlation between parameters representing visual function, hearing ability, and olfactory sense.

Adult↗

PubMed2004

Differences in olfactory and visual memory in patients with pathologically confirmed Alzheimer's disease and the Lewy body variant of Alzheimer's disease.

Recognition and remote memory for odors, faces, and symbols were assessed in patients with pathologically confirmed Lewy body variant of Alzheimer's disease (LBV), patients with pathologically confirmed Alzheimer's disease (AD), and healthy elderly controls. On recognition memory tasks, LBV and AD patients showed significantly lower discriminability (d') than controls, particularly for olfactory stimuli. However no significant differences were found in the bias measure (c). When participants rated familiarity (a proposed measure of remote memory) of olfactory stimuli LBV and AD patients reported significantly lower familiarity than controls. Familiarity ratings were significantly lower in LBV patients than in AD patients for olfactory, but not for visual stimuli. Consistent with prior reports, the LBV patients showed significantly poorer odor thresholds than AD patients. The results suggest that recognition memory for olfactory stimuli is impaired in LBV and AD. However, patients with LBV are more impaired than patients with AD on tasks requiring remote memory for olfactory but not visual stimuli. The findings suggest that odor memory tasks may be useful in the assessment of LBV and AD.

Aged↗

PubMedDate not supplied

The "sense of being stared at" does not depend on known sensory clues.

The "sense of being stared at" can be investigated by means of simple experiments in which subjects and lookers work in pairs, with the looker sitting behind the subject. In a random sequence of trials, the looker either looks at the back of the subject, or looks away and thinks of something else. More than 15,000 trials have already been conducted, involving more than 700 subjects, with an extremely significant excess of correct over incorrect guesses (Sheldrake [1999]). This effect was still apparent in experiments in which subjects were blindfolded and given no feedback, showing it did not depend on visual clues, nor on the subjects knowing if their guesses were right or wrong (Sheldrake [2000]). In this paper I describe experiments I conducted in schools in England in which the subjects were not only blindfolded and given no feedback, but looked at through closed windows. There was again a very significant excess of correct over incorrect guesses (p < 0.004). At my request, schoolteachers in Canada, Germany and the United States carried out similar experiments and found an even more significant positive effect than in my own experiments (p < 0.0002). The fact that positive results were still obtained when visual clues had been effectively eliminated by blindfolds, and auditory and olfactory clues by closed windows, implies that the sense of being stared at does not depend on the known senses. I conclude that peoples' ability to know when they are being looked at depends on an influence at present unknown to science.

Child↗

PubMed1998

Scratch density differentiates microsmic from normosmic and anosmic subjects on the University of Pennsylvania Smell Identification Test.

During assessment of smell function using the University of Pennsylvania Smell Identification Test, we observed that some persons with diminished smell perception seemed to perserverate in their attempts to release the odorant from the microencapsulated odorant strips. In this study we quantified the marked area of 1680 such strips from tests administered to 42 anosmics, normosmics, and microsmics. The density of pixels on the microencapsulated labels from the microsmic patients was greater than that from the other two groups, which did not differ significantly from one another. These data suggest (i) that persons with diminished olfactory ability attempt to increase the perceived intensity of the stimulus by marking the test's scent strips more vigorously and (ii) that the density of such marking may prove useful in detecting malingerers attempting to feign microsmia.

Aged↗

PubMed2006

Quantity-based judgments in the domestic dog (Canis lupus familiaris).

We examined the ability of domestic dogs to choose the larger versus smaller quantity of food in two experiments. In experiment 1, we investigated the ability of 29 dogs (results from 18 dogs were used in the data analysis) to discriminate between two quantities of food presented in eight different combinations. Choices were simultaneously presented and visually available at the time of choice. Overall, subjects chose the larger quantity more often than the smaller quantity, but they found numerically close comparisons more difficult. In experiment 2, we tested two dogs from experiment 1 under three conditions. In condition 1, we used similar methods from experiment 1 and tested the dogs multiple times on the eight combinations from experiment 1 plus one additional combination. In conditions 2 and 3, the food was visually unavailable to the subjects at the time of choice, but in condition 2, food choices were viewed simultaneously before being made visually unavailable, and in condition 3, they were viewed successively. In these last two conditions, and especially in condition 3, the dogs had to keep track of quantities mentally in order to choose optimally. Subjects still chose the larger quantity more often than the smaller quantity when the food was not simultaneously visible at the time of choice. Olfactory cues and inadvertent cuing by the experimenter were excluded as mechanisms for choosing larger quantities. The results suggest that, like apes tested on similar tasks, some dogs can form internal representations and make mental comparisons of quantity.

Animals↗

PubMed1965

GALVANIC SKIN REFLEX IN NEWBORN HUMANS.

Psychophysiological recordings of reactivity to light and sound and to tactile and olfactory stimulation demonstrate that the galvanic skin reflex is an observable and functional mechanism in the 20- to 67-hour-old newborn human.

Galvanic Skin Response↗

PubMed1975

[Akinetic mutism and bicingular softening. 3 anatomo-clinical cases].

The authors describe three pathological cases of akinetic mutism with, as a common basic lesion, bilateral infarction of the cingulate gyrus secondary to aneurysm of the anterior communicating artery (case n degrees 1), to a huge olfactory meningioma (case n degrees 2), both operated on, and to atheromatous occlusion of the anterior cerebral arterial system (case n degrees 3). These three cases enable a variety of "anterior and waking" akinetic mutism to be described which is unusual enough to be compared with other mesencephalic and diencephalic aspects of this syndrome. It is in fact an akinetic mutism characterized by: a certain dissociation in its non-response to various stimuli, a particularly marked appearance of wakefulness when day-time alertness is considered, conservation of the waking-sleeping rhythm, perception and reaction unpredictable and paradoxical in both degree and quality, complete absence of any spontaneous verbal communication in contrast to relative break-down of solicited communication which is infrequent, uncertain and unresponsive to the usual methods of stimulation, without any possibility of a code. In addition, there is a remarkable mimic and segmental general akinesia, resistant to the usual nociceptive stimuli, but sensitive to slight excitation of the manual and oral zones. Besides this special akinetic mutism, there are variously systematised signs, mostly asymmetrical, indicating lesion of the cortico-sub-cortical frontal structures bordering on the gyrus cinguli. This unusual behaviour pattern corresponds in these three cases to extensive anterior bilateral ischemic lesions of the cingulate gyrus regularly associated with bilateral infarctions confined to the medial aspect of F1 in the superficial territory of the two anterior cerebral arteries, to possible neurosurgical changes (ablation of the right frontal pole) and to compressive or ischaemic lesions of the gyrus rectus. These exclusively cortico-sub-cortical associated lesions are in contrast with the remarkably intact caudate nuclei, the pallidal, thalamic, hypothalamic and septal formations and the anterior pillars of the fornix. These findings compared with the results of experimental research carried out by M. Kennard, help, if help is needed, to resolve the apparent contradictions between the effects of therapeutic cingulectomies or cingulotomies and the scanty pathological data already available in cerebral vascular pathology.

Adult↗

PubMed1985

Early postnatal lead exposure: behavioral effects in common tern chicks (Sterna hirundo).

Exposure to lead early in life is known to affect behavioral and intellectual development. To develop an animal model we chose the common tern, Sterna hirundo, a species whose early developmental landmarks are well known. One potential for avian models lies in the reliance of birds on visual and acoustic rather than olfactory (and ultrasonic) modes of communication. One randomly chosen member of each of 8 pairs of young common tern chicks was injected with lead nitrate solution at a concentration of 0.2 mg/g. The pairs were not siblings but were matched for age (+/- 1 d) and weight (+/- 3 g). The second member of each pair was injected with an equal volume of sterile saline. Behavioral tests performed examined locomotion, balance and righting response, feeding tasks and begging, depth perception and response on a visual cliff, and behavioral thermoregulation. In each pair the control chick was heavier at 4 wk of age. For most behavioral measures, except begging and movement on a stationary incline, the lead-injected chicks performed less well than the control chicks. When presented with a novel feeding situation (reversal of fish position), the lead-injected chicks required significantly more time to eat the same number of fish. The single injection of lead thus affected a variety of behavioral patterns, with effects apparent within 5 d after injection.

Analysis of Variance↗

PubMed2005

Effects on hunger and satiety, perceived portion size and pleasantness of taste of varying the portion size of foods: a brief review of selected studies.

The portion size of foods has been identified as an important environmental factor known to affect short-term energy intake. Experiments that were conducted both in the free-living environment and in laboratory-based settings to investigate the effects of portion size on energy intake unanimously showed that as the portion size of food increased, so did subjects' energy intake. Despite the fact that the profound effects of portion size on energy intake are well documented, the mechanisms by which portion size affects energy intake are poorly understood. There is some evidence that sensory influences (e.g. visual and olfactory cues), cognitive factors (e.g. learning, social norms, monetary considerations), and post-ingestive consequences (e.g. sensations of hunger and fullness) related to the portion size of foods may interact to affect the amount of food that is consumed during a meal.

Energy Intake↗