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Results for “Olfactory Perception”

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At least 973 records · Page 54Linked to original sources

PubMed2000

Selective attention to the chemosensory modality.

Previous studies have shown that behavioral responses to auditory, visual, and tactile stimuli are modulated by expectancies regarding the likely modality of an upcoming stimulus (see Spence & Driver, 1997). In the present study, we investigated whether people can also selectively attend to the chemosensory modality (involving responses to olfactory, chemical, and painful stimuli). Participants made speeded spatial discrimination responses (left vs. right) to an unpredictable sequence of odor and tactile targets. Odor stimuli were presented to either the left or the right nostril, embedded in a birhinally applied constant airstream. Tactile stimuli were presented to the left or the right hand. On each trial, a symbolic visual cue predicted the likely modality for the upcoming target (the cue was a valid predictor of the target modality on the majority of trials). Response latencies were faster when targets were presented in the expected modality than when they were presented in the unexpected modality, showing for the first time that behavioral responses to chemosensory stimuli can be modulated by selective attention.

Attention↗

PubMed1986

Sensory control of maternal aggression in Rattus norvegicus.

Female rats become aggressive toward adult conspecifics during lactation. This change in social affect is dependent on the presence of the offspring, because maternal aggression disappears when the pups are removed. It was found that a similar decline occurs when the litter is placed in a glass flask while remaining in the home cage. In contrast, maternal aggression persists following placement of the pups in a nylon mesh bag. The pups did not vocalize while being in the mesh bags, so it appears that olfactory cues from the offspring constitute a critical element in the maintenance of maternal aggression in the rat. It has been suggested that the odor not only of the pups but also of the intruder may contribute to eliciting aggressive behavior in lactating rodents. In line with this proposal, it was found that mother rats spend about one third of the time preceding the first attack sniffing the body of the intruder. In contrast to findings in mice, housing of the prospective intruder behind a double wire mesh partition in the lactating female's home cage failed to reduce her aggressiveness toward him. Rats, then, may require more intimate contact with an individual than do mice for the aggression-reducing effect of familiarization to be observed.

Aggression↗

PubMed2000

The role of sensory stimulation in perinatal development: insights from comparative research for care of the high-risk infant.

Studies of avian and mammalian species have highlighted the importance of normal patterns of perinatal sensory experience to early perceptual and behavioral capabilities, including recognition and preference for maternal olfactory, auditory, and visual information, the capability for prenatal and postnatal auditory learning, and sensitivity to temporal and spatial features of sensory stimulation. This animal-based research suggests that the effects that alterations of perinatal sensory stimulation may have on early perceptual and behavioral development likely depend on a number of related factors, including (a) the timing of the stimulation relative to the developmental stage of the organism, (b) the amount of stimulation provided or denied the young organism, and (c) the type of sensory stimulation presented. This article reviews research drawn from comparative developmental psychology and psychobiology on perinatal perceptual development and explores how it can inform research and practice concerned with the developmentally appropriate care of the high-risk infant.

Acoustic Stimulation↗

PubMed2005

Ambient odors influence the amplitude and time course of visual distraction.

Behavioral performance was examined in a task of attentional capture by luminance under conditions of ambient odors (phenyl ethyl alcohol [PEA], olfactory stimulus, and allyl isothiocyanate [AIC], mixed olfactory/trigeminal stimulus). The AIC increased the amplitude and duration of capture, whereas the presence of PEA led capture to disappear. Furthermore, the PEA caused a general slowing in the speed of information processing. The amplitude and time course of capture were correlated to the irritating components of these odorants, whereas a control experiment showed that the general slowing caused by the PEA was correlated to a drop-off of the subjects' arousal level. These results suggest that ambient odors may exert differential influence of visual-attentional processes and that this influence may depend on the odor's properties.

Adult↗

PubMed1991

Impairment of olfactory, auditory, and spatial serial reversal learning in rats recovered from pyrithiamine-induced thiamine deficiency.

Rats that had recovered from pyrithiamine-induced thiamine deficiency (PTD) were compared with controls for spatial, auditory, and olfactory serial reversal learning (SRL); spatial matching to sample (MTS); auditory go-no-go discrimination; and open-field exploration. PTD rats made more errors reaching criterion for SRL in all modalities but showed normal transfer effects between problems. PTD rats were also impaired in learning the go-no-go and MTS tasks and showed consistent alterations in exploratory activity. It is argued that the PTD rat, like human Korsakoff patients, have impairments of learning and memory (but spared capacity for reference memory) that extend across sensory modalities. Postmortem analyses showed normal indices of cortical cholinergic, noradrenergic, dopaminergic, and serotonergic function and consistent bilateral lesions of the thalamus, which were centered on the internal medullary lamina, and the medial mammillary nucleus.

Animals↗

PubMed1994

Olfactory cues mediate food selection by young chicks.

An illness-induced aversion paradigm was used to assess the possible influence of olfactory cues on food selection by young chicks. At 2-3 days posthatching, chicks were exposed briefly to food scented with a novel odor (orange) followed by an injection of LiCl or saline. LiCl-injected chicks subsequently displayed stronger avoidance of orange-scented food than did the controls. Chicks in a second experiment were preexposed to novel-scented food, then either injected with LiCl or not injected. The LiCl chicks, but not the controls, later avoided food associated with the preexposure odor (relative to food treated with an unfamiliar odorant). Two- to three-day-old chicks are capable of associating specific food odors with negative consequences and modify their feeding behavior as a function of such experience.

Age Factors↗

PubMed1989

Dissociation of visual and olfactory conditioning in the neostriatum of rats.

In an experiment designed to demonstrate a double dissociation, the effects of bilateral electrolytic lesions of either the posteroventral or the ventrolateral regions of the neostriatum on the conditioned emotional response (CER) were examined. Posteroventral lesions impaired acquisition of the CER with a visual CS but not with an olfactory CS. Sham-operated posteroventral and ventrolateral lesioned animals acquired the visual CER normally. Ventrolateral lesions impaired acquisition of the CER with the olfactory CS but not with the visual CS. Sham-operated ventrolateral and posteroventral lesioned animals acquired the olfactory CER normally. In a second experiment the effect of post-training unilateral intrastriatal microinjections of (+)-amphetamine on acquisition of the visual and olfactory CERs was studied. Posteroventral injections improved retention of the visual, but not the olfactory CER. Ventrolateral injections improved retention of the olfactory, but not the visual CER. Saline and delayed (+)-amphetamine injection controls demonstrated that the improvement of retention in each case was a retroactive improvement of memory for the recently acquired CERs by (+)-amphetamine. These findings are consistent with previous reports of post-training memory facilitation mediated by dopaminergic function in the neostriatum. The results of both experiments are consistent with a regional functional heterogeneity hypothesis: the idea that anatomically linked areas of cortex and neostriatum process memories involving different stimuli in similar ways and that the integrity of these structures and their connections is necessary to establish and consolidate associative memory.

Amphetamine↗

PubMed2004

[Are there olfactory evoked alterations of breathing patterns?].

BACKGROUND: It is controversially discussed whether strictly olfactory stimuli are able to evoke changes of breathing patterns. A number work groups argue that the more or less noticeable irritative component of odors are responsible for a respiratory response. Other work groups regard changes of breathing pattern as an indicator for an intact smell ability during "pure" olfactory stimulation. METHODS: 12 normosmic young volunteers were repeatedly challenged with hydrogensulfide (H (2)S) for two seconds on inspiration in concentrations just above the threshold using a flow olfactometer. Clean air stimuli were presented randomly as control blanks. The breathing patterns were registered with a differential pressure transducer occluding one nostril via a tube. The signals were digitized and recorded on a PC. Nine parameters were calculated for each breath using a custom made LabView (R) software. The breath during stimulation was compared to the average of five breathing cycles prior to stimulation. An increase or reduction of each parameter was equally regarded by means of their absolute value. The sum was termed respiration index (RI). RESULTS: The mean RI (all trials of each test person) stimulated with H (2)S varied from 201 to 570; stimulated with clean air from 85 to 188. The difference was significant (p < 0,001). A significant group-difference for each single trial was seen as well. There was no significant increase or decrease of RI during 15 successive stimulations with H (2)S. CONCLUSIONS: Detectable short H (2)S-stimuli are able to evoke alterations of breathing patterns which can be identified by computer. Respiration-olfactometry is suitable to objectify odor perception.

Adult↗

PubMedDate not supplied

Mapping of sensory-responsive cells in the septal area of the rat.

A study of sensory-responsive characteristics of single cells of the septal area of male rats was undertaken to determine the distribution of stimulation-induced changes in septal activity. Single cells were systematically sampled in six planes transecting the rostral-caudal axis of the septal area and were tested for responsiveness to visual, auditory, tactual, gustatory and olfactory stimuli. Approximately 50% of the sampled population of septal cells was responsive to at least one stimulus. Most of the responses of septal cells to stimulation were excitatory and occurred at the onset of stimulation. Regions of concentration of sensory-responsiveness cells in the system were found to lie in medial areas of the septum consisting of the dorsomedial portion of the lateral septal nucleus, the medial septal nucleus and the ventral portions of the medial and lateral nuclei. Visual, auditory and tactual stimuli were most effective in producing changes in spontaneous activity of units in these regions. On the basis of relationships of the medial septal region to other limbic areas having sensory-responsive properties, it is concluded that the medial septal area is one component of a limbic sensory system.

Animals↗

PubMed1991

Acquisition and retention by hippocampal rats of simple, conditional, and configural tasks using tactile and olfactory cues: implications for hippocampal function.

Hippocampal rats were given simple, conditional, and configural tasks that required them to pull up strings to obtain food pellets. The tasks contrasted string size, odor, location, paired string size and location, or compounds of string size and odor. There was no anterograde or retrograde amnesia for the simple discriminations or for simple discrimination components of the other tasks. Hippocampal rats also learned conditional and configural tasks, although they were impaired on the configural task. Finally, the rats were impaired in postoperative retention of the conditional but not the configural task, although they displayed savings in relation to naive rats on the conditional task. The results do not support theories that the hippocampus is essential for conditional or configural learning but may support a modified form of configural theory in which the hippocampus contributes to, but is not essential for, learning or retention of configurations.

Animals↗

PubMed1991

Localized intracaudate dopamine D2 receptor activation during the post-training period improves memory for visual or olfactory conditioned emotional responses in rats.

Rats with cannulas aimed at the posteroventral (PV) or ventrolateral (VL) areas of the caudate nucleus were trained on a conditioned emotional response (CER) task. Post-training microinjections of the indirect catecholamine agonist, d-amphetamine (5 micrograms), or of the dopamine D2 receptor agonist, LY171555 (1 microgram), into the PV area improved retention of a CER with a visual CS, but had no effect on a CER with an olfactory CS. Post-training injections of the same two drugs into the VL area improved retention of a CER with an olfactory CS, but had no effect on a CER with a visual CS. Post-training injections of the dopamine D1 receptor agonist, SKF38393 (0.5, 1.0, 2.0 micrograms), into either site had no effects on either CER. These findings suggest that different areas of the caudate nucleus mediate acquisition of CERs with different CSs, possibly implicating the topographically organized corticostriatal innervation in the acquisition of certain types of memories in the caudate nucleus. The findings also suggest that dopamine D2 receptors in the caudate nucleus are involved in the acquisition of these CERs.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1999

Rats with low levels of brain docosahexaenoic acid show impaired performance in olfactory-based and spatial learning tasks.

Studies were carried out to determine if decreased levels of central nervous system docosahexaenoic acid (DHA), a result of consuming an n-3-deficient diet, had an effect on learning- and memory-related behaviors in adult male rats. Females were reared on an n-3-deficient or n-3-adequate diet beginning at 21 d of life. Their male pups, the F2 generation, were weaned to the diet of the dam and tested at 9-12 wk of age. An olfactory-based discrimination and Morris water maze task were used to assess performance. Whole brain was collected after the behavioral experiments and central nervous system fatty acid content was analyzed in olfactory bulb total lipid extracts. F2 generation male rats consuming the n-3-deficient diet had an 82% decrease in DHA compared to rats consuming the n-3-adequate diet. The n-3-deficient animals made significantly more total errors in a 7-problem, 2-odor discrimination task compared to the n-3-adequate group. Furthermore, the escape latency in the Morris water maze task was significantly longer for the n-3-deficient rats compared to the n-3-adequate rats. These results indicate that rats with decreased DHA levels in the central nervous system perform poorer in these tasks compared to rats with higher DHA levels and suggest the presence of learning deficits in these animals.

Animals↗

PubMed2004

Subunit-specific P2X-receptor expression defines chemosensory properties of trigeminal neurons.

The facial innervation pattern of trigeminal nerve fibres comprises the innervation of the nasal epithelium, where free trigeminal nerve endings contribute to detection and discrimination of chemical stimuli including odourants. The signal transduction mechanisms in sensory nerve endings underlying perception of chemical stimuli remain widely uncovered. Here, we characterized trigeminal ATP-activated P2X receptors in cultured rat trigeminal neurons and investigated their role in chemoperception. We identified a new subpopulation of neurons lacking typical nociceptive characteristics and expressing homomeric P2X(2) receptors. Using a certain group of chemicals known as trigeminal stimuli we found no direct activation of trigeminal neurons, but a modulation of P2X(2) receptor mediated currents. In contrast, P2X(3) receptor mediated currents of nociceptive trigeminal neurons remained unaffected by the tested chemicals. Therefore, we assume a functional role for the newly identified subpopulation in chemodetection of certain trigeminal stimuli.

Adenosine Triphosphate↗

PubMed2005

Novel visual stimuli activate a population of neurons in the primate orbitofrontal cortex.

Neurons were found in the rhesus macaque anterior orbitofrontal cortex that respond to novel but not to familiar visual stimuli. Some of these neurons responded to all novel stimuli, and others to only a subset (e.g., to novel faces). The neurons have no responses to familiar reward- or punishment-associated visual stimuli, nor to taste, olfactory or somatosensory inputs. The responses of the neurons typically habituated with repeated presentations of a novel stimulus, and five presentations each 1s was the median number for the response to reach half-maximal. The neurons did not respond to stimuli which had been novel and shown a few times on the previous day, indicating that the neurons were involved in long-term memory. The median latency of the neuronal responses was 120 ms. The median spontaneous firing rate was 1.3 spikes/s, and the median response to novel visual stimuli was 6.0 spikes/s. These findings indicate that the long-term memory for visual stimuli is information that is represented in a region of the primate anterior orbitofrontal cortex.

Analysis of Variance↗

PubMed2003

Time, space and hippocampal functions.

The hippocampus is one of the most researched structures of the brain. Studies of lesions in humans, primates and rodents have suggested to some that the primary role of the hippocampus is to act as a temporary memory buffer which is required for the consolidation of long-term memory. The famous case study of patient H.M., in particular, seemed to suggest that the hippocampus was of crucial importance for memory formation. However, recordings of single neurons in freely moving rodents did not support this notion. In such recordings, neurons were found that were active predominately when the animal passed through a particular area in space. Consequently, these neurons were termed 'place cells' and a theory was developed that suggested that the hippocampus acts as a 'cognitive map' that is required for spatial orientation. It was then found that H.M. had significant damage to his temporal lobes that included the amygdala, rhinal cortices, and other areas. Further case studies and selective hippocampal lesions in primates resulted in much milder amnestic symptoms, and lesions of defined cortical areas in the temporal lobes showed that a number of functions previously attributed to the hippocampus were in fact linked to these areas. Further analysis of neuronal activity in the hippocampus showed that not only is spatial information represented there, but also additional information, such as speed of movement, direction of movement, match or non-match detection, olfactorial identification, and others. In addition, it was found that selective lesions of the hippocampus in rodents impaired spatial navigation and memory formation only mildly. Only simultaneous lesions of several cortical areas in conjunction with the hippocamus could reproduce the impairments and symptoms that were previously thought to be observed after hippocampal lesions alone. In conclusion it is proposed that information processing and memory formation is shared by several brain areas that act as a functional system. This review presents evidence from many different studies that the hippocampus is part of this system and plays a supportive role in associating complex multimodal information and laying down new memory traces. In addition, the concept of allocating specific functions (such as the development of a cognitive map) exclusively to the hippocampus is rejected.

Animals↗

PubMed1989

Odor masking in the rat.

A computer controlled behavioral apparatus and olfactometer were used to determine the olfactory threshold of rats for propionic acid and to determine their ability to discriminate propionic acid in binary mixtures that contained the dissimilar odorants, limonene or carvone, or a similar odorant, acetic acid. The concentration of propionic acid that rats required to discriminate this substance from the other odorants was substantially above that of the threshold concentration, the increase being greatest with acetic acid. The increased levels of propionic acid needed for detection of this odorant in mixtures is attributed to masking by the other components. This study represents the first time behavioral methods have been used to demonstrate masking with odor mixtures in a rodent. The results indicate that it should be possible to use behavioral methods to define conditions for odor masking in animals so that physiological studies of the underlying mechanisms can be achieved.

Acetates↗

PubMed2001

Removing zinc from synaptic vesicles does not impair spatial learning, memory, or sensorimotor functions in the mouse.

Zinc-enriched (ZEN) neurons are distributed widely throughout the brain and spinal cord. Synaptic vesicle zinc in these neurons is thought to function as a neuromodulator upon its release into the synaptic cleft. Consistent with this possibility, zinc or zinc chelators can alter spatial learning, working memory, and nociception in rodents. Here we use zinc transporter-3 (ZnT3) knockout mice, which are depleted of synaptic vesicle zinc, to assess the consequences of removing this potential neuromodulator on the behavior of adult mice. ZnT3 knockout mice performed equally as well as wild-type mice in the rotarod, pole, and cagetop tests of motor coordination. They exhibited normal thermal nociception in the hot-plate and tail-flick tests, and had similar olfactory, auditory and sensorimotor gating capabilities as wild-type mice. ZnT3 knockout mice behaved similarly as wild-type mice in the open field test and in the elevated plus maze test of anxiety. They exhibited normal learning and memory in the passive avoidance, Morris water maze, and fear conditioning tasks, and normal working and reference memory in a water version of the radial arm maze. We conclude that synaptic vesicle zinc is not essential for mice to be able to perform these tasks, despite the abundance of ZEN neurons in the relevant regions of the CNS. Either the neuromodulatory effects of zinc are not relevant for the tasks tested here, or mice are able to compensate easily for the absence of synaptic vesicle zinc.

Animals↗

PubMed2004

Flies lacking all synapsins are unexpectedly healthy but are impaired in complex behaviour.

Vertebrate synapsins are abundant synaptic vesicle phosphoproteins that have been proposed to fine-regulate neurotransmitter release by phosphorylation-dependent control of synaptic vesicle motility. However, the consequences of a total lack of all synapsin isoforms due to a knock-out of all three mouse synapsin genes have not yet been investigated. In Drosophila a single synapsin gene encodes several isoforms and is expressed in most synaptic terminals. Thus the targeted deletion of the synapsin gene of Drosophila eliminates the possibility of functional knock-out complementation by other isoforms. Unexpectedly, synapsin null mutant flies show no obvious defects in brain morphology, and no striking qualitative changes in behaviour are observed. Ultrastructural analysis of an identified 'model' synapse of the larval nerve muscle preparation revealed no difference between wild-type and mutant, and spontaneous or evoked excitatory junction potentials at this synapse were normal up to a stimulus frequency of 5 Hz. However, when several behavioural responses were analysed quantitatively, specific differences between mutant and wild-type flies are noted. Adult locomotor activity, optomotor responses at high pattern velocities, wing beat frequency, and visual pattern preference are modified. Synapsin mutant flies show faster habituation of an olfactory jump response, enhanced ethanol tolerance, and significant defects in learning and memory as measured using three different paradigms. Larval behavioural defects are described in a separate paper. We conclude that Drosophila synapsins play a significant role in nervous system function, which is subtle at the cellular level but manifests itself in complex behaviour.

Action Potentials↗