[Effect of visual and olfactory deprivation on acoustically-directed homing orientation in kittens].
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Age Factors↗
SEARCH · PubMed Health
Results for “Olfactory Perception”
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Visceral afferent pathways to the thalamus and olfactory tubercle: behavioral implications.
The goal of this study was to support the hypothesis that visceral signals may integrate and influence behavior by way of direct pathways from the nucleus tractus solitarii (NTS) to the olfactory tubercle and the midline/intralaminar thalamus. An anterograde tracer, biotinylated dextran amine (BDA) was iontophoresed bilaterally into the caudal NTS to optimize terminal labeling. NTS-cortical projections traversed both limbs of the diagonal bands providing heavy innervation, and terminated lightly within layer 3 of the olfactory tubercle. NTS-thalamic projections terminated within anterior and, as previously shown, posterior divisions of nucleus paraventricularis thalami and avoided the adjoining mediodorsal thalamic nucleus. Heretofore unrecognized projections were traced to the parafascicular and reuniens thalamic nuclei, and the peripeduncular nucleus. Control experiments identified the nucleus gracilis as the principal source of ascending projections to ventroposterior lateral, posterior and intralaminar thalamic nuclei. Our data corroborate the supposition that olfactory signals may integrate with visceral stimuli in the striatal compartment of olfactory tubercle. NTS projections encompass thalamic nuclei that project topographically to the prefrontal cortex, hippocampus and ventral (limbic) striatum, regions activated by visceral stimulation. Structural data support the idea that compartments of the non-discriminative thalamus may contribute to perception and behavioral responses to visceral stimulation.
Afferent Pathways↗
Odor-taste mixtures.
A solution with both an odor and a taste may be considered to be a mixture that involves two sensory modalities. Estimates of the intensity of such mixtures appear to be additive. If the overall intensity of each of the unmixed components is compared with the overall intensity of the mixture, the additivity approaches 100%. If the intensities of the smell and taste of the unmixed components are compared with the overall intensity of the mixture, the additivity is less than 100%. Thus, the specific question that is given to the subjects influences the magnitude of the estimations. This suggests that the additive process involves a central (cognitive) mechanism. Considering that the perception of complex flavors also involves sensory information of touch, temperature, and possibly vision and hearing, a central interpretation seems appropriate. The influences of smell on the perception of taste also appear to involve a cognitive mechanism. These smell-taste confusions appear to be stimulus specific and are usually resolved in favor of taste. This may be true because the sensations of pressure, movement, and resistance are usually localized in the mouth. These accompanying sensations then suggest that the taste organs are active in determining the result even when no true taste is present. The influences of taste on the perception of smell are most pronounced when the tastant contains an odor. This suggests that the effect may be peripheral. That is, odorant molecules may be moving from the pharynx, through the posterior nares, to the olfactory receptors. If this interpretation is correct, the influences of taste on smell may be an odor-odor mixture involving "retronasal" and "nasal" olfaction.
Animals↗
Adaptation in the rodent olfactory bulb measured by fMRI.
Effective evaluation of the odor environment necessitates the ability to attenuate responses to potent background odors in favor of novel and less robust stimuli. Olfactory receptor neuron studies suggest that some of this adaptation takes place in the primary sensory neurons, but the more extensive adaptation seen in higher cortical areas implies the involvement of additional neural mechanisms. At 7.0 T, high-resolution fMRI was used to assess the response of the rodent olfactory bulb, the most peripheral cortical structure involved in olfactory processing, to a variety of odor stimuli. The results suggest that there are additional regulatory mechanisms in the olfactory bulb that result in greater adaptation in deeper areas than that seen in sensory receptors alone and that the resultant adaptation is positively affected by increasing stimulus duration and concentration and decreasing recovery time. The implications of these findings for the integration of peripheral input with perception are discussed.
Adaptation, Physiological↗
An investigation of some temporal aspects of olfactory coding with the model of multi-site electrical stimulation of the olfactory bulb in the rat.
Electrical stimulation of the olfactory bulb was used to investigate some temporal aspects of olfactory coding, with reference to respiration. Food-deprived rats implanted with permanent electrodes were trained to use bulbar multi-site stimulation patterns as discriminative stimuli for predicting the nature of an incoming reinforcement. Electrical pulse trains (100 Hz) were periodically delivered in phase with precisely defined moments of the respiratory cycle (during inspiration or expiration). Temporal aspects of olfactory coding were first considered through the measurement of the minimum duration of a stimulus necessary to identify this stimulus. The results showed that a bulbar stimulation lasting for 30 ms (3 pulses), and delivered during inspiration, was clearly identified by the rats. Stimulus identification induced a discriminative respiratory response which could manifest itself as early as the first cycle concomitant with the beginning of stimulation. It was then shown that a bulbar electrical stimulation pattern was identified with the same latency whether it occurred during expiration or during inspiration. Moreover, the perceptive events induced in those two conditions of stimulation were not different enough to be discriminated by the animals. The findings are discussed within the framework of olfactory information processing.
Animals↗
Intranasal chemosensory function of the trigeminal nerve and aspects of its relation to olfaction.
OBJECTIVES: The review outlines characteristics of the intranasal trigeminal chemosensory system. In addition, it provides selective comparisons of the trigeminal and olfactory systems, the two of which interact at multiple levels. RESULTS AND CONCLUSIONS: This interaction between the trigeminal and olfactory systems is an important determinant of sensations of odor. Further, it appears to change as a result of aging and disease. Thus, the interaction between the olfactory and trigeminal systems is not straightforward and may be difficult to predict, but it has a powerful influence on the perception of odors.
Aging↗
Identification of single dissimilar odors is achieved by humans with a single sniff.
The duration that a single odor needs to be sniffed for identification was determined for 18 humans. A hot wire anemometer and an oscilloscope were used to monitor the duration, volume and inhalation rate of sniffs. In Experiment 1 subjects used 1, 3 or 5 natural sniffs, or an unlimited number of natural sniffs to sample seven dissimilar single odors of moderate perceived intensity, and demonstrated that each odor could be identified with a single sniff. In Experiment 2 subjects demonstrated that each of the odors could be identified with the shortest sniff (0.42 sec) they could physically achieve. In Experiment 3 tests with two of the odorants at several concentrations showed that sniff duration influences identification over a narrow range of concentrations that is just above the recognition threshold. These results together with earlier data that described the optimum conditions for the detection of an odor and the perception of odor intensity, provide information that is necessary for the development of a standard olfactometer and standard methods for human olfactory measurements.
Discrimination Learning↗
The influence of gel strength on aroma release from pectin gels in a model mouth and in vivo, monitored with proton-transfer-reaction mass spectrometry.
The course of events from taking a food into the mouth to the perception of the food's flavor involves many steps, from dilution with saliva, mastication, and transportation of the compounds to the olfactory epithelium to transformation into signals that go to the brain. In addition, there are also the effects of the food's structure and properties. In this study, a proton-transfer-reaction mass spectrometer (PTR-MS) was used to investigate how four pectin-containing systems with different structures and strengths affected the release of aroma compounds in a model mouth and in the nose of an assessor. Both the model mouth and the in-nose measurements showed that the strength and structure of pectin-containing systems are important with regard to the quantity of aroma compounds that are released. Mastication and saliva were also shown to have a large influence on how much of the aroma compound is released from the mouth to the nose.
Chemical Phenomena↗
Efficient estimation of sensory thresholds with ML-PEST.
A set of C and C+2 routines are described that allow the efficient estimation of sensory thresholds in psychophysical experiments using a maximum-likelihood staircase procedure. They have been used effectively in visual, auditory, gustatory, and olfactory psychophysics.
Humans↗
Gustatory and olfactory contributions to alcohol consumption in rats.
To determine the relative contributions of taste and smell in the consumption of alcohol by rats, the present experiment tested normal rats (n = 14) and rats with either gustatory cortex ablations (n = 10), olfactory bulbectomies (n = 11), or combination gustatory cortex and olfactory bulb ablations (n = 12). Rats were tested under mild fluid deprivation using a two-bottle testing procedure. Thirteen concentrations of alcohol (0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, and 12%, v/v) were tested in ascending order. Results showed that at strong alcohol concentrations (7% through 11%) rats with combined gustatory cortex and olfactory bulb ablations consumed significantly more alcohol than normal control rats. Rats lacking gustatory cortex displayed a similar increased level of consumption with strong alcohol concentrations. It is suggested that the high level of consumption of strong alcohol concentrations by rats with central nervous system damage reflects an associative deficit rather than an alteration in taste or odor perception.
Alcohol Drinking↗
The alcoholic's taste perception of alcohol: preliminary findings.
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Adult↗
Non-olfactorial discrimination between foods by the dog.
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Animal Feed↗
Lateralization of membrane-associated protein kinase C in rat piriform cortex: specific to operant training cues in the olfactory modality.
Rats were trained on an olfactory and a control modality (auditory or visual) discrimination task and brain membrane-associated protein kinase C (mPKC) was subsequently assessed using quantitative autoradiography of radiolabelled phorbol ester binding. In rats which received olfactory-cued training, mPKC showed a highly significant lateralization in the piriform cortex but not in the hippocampus. Both olfactory-trained rats and control modality rats showed a significant increase in mPKC in the hippocampus when compared to naive rats. Thus, while behavioral training procedures appeared to result in a hippocampal increase in the activated state of this enzyme as has been reported elsewhere, only olfactory learning produced an piriform cortex lateralization in the activated state of the enzyme. While the functional significance of such a change in the distribution of protein kinase C is still unclear, it does suggest that the monitoring of this enzyme's activational state may prove to be a useful tool in the study of memory formation in a wide variety of behavioral contexts.
Animals↗
Molecular and cellular organization of insect chemosensory neurons.
Animals use their chemosensory systems to detect and discriminate among chemical cues in the environment. Remarkable progress has recently been made in our knowledge of the molecular and cellular basis of chemosensory perception in insects, based largely on studies in Drosophila. This progress has been possible due to the identification of gene families for olfactory and gustatory receptors, the use of electro-physiological recording techniques on sensory neurons, the multitude of genetic manipulations that are available in this species, and insights from several insect model systems. Recent studies show that the superfamily of chemoreceptor proteins represent the essential elements in chemosensory coding, endowing chemosensory neurons with their abilities to respond to specific sets of odorants, tastants or pheromones. Investigating how insects detect chemicals in their environment can show us how receptor protein structures relate to ligand binding, how nervous systems process complex information, and how chemosensory systems and genes evolve.
Animals↗
Cholinopositive effect of dilept (neurotensin peptidomimetic) as the basis of its mnemotropic effect.
Dilept eliminated learning disturbances in the extrapolation avoidance test, caused by chronic injections of scopolamine alone and in combination with madopar to rats. Dilept improved the dynamics of training and parameters of spatial memory impaired by olfactory bulbectomy (operation causing hypofunction of the central cholinergic system). The detected choline-positive effect of dilept together with pronounced dopaminergic activity necessitate its further development as a drug effective in positive and negative symptoms of schizophrenia and psychotic manifestations of Alzheimer's disease.
Alzheimer Disease↗
Effects of castration, blindness and anosmia on social reactivity in the male Mongolian gerbil (Meriones unguiculatus).
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Aggression↗
Arachidonic acid plays a role in rat vomeronasal signal transduction.
Sensory neurons of the vomeronasal organ (VNO) detect volatile chemicals that are released by conspecific animals and convey information about social and reproductive behavior. The signal transduction pathway in vomeronasal receptor neurons (VRNs) is not known in detail, but is believed to be distinct from that of the sensory neurons of the main olfactory system. Many of the identified olfactory transduction components are not expressed by VRNs. Using Ca2+ imaging and electrophysiological recordings, we investigated the signal transduction pathway of urine perception and the possible role of polyunsaturated fatty acids (PUFAs) as intracellular messengers in freshly dissociated rat VNO neurons. We found that application of urine induced a transient increase in intracellular Ca2+ that was dependent on the activity of phospholipase C and diacylglycerol (DAG) lipase. The Ca2+ transient was not dependent on depletion of intracellular Ca2+ stores but was dependent on the presence of extracellular Ca2+. Furthermore, the urine response was not sensitive to modulators of adenylate cyclase and inhibitors of inositol 1,4,5-trisphosphate receptors. Application of PUFAs (linolenic acid and arachidonic acid, synthesized in living cells from DAG) also elicited Ca2+ transients in fura 2 measurements and inward currents in whole-cell voltage-clamp recordings. Pharmacological inhibition of lipoxygenase and cyclooxygenase induced a transient increase in intracellular Ca2+, possibly by increasing the endogenous level of PUFAs, leading to activation of transduction channels. These data provide evidence for a role of PUFAs in rat vomeronasal signal transduction.
Adenylyl Cyclase Inhibitors↗
[Evoked potentials in cortical and subcortical structures of the visual system to photic and acoustic stimuli under conditions of early light deprivation].
Rabbits raised during one month in the dark have exhibited a lower amplitude and longer peak latencies of evoked potentials (EP) to photic stimuli in the visual cortex and the lateral geniculate body with a simultaneous increase of amplitude and decrease of EP latencies in these formations to acoustic stimuli. Similar changes have been observed in the EP amplitude as well as unvaried latencies in the superior colliculus. An assumption has been made that under light deprivation monosensory units change after the type of function deficit, while polysensory ones, change after activity increase type. The later sets in as a result of compensatory processes due to enhanced activity from the receptors of other sensory systems (auditory, olfactory, somaestetic, and others).
Animals↗