Showing papers on "Olfaction published in 1977"

Electrophysiological distinctions between the taste and smell of amino acids in catfish

Abstract: VERTEBRATES possess two principal systems, olfaction and taste, adapted to respond to peripheral chemical excitation. Olfaction in terrestrial vertebrates is the more acute chemosensory system, having lower thresholds to volatile stimuli than the gustatory thresholds to nonvolatile compounds1,2; thus, olfaction was termed the ‘distance’ sense and gustation the ‘contact’ sense. With fishes, however, chemical stimuli are present in the aqueous medium and it is difficult to distinguish between olfactory and gustatory stimuli or to explain the development of two chemical senses in the primitive aquatic vertebrates. Fishes exhibit important morphological distinctions between olfactory and gustatory systems both at the periphery and centrally3, and yet, in catfish, amino acids are the most effective stimuli known for both systems4,5. This sensory overlap does not reflect a simple duplication of receptor function, however, as the olfactory and gustatory systems of catfish differ in amino acid sensitivity, specificity and response characteristics, which could allow for the functional separation of the chemical senses in an aquatic environment.

Acquisition and Retention of Verbal Associations to Olfactory and Abstract Visual Stimuli of Varying Similarity.

Abstract: The similarity among a set of stimuli used in a paired-associate (PA) task was controlled by psychological scaling. Three lists of odorants and two lists of abstract figures (forms) with six stimuli in each list were constructed to have varying degrees of intralist similarity. Independent groups learned to associate digit responses with one stimulus list in a PA training session. Recognition of training stimuli presented among 12 distractor stimuli and recall of the associations was tested after 7 days. Within each modality, increased intralist similarity impaired PA acquisition. Between modalities, acquisition was inferior with the odor stimuli. During recognition testing, the olfactory modality supported inferior performance. In recall testing, equivalently learned responses in the two modalities were equally well retained. There appears to be a perceptual limitation in olfaction relative to vision that influences stimulus encoding and stimulus retrieval processes but that does not affect retrieval of associated responses.

The effect of olfactory deprivation by nasal tubes upon homing behavior in pigeons

Abstract: 1. As a test of the importance of olfaction to the navigational system of homing pigeons, a method of olfactory deprivation, the insertion of plastic tubes through the nostrils, has been employed. Birds wearing the tubes, and untreated controls, were singly released from two sites: a familiar one west of the loft, from which the birds had been released without tubes eight times previously, and an unfamiliar site south of the loft. 2. From the unfamiliar site anosmatic birds showed drastically impaired homing ability, both in terms of vanishing bearings and homing success (only 6 of 33 homing on the day of release vs. 33 of 36 controls). From the familiar site, tube-equipped birds showed homing performance which was only marginally poorer than that of controls. 3. The latter experiment shows that the effect of olfactory deprivation on homing is not a general behavioral influence on, for example, homing motivation, but is a consequence of the central importance of olfactory cues in determining home direction from unfamiliar territory. Anosmatic birds do home from familiar sites, presumably using an auxiliary pilotage mechanism relying on visual landmarks or other local cues.

Clinical testing of olfaction reassessed

Abstract: Odours in current use for testing olfaction (e.g., peppermint, camphor) cause considerable trigeminal nerve stimulation; this would render them relatively inefficacious in the detection of lesions of the main olfactory pathway. Musks and floral odours are considered to be relatively 'pure' olfactory stimulants, acting virtually exclusively via the first cranial nerve. These odours have been compared with standard odours in a group of patients whose olfactory pathways had been damaged by frontal tumours, surgical operation, head injury, multiple sclerosis and miscellaneous causes. Hyposmia or anosmia was detected more frequently and more reliably by musks and floral odours in all groups of patients; a number of patients had gross deficits of odour description without hyposmia or anosmia. Two-thirds of an unselected group of patients with multiple sclerosis had olfactory abnormalities. A substantial improvement in the rate of detection of organic lesions affecting the olfactory pathway can be achieved by substituting odours such as musk ketone, exaltolide, linalyl acetate and coumarin for those in current use.

Olfactory discrimination of squirrel monkey mothers by their infants

Abstract: Infant squirrel monkeys, 8 to 24 weeks of age, were tested for their ability to discriminate their own mother from another lactating mother by means of olfactory cues, visual cues, or a combination of both. Discrimination by olfactory cues was unequivocal. Addition of static visual cues did not enhance discrimination, and infants showed little evidence of discriminating the mother by means of static visual cues alone. These results suggest that olfaction may be a more significant factor in primate early attachment than has generally been assumed.

The ultrastructure of an olfactory sensillum on the maxillary palps of locusta migratoria (L.).

Abstract: The olfactory sensilla on the maxillary palp tip of Locusta migratoria (L.) resemble the surrounding contact chemoreceptors in general morphology. The perforated peg has a thicker wall than is commonly found in olfactory sensilla. The form and position of the sensilla are considered in relation of the olfactory function. The fine structure of the dendrites is discussed in relation to that described in other olfactory sensilla.

Olfactory Sarcoidosis: Report of Five Cases and Review of the Literature

Abstract: • Changes in the olfactory system in five patients with sarcoidosis were studied by clinical and histopathological examination. Every patient studied had hypogeusia and/or hyposmia as measured by psychophysical testing. In two patients who died with this disease, the olfactory bulbs and tracts were involved by granulomatous infiltration. Two other patients showed granulomas and chronic inflammation in nasal biopsy specimens. The fifth patient was studied only clinically. Changes in olfactory and gustatory acuity are rarely searched for in patients with sarcoidosis, but they may be important indicators of major and later irreversible damage to the CNS. If diminished olfaction is established in suspect patients, nasal biopsy and examination of the CNS should be performed to confirm the presence of active sarcoidosis. Appropriate therapy may prevent damage to the patient's sensory capabilities and CNS function.

Olfactory discrimination between glycine and deuterated glycine by fish

Abstract: Electrophysiological and behavioural experiments showed that whitefish (Coregonus clupeaformis) were able to discriminate between glycine and fully deuterated glycine by olfaction, while both chemicals stimulated the olfactory receptors to induce bulbar responses of similar magnitude

A qualitative and quantitative investigation of olfactory and nasal respiratory mucosal surfaces of cow and sheep based on various ultrastructural and biochemical methods

Abstract: Many hypotheses have been developed to account for the process of olfaction (for reviews see MOULTON and BEIDLER, 1967; DAVIES, 1971 and POYNDER, 1974), but at the present time none of them has been verified. The olfactory organ demonstrates very interesting receptor properties. It interacts with a great variety of compounds, called odorants (STAHL, 1973). Appropriate biochemical and biophysical methods including the separation of sensory surfaces should be able to provide important evidence about receptive mechanisms and attempts to use such techniques have begun in recent years (e.g. KONORRING,CH and NORRING, 1969; ASH and SKOGEN, 1970; KOYAMA et al., 1971; KOROLEV and FROLOV, 1973; MENCO et al., 1974; MARGOLIS, 1975). Techniques for separating receptor structures have also been suggested by OTTOSON (1970), but sofar none of these methods has yielded a pure fraction of receptor endings (see DODD, 1974). The present account will deal mainly with the anatomy of the bovine olfactory epithelium emphasizing prospects for isolating receptor moieties. The adjacent nasal respiratory epithelium has also been investigated since, like the olfactory bipolar nervous cells such respiratory cells bear cilia. In the latter case, however, they are motile, rather than sensory, thus enabling a determination of features which are specific for the olfactory cilia and a comparison between two adjacent epithelium types allows such specific characterizations (LUCAS and DOUGLAS, 1934; SLEIGH, 1974). The cow has been used as an experimental animal, since the size of its olfactory organ and the availability of samples seemed most convenient for this work. Some of the studies presented here were carried out on sheep. Indications for behaviour towards odorants in cows have been reviewed by ERNST and PUSHKARSKII (1975). In Chapter 1, the distal processes of both epithelium types are described, using different microscopical methods, including light microscopy, scanning electron microscopy, thin section transmission electron microscopy and thick section high- voltage transmission electron microscopy. This latter method was used in the hope that it would permit olfactory cilia to be followed over their whole lengths. In this chapter some attention will also be devoted to macroscopic observations. Chapter 2 deals with the results of freeze-etch and electron spin resonance studies on both epithelium types. Both techniques allow predictions of some of the molecular properties of the receptive area through investigation of intact tissue in vitro. Chapter 3 deals with a quantitative analysis of the morphological data. Statistical methods are used where it is possible. Several features of the olfactory nerve endings are compared for different nasal areas and for adult as opposed to juvenile animals. Special emphasis is placed on the ciliary processes. Olfactory and respiratory cilia are also compared with each other. Furthermore, estimates for possible receptor concentrations based chiefly on freezeetch results are presented. Such quantitative information is important for biochemical work, since it indicates whether one can consider nerve ending preparations as homogeneous or if one has to take into account that biochemical preparations may contain morphologically different nerve ending types. Furthermore, some ideas about receptor quantities which might be isolated can be obtained. Finally, Chapter 4 deals with attempts to isolate peripheral receptor membranes. The conventional criteria used by others for assessing the purity of the fractions have been shown to be inadequate (DODD, 1974); this prompted us to initiate anatomical studies on the bovine olfactory mucosa, so as to provide ourselves with a more adequate basis for future biochemical studies.

Dynamic Aspects of Central Olfactory Processing

Abstract: Perhaps because the sense of smell involves the discrimination of molecules by neural tissue, most neurophysiological studies of vertebrate olfaction have used purified compounds as stimuli and have been directed at relating neural response parameters to the structural and/or physicochemical properties of molecules. In studies of odor responses by individual neurons (single units), a commonly employed paradigm has been one in which individual members from a preselected battery of “odors” (volatile molecules in otherwise highly purified air) are puffed sequentially onto the nasal mucosa and an attempt is made to derive the relevant structural and/or physicochemical parameters of odor from the relative response spectra of the units recorded. When employed in studies of peripheral olfactory neurons (cf. Gesteland, Lettvin and Pitts, 1965), this paradigm is consistent with the assumption that these neurons contain receptor sites for odoriferous molecules and in effect is aimed at a preliminary answer to the two interrelated questions of how specific are the receptor sites and do the peripheral neurons have more than one type of receptor site. This general paradigm also has been used in studies of central olfactory neurons to test hypotheses about the physical dimensions of odors. For example, Higashino, Takeuchi and Amoore (1969) attempted to verify a stereochemical theory of odor quality by using a battery of pure chemical stimuli and comparing the response spectra of single units recorded in the olfactory bulbs with generalization gradients derived from psychophysical studies.

Surface of the olfactory region in man observed by scanning electron microscope

Abstract: This report describes the surface of the regio olfactoria of a 25-year-old man as observed in the scanning electron-microscope. Corresponding to the distal ends of the receptor cells, the surface displays various planes: (a) Upper-most is a film of mucus of varying thickness. (b) The olfactory hairs, which are arranged closely together, mostly in a parallel fashion in layers, dip into this mucus film. The long, distal parts of the olfactory hairs are of a rather uniform shape and form, together with the mucus film, a single functional unit. (c) Now follows a layer consisting of the short parts of the olfactory hairs. They branch from the olfactory vesiculae, mostly in a stellar fashion (5-12 on one vesicula) and arch themselves, after a short course, into the mucus film. (d) There then follows the plane of the olfactory vesiculae, mostly bulbous, partly club- and pyramidal in shape. (e) After that comes the plane of the microvilli receptors, which have about 100 or more villi on one cell. (f) Right at the bottom is the apical surface of the supporting cells, different in size, showing microvilli in a regularly arranged pattern. Because of the various planes of the surface of the olfactory region and because of the close situation of the long, distal parts of the olfactory hairs and their rather uniform shape, one could assume, from observations in the scanning electron microscope, that the olfactory-active molecules react immediately with the functional unit of mucus film and long distal parts of the olfactory hairs, so that for the different sense of smell, a quite different structure of the olfactory-active molecules must be assumed as a different shape of the distal ends of the olfactory receptors.

Physical and Cognitive Limitations on Olfactory Processing in Human Beings

Abstract: Chemical communication via natural secretions is thought to play at best a minor role in the lives of human beings, but a major role in the lives of many other species It is unlikely that the primary reason for this difference lies strictly in the realm of sensory functioning Even if man is not the most sensitive creature on earth his sensitivity is nonetheless remarkable and undoubtedly rivals that of many other animals Furthermore, electrophysiological evidence suggests that there is considerable similarity in olfactory reception throughout the vertebrates (Doving, 1966; Doving and Lange, 1967; Koster and MacLeod, 1975) Accordingly, the study of man’s sense of smell may teach much about olfaction in other vertebrates

Olfaction in Relation to Reproduction in Domestic Animals

Abstract: In a consideration of the role of odour in reproduction of domestic animals their behaviour generally and the necessity for them to communicate with one another must be taken into account.

Carnosine in olfaction : Proton magnetic resonance spectral evidence for tissue-specific carnosine binding sites.

Abstract: The amount and specificity of binding ofL-carnosine (β-alanyl-L-histidine) by crude soluble and particulate fractions of several tissues were investigated with proton magnetic resonance (1HMR) spectrometry. It was found that the particulate fraction of only nasal olfactory mucosa exhibited a specific binding requiring a particular orientation of the carnosine molecule relative to the binding site. This suggests that whatever role carnosine may play in olfaction is expressed within the nasal olfactory mucosa rather than elsewhere in the olfactory pathway. Possible binding of carnosine to carnosinase was observed in the soluble fractions of nasal olfactory mucosa and kidney. However, the bulk of the carnosine present in the nasal olfactory mucosa in vivo probably is not bound within the cells of this tissue as a complex with soluble protein. These observations are of interest because the nasal olfactory mucosa is the neural tissue that has the highest activities of the enzymes catalyzing the synthesis and degradation of carnosine.

A note on the role of olfaction in taste aversion learning

Abstract: A taste aversion was induced by the single or multiple pairing of saccharin and methotrexate. In one experiment the presence of saccharin in the environment of condtioned animals prior to the test trials resulted in an attenuation of the aversion, that is, facilitated extinction of the conditioned response. In a second experiment the consumption of plain water by conditioned animals was significantly reduced when animals were tested in the presence of other animals that were provided with saccharin, the CS solution. The data suggest that primary stimulus generalization in the form of olfactory cues can influence the manifestation of taste aversion behavior by decreasing the magnitude of the avoidance response or by decreasing the consumption of fluid by control animals.

Coacervate‐like Membrane Structures and Olfactory Transduction

Abstract: Current theories concerning the olfactory transduction process are discussed. A hypothesis is formulated, according to which the olfactory receptor membrane contains regions where it has the structure of a lipid-protein coacervate. Such structures may well occur in living cells. Such a membrane would have the ability to change its permeability in response to adorants and a sensitivity comparable to that of the sense of smell. The model also explains the fact that different receptor cells have different sensitivity patterns towards odorants. The model is consistent with the results of experiments that seek to establish the locus of odorant action.

Measurment of the Velocity at the Nares of the Olfactory Organ of Fishes with a Laser Velocimeter

Abstract: The flow of water through the olfactory organ of fishes is of interest in order to understand the first step in the process of olfaction: the way molecules are brought to transmit information about their nature to the receptor cells in the sensory epithelium of the organ. The olfactory organ of fishes demonstrates the great variability that is found within specialized organs due to the adaptation process in different species to diverse environmental and behavioural conditions. The understanding of the evolution of such a specialized organ may throw some light on the evolution of determinate taxonomic groups. This implies that the influence of the morphological details of the organ on the flow has to be understood. The group selected for the present investigation are the so called Cyprinodonts. Their olfactory organs show evolutionary divergence in several different directions. Two species, Aplocheilus lineatus and Xiphophorus helleri were selected for the first investigations. In addition to measurements in vivo it is the idea to reproduce their olfactory organs as a model at a scale enlarged by a factor of about 200.