The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Afif J Aqrabawi - One of the best experts on this subject based on the ideXlab platform.
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olfactory memory representations are stored in the anterior olfactory nucleus
Nature Communications, 2020Co-Authors: Afif J AqrabawiAbstract:The anterior olfactory nucleus (AON) is the initial recipient of Odour information from the olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic Odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant Odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of Odour memory. Our findings offer a new model for studying the mechanisms underlying memory representations. Odours are powerful stimuli used by most organisms to guide behaviour. Here, the authors identify populations of neurons within the anterior olfactory nucleus (AON) which are necessary and sufficient for the behavioural expression of Odour memory.
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hippocampal projections to the anterior olfactory nucleus differentially convey spatiotemporal information during episodic Odour memory
Nature Communications, 2018Co-Authors: Afif J Aqrabawi, Jun Chul KimAbstract:The hippocampus is essential for representing spatiotemporal context and establishing its association with the sensory details of daily life to form episodic memories. The olfactory cortex in particular shares exclusive anatomical connections with the hippocampus as a result of their common evolutionary history. Here we selectively inhibit hippocampal projections to the anterior olfactory nucleus (AON) during behavioural tests of contextually cued Odour recall. We find that spatial Odour memory and temporal Odour memory are independently impaired following inhibition of distinct, topographically organized hippocampal-AON pathways. Our results not only reveal a longstanding unknown function for the AON but offer new mechanistic insights regarding the representation of Odours in episodic memory.
Richard M Stuetz - One of the best experts on this subject based on the ideXlab platform.
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Odour measurements for sewage treatment works
Water Research, 2001Co-Authors: P Gostelow, Simon A Parsons, Richard M StuetzAbstract:Public concern over Odours from sewage treatment works is increasing. More people are being exposed to Odours, due to development around existing works or construction of new works. Increased awareness of both the environment and individual rights has meant people are now more likely to complain. Odour abatement and control is a major issue for sewage works operators. To control Odours, they must first be measured. This is no easy task as response to Odours is subjective. Our understanding of the sense of smell is incomplete, and there is no single measure that will directly relate to the likelihood of complaint. Odour measurement has often been regarded as an art as opposed to a science. Odour measurement techniques fall into two classes. Sensory measurements employ the human nose and measure the effects of the Odour as perceived by an observer. Analytical measurements characterise Odours in terms of their chemical composition and attempt to quantify the odorants present. Both methods are less than ideal--sensory measurements can be overly subjective and the interpretation of results requires care. Analytical measurements are complicated by the large number of odorants present, often at concentrations close to detection limits. Our incomplete understanding of Odour perception makes linking analytical and sensory measurements difficult. This paper reviews the methods applied to sewage treatment works Odour measurement. Sensory and analytical measurements are reviewed, along with a recent development, the electronic nose.
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Assessment of Odours from sewage treatment works by an electronic nose, H2S analysis and olfactometry
Water Research, 1999Co-Authors: Richard M Stuetz, Richard A Fenner, Güleda EnginAbstract:An electronic nose based on a non-specific conducting polymer array was evaluated against sewage Odour concentrations from ten sewage treatment works. Sensor responses from the twelve sensor array were compared using canonical correlation (a data reduction technique) with threshold Odour numbers (TON) made by dynamic dilution olfactometry. The results suggest that for sewage Odours from a range of locations within different treatment works, no universal relationship is present, whereas a strong correlation can be produced between TON and the electronic nose responses (as represented by a canonical variable) for sewage Odours from a single works. Further correlations were achieved between the Odour potential of a liquid sewage and the NOSE output of a quiescent sewage liquor. Hydrogen sulphide (H2S) concentrations, commonly used as measures of Odour strength, were also compared with TON and found not to be a good marker compound for measuring these sewage Odour concentrations. The results demonstrated the ability of an electronic nose to respond to sewage Odours over a range of Odour concentrations (125-781066 Odour units/m3) and suggest the potential application of such an instrument to monitor Odour emission in a sewage works, as well as assessing the efficiency of Odour abatement units.
Ring T. Cardé - One of the best experts on this subject based on the ideXlab platform.
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moment to moment flight manoeuvres of the female yellow fever mosquito aedes aegypti l in response to plumes of carbon dioxide and human skin Odour
The Journal of Experimental Biology, 2011Co-Authors: Teun Dekker, Ring T. CardéAbstract:SUMMARY Odours are crucial cues enabling female mosquitoes to orient to prospective hosts. However, their in-flight manoeuvres to host Odours are virtually unknown. Here we analyzed in 3-D the video records of female Aedes aegypti mosquitoes flying in a wind tunnel in response to host Odour plumes that differed in spatial structure and composition. Following a brief (∼0.03 s) encounter with CO 2 , mosquitoes surged upwind and, in the absence of further encounters, counterturned without displacing upwind. These patterns resemble moth responses to encounter and loss of a filament of pheromone. Moreover, CO 2 encounters induced a highly regular pattern of counterturning across the windline in the horizontal (crosswind) and vertical planes, causing the mosquito to transect repeatedly the area where CO 2 was previously detected. However, despite the rapid changes across all three axes following an encounter with CO 2 , the angular velocities remained remarkably constant. This suggests that during these CO 2 -induced surges mosquitoes stabilize flight through sensors, such as the halteres and Johnston organs, sensitive to Coriolis forces. In contrast to the instantaneous responses of the mosquito CO 2 , a brief encounter with a filament of human skin Odour did not induce a consistent change in mosquito flight. These differential responses were reflected in further experiments with broad plumes. A broad homogeneous plume of skin Odour induced rapid upwind flight and source finding, whereas a broad filamentous plume of skin Odour lowered activation rates, kinetic responses and source finding compared with homogeneous plumes. Apparently, yellow fever mosquitoes need longer continuous exposure to complex skin-Odour blends to induce activation and source finding.
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carbon dioxide instantly sensitizes female yellow fever mosquitoes to human skin Odours
The Journal of Experimental Biology, 2005Co-Authors: Teun Dekker, Martin Geier, Ring T. CardéAbstract:SUMMARY Female mosquitoes are noted for their ability to use Odours to locate a host for a blood meal. Two sensory organs contribute to their sense of smell: the maxillary palps, which measure the level of CO 2 , and the antennae, which detect other host-released Odours. To establish the relative importance and interactions of CO 2 and other body emissions in freely flying mosquitoes, we presented female yellow fever mosquitoes Aedes aegypti L. with broad plumes of human skin Odour and CO 2 at natural concentrations and dilutions thereof in a wind tunnel. 3-D video-recorded flight tracks were reconstructed. Activation, flight velocity, upwind turning and source finding waned quickly as skin Odours were diluted, whereas in the presence of CO 2 these parameters remained unchanged over more than a 100-fold dilution from exhaled concentrations. Although mosquitoes were behaviourally less sensitive to skin Odours than to CO 2 , their sensitivity to skin Odours increased transiently by at least fivefold immediately following a brief encounter with a filament of CO 2 . This sensitization was reflected in flight velocity, track angle, turning rate upon entering and exiting the broad Odour plume and, ultimately, in the source-finding rate. In Ae. aegypti , CO 2 thus functions as a `releaser9 for a higher sensitivity and responsiveness to skin Odours. The initially low responsiveness of mosquitoes to skin Odours, their high sensitivity to CO 2 , and the sensitization of the olfactory circuitry by CO 2 are ecologically relevant, because rapidly fluctuating CO 2 levels reliably signal a potential host. Possible mechanisms of the instantaneous sensitization are considered.
Teun Dekker - One of the best experts on this subject based on the ideXlab platform.
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moment to moment flight manoeuvres of the female yellow fever mosquito aedes aegypti l in response to plumes of carbon dioxide and human skin Odour
The Journal of Experimental Biology, 2011Co-Authors: Teun Dekker, Ring T. CardéAbstract:SUMMARY Odours are crucial cues enabling female mosquitoes to orient to prospective hosts. However, their in-flight manoeuvres to host Odours are virtually unknown. Here we analyzed in 3-D the video records of female Aedes aegypti mosquitoes flying in a wind tunnel in response to host Odour plumes that differed in spatial structure and composition. Following a brief (∼0.03 s) encounter with CO 2 , mosquitoes surged upwind and, in the absence of further encounters, counterturned without displacing upwind. These patterns resemble moth responses to encounter and loss of a filament of pheromone. Moreover, CO 2 encounters induced a highly regular pattern of counterturning across the windline in the horizontal (crosswind) and vertical planes, causing the mosquito to transect repeatedly the area where CO 2 was previously detected. However, despite the rapid changes across all three axes following an encounter with CO 2 , the angular velocities remained remarkably constant. This suggests that during these CO 2 -induced surges mosquitoes stabilize flight through sensors, such as the halteres and Johnston organs, sensitive to Coriolis forces. In contrast to the instantaneous responses of the mosquito CO 2 , a brief encounter with a filament of human skin Odour did not induce a consistent change in mosquito flight. These differential responses were reflected in further experiments with broad plumes. A broad homogeneous plume of skin Odour induced rapid upwind flight and source finding, whereas a broad filamentous plume of skin Odour lowered activation rates, kinetic responses and source finding compared with homogeneous plumes. Apparently, yellow fever mosquitoes need longer continuous exposure to complex skin-Odour blends to induce activation and source finding.
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carbon dioxide instantly sensitizes female yellow fever mosquitoes to human skin Odours
The Journal of Experimental Biology, 2005Co-Authors: Teun Dekker, Martin Geier, Ring T. CardéAbstract:SUMMARY Female mosquitoes are noted for their ability to use Odours to locate a host for a blood meal. Two sensory organs contribute to their sense of smell: the maxillary palps, which measure the level of CO 2 , and the antennae, which detect other host-released Odours. To establish the relative importance and interactions of CO 2 and other body emissions in freely flying mosquitoes, we presented female yellow fever mosquitoes Aedes aegypti L. with broad plumes of human skin Odour and CO 2 at natural concentrations and dilutions thereof in a wind tunnel. 3-D video-recorded flight tracks were reconstructed. Activation, flight velocity, upwind turning and source finding waned quickly as skin Odours were diluted, whereas in the presence of CO 2 these parameters remained unchanged over more than a 100-fold dilution from exhaled concentrations. Although mosquitoes were behaviourally less sensitive to skin Odours than to CO 2 , their sensitivity to skin Odours increased transiently by at least fivefold immediately following a brief encounter with a filament of CO 2 . This sensitization was reflected in flight velocity, track angle, turning rate upon entering and exiting the broad Odour plume and, ultimately, in the source-finding rate. In Ae. aegypti , CO 2 thus functions as a `releaser9 for a higher sensitivity and responsiveness to skin Odours. The initially low responsiveness of mosquitoes to skin Odours, their high sensitivity to CO 2 , and the sensitization of the olfactory circuitry by CO 2 are ecologically relevant, because rapidly fluctuating CO 2 levels reliably signal a potential host. Possible mechanisms of the instantaneous sensitization are considered.
Michael H Ferkin - One of the best experts on this subject based on the ideXlab platform.
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effects of pregnancy lactation and postpartum oestrus on Odour signals and the attraction to Odours in female meadow voles microtus pennsylvanicus
Animal Behaviour, 1995Co-Authors: Michael H Ferkin, Robert E JohnstonAbstract:Abstract Our understanding of communication by female mammals about reproductive state is currently limited by a paucity of information about signalling during pregnancy and lactation. To address this situation, Odour communication was examined in meadow voles by means of preference tests. In experiment 1, males showed no preference for Odours of a reference female versus a pregnant female or Odours of a reference female versus a lactating female throughout most of pregnancy and lactation. However, preferential attraction to one of these scents occurred around parturition. Just before parturition (day 19-20 of gestation) males showed a preference for the Odour of a reference female over that of a pregnant female. Immediately after parturition, during postpartum oestrus (day 1-2 of lactation), however, male preferences reversed so that males preferred scent of a postpartum oestrous female over that of a reference female. In experiment 2, the Odour preferences of females were examined across pregnancy and lactation. Females maintained a preference for Odours of a male over a reference female during pregnancy, postpartum oestrus and lactation. These results differ from those reported for other species in which females show a repeated oestrous cycle. These results also suggest the existence of some complexities of Odour communication during the transition from pregnancy, postpartum oestrus and lactation in a species in which females show an induced oestrus.
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seasonal control of Odour preferences of meadow voles microtus pennsylvanicus by photoperiod and ovarian hormones
Reproduction, 1991Co-Authors: Michael H Ferkin, I ZuckerAbstract:During the spring-summer breeding season, female meadow voles prefer Odours of males over those of females, but in the autumn-winter season of reproductive quiescence this preference is reversed. Females housed in long (14 h light/day) and short (10 h light/day) photoperiods, respectively, had Odour preferences comparable to those of spring and autumn voles, respectively. The preference of long-photoperiod voles for male over female Odours was reversed by ovariectomy and restored by treatment with oestradiol. By contrast, neither ovariectomy nor oestradiol affected Odour preferences of short-photoperiod voles. Long days appear to influence olfactory preferences by altering ovarian hormone secretion. The failure of oestradiol to affect Odour preferences in short photoperiods suggests that the neural substrates mediating this behavioural response are refractory to oestrogens during the nonbreeding season.
