Participants claiming to be good at evoking vivid olfactory images are assumed to have better access to odor memory. It was hypothesized that this would be reflected in better odor naming and recognition task performance. Two extreme groups of participants high and low in self-reported olfactory imagery ability were exposed to familiar and unfamiliar odors in an incidental learning session. This was followed by an episodic odor recognition and odor naming task 20 minutes later. Imagery ability was unrelated to naming and recognition. This might indicate that if high imagers have a better access to odor memory, it is not due to a stronger link between language and odor memory or better incidental encoding.

Learning can be either non-associative or associative, though the molecular mechanisms underlying both remain enigmatic. The nematode Caenorhabditis elegans can adapt to both the AWC sensed odorants benzaldehyde (Bnz) and isoamyl alcohol (IsoA) and reciprocally cross-adapt. Surprisingly, however, these four adaptation permutations actually represent two distinct forms of learning: non-associative habituation and associative learning by pairing with starvation. Conditioning to the single odorant IsoA leads to both associative and non-associative memory traces, which can be preferentially accessed by choice of a Bnz or IsoA retrieval stimulus, respectively. Furthermore, we show that the molecular mechanisms underlying each form of memory can be genetically double dissociated, with insulin signalling and egl-4 being required for associative learning and osm-9 and arr-1 being essential for IsoA olfactory habituation. This represents the first demonstration where the form of learning displayed after conditioning to a single stimulus is a function of the retrieval stimulus employed.

Learning can be either non-associative or associative, though the molecular mechanisms underlying both remain enigmatic. The nematode Caenorhabditis elegans can adapt to both the AWC sensed odorants benzaldehyde (Bnz) and isoamyl alcohol (IsoA) and reciprocally cross-adapt. Surprisingly, however, these four adaptation permutations actually represent two distinct forms of learning: non-associative habituation and associative learning by pairing with starvation. Conditioning to the single odorant IsoA leads to both associative and non-associative memory traces, which can be preferentially accessed by choice of a Bnz or IsoA retrieval stimulus, respectively. Furthermore, we show that the molecular mechanisms underlying each form of memory can be genetically double dissociated, with insulin signalling and egl-4 being required for associative learning and osm-9 and arr-1 being essential for IsoA olfactory habituation. This represents the first demonstration where the form of learning displayed after conditioning to a single stimulus is a function of the retrieval stimulus employed.

Nostalgia is a psychological phenomenon we all can relate to but have a hard time to define. What characterizes the mental state of feeling nostalgia? What psychological function does it serve? Different published materials in a wide range of fields, from consumption research and sport science to clinical psychology, psychoanalysis and sociology, all have slightly different definition of this mental experience. Some claim it is a psychiatric disease giving melancholic emotions to a memory you would consider a happy one, while others state it enforces positivity in our mood. First in this paper a thorough review of the history of nostalgia is presented, then a look at the body of contemporary nostalgia research to see what it could be constituted of. Finally, we want to dig even deeper to see what is suggested by the literature in terms of triggers and functions. Some say that digitally recorded material like music and videos has a potential nostalgic component, which could trigger a reflection of the past in ways that was difficult before such inventions. Hinting towards that nostalgia as a cultural phenomenon is on a rising scene. Some authors say that odors have the strongest impact on nostalgic reverie due to activating it without too much cognitive appraisal. Cognitive neuropsychology has shed new light on a lot of human psychological phenomena‘s and even though empirical testing have been scarce in this field, it should get a fair scrutiny within this perspective as well and hopefully helping to clarify the definition of the word to ease future investigations, both scientifically speaking and in laymen‘s retro hysteria.Keywords:

The purpose of the present study was to determine olfactory detection thresholds in human subjects for a set of six sulfur-containing odorants which are known to be components of mammalian predator odors. Using a threealternative ascending staircase procedure, the olfactory sensitivity of 12 healthy adult human subjects, 6 males and 6 females was assessed with 2-propylthietane, 2,2-dimethylthietane, 3-mercapto-3-methylbutan-1-ol, 3-mercapto-3- methylbutyl formate, 3-methyl-1-butanethiol, and methyl-2-phenylethyl sulfide. The results showed that A) all six predator odorants were detected at concentrations below 1 ppb (parts per billion), and one of them (3-mercapto-3-methylbutyl formate) even at a concentration below 1 ppt (parts per trillion), B) structurally similar odorants yielded significantly different threshold values, and C) no significant sex differences were found in olfactory sensitivity with any of the six odorants. The findings obtained from the present study show that human subjects were not generally less sensitive to the predator odorants tested here compared to spider monkeys despite having a markedly lower number of olfactory receptor types. Further, they suggest that humans may be more sensitive to predator odorants compared to a variety of non-predator odorants. One possible explanation for the high olfactory sensitivity observed here is the fact that sulfur compounds typically can be detected at low concentrations. An alternative explanation derives from an evolutionary perspective as our human ancestors were a potential prey of large carnivores and  thus a high olfactory sensitivity for predator odors should be adaptive for humans.

Lygus hesperus is an important pest on different crops including cotton and alfalfa in the western U.S. Anaphes iole is a common parasitoid of Lygus spp. eggs in the U.S. and has potential as a biological control agent against L. hesperus in different crops. Its foraging behavior has been studied to a limited extent, but it is unknown whether A. iole females rely on plant volatiles to locate host habitats. L. hesperus feeding and oviposition are known to induce emission of plant volatiles in cotton and maize, but no studies have addressed the role of plant volatiles in the host searching behavior of A. iole. The objectives of this study were to evaluate the attraction of A. iole females toward volatiles derived from L. hesperus habitats and flight response of A. iole females toward cotton plants harboring L. hesperus eggs or treated with methyl jasmonate. Results from olfactometry bioassays showed that female wasps were attracted to odors emanating from different plant-L. hesperus complexes and from adult L. hesperus, while plants damaged by non-hosts or mechanically-damaged were not attractive. These findings suggested that A. iole females use specific plant volatiles released following L. hesperus feeding and oviposition to locate host habitats. In addition, in flight chamber tests A. iole females discriminated between cotton plants with moderate (41 eggs) and high (98 eggs) levels of L. hesperus infestations relative to uninfested plants, but not between plants with low (7 eggs) infestations compared to uninfested plants. In larger scale experiments conducted in the greenhouse, female wasps responded to L. hesperus-infested plants but not to methyl jasmonate-treated plants under similar conditions. Overall, results from this study revealed that A. iole females employ volatile signals to locate its host’s habitat and that they are attracted to plants damaged by L. hesperus feeding and oviposition. However, further research should seek to identify the chemical elicitors involved in the release of plant volatiles attractive to A. iole females.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 103-111).

The principal nucleus of the bed nucleus of the stria terminalis (BNSTp) is an integral component of the mouse accessory olfactory system, and plays a key role in pheromonal processing. In males, this region is not only larger and contains more neurons than in females, but the cells are also larger. The present study examined the relationship between preference for opposite-sex odour and regional volume, cell number and cell size within the BNSTp of both male and female mice. No correlations were found between olfactory preferences and any of the three morphological BNSTp parameters. However, the olfactory preference task results were not congruent with previous research. Therefore, it remains inconclusive whether relationships exist between olfactory preference behaviour and morphology of the BNSTp.

Olfactory ensheathing cells (OECs) are the chief glial population of the mammalian olfactory nervous system and are thought to be responsible for the successful directional growth of new olfactory axons throughout the life of adult mammals. Due to this unique property, OECs have been targeted as a potential cellular transplantation therapy for spinal cord injury. In order to effectively isolate OECs for intraspinal transplantation, more knowledge must be gained on their phenotypic properties. We investigated the neurochemical features of OECs in a variety of mammalian species (including hamsters, rabbits, monkeys, mice, and pigs) using three biomarkers: glial fibrillary acidic protein (GFAP), S100β, and α-smooth muscle actin (αSMA). In addition, we tested the ability of a few biomatrices to sustain and promote OEC growth and survival in vitro. The rationale for using biomatrices is to provide a supportive environment for glial and axonal growth in the spinal lesion. Here, we found that mucosal and bulbar OECs from all five of the aforementioned mammalian species express S100β. Expression of GFAP, however, was not consistent across the five species. Both mucosal and bulbar OECs of monkeys express αSMA; only bulbar OECs of hamsters and only mucosal OECs of rabbits express αSMA as well. Though αSMA immunostaining was not detected in the OECs of adult mice, in adult mutant mice lacking αSMA expression, OECs displayed perturbed ultrastructural morphology. None of the biomatrices used (methacrylated glycol chitosan, arginine-glycine-aspartic acid – grafted methacrylated glycol chitosan, and agarose) were able to promote OEC proliferation. Isolated strips of rodent olfactory lamina propria (the deep connective tissue layer in the olfactory mucosa containing primary sensory axons and OECs) showed sustained growth when cultured for 10 days. In sum, these findings highlight the following points: the efficacy of S100β and αSMA as biomarkers for mammalian OECs in vivo; the potential for isolated strips of lamina propria to provide a natural, supportive environment for OECs during intraspinal transplantation; the failure of methacrylated glycol chitosan and its derivatives, as well as agarose, to promote OEC proliferation. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2012-07-27 15:29:47.642

Electronic noses are targeted at determining odour character in a fashion that emulates conscious odour perception in mammals. The intention of this study was to develop an organisational framework for electronic noses and deploy a sample cheese odour discriminator within this framework. Biological olfactory systems are reviewed with the purpose of extracting the organisational principles that result in successful olfaction. Principles of gas handling, chemoreception, and neural processing are considered in the formulation of an organisational framework. An electronic nose is then developed in accordance with the biologically inspired framework. Gas sensing is implemented by an array of six commercially available (tin oxide) semiconductor sensors. These popular gas sensors are known to lack stability thus necessitating hardware and signal processing measures to limit or compensate for instability. An odorant auto-sampler was developed to deliver measured amounts of odorant to the sensors in a synthetic air medium. Each measurement event encodes a simulated sniff, and is captured across six sensor channels over a period of 256 seconds at a sampling rate of 1Hz. The simulated sniff captures sensor base references and responses to odorant introduction and removal. A technique is presented for representation and processing of sensor-array data as a two-dimensional (2D) image where one dimension encodes time, and the other encodes multi-channel sensory outputs. The near optimal, computationally efficient 2D Discrete Cosine Transform (DCT) is used to represent the 2D signal in a decorrelated frequency domain. Several coefficient selection strategies are proposed and tested. A heuristic technique is developed for the selection of transform domain coefficients as inputs to a non-linear neural network based classifier. The benefits of using the selection heuristic as compared to standard variance-based selection are evident in the results. Benefits include: significant dimensionality reduction with concomitant reduction in classifier size and training time, improved generalisation by the neural network and improved classification performance. The electronic nose produced a 99.1% classification rate across a set of seven different cheeses. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.