Olfactory sensing is ubiquitous across animals and important for survival. Yet, its characteristics, mechanisms, and functions in humans remain not well understood. In this dissertation, I present four studies on human olfactory perception. Study I investigates the impact of short-term exposures to an odorant on long-term olfactory learning and habituation, while Study II examines human ability to localize smells; Study III probes visual-olfactory integration of object representations, and Study IV explores the role of olfaction in sensing nutrients. Several conclusions are drawn from these studies. First, brief intermittent exposures to even a barely detectable odorant lead to long-term incremental odorant-specific habituation. Second, humans localize smells based on gradient cues between the nostrils. Third, there is a within-hemispheric advantage in the integration of visual-olfactory object representations. Fourth, olfaction partakes in nutrient-sensing and facilitates the detection of food. Some broader implications of our findings are discussed.

Aim: The aim of present study was to determine the frequency of taste and smell disorders occuring in patients receiving chemotherapy for cancer. Methods: The study was of an empirical cross sectional quantitative descriptive design. During one month, consecutive cancer patients at outpatient units in two Swedish hospitals were asked to participate in the study by completing a questionnaire that had been developed previously for a similar study. All participants had undergone at least 1 cycle of intravenous chemotherapy or  a minimum of seven days of oral chemotherapy. Results: A total of 102 patients completed the questionnaire. Results show that 55 % experienced taste disorders and  42 % experienced smell disorders. Both disorders are more common in women than in men. Of patients with taste disorders 47 % reported that it  impacted on their daily life to some degree and of patients with smell disorders the corresponding number was 33%. Patients with smell disorders reported a smaller degree of impact on their daily life than did patients with taste disorders. Conclusion: Both taste and smell disorders are common in cancer patients treated within chemotherapy. More research into factors that might eliminate or dimnish these problems is needed.

In nowadays, advertisement and DM overwhelm our life, and visual Marketing is overused for a long time. Therefore, other marketing tools about sense organs may become new field. According previous researches pointed out, sense of smell may be most powerful but lower developed sense, and people have strong recognition and memory pattern about sense of smell as well. As a result, scent could be a good method to apply in the brand and marketing. Besides, there are plenty of foreign researches about sense of smell, but there are only few domestic papers which focus on this issue. Under this circumstances, it is hard to determine whether the foreign researches could apply in Taiwan. Therefore, the proposition of this study are as following¡G (1) Analysis the influence about environment scent to emotion, recall, evaluation and behavior about consumer.(2) Analysis the influence about environment scent under different product types to emotion, recall, evaluation, and behavior about consumer. (3) Analysis the influence about environment scent under different consumer characteristics to emotion, recall, evaluation, and behavior about consumer. In this study, environment scent is independent variables, and product type and consumer characteristic are moderators. This research is a 2(environment scent) x 2(product type) experiment design. Comparing the result of consumer emotion, recall, evaluation, behavior between groups about using environment scent or not, product types and consumer characteristics. The conclusions are summarized as follows¡G (1) Having environment scent is more obvious about consumer emotion, recall, evaluation, and behavior. (2)There is no difference under product types about consumer emotion, recall, evaluation, and behavior. (3) There is interaction between under consumer characteristic about consumer emotion, recall, evaluation, and behavior.

Since ancient times, coffee has been a savory drink for most of the world's population. It is the second most widely distributed commodity after crude oil in the world. Hence, there has always been a pressure on the coffee industry to produce more volume of good quality coffee. The coffee industry has not been able to meet this increasing coffee demand due to various reasons, such as low crop yield, high coffee rejection rate etc. Historically, the coffee production industry has had high rejection rates due to inadequate knowledge about the defects that plague coffee and the lack of research to detect and eliminate the defective coffee beans. In this thesis, an attempt has been made to minimize the rejection rate of coffee beans due to a specific defect called "Potato Defect". Potato defect is very prominent in East African countries for reasons not yet known. It is caused by an increase in the concentration of 2-isopropyl -3-methoxypyrazine (IPMP), present in parts per billion concentration in coffee beans. In this thesis, various techniques have been evaluated to detect the increased concentration of IPMP, and then eliminate the 'potato defect' infected coffee beans. As these proposed techniques need to be implemented on an industrial scale, special care has been taken to keep the inspection time of coffee beans as low as possible to minimize its negative impact on the overall coffee production rate. Considering both sensitivity and time, non destructive methods such as ion mobility spectrometry, cavity ring down spectrometry and electronic nose were assessed for their suitability to identify low concentrations of IPMP in the complex matrix of coffee volatiles. Experiments were also conducted by Solid Phase Micro Extraction (SPME), followed by multidimensional gas chromatography with simultaneous olfactory and mass spectrometric detection (GC- MS-O) technology to validate information related to the 'potato defect'. GC-MS-O could detect IPMP present in whole green coffee beans while other researchers only detected IPMP in ground coffee. The findings of this thesis opens the doors for the coffee industry to establish non destructive, sensitive methodology to analyze further coffee aroma.

The procerebrum of terrestrial molluscs is an important processing centre for olfaction. While the physiology of the procerebrum is relatively well characterized, the procerebrum's structure and organization has not been previously investigated in detail. The goal of this thesis is to better characterize the structural organization of the procerebrum and to understand how it compares with other olfactory systems. / The morphology of the procerebral neurons in the snail Helix aspersa was investigated through intracellular injections of biocytin. The population of cells is heterogeneous, but no formal categorization of neuronal types was possible. The main difference among cells lies in the placement of the cells' neurites. Furthermore, contradicting previous results, certain neurons were found to have neurite projections outside the procerebrum, travelling as far as the contralateral cerebral ganglion. / To investigate if differences in sites of arborization represent functional differences, the distribution of synaptic contacts on labelled cells was studied using serial sections and electron microscopy. Neurons with different sites of arborization have distinct patterns of synapse distribution. Cells with arborizations in the procerebrum but not in the internal mass have large varicosities specialized for output. Cells that arborize in the internal mass or outside the procerebrum have mostly input synapses proximal to the soma and mostly output synapses in the terminal region of the neurites. These latter cells appear to transmit information from the procerebral cell body mass to other brain regions. The implications of these data are, firstly, that the procerebrum directly distributes processed information throughout the nervous system. Secondly, the procerebral neuron population may be divisible into two subgroups: intrinsically arborizing interneurons and projection neurons. / These results suggest a novel mechanism by which compartmentalization could be achieved in the procerebrum. Compartmentalization is believed to be important for processing olfactory information, is present in most olfactory centres but has not previously been described in the molluscan olfactory system. I propose that varicosities on the local interneurons generate foci of activity in the procerebrum which, in turn, activate specific subsets of output neurons, similar to what happens in other olfactory systems.

No description available.

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.

The aim of this doctoral dissertation was to examine effects of olfactory imagery on other sensory and perceptual processes, and to explore brain areas involved in generation of olfactory mental images. Four studies, three behavioral and one functional neuroimaging (Positron Emission Tomography, or PET), were conducted, and healthy volunteers participated in all four studies. In Study 1, participants were better at detecting weak odors when they simultaneously imagined the same compared with a different odor as the one being detected. This effect of olfactory imagery was specific, as the request to imagine objects visually did not have any effect on detection of weak odors. In Studies 2 and 3, effects of presented and imagined odors on taste perception were compared. Effects of imagined odors were equivalent to the effects of presented odors when an objective measure of taste perception (detection of a weak tastant, Study 3) was used, and comparable but more limited when a subjective measure of taste perception (intensity ratings, Study 2) was used. In Study 4, PET technology was used to investigate changes in cerebral blood flow (CBF) associated with odor imagery. Participants were screened and selected for their odor imagery ability, using the behavioral paradigm developed in Study 1. Increased CBF associated with odor imagery was revealed in several areas relevant for olfaction: the left primary olfactory cortical region including piriform cortex, the left secondary olfactory cortical region (posterior orbitofrontal cortex), and the rostral insula bilaterally. Interestingly, increased activity in the primary olfactory cortex and the rostral insula was observed both in the odor imagery and the odor perception subtraction. Based on the obtained findings, I concluded that the effects of imagined odors on sensory processes are specific when compared with visual imagery, and similar to the effects of presented odors. Furthermore, the neural

Food intake is regulated by both appetite and orosensory reward systems. Appetite systems stimulate or reduce hunger, while orosensory reward motivates consumption of high fat sweet foods, resulting in food enjoyment. The majority of advanced cancer patients suffer from malnutrition and wasting, which may be caused by a loss of appetite due to physiological changes or a hindered orosensory reward system due to taste and smell (chemosensory) changes or both. Orosensory reward systems were hypothesized to be impaired in advanced cancer. To understand the influence of chemosensory alterations on food intake and enjoyment, the nature (intensity) of chemosensory alterations in cancer patients and their relationship with ingestive behaviour and quality of life (QOL) were investigated (study 1). Advanced cancer patients (n=192) more frequently self-reported tastes and odours to be heightened rather than diminished (p=0.035). Patients with perceived chemosensory alterations had poorer QOL (p=0.0176) and lower caloric intake (p=0.0018) compared to patients with no alterations. Cannabinoids (e.g. -9-tetrahydrocannabinol, -9-THC) increase food intake by stimulating both appetite and orosensory reward systems as well as potentially enhancing chemosensory function. To palliate chemosensory alterations and poor appetite, advanced cancer patients (n=21, study 2) with these symptoms were randomized to receive either -9-THC (2.5mg) or placebo oral capsules twice daily for 18 days. Compared to patients receiving placebo, -9-THC-treated patients reported that food tasted better (p=0.04), they had improved chemosensory perception (p=0.026), increased preference and intake of high protein foods (p=0.008), and improved appetite (p=0.05), quality of sleep (p= 0.025), and relaxation (p= 0.045). Like cancer patients, tumour-bearing rats appeared to experience a loss of orosensory reward, showing tumour-associated anorexia when fed a rewarding diet to the same degree as on a usual diet (study 3). -9-THC significantly increased caloric intake compared to vehicle for both tumour-bearing (p=0.0146) and healthy rats (p=0.0004), suggesting endocannabinoid-mediated appetite systems are functioning in this tumour model. The findings of this thesis suggest orosensory reward systems to be impaired in advanced cancer, decreasing the liking and motivation to eat. -9-THC treatment may help to palliate perceived chemosensory alterations and loss of appetite and food enjoyment in advanced cancer. / Food Science and Technology

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.