Measurement of Neocortical Responses to Odors using Optical Imaging

Using multi-channel near-infrared spectroscopy, the authors sought to monitor cortical activity during the sensory evaluation period to evaluate the effect of flavorings on taste caused by central integration of olfactory and gustatory modalities. They noted that the neocortical response to a test solution showed adaptation by the conditional sugar solution, which was administered 60 seconds before the test solution. Sugar-sugar self adaptation was greater than sugar-artificial sweetener cross adaptation recorded at specific regions of the frontal and temporal cortex. The magnitude of sugar-flavored artificial sweetener cross adaptation tended to approach that of sugar-sugar self adaptation. Therefore, the similarity of the adaptation of cortical responses might be an important indicator in the screening of effective flavorings in order to improve taste.

The Technology Demonstration of the Third Generation JPL Electronic Nose on the International Space Station

This chapter describes the development, operation, and experimental results of the Third Generation JPL Electronic Nose (ENose), which operated on board the International Space Station (ISS) as a technology demonstration for seven months from 2008-2009. The JPL ENose is an array of chemiresistive sensors designed to monitor the environment for the sudden release of targeted chemical species, such as leaks or spills. The Third Generation JPL ENose was designed to detect, identify, and quantify eleven chemical species, three inorganic, ammonia, mercury, and sulfur dioxide, and eight organic compounds, which represent common classes of organic compounds such as alcohols, aromatics, and halocarbons. Chemical species were quantified at or below their 24 hour Spacecraft Maximum Allowable Concentrations (SMAC), generally in the parts-per-million range; some targeted species were detected in the parts-per-billion range. Analysis of third generation JPL ENose monitoring data on ISS show the short term presence of low concentrations of alcohols, octafluoropropane, and formaldehyde as well as frequent short term unknown events. Repeated unknown events were identified post-flight as sulfur hexafluoride.

Electronic Mucosa

In this chapter, the authors discuss a new concept that involves the development of a new type of sensor array and a new type of time-dependent signal processing method that they call an artificial (or electronic) olfactory mucosa. This so-called e-mucosa employs large sets of spatially distributed odour sensors and gas chromatographic-like retentive micro-columns. It has been inspired by the architecture of the human nose with the olfactory epithelium region located in the upper turbinate. The authors describe the fabrication of an e-mucosa and the use of a convolution method to analyse the time-varying signals generated by it and thus classify different odours. They believe that as this concept evolves it could result in a superior instrument to the sensor-based e-noses currently available today.

Odor Perception

Though olfaction is one of the necessary senses and indispensable for the maintenance of the life of the animal, the mechanism of olfaction had not yet been understood well compared with other sensory systems such as vision and audition. However, recently, the most basic principle of “signal transduction on the reception and transmission for the odor” has been clarified. Therefore, the important next problem is how the information of odors about is processed in the Central Nervous System (CNS) and how odor is perceived in the human brain. In this chapter, the basic olfactory systems in animal and human are described and examples such as “olfactory acuity, threshold, adaptation, and olfactory disorders” are discussed. The mechanism of olfactory information processing is described under the results obtained by using a few new non-invasive measuring methods. In addition, from a few recent studies, it is shown that olfactory neurophysiological information is passing through some deep central regions of the brain before finally being processed in the orbito-frontal areas.

Odor Code Sensor and Odor Reproduction

In biological olfactory systems, odor receptors receive odor molecules by recognizing the molecular information. Humans can sense the odor by the signal from these activated receptors. The combination of the activated receptors is called “odor code,” and the odor codes are expressed as an “odor cluster map” of glomeruli on the olfactory bulb surface. The odor code is essential information for qualitative and quantitative analyses of odor sensation. In this chapter, development of odor sensors based on the odor code concept and an attempt to extract the parameters for odor coding from molecular informatics are described. Application of the obtained odor code for odor reproduction is also presented.

Incorporating Fluid Dynamics Considerations into Olfactory Displays

In this chapter, the authors describe fluid dynamics considerations regarding odor dispersal in real environments and their relationship with realistic odor presentation using an olfactory display. The authors propose the use of a Computational Fluid Dynamics (CFD) simulation in conjunction with the olfactory display. A CFD solver is employed to calculate the turbulent airflow field in a given environment and the dispersal of odor molecules from their source. The simulation result is used to reproduce realistic changes in the odor concentration with time and space at the nose. The results of sensory tests are presented as a demonstration of CFD-based odor presentation. The effect of body heat on odor dispersal in indoor environments and how it affects odor perception is also discussed.

Aroma Chip Using a Functional Polymer Gel

Conventionally, the controlled release of aroma molecules has been achieved by employing mechanical devices; however, it has not been possible to avoid the noise and gusts of air that devices emit prior to transmitting aroma information. Another problem is the adherence of odor components to the device structure, because the aroma source is located inside or at the bottom of the device. In this chapter, the authors focus on a chemical container of a functional polymer gel (temperature-responsive hydrogel) that features a reversible phase transition between sol and gel and the controlled release of aroma molecules using a Peltier module to control temperature. By this approach, they developed a soundless olfactory display based on an aroma chip and solved the problem of the adhesion of odor components by placing a card-based aroma source (aroma-chip array) on the top of the olfactory display.

Introduction to Olfaction

This chapter introduces the basic anatomy and physiology of the neural systems involved in the detection and identification of odors by vertebrate animals. It describes the cellular architecture and function of these systems, tracing the path of sensory signals from the initial steps of sniffing and chemical stimulus transduction in the nose, through to the synaptic processing pathways in the circuits of the olfactory bulb and major areas of olfactory cortex. Included are reviews of the latest research findings and hypotheses shaping our fundamental understanding of olfactory mechanisms, with particular emphasis on mammalian olfaction.

Display Technology of Images with Scents and Its Psychological Evaluation

Scent is an important component of every individual’s real life; it has many psychological and physical effects. Therefore, if a visual image is presented along with a matching scent, we expect it will possibly carry more detailed information and be perceived as a more realistic sensation than it would have on its own. In order to do so, it is necessary to solve some problems. First, the qualities for a device to be able to integrate a scent with an image are discussed. Second, a new method in which scents are emitted through a display screen in the direction of a viewer in order to enhance the reality of visual images is described. Third, the psychological effects on a viewer when scents are integrating with images are described. The authors investigated the viewing experiences and eye catching effects when applied to movies, a digital-signage, and virtual reality.

Evaluating the Psychobiologic Effects of Fragrances through Salivary Biomarkers

Olfactory stimulation by odorant molecules produces neurobiologic responses that manifest in the salivary proteome. This chapter highlights recent progress in the use of salivary biomarkers to augment conventional psychological assessments of the effects of fragrances and odors. New, low-cost, portable salivary biosensors enable point-of use measurements of physiological effects of fragrances in naturalistic settings. The ability to operationalize measurement of the sedative state induced by a fragrance will clarify the mechanistic underpinnings of olfactory stimulation and facilitate investigations of structure-odor relationships that are necessary for the synthesis of new odorant molecules.