Olfactory Experience Research Articles

Indoor environmental quality perceptions of social housing residents

The need to reduce the carbon footprint of the current stock of multi-unit residential buildings (MURBs) creates an opportunity to improve the indoor environmental quality (IEQ), particularly in buildings occupied by vulnerable populations. This investigation presents IEQ findings from an occupant survey of 180 suites across seven social housing MURBs. The results show many residents are reporting discomfort in all three categories of outcomes surveyed, thermal comfort, olfactory comfort and health symptoms. Residents in two of the seven buildings have higher thermal discomfort, and initial analysis suggests that higher glazing ratios may be a contributing factor. Windows are generally associated with higher solar gains and drafts, making them a good retrofit target for energy and IEQ gains. Resident interventions, such as use of fans or window air conditioning units, were not effective. Olfactory discomfort is another challenge for residents, 80% of whom reported discomfort on at least a weekly basis. Retrofits that exhaust odors from within the suite and limit inter-suite odor transfer could improve olfactory conditions. The buildings that have higher rates of olfactory and thermal discomfort also have higher frequency of health symptoms, warranting further investigation of interrelationships among the outcomes. Residents who report thermal discomfort more frequently report olfactory discomfort and experience more frequent health symptoms. Overall, these results are useful benchmarks of the current IEQ status of this type of building. Understanding the results is helpful for targeting retrofit strategies across multiple IEQ dimensions.

Spatial aspects of olfactory experience

AbstractSeveral theorists argue that one does not experience something as being at or coming from a distance or direction in olfaction. In contrast to this, I suggest that there can be a variety of spatial aspects of both synchronic and diachronic olfactory experiences, including spatial distance and direction. I emphasise, however, that these are not aspects of every olfactory experience. Thus, I suggest renouncing the widespread assumption there is a uniform account of the nature, including the spatial nature, of what is experienced in olfactory experience.

Experience-dependent tuning of early olfactory processing in the adult honey bee, Apis mellifera.

Experience-dependent plasticity in the central nervous system allows an animal to adapt its responses to stimuli over different time scales. In this study, we explored the impacts of adult foraging experience on early olfactory processing by comparing naturally foraging honey bees, Apis mellifera, with those that experienced a chronic reduction in adult foraging experience. We placed age-matched sets of sister honey bees into two different olfactory conditions, in which animals were allowed to forage ad libitum In one condition, we restricted foraging experience by placing honey bees in a tent in which both sucrose and pollen resources were associated with a single odor. In the second condition, honey bees were allowed to forage freely and therefore encounter a diversity of naturally occurring resource-associated olfactory experiences. We found that honey bees with restricted foraging experiences had altered antennal lobe development. We measured the glomerular responses to odors using calcium imaging in the antennal lobe, and found that natural olfactory experience also enhanced the inter-individual variation in glomerular response profiles to odors. Additionally, we found that honey bees with adult restricted foraging experience did not distinguish relevant components of an odor mixture in a behavioral assay as did their freely foraging siblings. This study highlights the impacts of individual experience on early olfactory processing at multiple levels.

Alanine tRNA Translate Environment into Behavior in <i>Caenorhabditis Elegans</i>

Caenorhabditis elegans nematodes produce and keep imprints of attractive chemosensory cues to which they are exposed early in life. These imprints enhance adult chemo-attraction to the same cues. Depending on the number of odor-exposed generations, imprinting is transiently or stably inherited. Strinkingly, we have found that early odor-exposed C. elegans produce odor-specific forms of the transfer RNAAla (UGC). Naive animals fed on these tRNAs acquire transient or stable odor-specific imprinting. The tRNAAla (UGC) controls C. elegans chemo-attractive responses through the multifunctional Elongator complex. Mutations that affect the functions of Elongator sub-units 1 or 3, either impaired chemo-attraction, or definitely abolish responses to the odors nematodes were exposed. We hypothesize that early olfactory experiences translate into tRNAAla (UGC) bearing odor-specific signatures. These diffusible odor memory, together with Elongator, can stably reprogram the C. elegans chemo-attractive behavior.

Gene expression profiling of the olfactory tissues of sex-separated and sex-combined female and male mice

Olfactory experience can alter the molecular and cellular composition of chemosensory neurons within the olfactory sensory epithelia of mice. We sought to investigate the scope of cellular and molecular changes within a mouse’s olfactory system as a function of its exposure to complex and salient sets of odors: those emitted from members of the opposite sex. We housed mice either separated from members of the opposite sex (sex-separated) or together with members of the opposite sex (sex-combined) until six months of age, resulting in the generation of four cohorts of mice. From each mouse, the main olfactory epithelium (MOE), vomeronasal organ (VNO), and olfactory bulb (OB) were removed and RNA-extracted. A total of 36 RNA samples, representing three biological replicates per sex/condition/tissue combination, were analyzed for integrity and used to prepare RNA-seq libraries, which were subsequently analyzed via qPCR for the presence of tissue- or sex-specific markers. Libraries were paired-end sequenced to a depth of ~20 million fragments per replicate and the data were analyzed using the Tuxedo suite.

Elucidating the impact of critical determinants on purchase decision in virtual reality products by Analytic Hierarchy Process approach

Virtual Reality (VR) is a technology that uses a specialized user interface to connect people to the virtual world, where they can enjoy a multitude of visual, auditory, olfactory, and tactile experiences. In this study, the analytic hierarchy process method is used to analyze the following four factors that affect consumers’ purchase decisions with respect to VR products: VR system requirements, purchase-oriented marketing of VR products, VR application types, and user-friendliness of VR products. Additionally, this study also examines consumer preferences for various VR products. Despite the interviewees’ concerns regarding computing power, product pricing, after-sales services, knowledge learning, and user-friendliness, the results of this study reveal that what they need most are VR products that can be used on the go. Therefore, portable VR is expected to be the trend as people are hoping to use VR applications whenever and wherever they wish to use them. This research provides the theoretical and managerial implications for understanding the potential trends for VR products and thus develops the appropriate marketing strategies for them.

Olfactory Objecthood

In the contemporary analytic discussions concerning human olfactory perception, it is commonly claimed that (1) olfactory experiences are representations having content and (2) olfactory experiences represent odours, like coffee odour or vanilla odour. However, despite these common assumptions, there seems to be an ontological controversy between two views: the first states that odours are perceptually represented as features and the second states that they are represented as objects. In this paper, I aim to systematically address the “feature or object” status of represented odours by concerning whether odours are represented (a) as subjects of properties, (b) as mereological wholes, and (c) entities persisting in a way characteristic for objects. I argue that olfactorily represented odours constitute a sui generis category and cannot be easily classified as objects or features. Such investigations constitute a step in establishing whether various human modalities are unified by organising the environment according to the same categories.

The effect of different emotional states on olfactory perception: A preliminary study

AbstractEmotion evoked by odours can be determined or modulated by several factors, including odorant–receptor interactions and olfactory experiences. As a result of these factors, some odours can induce an emotional discrepancy, such as a conflict between innately determined and experience‐based emotions. This study examined whether the difference between two subjective ratings, pleasantness and liking, for an odour can influence olfactory perception, and explored whether the emotional discrepancy had any effect on olfaction. We conducted a psychophysical experiment wherein 12 participants (six women and six men, mean age = 22.0 years) evaluated 36 odours. Participants were instructed to evaluate each odorant in terms of four qualities: (i) pleasantness, (ii) liking, (iii) olfactory perceptual descriptors, and (iv) odour intensity. Participants were also asked to note the difference between pleasantness and liking, whereby the former referred to instinctive and innate feelings and the latter to experience‐based and acquired feelings. Ten odorants exhibited a discrepancy between pleasantness and liking ratings. Another 10 odorants exhibited a significant relationship between the choice of perceptual descriptors and intensity; this was not true of the 10 discrepant odorants. This preliminary study showed that differences in pleasantness and liking ratings can affect the selection of olfactory descriptors, according to odour intensity. The findings suggest that olfactory lexical semantic representations could be confused by discrepant odour‐evoked emotions.

Epigenetic Modifications in the Rat Neonate Olfactory Bulb and Anterior Piriform Cortex Associated with Olfactory and Tactile Experiences

Rodents are macrosmatic; they depend heavily on the olfactory system, which includes the olfactory bulb and anterior piriform cortex, to navigate their environment. The olfactory system is key to the survival of neonatal pups in order to learn the scents of the dam, which aid in nipple attachment and overall attachment to the caregiver. This attachment‐based learning was mimicked in rodents using a laboratory‐based experimental design in which neonatal pups were classically conditioned to associate the novel scent of peppermint with stroking, an action that mimics sensory cues associated with caregiving. The effects of attachment‐based learning on mRNA levels of epigenetic regulators, as well as epigenetic modifications of Bdnf and Reln, genes involved in neuroplasticity, are unknown.We investigated changes in gene expression of Bdnf, Reln, and epigenetic regulators (DNMT1, DNMT3a, DNMT3b, HDAC1, HDAC2, HDAC5, TET1, Gadd45B, and MeCP2) following infant olfactory learning. Using an odor‐stroke paradigm, Long‐Evans rat pups (postnatal days 6 or 7) (n=46) were assigned to either a paired (simultaneous peppermint odor and stroking), unpaired (non‐simultaneous peppermint odor and stroking), or odor‐/stroke‐only condition. Brains were harvested 30 minutes after conditioning. Using Real‐time PCR, we found experience‐induced changes in gene expression profiles in both brain regions. For example, Bdnf exon IV gene expression in the olfactory bulb significantly increased in rats that received contiguous presentation of both stimuli; however, gene expression of HDAC2, HDAC5, TET1, and Gadd45B significantly decreased in the same subjects. In the anterior piriform cortex, there were significant increases in gene expression of Bdnf exons I and IV, DNMT3b, and Gadd45B in both paired and unpaired subjects. Understanding the unknown epigenetic modifications involved in attachment‐based learning may elucidate the mechanisms of the emotional connection an infant learns for the caregiver and its profound influence on neurological development.Support or Funding InformationSpecial thanks to Dr. Roth and Tiffany Doherty for their support and guidance along with Lauren Webb's and Tiffany's completion of odor‐stroke conditioning. This research is funded through grants P20GM103653, R01HD087509, and private donation funds to Dr. Roth.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Effect of Reciprocal Cross-Fostering of Pups in Two Species of Mice Mus musculus and Mus spicilegus: An Altered Response to Con- and Heterospecific Odors

The effect of pup cross-fostering by the house mouse Mus musculus and the mound-building mouse M. spicilegus on the odor preferences of sexually mature individuals has been studied for the first time. House and mound-building mice reared by females of a closely related species did not prefer any of the odors, in contrast to intact individuals of these species. Some individuals reared by females of a closely related species preferred the odor of foster species to conspecific odor. Early olfactory experience has been shown to alter the response of house mice and mound-building mice to odors of their own species and foster species.

Multisensory games-based learning - lessons learnt from olfactory enhancement of a digital board game

Serious games are becoming an alternative educational method in a variety of fields because of their potential to improve the quality of learning experiences and to facilitate knowledge acquisition and content understanding. Moreover, entertainment-driven learners are more easily motivated to benefit from the learning process through meaningful activities defined in a game context. Interfacing educational computer games with multisensorial interfaces allows for a seamless integration between virtual and physical environments. Multisensorial cues can improve memory and attention and increase the cognitive and sensory-motor performance. Despite of the increasing knowledge in sensory processes, multisensory experiences and interactions in computer based instruction remain insufficiently explored and understood. In this paper, we present a multisensory educational game - Fragrance Channel - and we investigate how enabling olfaction can contribute to users' learning performance, engagement and quality of experience. We compare results obtained after experiencing Fragrance Channel in the presence and absence of olfactory feedback on both a mobile and a PC. A knowledge test administered before and immediately after showed that our proposed educational game led to an improvement of performance in all the explored conditions. Subjective measurements carried out after the olfactory experience showed that students enjoyed the scenario and appreciated it as being relevant.

ODORS, OBJECTS, AND OLFACTION

Abstract Olfaction represents odors, if it represents anything at all. Does olfaction also represent ordinary objects like cheese, fish, and coffee beans? Many think so. It is argued here that such a view is in error. Instead, we should affirm an austere account of the intentional objects of olfaction: olfactory experience is about odors, not objects. Visuocentric thinking about olfaction has tempted some philosophers to say otherwise.

The Influence of Early Olfactory Experience on Mate Choice in Mammals: Evolutionary Aspects

The present review addresses the results of behavioral studies in cross-fostered rodent pups and the evolutionary significance and consequences of imprinting and early olfactory experience. The ability to assess the degree of relation to a potential mate can prevent inbreeding and the associated accumulation of deleterious mutations. Rodents are capable of recognizing related individuals by smell. This ability is formed in postnatal ontogenesis as a result of different mechanisms: “preassociation” and phenotypic correlation. The ability to distinguish representatives of their own and closely related species forms at an early age and is the basis for precopulative isolation mechanisms. Some mammals show an altered response to the odor of conspecifics after being fostered by individuals of other species, whereas other mammalian species do not show these changes. Certain features of odor response modification by early olfactory experience are species- and sexspecific. The critical period of behavioral reaction modification in response to odors occurs during the synaptogenesis period, which is indicative of the possible formation of new neuronal connections and synapses under the influence of early olfactory experiences. Certain behavioral and physiological responses were shown to be autonomous, as had an innate character and could not be altered by olfactory experience, whereas the others could change. The results of the studies, taken in their entirety, indicate a high degree of plasticity in the mammalian olfactory system, especially during short, sensitive developmental periods.

Smelling Machine History: Olfactory Experiences of Information Technology.

This article analyses users' olfactory recollections of computers, based on large-scale, online inquiry material collected between 2002 and 2003 and in 2013. It discusses how olfactory experiences and recollections can be classified based on narration and the causes of odors. Furthermore, it explores the changes of olfactory recollections over the course of ten years, and deals with age and gender in these recollections and in their representations. This project develops new paths and possibilities for studying the cultural history of technology and the collection of research material, as well as the exhibition of the history of computing by examining the historical, cultural, political, and economic dimensions of sensations and senses.

Olfactory Theater: Tracking Scents in Aeschylus's Oresteia

Olfactory Theater:Tracking Scents in Aeschylus's Oresteia Amy Lather Here's the smell of blood still: all the perfumes of Arabia will not sweeten this little hand. Lady Macbeth, Act V, Scene 1, line 53 Vivid imagery of dripping fluids proliferates in Aeschylus's Oresteia, and there is also a distinctive smell attributed to one of these liquids: human blood.1 Cassandra and the Erinyes are capable of sniffing out this odor with their non-human senses of smell, which liken them to hounds on the scent in a metaphor that is repeatedly applied to both of them (e.g., Ag. 1093–94, 1184–85; Cho. 924; Eum. 244–47). A powerful sense of smell is portrayed as both bestial and divine, irrational and omniscient, enabling these characters to make accurate identifications without recourse to sight: Cassandra viscerally reacts to Agamemnon's imminent slaughter through her confrontation with the smell of blood (Ag. 1308–12), and the Erinyes are able to track Orestes by means of smell even after he has purified himself (Eum. 244–47). The miasma of the house of Atreus thus assumes an olfactory form that proves impossible to fumigate, in spite of the incense and burning sacrifices that feature prominently in the Agamemnon in particular.2 The smell of bloodshed, then, tracks the course of the house's curse, [End Page 33] giving a literal force to the characterization of Cassandra and the Erinyes as "hounds on the scent." The Oresteia has been well analyzed for its dense networks of imagery, and its use of bestial and sacrificial language has received particular attention.3 This paper seeks to enrich our understanding of the significance of such language by attending to the trilogy's depiction of smell and its relation to humans, animals, and gods.4 For the particular smells that feature in the Oresteia—incense, roasting meat, and blood—are also those that would have permeated the air of the theater given the large number of sacrifices that were performed at the opening of the festival.5 By integrating the olfactory atmosphere of the performance setting into the language of the drama, Aeschylus implicates both characters and spectators in the same olfactory experience. Smell, in other words, provides a mode through which the audience can synaesthetically engage with the sights and sounds of the action onstage.6 In this way, the language of [End Page 34] olfaction in this trilogy contributes to what Peter Meineck (2012.4) terms "an embodied cognitive relationship between performance and spectator," in which the live performance compels spectators not just to see, but also to feel. And it is precisely the shifting and incorporeal nature of smell that makes it apt for the role that it plays in this trilogy, which is to destabilize the traditional hierarchy of gods, humans, and animals through the well-known odors associated with each.7 I. THE AGAMEMNON The Agamemnon is pervaded by scent from the outset. The first indication of an olfactory presence comes from the Chorus' inquiry about the city's blazing altars (91–96), βωμοὶ δώροισι φλέγονται·ἄλλη δ' ἄλλοθεν οὐρανομήκηςλαμπὰς ἀνίσκειφαρμασσομένη χρίματος ἁγνοῦμαλακαῖς ἀδόλοισι παρηγορίαις,πελανῷ μυχόθεν βασιλείῳ. The altars are all ablaze with gifts, in every place a flame rises heaven-high, coaxed by the gentle guileless comfort of pure anointing oil, a thickly-flowing offering from the inner stores of the palace.8 In referring to the "pure anointing oil," the Chorus evokes the fragrance associated with burning altars, a smell that is explicitly defined later as "sweet-smelling" by Clytemnestra ("While they lulled the altar-flames in the gods' abodes by feeding them with sweet-smelling incense," ἐν θεῶν ἕδραις / θυηφάγον κοιμῶντες εὐώδη φλόγα, 596–97). A similar portrayal of this intermingling of smoke and scent comes from a fragment [End Page 35] of Sophocles that describes how "the altar in the street shines with fire, releasing a vapor from drops of myrrh, exotic scents" (λάμπει δ' ἀγυιεὺς βωμὸς ἀτμίζων πυρὶ / σμύρνης σταλαγμούς, βαρβάρους εὐοσμίας, frag. 370, trans. Lloyd-Jones 1994, slightly modified). The purpose of such offerings was to create a shared olfactory experience for humans and gods alike, as a fragrant smell was both pleasing to the gods and one of the defining features of immortal bodies.9 To give a few illustrative examples, Zeus in Book 15 of the Iliad is "wreathed in a fragrant cloud...

Smelling objects

Objects are central to perception and our interactions with the world. We perceive the world as parsed into discrete entities that instantiate particular properties, and these items capture our attention and shape how we interact with the environment. Recently there has been some debate about whether the sense of smell allows us to perceive odours as discrete objects, with some suggesting that olfaction is aspatial and doesn’t allow for object-individuation. This paper offers two empirically tractable criteria for assessing whether particular objects are exhibited in perceptual experience—(1) susceptibility to figure-ground segregation and (2) perceptual constancies—and argues that these criteria are fulfilled by olfactory perception, and thus there are olfactory objects. I argue that there are, in fact, two different ways that olfaction allows for figure-ground segregation. First, I look at various Gestalt grouping principles, which are thought to govern when features are perceived as grouped into structured wholes, segregated from everything around them. I argue that these principles apply to olfactory experience, providing evidence of non-spatial figure-ground segregation. Second, I defend the contentious idea that a spatial variety of figure-ground segregation can also occur in olfaction. To see this, however, we need to look to empirical evidence showing that tactile stimulation and bodily movements play a crucial role in olfactory phenomenology. Finally, I draw on empirical evidence and olfactory phenomenology to argue that there are perceptual constancies in olfactory experience, allowing us to perceive odours as coherent objects that survive shifts in our perspectives on the world.

Olfactory-Experience- and Developmental-Stage-Dependent Control of CPEB4 Regulates c-Fos mRNA Translation for Granule Cell Survival

Mammalian olfactory bulbs (OBs) require continuous replenishment of interneurons (mainly granule cells [GCs]) to support local circuits throughout life. Two spatiotemporally distinct waves of postnatal neurogenesis contribute to expanding and maintaining the GC pool. Although neonate-born GCs have a higher survival rate than adult-born GCs, the molecular mechanism underlying this survival remains unclear. Here, we find that cytoplasmic polyadenylation element-binding protein 4 (CPEB4) acts as a survival factor exclusively for early postnatal GCs. In mice, during the first 2 postnatal weeks, olfactory experience initiated CPEB4-activated c-Fos mRNA translation. In CPEB4-knockout mice, c-FOS insufficiency reduced neurotrophic signaling to impair GC survival and cause OB hypoplasia. Both cyclic AMP responsive element binding protein (CREB)-dependent transcription and CPEB4-promoted translation support c-FOS expression early postnatal OBs but disengage in adult OBs. Activity-related c-FOS synthesis and GC survival are thus developmentally controlled by distinct molecular mechanisms to govern OB growth.

SMELL-S and SMELL-R: Olfactory tests not influenced by odor-specific insensitivity or prior olfactory experience

Smell dysfunction is a common and underdiagnosed medical condition that can have serious consequences. It is also an early biomarker of neurodegenerative diseases, including Alzheimer's disease, where olfactory deficits precede detectable memory loss. Clinical tests that evaluate the sense of smell face two major challenges. First, human sensitivity to individual odorants varies significantly, so test results may be unreliable in people with low sensitivity to a test odorant but an otherwise normal sense of smell. Second, prior familiarity with odor stimuli can bias smell test performance. We have developed nonsemantic tests for olfactory sensitivity (SMELL-S) and olfactory resolution (SMELL-R) that use mixtures of odorants that have unfamiliar smells. The tests can be self-administered by healthy individuals with minimal training and show high test-retest reliability. Because SMELL-S uses odor mixtures rather than a single molecule, odor-specific insensitivity is averaged out, and the test accurately distinguished people with normal and dysfunctional smell. SMELL-R is a discrimination test in which the difference between two stimulus mixtures can be altered stepwise. This is an advance over current discrimination tests, which ask subjects to discriminate monomolecular odorants whose difference in odor cannot be quantified. SMELL-R showed significantly less bias in scores between North American and Taiwanese subjects than conventional semantically based smell tests that need to be adapted to different languages and cultures. Based on these proof-of-principle results in healthy individuals, we predict that SMELL-S and SMELL-R will be broadly effective in diagnosing smell dysfunction.

Cultivating Beauty and Good Taste

Imagine a world where desirable traits are easily programmable. Farmers can select to grow plant varieties that both surprise and delight even the most sophisticated taste buds. Nutrient content and crop yields are improved to fight hunger and malnutrition in vulnerable populations. Vibrant floral varieties can be grown in your home garden that not only exhibit optimized fragrance profiles, but also emit their lovely aromas in robust and conveniently timed bursts. With modern plant genomics offering unprecedented access to the genetic basis of phenotypes and with gene editing technologies allowing precision modulation, such a far-fetched, sci-fi reality might actually be within foreseeable reach.

Host Plant Species Differentiation in a Polyphagous Moth: Olfaction is Enough

Polyphagous herbivorous insects need to discriminate suitable from unsuitable host plants in complex plant communities. While studies on the olfactory system of monophagous herbivores have revealed close adaptations to their host plant’s characteristic volatiles, such adaptive fine-tuning is not possible when a large diversity of plants is suitable. Instead, the available literature on polyphagous herbivore preferences suggests a higher level of plasticity, and a bias towards previously experienced plant species. It is therefore necessary to take into account the diversity of plant odors that polyphagous herbivores encounter in the wild in order to unravel the olfactory basis of their host plant choice behaviour. In this study we show that a polyphagous moth, Spodoptera littoralis, has the sensory ability to distinguish five host plant species using olfaction alone, this being a prerequisite to the ability to make a choice. We have used gas chromatography mass spectrometry (GC-MS) and gas chromatography electroantennographic detection (GC-EAD) in order to describe host plant odor profiles as perceived by S. littoralis. We find that each plant emits specific combinations and proportions of GC-EAD active volatiles, leading to statistically distinct profiles. In addition, at least four of these plants show GC-EAD active compound proportions that are conserved across individual plants, a characteristic that enables insects to act upon previous olfactory experiences during host plant choice. By identifying the volatiles involved in olfactory differentiation of alternative host plants by Spodoptera littoralis, we set the groundwork for deeper investigations of how olfactory perceptions translate into behaviour in polyphagous herbivores.