What is the function of new neurons entering the olfactory bulb? Many insights regarding the molecular control of adult neurogenesis have been uncovered, but the purpose of new neurons entering the olfactory bulb has been difficult to ascertain. Here, studies investigating the role of adult neurogenesis in olfactory discrimination in mice are reviewed. Studies in which adult neurogenesis is affected are highlighted, with a focus on the role of environment enrichment and what happens during (...) ageing. There is evidence for a role of adult neurogenesis in fine discrimination tasks, as underscored by studies that enhance adult neurogenesis. This is also observed in ageing studies, where older mice with reduced levels of adult neurogenesis perform poorly in olfactory discrimination. Differences in methodology that could account for alternative conclusions, and the importance of specificity in methods being used to investigate the effect of adult neurogenesis in olfactory performance are emphasized. (shrink)

The anterior cingulate cortex (ACC) is a complex and continually evolving brain region that remains a primary focus of research due to its multifaceted functions. Various studies and analyses have significantly advanced our understanding of how the ACC participates in a wide spectrum of memory and cognitive processes. However, despite its strong connections to brain areas associated with hippocampal and olfactory neurogenesis, the functions of the ACC in regulating postnatal and adult neurogenesis in these regions are still (...) insufficiently explored. Investigating the intricate involvement of the ACC in neurogenesis could enhance our comprehension of essential aspects of brain plasticity. This involvement stems from its complex circuitry with other relevant brain regions, thereby exerting both direct and indirect impacts on the neurogenesis process. This review sheds light on the promising significance of the ACC in orchestrating postnatal and adult neurogenesis in conditions related to memory, cognitive behavior, and associated disorders. (shrink)

Fezf1 and Fezf2 are highly conserved transcription factors that were first identified by their specific expression in the anterior neuroepithelium of Xenopus and zebrafish embryos. These proteins share an N‐terminal domain with homology to the canonical engrailed repressor motif and a C‐terminal DNA binding domain containing six C2H2 zinc‐finger repeats. Over a decade of study indicates that the Fez proteins play critical roles during nervous system development in species as diverse as fruit flies and mice. Herein we discuss recent progress (...) in understanding the functions of Fezf1 and Fezf2 in neurogenesis and cell fate specification during mammalian nervous system development. Going forward we believe that efforts should focus on understanding how expression of these factors is precisely regulated, and on identifying target DNA sequences and interacting partners. Such knowledge may reveal the mechanisms by which Fezf1 and Fezf2 accomplish both independent and redundant functions across diverse tissue and cell types. (shrink)

The philosophy of perception has been mostly focused on vision, to the detriment of other modalities like audition or olfaction. In this paper I focus on olfaction and olfactory experience, and raise the following questions: is olfaction a perceptual-representational modality? If so, what does it represent? My goal in the paper is, firstly, to provide an affirmative answer to the first question, and secondly, to argue that olfaction represents odors in the form of olfactory objects, to which (...) class='Hi'>olfactory qualities are attributed. In order to do this I develop an empirically adequate notion of olfactory object that is sensitive to the peculiarities of olfaction, and defend it against various objections. (shrink)

Much of the philosophical work on perception has focused on vision. Recently, however, philosophers have begun to correct this ‘tunnel vision’ by considering other modalities. Nevertheless, relatively little has been written about the chemical senses—olfaction and gustation. The focus of this paper is olfaction. In light of new physiological and psychophysical research on olfaction, I consider whether olfactory experience is object-based. In particular, I explore the claim that “odor objects” constitute sensory individuals. It isn’t obvious—at least at the outset—whether (...) they meet the widely accepted principles of object individuation and recognition at work in the visual and auditory cases. Among the general issues I consider, then, is whether these traditional principles form necessary, or simply sufficient, conditions on object perception. As we see, at the very least, considering the object-recognition model of olfaction challenges us to look more closely at well-entrenched models of object perception. But the payoff of doing so is high. We not only learn something about a modality that philosophers have historically neglected; by asking new questions and challenging old assumptions, we also further our understanding of perception in general. (shrink)

This chapter argues that olfactory experiences represent either everyday objects or ad hoc olfactory objects as having primitive olfactory properties, which happen to be uninstantiated. On this picture, olfactory experiences reliably misrepresent: they falsely represent everyday objects or ad hoc objects as having properties they do not have, and they misrepresent in the same way on multiple occasions. One might worry that this view is incompatible with the plausible claim that olfactory experiences at least sometimes (...) justify true beliefs about the world. This chapter argues that there is no such incompatibility. Since olfactory experiences reliably misrepresent, they can lead to true and justified beliefs about putatively smelly objects. (shrink)

The transcription factor CREB has been implicated in signalling pathways relevant for pathogenesis and therapy of depression. CREB is upregulated and activated in the hippocampus by chronic antidepressant treatment, similarly as neurogenesis. Surprisingly, a recent study using CREB‐deficient mice also demonstrates an upregulation of neurogenesis correlating with an antidepressant behavioral phenotype.1 Interestingly, CREB‐deficient mice show a rapid behavioral response to antidepressants, while wild‐type mice do not. This minireview tries to reconcile these new findings with established concepts on CREB, (...) neurogenesis and depression. It also outlines some crucial experiments and lines of future research that could clarify some of the pending questions. BioEssays 29:957–961, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Mental Imagery, whereby we experience aspect of a perceptual scene or perceptual object in the absence of direct sensory stimulation is ubiquitous. Often the existence of mental imagery is demonstrated by asking one’s reader to volitionally generate a visual object, such as closing ones eyes and imagining an apple. However, mental imagery also arises in auditory, tactile, interoceptive, and olfactory cases. A number of influential philosophical theories have attempted to explain mental imagery in terms of belief-based forms of representation (...) using the Dependence Thesis, dependence upon means of access, such as enactivism, or in terms of the similarity of content with perceptual processing. The focus of this paper concerns the later approach and in particular assessing if Nanay’s promissory note that his theory is applicable to modalities other than vision, such as smell, seems likely to be of theoretical tender. The thesis argued for in this paper is that olfactory imagery exists and is best accounted for by considering it as a type of perceptual processing with a unique representational format relative to the olfactory perceptual modality. The paper concludes by summarizing the applicability of Nanay’s theory of mental imagery for olfaction and suggests some further issues that arise when transitioning to multi-modal mental imagery. (shrink)

Adult neurogenesis is an exciting and rapidly advancing field of research. It addresses basic biological questions, such as the how and why of de novo neuronal production during adulthood, as well as medically relevant issues, including the potential link between adult neural stem cells and psychiatric disorders, or how stem cell manipulation might be used as a strategy for neuronal replacement. Current research mainly focuses on rodents, but we review here recent examination of non‐mammalian vertebrates, which demonstrates that bona (...) fide adult neural stem cells exist in these species. Importantly, especially in teleost fish, these cells can be abundant and located in various brain areas. Hence, non‐mammalian vertebrate species provide invaluable comparative material for extracting core mechanisms of adult neural stem cell maintenance and fate. BioEssays 29:745–757, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

The philosophy of perception has been dominated by vision, with very little discussion of the chemical senses – olfaction and gustation. In this second entry of a pair on olfactory experience, I consider what olfaction has to tell us about two issues: the nature of perceptual objects and the nature of perceptual properties and, in particular, the secondary qualities. Given the scant work on olfaction in the philosophical literature, my discussion not only surveys what philosophers have said about olfaction (...) so far, but considers the most plausible views and/or most pressing questions in each area of inquiry. (shrink)

Much of the philosophical work on perception has focused on vision. Recently, however, philosophers have been turning their attention to the ‘other modalities’. In a pair of entries, I consider olfaction—a sense modality that, along with gustation, has been largely overlooked by philosophers. In this first entry, I consider the challenge that olfactory experience presents to upholding a representational view of the sense modalities. It is common for philosophers to think that visual experience is world‐directed and, in particular, that (...) it is representational. World‐directed views contrast with subjectivist views—views according to which experiences are raw feels or mere sensations. Unlike visual experience, olfactory experience doesn't obviously support a representational view. Indeed, given its phenomenology, a subjectivist view of olfactory experience might seem unavoidable. But it is not. Once we begin to unravel ourselves from the dominant visual model of perception, we see that there is a representational view available that honors the phenomenology of olfactory experience. In turn, we learn that although there are some basic similarities between visual experience and olfactory experience, there are significant differences that prevent us from making easy generalizations from the visual case. (shrink)

The discovery of neurogenesis and neural stem cells (NSC) in the adult CNS has overturned a long‐standing and deep‐routed “dogma” in neuroscience, established at the beginning of the 20th century. This dogma lasted for almost 90 years and died hard when NSC were finally isolated from the adult mouse brain. The scepticism in accepting adult neurogenesis has now turned into a rush to find applications to alleviate or cure the devastating diseases that affect the CNS. Here we highlight (...) a number of methodological, technical and conceptual drawbacks responsible for the historical denial of adult neurogenesis. Furthermore, we discuss old and new issues that need to be faced before NSC or endogenous neurogenesis can safely enter into the doctor's bag for therapies. BioEssays 30:135–145, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

It has been suggested that there maybe no olfactory illusions. This manuscript examines this claim and argues that it arises because olfactory illusions are not typically accompanied by an awareness of their illusory nature. To demonstrate that olfactory illusions do occur, the relevant empirical literature is reviewed, by examining instances of where the same stimulus results in different percepts, and of where different stimuli result in the same percept. The final part of the manuscript evaluates the evidence (...) favoring the existence of olfactory illusions, and then examines why they may not typically be accompanied by awareness. Three contributory mechanisms are discussed, relating to difficulty of verification and paucity of olfactory knowledge, the role of change blindness, and restricted access consciousness in this sense. (shrink)

Olfactory rivalry can occur when a binary mixture is sniffed repeatedly, with one percept dominating then the other. Experiment 1 demonstrated olfactory rivalry using several new techniques. Experiments 2 and 3 examined whether participants can notice rivalry. Participants received trials composed of odor pairs: either a mixture followed by the same mixture; or a pure odor followed by the same pure odor. On some trials participants judged whether the two stimuli were the same or different, to see if (...) they could detect rivalry. On other trials participants judged the quality of each odor, allowing us to determine whether rivalry occurred. We found evidence for rivalry when we compared reports of odor quality for one stimulus and then the other, but no evidence that participants could detect this change. These findings are consistent with the idea that people can experience olfactory illusions, but may not know they have occurred. (shrink)

Much of the philosophical work on perception has focused on vision, with very little discussion of the chemical senses—olfaction and gustation. In this paper, I consider the challenge that olfactory experience presents to upholding a representational view of the sense modalities. Given the phenomenology of olfactory experience, it is difficult to see what a representational view of it would be like. Olfaction, then, presents an important challenge for representational theories to overcome. In this paper, I take on this (...) challenge and argue for a representational account of olfactory experience that honors its phenomenology. (shrink)

Several 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. (shrink)

Although vision is the de facto model system of consciousness research, studying olfactory consciousness has its own advantages, as this collection of articles emphatically demonstrates. One advantage of olfaction is its computational and phenomenological simplicity, which facilitates the identification of basic principles. Other researchers study olfactory consciousness not because of its simplicity, but because of its unique features. Together, olfaction's simplicity and its distinctiveness make it an ideal system for testing theories of consciousness. In this research topic, the (...) results of recent research into olfactory consciousness are presented. (shrink)

Any living organism interacts with and responds specifically to environmental molecules by expressing specific olfactory receptors. In this paper, this specificity will be first examined in causal terms with particular emphasis on the mechanisms controlling olfactory gene expression, cell-to-cell interactions and odor-decoding processes. However, this type of explanation does not entirely justify the role olfactory receptors have played during evolution, since they are also expressed ectopically in different organs and/or tissues. Homologous olfactory genes have in fact (...) been found in such diverse cells and/or organs as spermatozoa, testis and kidney where they are assumed to act as chemotactic sensors or renin modulators. To justify their functional diversity, homologous olfactory receptors are assumed to share the same basic role: that of conferring a self-identity to cells or tissues under varying environmental conditions. By adopting this standpoint, the functional attribution as olfactory or chemotactic sensors to these receptors should not be seen either as a cause conditioning receptor gene expression, or as a final effect resulting from genetically predetermined programs, but as a direct consequence of the environmental conditions olfactory receptor genes have explored during evolution. The association of odorant patterns with specific environmental or contextual situations makes their relationship semiotically triadic, due to the emergence of an interpretant capable of perceiving odorants as meaningful signs out of a noisy background. This perspective highlights the importance of odorant-receptor relationships as respect to the properties of the interacting partners. It is our contention that only when taken together can these different explanatory strategies provide a realistic account of how olfactory receptor genes have been structurally and functionally modified during evolution. (shrink)

The Westermarck effect (sexual inhibition among individuals raised together) is argued to be mediated olfactorily. Various animals, including humans, distinguish among individuals by scent (significantly determined by MHC genotype), and some avoid cosocialized associates on this basis. Possible models of olfactory mechanisms in humans are evaluated. Evidence suggests aversions develop during an early sensitizing period, attach to persons as much as to their scents, and are more powerful among females than among males. Adult to child aversions may develop similarly, (...) but more likely result from stimulus generalization. This hypothesis accords with current evidence and yields testable predictions (e.g., anosmia will prevent inhibition) that, should they be supported, will conclusively ground the Westermarck effect in a biological mechanism. (shrink)

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 Bfeature (...) 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. (shrink)

Smell perception plays an important role in eating behavior and might be involved in body weight gain. Since a body of literature implies that olfactory perception and function is hampered in obesity, we here investigate neuroanatomical correlates of this phenomenon. We assessed olfactory bulb volume with magnetic resonance imaging in 67 healthy participants with a body mass index from 18.9 to 45.4 kg/m2. Moreover, we obtained psychophysiological data on olfactory ability and self-report measurements on eating behavior. Additionally, (...) we collected parameters associated with metabolic health in obesity to investigate recently proposed mechanistic explanatory models of why olfaction may be altered in obesity. We showed that OB volume was significantly lower in participants with obesity when compared to those of normal weight. Moreover, we found weak to moderate negative correlations between OB volume and BMI and related measures of metabolic health, especially leptin, body fat percentage, waist-height ratio and insulin resistance. However, neither OB volume nor BMI were related to olfactory function in our young and healthy sample. Nevertheless, our results provide first indications that obesity is associated with brain anatomical changes in the OBs. (shrink)

Cannabis sativa L. is grown and marketed under a large number of named strains. Strains are often associated with phenotypic traits of interest to consumers, such as aroma and cannabinoid content. Yet genetic inconsistencies have been noted within named strains. We asked whether genetically inconsistent samples of a commercial strain also display inconsistent aroma profiles. We genotyped 32 samples using variable microsatellite regions to determine a consensus strain genotype and identify genetic outliers for four strains. Results were used to select (...) 15 samples for olfactory testing. A genetic outlier sample was available for all but one strain. Aroma profiles were obtained by 55 sniff panelists using quantitative sensory evaluation of 40 odor descriptors. Within a strain, aroma descriptor frequencies for the genetic outlier were frequently at odds with those of the consensus samples. It appears that within-strain genetic differences are associated with differences in aroma profile. Because these differences were perceptible to untrained panelists, they may also be noticed by retail consumers. Our results could help the cannabis industry achieve better control of product consistency. (shrink)

Amodal completion is the representation of those parts of the perceived object that we get no sensory stimulation from. While amodal completion is rife and plays an essential role in all sense modalities, philosophical discussions of this phenomenon have almost entirely been limited to vision. The aim of this paper is to examine in what sense we can talk about amodal completion in olfaction. We distinguish three different senses of amodal completion – spatial, temporal and feature-based completion – and argue (...) that all three are present and play a significant role in olfaction. (shrink)

Does the sense of smell involve the perception of odor objects? General discussion of perceptual objecthood centers on three criteria: stimulus representation; perceptual constancy; and figure-ground segregation. These criteria, derived from theories of vision, have been applied to olfaction in recent philosophical debates about psychology. An inherent problem with such framing of olfactory objecthood is that philosophers explicitly ignore the constitutive factors of the sensory systems that underpin the implementation of these criteria. The biological basis of odor coding is (...) fundamentally different from the coding principles of the visual system. This article analyzes the three measures of perceptual objecthood against the biological background of the olfactory system. It contrasts the coding principles in olfaction with the visual system to show why these criteria of objecthood fail to be instantiated in odor perception. The argument demonstrates that olfaction affords perceptual categorization without the need to form odor objects. (shrink)

This book reconsiders the major current topics in the philosophy of perception using olfaction as the paradigm sense. The author reveals how many of the most basic concepts of philosophy of perception are based on peculiarities of visual perception not found in other modalities, and addresses how different the philosophy of perception would be if based on olfaction. The book addresses several aspects of olfaction, including perceptual qualities, percepts, olfaction and cognitive processes, and consciousness. The first part of the book (...) considers perception with respect to its ability to guide behaviors and to make information available to cognitive processes. The author continues by addressing the differences between conscious and non-conscious olfactory perception, and presents an argument for an important role of attention in conscious processes. The book concludes by discussing the function of conscious brain processes and their link to guiding behaviors in complex situations. (shrink)

Research into early Chinese olfactory culture is only just beginning. This paper argues that before the arrival of Buddhism, elite scent culture had already begun to be transformed by the importation of foreign aromatics, though these substances arrived shorn of their original cultural context. Prior to the importing of intense foreign perfumes, the aromatics available were mostly local, and traditional Chinese practice stressed the use of individual scents in religious contexts, a concept which also had a profound influence on (...) secular usage. The same is true of early osmographies, which link particular kinds of smells—including many that might be considered unpleasant—to the changing seasons. When foreign spices and aromatics arrived in China for the first time, a phenomenon later literature specifically associates with the reign of Han Wudi, this resulted in the development of new complex and powerful perfumes. This in turn may have had a significant impact upon the material culture of Han China, with the spread of personal scenting devices and incense burners. (shrink)

Visual experience is often characterised as being essentially spatial, and auditory experience essentially temporal. But this contrast, which is based upon the temporal structure of the objects of sensory experience rather than the experiences to which they give rise, is somewhat superficial. By carefully examining the various sources of temporal variation in the chemical senses we can more clearly identify the temporal profile of the resulting smell and taste (aka flavour) experiences. This in turn suggests that at least some of (...) the objects of olfactory experience have significant temporal structure, including interactions between odorants and the body’s own sensory systems. This can help to inform our understanding not only of the metaphysics of olfaction, but the temporal structure of sensory processing and experience in other sense-modalities, including vision and audition. (shrink)

Clare Batty has recently argued that the content of human olfactory experience is 'a very weak kind of abstract, or existentially quantified content', and so that 'there is no way things smell'. Her arguments are based on two claims. Firstly, that there is no intuitive distinction between olfactory hallucination and olfactory illusion. Secondly, that olfaction 'does not present smell at particular locations', and 'seems disengaged from any particular object'. The present article shows both of these claims to (...) be false. It shows that naïve subjects find it quite natural to draw a distinction between olfactory hallucination and olfactory illusion. And it argues that the phenomenology of normal olfactory experience is of particular objects as having smells. Two confusions are responsible for Batty thinking otherwise: (1) Batty's examples are cases of extreme pungency, and she mistakes a peculiarity of intense perceptions for a property of olfaction more generally; (2) Batty focuses on very short time slices and so confuses limitations on the information carried by a single sniff for a limitation on the logical form of all olfactory content. (shrink)

Our sense of smell pervasively influences our most common behaviors and daily experience, yet little is known about olfactory consciousness. Over the past decade and a half research in both the fields of Consciousness Studies and Olfaction has blossomed, however, olfactory consciousness has received little to no attention. The olfactory systems unique anatomy, functional organization, sensory processes, and perceptual experiences offers a fecund area for exploring all aspects of consciousness, as well as a external perspective for re-examining (...) the assumptions of contemporary theories of consciousness. It has even been suggested that the olfactory system may represent the minimal neuroanatomy that is required for conscious processing. Here, we seek contributions that should serve as the foundation for future research concerning consciousness using olfaction as a model. -/- Given the variegated nature of research on consciousness, we seek original papers including review articles, original research, and theoretical contributions concerning the nature of olfactory consciousness. The scope of the special edition widely incorporates olfaction as it relates to Consciousness, Awareness, Attention, Phenomenal- or Access-Consciousness, and Qualia. Research concerning olfaction and cross-modal integration as it relates to conscious experience is also welcome. -/- As the initial foray into this uncharted area of research, we welcome contributions from across all disciplines contributing to cognitive neuroscience, including neurobiology, neurology, psychology, philosophy, linguistics, and computer sciences. It is our hope that this special edition will serve as the impetus for future interdisciplinary research on olfaction and consciousness. (shrink)

We can learn much about perceptual experience by thinking about how it can mislead us. In this paper, I explore whether, and how, olfactory experience can mislead. I argue that, in the case of olfactory experience, the traditional distinction between illusion and hallucination does not apply. Integral to the traditional distinction is a notion of ‘object-failure’—the failure of an experience to present objects accurately. I argue that there are no such presented objects in olfactory experience. As a (...) result, olfactory experience can only mislead by means of a kind of property hallucination. The implications of my arguments are twofold. First, we see that accounts of representational content cannot always be based on the visual model. And, secondly, we see that we must recast the notion of nonveridicality, allowing for a notion of non-veridical experience that is disengaged from any particular object. (shrink)

While there is a growing philosophical interest in analysing olfactory experiences, the mereological structure of odours considered in respect of how they are perceptually experienced has not yet been extensively investigated. The paper argues that odours are perceptually experienced as having a mereological structure, but this structure is significantly different from the spatial mereological structure of visually experienced objects. Most importantly, in the case of the olfactory part-structure, the classical weak supplementation principle is not satisfied. This thesis is (...) justified by referring to empirical results in olfactory science concerning the human ability to identify components in complex olfactory stimuli. Further, it is shown how differences between olfactory and visual mereologies may arise from the way in which these modalities represent space. (shrink)

Seattle rain smelled different from New Orleans rain…. New Orleans rain smelled of sulfur and hibiscus, trumpet metal, thunder, and sweat. Seattle rain, the widespread rain of the Great Northwest, smelled of green ice and sumi ink, of geology and silence and minnow breath.— Tom Robbins, Jitterbug PerfumeMuch of the philosophical literature on perception has focused on vision. This is not surprising, given that vision holds for us a certain prestige. Our visual experience is incredibly rich, offering up a mosaic (...) of apparent three-dimensional objects. For this reason, it is commonplace to suppose that visual experience is world-directed, with the view taking its most popular form in the representational, or content, view. World-directed views contrast with what we might call subjectivist views — views according to which experiences are raw feels or mere sensations. (shrink)

Previous studies claim there are few olfactory metaphors cross-linguistically, especially compared to metaphors originating in the visual and auditory domains. We show olfaction can be a source for metaphor and metonymy in a lesser-described language that has rich lexical resources for talking about odors. In Seri, an isolate language of Mexico spoken by indigenous hunter-gatherers, we find a novel metaphor for emotion never previously described – “anger stinks”. In addition, distinct odor verbs are used metaphorically to distinguish volitional vs. (...) non-volitional states-of-affairs. Finally, there is ample olfactory metonymy in Seri, especially prevalent in names for plants, but also found in names for insects and artifacts. This calls for a re-examination of better-known languages for the overlooked role olfaction may play in metaphor and metonymy. The Seri language illustrates how valuable data from understudied languages can be in highlighting novel ways by which people conceptualize themselves and their world. (shrink)

One of the crucial characteristics of the olfactory modality is that olfactory experiences commonly present odours as pleasant or unpleasant. Indeed, because of the importance of the hedonic aspects of olfactory experience, it has been proposed that the role of olfaction is not to represent the properties of stimuli, but rather to generate a valence-related response. However, despite a growing interest among philosophers in the study of the chemical senses, no dominant theory of sensory pleasure has emerged (...) in the case of human olfaction. The aim of this paper is to develop an argument based on the way in which olfactory valence is neurally encoded; one that demonstrates an advantage of the indicative representational approach to olfactory valence over approaches that characterise valence in terms of desires or commands. The argument shows that it is plausible to understand olfactory valence, at least in part, in terms of indicative representations. (shrink)

We know that microbes contribute to the production of odors that some animals use to communicate, but how common is this phenomenon? Recent studies capitalizing on new molecular technologies are uncovering fascinating associations between microbes and odors of wild animals, but causality is difficult to ascertain. Fundamental questions about the nature of these unique host‐microbe interactions also remain unanswered. For instance, do microbes benefit from signaling associations with hosts? How does microbial community structure influence signal production? How do hosts regulate (...) microbes in order to generate appropriate signals? Here, we review the current state of knowledge on microbially produced signals in animals and discuss key research foci that can advance our understanding of microbial‐based signaling in the animal world. (shrink)