The olfactory system was traditionally thought to lack a thalamic relay to mediate top-down influences from memory and attention in other perceptual modalities. Olfactory perception was therefore often described as an outlier among perceptual modalities. It was argued as a result that olfaction was a canonical example of a direct perception. In this paper we review functional and anatomical evidence which demonstrates that olfaction depends on both direct pathway connecting anterior piriform cortex to orbitofrontal cortex and an indirect (...) thalamic circuit connecting posterior piriform cortex and orbitofrontal cortices to the olfactory system. We argue that the indirect corticothalamic circuit has the structure to potentially mediate mediates top-down influences of memory and attention in olfactory perception. This suggests that olfaction is not an outlier after all. (shrink)

In the philosophy of perception, olfaction is the perennial problem child, presenting a range of difficulties to those seeking to define its proper referents, and its phenomenological content. Here, we argue that many of these difficulties can be resolved by recognizing the object-like representation of odors in the brain, and by postulating that the basic objects of olfaction are best defined by their biological value to the organism, rather than physico-chemical dimensions of stimuli. Building on this organism-centered account, (...) we speculate that the phenomenological space of olfaction is organized into a number of coarse affective dimensions that apply categorically. This organization may be especially useful for coupling sensation to decision-making and instrumental action in a sensory modality where the stimulus space is especially complex and high-dimensional. (shrink)

Olfaction represents odors, if it represents anything at all. Does olfaction also represent ordinary objects like cheese, fish and coffee-beans? Many think so. This paper argues that it does not. 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.

My general topic is whether limitations in olfaction’s conceptual and generally mental capabilities hinder its suitability for playing significant and sophisticated roles in theatrical productions of the standard narrative type. This is a big question and I only scratch the surface here. I begin with a brief look at smell’s most prominent roles in the theatre, as illustration and to evoke mood and atmosphere. Next, I consider the relation between smell and the experience of space, looking first at a (...) kind of power it has that is sometimes overlooked. Third, I examine a conundrum about what the objects we smell, as opposed to the objects we see, do and do not represent in a theatrical performance. Finally, the conundrum leads into a deeper discussion of whether scents or the objects we smell do the representing in theatre. (shrink)

Objective tests of olfaction are widely available to aid in the assessment of olfaction. Their clearest role is in the characterization of olfactory changes, either reported by or suspected in a patient. There is a rapidly growing literature concerned with the association of olfactory changes with certain neuropsychiatric conditions and the use of olfactory testing to supplement conventional assessments in clinical and research practice is evolving. Neural pathways important for olfactory processing overlap extensively with pathways important for cognitive (...) functioning, and especially those important for executive functioning, many of which are concentrated in the frontal lobes. Previous work has identified associations between performance on certain olfactory tests and executive functioning and behavioral measures. More recently, similar associations have also been identified in non-clinical samples, raising new questions as to the utility of olfactory test scores as proxy measures for non-olfactory phenomena. In this systemic review, we sought to identify studies, both clinical and non-clinical, that investigated the associations of olfaction with performance on tasks sensitive to frontal lobe functioning. Our search criteria led to the identification of 70 studies published in English. We examined in detail and tabulated the data from these studies, highlighted each study's key findings, and critically evaluated these studies. We use the results of this review to reflect on some of the current and future challenges concerning the use of olfactory testing in clinical neuropsychiatric practice and research and speculate on the potential benefits of administering phonemic fluency in combination with olfactory testing to enhance its predictive value. (shrink)

While philosophers of perception develop representational theories of olfactory experiences, there are doubts regarding whether features of olfactory perception can be accommodated within the representationalist framework. In particular, it is argued that the function of olfaction is not to represent stimuli but rather to evaluate it. The paper claims that the major representational accounts of olfaction have problems in accommodating the evaluative aspects of olfactory phenomenology. However, an alternative position, named “olfactory evaluativism,” is proposed which is free of (...) these problems and may serve as a foundation for further developments of representational approach to olfactory experiences. (shrink)

Many have suggested that, unlike the so-called higher-senses, the lower-senses are not capable of providing aesthetic experience. Supporting this is, what I will call, the Transparency-Exteroceptivity Argument, which says that a necessary feature for aesthetic experience is lacking in the case of the lower-senses, namely transparency/exteroceptivity. I argue, contrary to the Transparency-Exteroceptivity Argument, that olfaction can provide transparent access to the properties of particular external objects. I argue that the Transparency-Exteroceptivity Argument relies on a misleading visuocentric and unimodal view (...) of the senses, is guilty of hasty generalization, and should be rejected. (shrink)

This book offers a broad and timely perspective on research on olfaction and its current technological challenges. It specifically emphasizes the interdisciplinary context in which olfaction is investigated in contemporary research. From aesthetics to sociology, from bioengineering to anthropology, the different chapters discuss a wide variety of issues arising from olfaction research and its application in different contexts. By highlighting the overlaps between different areas of research, the book fosters a better communication between disciplines and leads towards (...) a better understanding of the role of olfaction in human perception and cognition. This inspiring read is of interest to students, researchers and practitioners in psychology, philosophy, bioengineering, and cultural studies. (shrink)

How much does stimulus input shape perception? The common-sense view is that our perceptions are representations of objects and their features and that the stimulus structures the perceptual object. The problem for this view concerns perceptual biases as responsible for distortions and the subjectivity of perceptual experience. These biases are increasingly studied as constitutive factors of brain processes in recent neuroscience. In neural network models the brain is said to cope with the plethora of sensory information by predicting stimulus regularities (...) on the basis of previous experiences. Drawing on this development, this chapter analyses perceptions as processes. Looking at olfaction as a model system, it argues for the need to abandon a stimulus-centred perspective, where smells are thought of as stable percepts, computationally linked to external objects such as odorous molecules. Perception here is presented as a measure of changing signal ratios in an environment informed by expectancy effects from top-down processes. (shrink)

In the contemporary analytic discussions concerning human olfactory perception, it is commonly claimed that olfactory experiences are representations having content and 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 represented by olfaction should be characterised as features and the second states that they should be interpreted as objects. In this paper, I aim to systematically address the “feature (...) or object” status of odours by comparing their ontological characteristics to those possessed by visually represented objects and features. I argue that olfactorily represented odours constitute a sui generis ontological category which differs from the categories of visually represented entities and cannot be easily classified as objects or features. Such investigations constitute a step in establishing whether various human modalities are ontologically unified by organising the environment according to the same categories. (shrink)

Quality-space theory (QST) explains the nature of the mental qualities distinctive of perceptual states by appeal to their role in perceiving. QST is typically described in terms of the mental qualities that pertain to color. Here we apply QST to the olfactory modalities. Olfaction is in various respects more complex than vision, and so provides a useful test case for QST. To determine whether QST can deal with the challenges olfaction presents, we show how a quality space (QS) (...) could be constructed relying on olfactory perceptible properties and the olfactory mental qualities then defined by appeal to that QS of olfactory perceptible properties. We also consider how to delimit the olfactory QS from other modalities. We further apply QST to the role that experience plays in refining our olfactory discriminative abilities and the occurrence of olfactory mental qualities in non-conscious olfactory states. QST is shown to be fully applicable to and useful for understanding the complex domain of olfaction. (shrink)

Cognitive sciences and neurology finally put the stress on olfaction and its dysfonctionalities. Their researches may explain linguistic phenomenoms (insuitability between language and odors) or litterary issues (proustian memory). Neurology and anthropology apparently conclude that there is a fundamental inadequation between human language and odors, opposed to language and colors’s subtle and narrow links.

Olfaction offers unique entry into the non-human world, but Western culture constrains such opportunities because of the dominance of the visual mode of perception. We begin by briefly reviewing philosophical arguments against olfaction as a reliable cognitive input. We then build a biological case for the similarity of non-human and human olfaction. Subsequently, we argue that some contemporary societies still make use of olfaction for organizing themselves in space and time. We end by suggesting that (...) class='Hi'>olfaction offers promise for advancing inquiry into the human-nature relationship that is so important to many environmental philosophers, scientists and activists. (shrink)

Olfaction offers unique entry into the non‐human world, but Western culture constrains such opportunities because of the dominance of the visual mode of perception. We begin by briefly reviewing philosophical arguments against olfaction as a reliable cognitive input. We then build a biological case for the similarity of non‐human and human olfaction. Subsequently, we argue that some contemporary societies still make use of olfaction for organizing themselves in space and time. We end by suggesting that (...) class='Hi'>olfaction offers promise for advancing inquiry into the human‐nature relationship that is so important to many environmental philosophers, scientists and activists. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:The fifth chapter of Saint Bonaventure's Long Life of Saint Francis, the Legenda maior , is a veritable blazon of the body of Francis and its senses, physical and spiritual. The first chapter in the so-called "Inner Life" – the sequence of eight chapters on the virtues of St. Francis – Chapter Five is notable for its insistent focus on sensory experience, due both to Francis's physical mortifications and (...) to his consciousness of the world's beauty, the "comfort" provided to him by the "creatures" he touched, tasted, heard, and saw. The chapter opens with a declaration of Francis's choice to "carry in his own body the armor of the cross" by holding "in check his sensual appetites," practicing self-denial lest he give in "to the earthbound inclinations of the senses," and they impede his spiritual progress. It ends, after an account of four miracles involving tactile, gustatory, auditory, and visual experience, respectively, with a laud of God, the "entire fabric of [whose] universe / came to the service / of the sanctified senses of the holy man." The pivot upon which the narrative turns from deprivation to gratification is, as editors of the Legenda have noted, "a carefully crafted paragraph" on Francis's freely flowing tears, a paragraph "which needs to be understood in light of Bonaventure's theology of the spiritual senses."That theology has been interpreted, however, in vastly different ways by two major twentieth-century theologians, Karl Rahner and Hans Urs von Balthasar, as the comparative work of Stephen Fields has shown, and as Balthasar himself, writing partly in response to Rahner, emphatically points out. Curiously, neither Rahner nor Balthasar pay particular attention to Chapter Five of the Legenda maior. In this essay I read that chapter closely, partly in light of the questions raised by the disagreement between Rahner and Balthasar . I argue that the operation of the spiritual senses in Francis's soul already at the purgative stage is understood by Bonaventure to have affected Francis's corporeal sensory experience, not as a general habitus but in isolated, expressive acts or perceptions involving particular senses at particular times and places. These corporeal perceptions of God's presence and glory in his creatures are, furthermore, an impressive means and safeguard for Francis's eternal beatitude: "Blessed are those who mourn, for they shall be comforted" .For this reason Chapter Five singles out four episodes in Francis's life that correspond to the four dotes or endowments of the glorified body. These four episodes explicitly highlight four of the five physical senses, but omit, significantly, any direct reference to the fifth sense, that of olfaction. Represented indirectly in Chapter Five, I propose, through a decisive act of charitable discretion, the spiritual sense of smell becomes explicit in Bonaventure's Legenda maior in Chapter Fifteen, when Francis's body is laid to rest in the odor of sanctity. Linked to his earlier exodus from a worldly to a virtuous life, the descriptions of Francis's "passing" from this mortal life in Chapter Fourteen and of the "transferal" of his body in the immediately following final chapter return to, complete, and perfect the imagistic pattern of sensory experience established in Chapter Five. As a figure for the virtue of discretion and thus for the free exercise of the rational will at the core of the human personality , the obscure and seemingly unimportant olfactory sense proves to be a vital key for unfolding Bonaventure's Christocentric anthropology.Purgation, the Spiritual Senses, and the DotesChapter Five is incontestably associated with the purgative stage of St. (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)

Is the sense of smell a source of aesthetic perception? Traditional philosophical aesthetics has centered on vision and audition but eliminated smell for its subjective and inherently affective character. This article dismantles the myth that olfaction is an unsophisticated sense. It makes a case for olfactory aesthetics by integrating recent insights in neuroscience with traditional expertise about flavor and fragrance assessment in perfumery and wine tasting. My analysis concerns the importance of observational refinement in aesthetic experience. I argue that (...) the active engagement with stimulus features in perceptual processing shapes the phenomenological content, so much so that the perceptual structure of trained smelling varies significantly from naive smelling. In a second step, I interpret the processes that determine such perceptual refinement in the context of neural decision-making processes, and I end with a positive outlook on how research in neuroscience can be used to benefit philosophical aesthetics. (shrink)

Smell 'sensations' are among the most mysterious of conscious experiences, and have been cited in defense of the thesis that the character of perceptual experience is independent of the physical events that seem to give rise to it. Here we review the scientific literature on olfaction, and we argue that olfaction has a distinctive profile in relation to the other modalities, on four counts: in the physical nature of the stimulus, in the sensorimotor interactions that characterize its use, (...) in the structure of its intramodal distinctions and in the functional role that it plays in people's behaviour. We present two thought experiments in which we detail what would be involved in transforming sounds into smells, and also smells into colours. Through these thought-experiments, we argue that the experiential character of smell derives precisely from the structural features of olfaction, and that an embodied account of olfactory phenomenology is called for. (shrink)

The dual role of olfaction in both smelling and tasting, i.e. flavour perception, makes it an important test case for philosophical theories of sensory individuation. Indeed, the psychologist Paul Rozin claimed that olfaction is a “dual sense”, leading some scientists and philosophers to propose that we have not one, but two senses of smell: orthonasal and retronasal olfaction. In this paper I consider how best to understand Rozin’s claim, and upon what grounds one might judge there to (...) be one or two distinct olfactory modalities. I conclude that while Rozin may be right that humans have dual occurrences of an olfactory ‘sense’, the concept of a sense-modality, and hence the ‘sense’ of smell, is ambiguous between two different notions: a physiological sensory channel and an experiential modality, along the lines suggested by J. J. Gibson. Furthermore, recognising that these are complementary rather than competing conceptions of a sense-modality enables the formulation of a powerful ‘dual-concept’ framework for posing and addressing questions concerning the complex architecture of human multisensory experience. (shrink)

Neurobiology studies mechanisms of cell signalling. A key question is how cells recognise specific signals. In this context, olfaction has become an important experimental system over the past 25 years. The olfactory system responds to an array of structurally diverse stimuli. The discovery of the olfactory receptors (ORs), recognising these stimuli, established the olfactory pathway as part of a greater group of signalling mechanisms mediated by G-protein-coupled receptors (GPCRs). GPCRs are the largest protein family in the mammalian genome and (...) involved in numerous fundamental physiological processes. The OR family exhibits two characteristics that make them an excellent model system to understand GPCRs: its size and the structural diversity of its members. Research on the OR binding site investigates what amino acid sequences determine the receptor-binding capacity. This promises a better understanding of how the basic genetic makeup of GPCRs relates to their diversification in ligand-binding capacities. (shrink)

In this paper, I provide an account of the spatiality of olfactory experiences in terms of topological properties. I argue that thinking of olfactory experiences as making the subject aware of topological properties enables us to address popular objections against the spatiality of smells, and it makes sense of everyday spatial olfactory phenomenology better than its competitors. I argue for this latter claim on the basis of reflection on thought experiments familiar from the philosophical literature on olfaction, as well (...) as on the basis of some empirical data about the localization of smells. I conclude by suggesting how the naïve‐topology framework could be applied in debates about the spatiality of other types of experiences. (shrink)

According to a common opinion, human olfactory experiences are significantly different from human visual experiences. For instance, olfaction seems to have only rudimentary abilities to represent space; it is not clear whether olfactory experiences have any mereological structure; and while vision presents the world in terms of objects, it is a matter of debate whether there are olfactory object-representations. This paper argues that despite these differences visual and olfactory experiences share a hierarchical subject/property structure. Within this structure, olfactorily experienced (...) odours and visual objects have the same status: they are primary subjects which unify other represented elements into perceptual units. (shrink)

Here, I outline the idea of a unified hypothesis of sensory perception, developed from the theoretical vibrational mechanism of olfaction, which can be applied across all sensory modalities. I propose that all sensory perception is based upon the detection of mechanical forces at a cellular level, and the subsequent mechanotransduction of the signal via the nervous system. Thus, I argue that the sensory modalities found in the animal kingdom may all be viewed as being mechanoreceptory, rather than being discrete (...) neurophysiological systems which evolved independently of each other. I go on to argue that this idea could potentially explain language evolution, with birdsong being an example of a more simple form of non-Saussurean language that employs ‘frequency-mimicking’ to produce a vocal signal which describes acoustic, chemical and electromagnetic vibrational frequencies detected within in the environment. I also give examples of how this hypothesis could potentially explain phenomena such as vocal mimicry in animals, as well as the human perception of musicality and the occurrence of synaesthesia; a condition found in humans, where the stimulation of one sensory modality results in the stimulation of another. For example, auditory stimuli are detected and are heard as an acoustic signal, as well as being perceived as colour by the visual system. (shrink)

Contemporary literature on consciousness, with some exceptions, rarely considers the olfactory system. In this article the characteristics of olfactory consciousness, viewed from the standpoint of the phenomenal /access distinction, are examined relative to the major senses. The review details several qualitative differences in both olfactory P consciousness and A consciousness . The basis for these differences is argued to arise from the functions that the olfactory system performs and from the unique neural architecture needed to instantiate them. These data suggest, (...) at a minimum, that P and A consciousness are uniquely configured in olfaction and an argument can be made that the P and A distinction may not hold for this sensory system. (shrink)

It is arguably the case that olfactory system contains two senses that share the same type of stimuli, sensory transduction mechanism, and processing centers. Yet, orthonasal and retronasal olfaction differ in their types of perceptible objects as individuated by their sensory qualities. What will be explored in this paper is how the account of orthonasal smell developed in the Molecular Structure Theory of smell can be expanded for retronasal olfaction (Young, 2016, 2019a-b, 2020). By considering the object of (...) olfactory perception to be the molecular structure of chemical compounds composing odor plumes, Molecular Structure Theory provides a means for determining an odor’s olfactory quality, how odors can be identified and individuated, and how we perceive smellscapes. Surveying the differences between orthonasal and retronasal olfaction provides the basis for the central argument of the paper that the perceptible objects we refer to as smells and individuated on the basis of their olfactory qualities are only relative to orthonasal olfaction. Retronasal olfaction it is speculatively concluded might play an essential role in our perception of flavorful objects. (shrink)

Véronique Adam : Les neurosciences ne s’intéressent que depuis très récemment à l’olfaction. Pourriez‑vous expliquer pourquoi ce sens est devenu un objet d’étude plus prégnant? Jean-Louis Millot : En fait, l’olfaction demeure encore peu étudiée comparée à d’autres modalités sensorielles. De manière générale, les neurosciences cognitives actuelles, comme d’autres investigations scientifiques chez l’homme par le passé, se focalisent davantage sur les compétences cognitives complexes, telles qu...

Nella filosofia moderna la coscienza e la memoria sono state considerate fattori identitari cruciali. L’articolo analizza il ruolo svolto dagli odori nella costituzione dell’identità personale, distinguendo tre livelli: corporeo , socio-culturale e personale . Da un lato, il proprio odore corporeo funge da principium individuationis. Dall’altro, gli odori costituiscono la base di una comunità chiusa ed estremamente conservatrice. Infine, il sé emerge rammentando le proprie «storie» e i ricordi sugli odori.Consciousness and memory were considered identitary key factors in modern philosophy. (...) The article deals with the role played by smells in constituting the identity of the self, on three levels: corporeal , social-cultural , and personal . On the one hand, own’s body smell acts as a principium individuationis. On the other, smells ground a closed and utmost conservative community. Finally, self emerges by recollecting his/her own «stories» and memories about smells. (shrink)

In a recent paper, Cayirlioglu et al. report that the disruption of a specific miRNA, miR‐279, which normally acts to inhibit the transcription factor Nerfin‐1, uncovers a population of hybrid CO2 neurons in the Drosophila maxillary palp.1 Normally, fruit fly CO2 neurons are found only in the antennae, while mosquito CO2 neurons are found only in the maxillary palps. The hybrid neurons in this miRNA mutant may, thus, recapitulate an evolutionary intermediate unseen since the divergence of these two dipteran lineages (...) over 250 million years ago. BioEssays 30:621–623, 2008. © 2008 Wiley Periodicals, Inc. (shrink)