Human Olfaction

Olfaction, or sense of smell, is one of the many sensory/perceptual systems that humans use to process external stimuli. Human olfaction is relatively understudied. More literature has focused on olfaction in animals for which olfaction plays a larger role in critical functioning and survival. This bibliography provides key resources for information about human olfaction and then outlines twelve general topics that are of considerable value to understanding this primary sensory system. It begins by providing some general resources that outline the functions of olfaction in humans. Next, it explores the anatomy and physiology of the human olfactory system, recognizing that our understanding has been largely guided by studying animals. It addresses several important theories of human olfaction, including ones that have attempted to understand the initial receptor-level processing of stimuli and ones that have been developed to explain the whole system. After considering some historical issues in studying olfaction, it outlines the various ways that human olfaction is studied. It considers some issues in olfaction that are related to cognitive processes, such as language and memory. A critical topic in the chemical senses of smell and taste that is somewhat less relevant in other sensory systems is that of hedonics (pleasure or liking). This bibliography explores sex differences, which, though small, seem to be more prevalent than in other sensory systems. In addition, this bibliography explores the effect of age on olfaction, both in terms of the development of olfaction in children and the decline of olfaction in aging. The entry ends with clinical implications, primarily of smell loss. In light of the Covid-19 pandemic, which brought newfound appreciation for the importance of sense of smell in human experience, a summary of the effect of Covid-19 on human sense of smell is included. In this bibliography pioneering studies are emphasized, although reviews are included in cases where the literature is too extensive to be summed up by single studies.

A Study to Verify the Practicality of Introducing an Arson Dog (K-9) Unit in Field Investigations

Combustion improvers are often found in acts of arson. Until recently, in fire investigations in Korea, these substances have been identified only by the olfactory sense of the fire inspectors or conventional gas detectors. These methods are neither efficient nor feasible in damaged buildings or large areas. Research on the canine sense of smell has shown that a dog can distinguish the remains of combusted hydrocarbon compounds, even in a large, open area. Field tests confirmed that arson dogs can find combustion improvers at fire sites in about five to 77 s. Therefore, this study verified the practicality of introducing arson dog units in field investigations of fire sites to identify combustion improvers sprayed for committing arson.

Morphology of the Human Olfactory Analyzer

The sense of smell provides people with valuable information about the biochemical environment and their own body. Olfactory disorders occur in pathologies of the nasal cavity, liver cirrhosis, psychological and endocrine diseases. Smell affects various psychological aspects of people's lives, forming positive and negative emotional memories associated with smells. With the dysfunction of the olfactory analyzer, a person will not do the analysis whether the food is good, will not be able to feel the presence of poisonous gases in the air, bad breath. This puts a person in an awkward position and increases the risk of social isolation. The purpose of the study was to highlight the components of the normal structure and functioning of the human olfactory analyzer. Identification of odors in the environment and from one's own body is provided by the olfactory analyzer. Primary odors as camphor, floral, fruity, spicy, tarry, burnt and putrid in different quantities form secondary odors. Aromas are composed of volatile molecules called odorants. The smallest amount of odorant that causes an odor sensation is called the odor threshold. In people with coronavirus disease the sense of smell temporarily disappears (anosmia); it is reduced (hyposmia) in liver cirrhosis and rhinitis, and in Alzheimer's disease and schizophrenia besides hyposmia there is olfactory hallucination (phantosmia). Olfactory dysfunction adversely affects children's cognitive abilities. Fragrances change emotions and behavior. Aromas are used to regulate the physical and psychological state of the patient. Volatile molecules of fragrances penetrate through the layer of mucus that covers the olfactory epithelium located in the olfactory region of the nasal mucosa. The olfactory epithelium consists of olfactory, supportive and basal epitheliocytes, as well as secretory cells of the olfactory glands. Olfactory cells are modified nerve cells that have a body, an axon, and a dendrite, which ends with a receptor in the form of olfactory cilia. Volatile molecules interact with the olfactory cilia and then with the receptor protein, which is located on the olfactory cell bodies. In humans, olfactory cells have 350 receptor proteins. One type of receptor can register molecules of several different odorants. Molecules of the same odorant can activate several different receptors simultaneously. The nerve impulse from the olfactory cells (bodies of I neurons) reaches the nerve cells (bodies of II neurons) of the olfactory bulbs via their central outgrowths (olfactory filaments). Axons of nerve cells of olfactory bulbs continue to bodies of III neurons, which are located in subcortical centers of the brain (almond-shaped body, nuclei of the transparent septum). In human, to analyze a particular odor, axons from bodies of III neurons continue to cortex, namely to the area of the uncus of the parahippocampal gyrus

Genetic Etiology of Idiopathic Hypogonadotropic Hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) is a group of rare developmental disorders characterized by low gonadotropin levels in the face of low sex steroid hormone concentrations. IHH is practically divided into two major groups according to the olfactory function: normal sense of smell (normosmia) nIHH, and reduced sense of smell (hyposmia/anosmia) Kallmann syndrome (KS). Although mutations in more than 50 genes have been associated with IHH so far, only half of those cases were explained by gene mutations. Various combinations of deleterious variants in different genes as causes of IHH have been increasingly recognized (Oligogenic etiology). In addition to the complexity of inheritance patterns, the spontaneous or sex steroid-induced clinical recovery from IHH, which is seen in approximately 10–20% of cases, blurs further the phenotype/genotype relationship in IHH, and poses challenging steps in new IHH gene discovery. Beyond helping for clinical diagnostics, identification of the genetic mutations in the pathophysiology of IHH is hoped to shed light on the central governance of the hypothalamo-pituitary-gonadal axis through life stages. This review aims to summarize the genetic etiology of IHH and discuss the clinical and physiological ramifications of the gene mutations.

The Sense of Smell in Logopaedic Theory and Practice

Olfactory disorders concern many diseases of laryngological, neurological, oncological and gerontological origins, and sometimes are one of the diagnostic symptoms of a serious illness. The aim of this article is to describe the sense of smell (anatomy, physiology, functions, etiology and characteristics of disorders) and, in particular, to present this sense in the context of logopedic theory and practice. Speech therapists may inter alia assess the functioning of the sense of smell on the basis of an interview with the patient or caregiver, make a general evaluation of the functioning of the sense of smell, using different olfactory samples. As part of speech therapy, speech therapists may include stimulation of the sense of smell through various exercises, e.g. odour differentiation exercises, exercises in guessing and naming different odours, exercises in differentiating odour intensity, exercises in searching the source of smell.

The Complexity of Olfactory Art The Use of Scent as Concept and Context in the Work of Art

The sense of smell is a powerful sense that offers many possibilities. To speak of olfactory art, there must be the intention to use odour or olfaction as both context and concept of the work of art. For this, we speak about the terms Olfactory Context and Olfactory Concept. The Olfactory Context can be divided into the Intrinsic and Intentional Odour Values. The intrinsic odour value brings with it their significance, while the intentional odour value gives an extra meaning to a smell. In addition, the Olfactory Perception is part of the Olfactory Concept of the artwork. To perceive this, the smell must be transferred to the spectator. The way in which an odour is transferred in a work largely determines how the smell is interpreted in relation to the work. The odour transfer and odour situation determine how an odour gets to the viewer. We call these methods of odour transfer Olfactory Transfers and divide them into five categories: Flowers, Smell Devices, Scent Spaces, Time and Translations. In most cases, Olfactory Transfers are used in crossovers. Together with the various possibilities of using the Olfactory Context, they also demonstrate the Complexity of Olfactory Art. The 1st Olfactory Art Manifest explains the differences in olfactory art, while the 2nd Olfactory Art Manifest demonstrates the Complexity of Olfactory Art.

“Smell improvement by anti-IgE and anti-IL 5 biologics in patients with CRSwNP and severe asthma– A real life study”

Background. Chronic rhinosinusitis with nasal polyps (CRSwNP), characterized by partial (hyposmia) or total (anosmia) loss of smell, is commonly associated with asthma and/or nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD), worsens disease severity and quality of life. The objective of this study was to determine whether, in real-life conditions, biological treatments prescribed for severe asthma can improve olfaction in patients with CRSwNP. A further objective was to compare smell improvement in N-ERD and non-N-ERD subgroups. Methods. A multicenter, non-interventional, retrospective, observational study was performed, including 206 patients with severe asthma undergoing biological treatment (omalizumab, mepolizumab, benralizumab, or reslizumab) with CRSwNP. Results. Improved olfaction was found after treatment with all monoclonal antibodies: omalizumab (35.8%), mepolizumab (35.4%), reslizumab (35.7%), and benralizumab (39.1%), with no differences between groups. Patients with atopy, greater use of short course systemic corticosteroids, and larger polyp size were more likely to experience improvement in smell. The proportion of patients experiencing smell improvement was similar between the N-ERD (37%) and non-N-ERD (35.7%) groups. Conclusions. This is the first study to compare real-life improvement in sense of smell among patients undergoing long-term treatment with omalizumab, mepolizumab, reslizumab, or benralizumab for severe asthma and associated CRSwNP. Approximately 4 out of 10 patients reported a subjective improvement in sense of smell (with non-significant differences between biologic drugs). No differences were found in smell improvement between the N-ERD and non-N-ERD group.

An Update on Smell and Sensuality

When thinking of smell, we usually consider it only as one of the five senses. Compared to the rest of senses, smell has been underestimated. By conducting a research, we will be able to discover how mistaken we are. The human sense of smell is more powerful than it's usually given credit for and plays a major role in human health and behavior than many experts in the field are aware of the sense of smell is present in our daily activities and, depending on the gender, perception may differ, as well as from the anatomical structure of the olfactory organ between genders to the stimulus of the odor. The fragrances determine our everyday food choices, places where we choose to spend with our life partner. Scents can determine our sexual behavior, in building infant-parent connection and create our habits as well. It can also warn us against the selection of food, persons, also death. In this case, the loss of smell can be related with an olfactory organ dysfunction, but as well can have an endocrine, genetic or psychical basis. The olfactory dysfunction can change our habits and basically our whole life. It is irrefutable that while talking about smell which we consider as one of the senses, we can talk about sensuality which broadly covers the relationship between smell and perception of reality. Sensuality in a general sense can be defined as the perception of the surrounding things through the senses, as sensory pleasure, and unlike sexuality, which can be translated as the reception of biological, psychological and physical stimuli. Aim of the study: Currently all of our senses are mostly well known. We are trying to consider the topic from many different sides to make ourselves more and more advanced. We are trying to unite a couple of subjects to prove that we can connect one with another to explore how advanced our organism is. In this research we are trying to look closely at the two different topics and glue them together. Trying to improve and update the connection between the sense of smell and sensuality. This is possible due to the relationship between the smell and the part of our brain responsible for memories and memory, i.e. the limbic system. In this way, we can process the aroma stimulus into memories, we associate smells with specific situations, places, people or things [1]. Therefore, the objectives we have in this study are the following: The nose as an olfactory organ and the anatomical differences as to structure; the olfactory system is strictly connected with the sense of smell; sex, as a gender, something that make us different from each other; physical and psychological disorders and influence of smell. Taking into consideration the amount of work and research on the sense of smell and the still uncertain issues related to it, it is certain how important it is for life and science to fully understand its properties. Over time, with the development of science and technology, there is an increasing wish to learn about such a complicated machine as the human body. Material and methods: In the first part of this research, we will gather all the information that is commonly available so far in the international bibliography, as well as the achievements and utilities obtained to date. Following we will analyse all the new concepts that exist on the topic of sense of smell in connection with sex and sensuality, also how the smell can change due to various disorders and try to summarise it based on the latest research.

Olfaction in COPD

Background: Olfaction is poorly characterized in COPD. To test the hypothesis that olfaction is reduced in COPD, we assessed olfaction with the “Sniffin’ Sticks” test and a questionnaire addressing olfaction in COPD and a corresponding control group in respect to age and sex. We also explored whether there is an association between COPD, chronic rhinosinusitis without nasal polyps (CRSsNP), and other predefined covariates with olfactory function. Methodology: Olfactory function was assessed by the score for threshold (T), discrimination (D) and identification (I), and the composite TDI score in the “Sniffin’ Sticks” test and by self-reported evaluation of impaired olfaction and of “decreased sense of smell and taste” in the 22-item Sino-Nasal Outcome Test (SNOT-22) in 90 COPD patients and 93 controls. A clinical interview and ENT-examination with nasal endoscopy, skin prick test and spirometry with reversibility were performed. Results: The TDI, D and I scores were significantly lower in the COPD group than in the control group. The T score was not significantly different between the two groups. Hyposmia and anosmia were present in up to 79% of patients with COPD. The prevalence of self-reported impaired olfactory function and for 'decreased sense of smell and taste'; - was more than two-fold greater in the COPD than in the control group. COPD, higher age, male sex and allergy were associated with a lower TDI score, while CRSsNP was not associated with the TDI score. Conclusions: COPD is associated with olfactory dysfunction and the underlying mechanisms for this dysfunction should be elucidated.