Nature and human well-being: The olfactory pathway.

The world is undergoing massive atmospheric and ecological change, driving unprecedented challenges to human well-being. Olfaction is a key sensory system through which these impacts occur. The sense of smell influences quality of and satisfaction with life, emotion, emotion regulation, cognitive function, social interactions, dietary choices, stress, and depressive symptoms.

Alzheimer and Parkinson diseases, frontotemporal lobar degeneration and amyotrophic lateral sclerosis overlapping neuropathology start in the first two decades of life in pollution exposed urbanites and brain ultrafine particulate matter and industrial nanoparticles, including Fe, Ti, Al, V, Ni, Hg, Co, Cu, Zn, Ag, Pt, Ce, La, Pr and W are key players. Metropolitan Mexico City health crisis is in progress.

The neuropathological hallmarks of Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal lobar degeneration (FTLD), and amyotrophic lateral sclerosis (ALS) are present in urban children exposed to fine particulate matter (PM), combustion and friction ultrafine PM (UFPM), and industrial nanoparticles (NPs). Metropolitan Mexico City (MMC) forensic autopsies strongly suggest that anthropogenic UFPM and industrial NPs reach the brain through the nasal/olfactory, lung, gastrointestinal tract, skin, and placental barriers. Diesel-heavy unregulated vehicles are a key UFPM source for 21.

Inhalation-modulated detection of olfactory BOLD responses in the human brain.

Introduction: In contrast to other sensory domains, detection of primary olfactory processes using functional magnetic resonance imaging has proven to be notably challenging with conventional block designs. This difficulty arises from significant habituation and hemodynamic responses in olfactory areas that do not appear to align with extended boxcar functions convolved with a generic hemodynamic response model. Consequently, some researchers have advocated for a transition to event-related designs, despite their known lower detection power compared to block designs.

Reduced neural responses to pleasant odor stimuli after acute psychological stress is associated with cortisol reactivity.

Acute stress alters olfactory perception. However, little is known about the neural processing of olfactory stimuli after acute stress exposure and the role of cortisol in such an effect. Here, we used an event-related olfactory fMRI paradigm to investigate brain responses to odors of different valence (unpleasant, pleasant, or neutral) in healthy young adults following an acute stress (Trier Social Stress Test, TSST) induction (N = 22) or a non-stressful resting condition (N = 22).

Mood Impairment in Patients with Olfactory Loss Predicts a More Pronounced Recovery of Olfactory Function.

Background: Here, we refer to our publication "Symptoms of depression change with olfactory function" [Sci Rep. 2022 Apr 5;12(1):5656].

Objectives: Depression decreases with olfactory improvement, but the question remains open of whether patients who indicate more suffering regarding mood impairment exhibit a different pattern of recovery from olfactory loss compared to those who suffer less.

Past, Present, and Future of Human Chemical Communication Research.

Although chemical signaling is an essential mode of communication in most vertebrates, it has long been viewed as having negligible effects in humans. However, a growing body of evidence shows that the sense of smell affects human behavior in social contexts ranging from affiliation and parenting to disease avoidance and social threat. This article aims to (a) introduce research on human chemical communication in the historical context of the behavioral sciences; (b) provide a balanced overview of recent advances that describe individual differences in the emission of semiochemicals and the neural mechanisms underpinning their perception, that together demonstrate communicative function; and (c) propose directions for future research toward unraveling the molecular principles involved and understanding the variability in the generation, transmission, and reception of chemical signals in increasingly ecologically valid conditions.

Increased sensitivity to unpleasant odor following acute psychological stress.

Previous studies have reported increased sensitivity to malodor after acute stress in humans. However, it is unclear whether stress-related "hypersensitivity" to odors depends on odor pleasantness. Forty participants (mean age 19.

Olfactory Dysfunction: Etiology, Diagnosis, and Treatment.

Background: Disorders of the sense of smell have received greater attention because of the frequency with which they occur as a symptom of SARS-CoV-2 infection. Olfactory dysfunction can lead to profound reduction in quality of life and may arise from many different causes.

Methods: A selective literature review was conducted with consideration of the current version of the guideline issued by the Association of the Scientific Medical Societies in Germany.

Assortative mate preferences for height across short-term and long-term relationship contexts in a cross-cultural sample.

Height preferences reflecting positive assortative mating for height-wherein an individual's own height positively predicts the preferred height of their mate-have been observed in several distinct human populations and are thought to increase reproductive fitness. However, the extent to which assortative preferences for height differ strategically for short-term versus long-term relationship partners, as they do for numerous other indices of mate quality, remains unclear. We explore this possibility in a large representative sample of over 500 men and women aged 15-77 from Canada, Cuba, Norway and the United States.

Taste perception in children with different caries activity.

Purpose: The aim of the study was to investigate whether caries-active and caries-free children differ in terms of their taste perception for sweet, sour, salty and bitter.

Methods: The study group consisted of 100 children aged 5-10 years: 50 caries-free children and 50 children with at least four untreated carious lesions. Taste perception was analysed using two test systems.

Reply to Semin et al. Can Humans Discriminate Horse 'Fear' Chemosignals from Control Chemosignals? Comment on "Sabiniewicz et al. A Preliminary Investigation of Interspecific Chemosensory Communication of Emotions: Can Humans () Recognise Fear- and Non-Fear Body Odour from Horses (). 2021, , 3499".

Whereas several recent studies demonstrated that some animal species are able to recognize human emotions based on information from body odor [...

Human odor exploration behavior is influenced by olfactory function and interest in the sense of smell.

Olfaction plays an important role in social interaction. This study examined the influence of chemosensory and cognitive abilities on conscious odor sniffing behaviors in humans. Participants (N = 349) were surveyed using a questionnaire for the frequency of behaviors in terms of odor exploration from intrinsic and external sources.

Regional brain morphology of the primary somatosensory cortex correlates with spicy food consumption and capsaicin sensitivity.

Habitual spicy food consumption leads to altered perception of capsaicin. Little is known about the neural morphological correlates of habitual spicy food intake and related trigeminal perceptions. In this study, we used voxel-based morphometry to identify brain regions where regional gray matter volume (GMV) correlates to spicy food consumption.

A Preliminary Investigation of Interspecific Chemosensory Communication of Emotions: Can Humans () Recognise Fear- and Non-Fear Body Odour from Horses ().

Mammalian body odour conveys cues about an individual's emotional state that can be recognised by conspecifics. Thus far, little attention has been paid to interspecific odour communication of emotions, and no studies have examined whether humans are able to recognise animal emotions from body odour. Thus, the aim of the present study was to address this question.

Lipidomic profile of human nasal mucosa and associations with circulating fatty acids and olfactory deficiency.

The nasal mucosa (NM) contains olfactory mucosa which contributes to the detection of odorant molecules and the transmission of olfactory information to the brain. To date, the lipid composition of the human NM has not been adequately characterized. Using gas chromatography, liquid chromatography coupled to mass spectrometry and thin layer chromatography, we analyzed the fatty acids and the phospholipid and ceramide molecular species in adult human nasal and blood biopsies.

Improved Odor Identification Ability and Increased Regional Gray Matter Volume After Olfactory Training in Patients With Idiopathic Olfactory Loss.

Idiopathic olfactory loss (IOL) is thought as an early marker for neurodegenerative disease. This study investigated the effect of olfactory training (OT) on regional gray matter volume (GMV) among patients with IOL. A total of 24 patients (mean age 64.

Validation of Olfactory Network Based on Brain Structural Connectivity and Its Association With Olfactory Test Scores.

Olfactory perception is a complicated process involving multiple cortical and subcortical regions, of which the underlying brain dynamics are still not adequately mapped. Even in the definition of the olfactory primary cortex, there is a large degree of variation in parcellation templates used for investigating olfaction in neuroimaging studies. This complicates comparison between human olfactory neuroimaging studies.

Increased Brain Reward Responsivity to Food-Related Odors in Obesity.

Objective: Food odors serve as powerful stimuli signaling the food quality and energy density and direct food-specific appetite and consumption. This study explored obesity-related brain activation in response to odors related to high- or low-energy-dense foods.

Methods: Seventeen participants with obesity (BMI > 30 kg/m ; 4 males and 13 females) and twenty-one with normal weight (BMI < 25 kg/m ; 9 males and 12 females) underwent a functional magnetic resonance imaging scan in which they received chocolate (high-energy-dense food) and cucumber (low-energy-dense food) odor stimuli.

Naphthalene: irritative and inflammatory effects on the airways.

Objective: This cross-sectional study determined whether acute sensory irritative or (sub)chronic inflammatory effects of the eyes, nose or respiratory tract are observed in employees who are exposed to naphthalene at the workplace.

Methods: Thirtynine healthy and non-smoking male employees with either moderate (n = 22) or high (n = 17) exposure to naphthalene were compared to 22 male employees from the same plants with no or only rare exposure to naphthalene. (Sub)clinical endpoint measures included nasal endoscopy, smell sensitivity, self-reported work-related complaints and the intensity of naphthalene odor and irritation.

Brain response to odors presented inside the nose, directly in front of the nose or with ambient air.

Objective: Functional magnetic resonance imaging (fMRI) allows the measurement of changes in blood flow in association with changes in brain activity. This technique has been used frequently to study brain activation in response to odorous stimuli. The aim of this study was to evaluate the effects of odor delivery conditions on brain responses obtained with fMRI.

Apparently Minor Head Trauma Can Lead to Anosmia: A Case Report.

We report the case of a 49-year-old female patient who suffered from anosmia following an apparently mild head trauma when bumping into a door at her home. She reported no other accompanying symptoms after the injury that day. Olfactory function was completely lost, which was noted the day after the trauma.

Greater hippocampal gray matter volume in subjective hyperosmia: a voxel-based morphometry study.

Subjective hyperosmia refers to a self-reported olfactory ability that is superior to a normal, intact sense of smell (normosmia), and is associated with olfactory emotional experience. The current study used voxel-based morphometry to investigate the gray matter volume (GMV) in people with self-rated hyperosmia (subjective hyperosmia, SH, N = 18) in comparison to people with self-rated normal olfaction (subjective normosmia, SN, N = 14). Participants' olfactory function were assessed by the extensive olfactory test battery, the "Sniffin' Sticks" test.

Brain Responses to Food Odors Associated With BMI Change at 2-Year Follow-Up.

The understanding of food cue associated neural activations that predict future weight variability may guide the design of effective prevention programs and treatments for overeating and obesity. The current study investigated the association between brain response to different food odors with varied energy density and individual changes of body mass index (BMI) over 2 years. Twenty-five participants received high-fat (chocolate and peanut), low-fat (bread and peach) food odors, and a nonfood odor (rose) while the brain activation was measured using functional magnetic resonance imaging (fMRI).

The Aetiology of Olfactory Dysfunction and Its Relationship to Diet Quality.

People with olfactory loss may choose foods rich in sugar, salt and fat to compensate their loss-foods that constitute a Western-style diet (WSD). However, olfactory dysfunction has not been consistently linked to any particular type of dietary change. Here we considered whether the aetiology of olfactory dysfunction may affect consumption of a WSD.