Odor Preference Research Articles

Four Neurotoxic Insecticides Impair Partner and Host Finding in the Parasitoid Leptopilina heterotoma and Bioactive Doses Can Be Taken up Via the Host

In modern agriculture, control of insect pests is achieved by using insecticides that can also have lethal and sublethal effects on beneficial non-target organisms. Here, we investigate acute toxicity and sublethal effects of four insecticides on the males’ sex pheromone response and the female host finding ability of the Drosophila parasitoid Leptopilina heterotoma. The nicotinic acetylcholine receptor antagonists acetamiprid, flupyradifurone and sulfoxaflor, as well as the acetylcholinesterase inhibitor dimethoate were applied topically as acetone solutions. Males treated with all four insecticides no longer preferred the female sex pheromone in a T-olfactometer. Duration of wing fanning, an element of the pheromone-mediated male courtship behavior, was also reduced by all four insecticides. The ability of females to orientate towards host-infested feeding substrate was not affected by acetamiprid in the tested dose range. However, treatment with dimethoate, flupyradifurone and sulfoxaflor resulted in the loss of the females’ preference for host odor. At the lowest doses interfering with olfactory abilities of L. heterotoma in this study (acetamiprid: 0.21 ng, dimethoate: 0.105 ng, flupyradifurone: 2.1 ng and sulfoxaflor: 0.21 ng), ≥ 90% of the wasps survive insecticide treatment. Male pheromone responses and female host finding were also disturbed in those L. heterotoma that had developed in D. melanogaster larvae reared on dimethoate-treated feeding medium at sublethal levels. Hence, doses of this insecticide sufficient to interfere with chemical orientation of L. heterotoma can be taken up by the parasitoid via the food chain.

Characterizing olfactory brain responses in young infants.

Odor perception plays a critical role in early human development, but the underlying neural mechanisms are not fully understood. To investigate these, we presented appetitive and aversive odors to infants of both sexes at one month of age while recording functional magnetic resonance imaging (fMRI) and nasal airflow data. Infants slept during odor presentation to allow MRI scanning. We found that odors evoke robust fMRI activity in bilateral olfactory cortex and thalamus, and that fMRI response magnitudes in olfactory cortex differ across odors. However, in contrast with prior work in adults, we did not find compelling evidence that odor stimuli evoke discriminable fMRI activity patterns in olfactory cortex or thalamus using two different multivariate pattern analysis techniques. Finally, the average inhale airflow rate was higher for appetitive odors than aversive odors, which tentatively suggests that infants could modulate their respiration to reflect odor valence. Overall, these results show strong neural responses to odors at this early developmental stage, and highlight nasal airflow as a behavioral metric for assessing odor preference in infants.Significance statement The sense of smell facilitates several adaptive behaviors in infants (e.g., feeding, soothing), but the brain areas supporting infant olfaction are understudied. Here, we delivered appetitive and aversive odors to sleeping infants during functional magnetic resonance imaging. We show that odors evoke activity in olfactory brain regions and thalamus already at one month of age, and activity levels vary across odors in some of these regions (e.g., piriform cortex, amygdala). However, we did not find strong evidence for pattern-based odor information in the same brain areas. Finally, preliminary nasal airflow findings suggest that infants inhale more vigorously in response to appetitive compared to aversive odors. Taken together, these findings advance our understanding of the neural mechanisms of infant olfaction.

The effects of social loss and isolation on partner odor investigation and dopamine and oxytocin receptor expression in female prairie voles.

In humans, grief is characterized by intense sadness, intrusive thoughts of the deceased, and intense longing for reunion with the deceased. Human fMRI studies show hyperactivity in emotional pain and motivational centers of the brain when an individual is reminded of a deceased attachment figure, but the molecular underpinnings of these changes in activity are unknown. Prairie voles (Microtus ochrogaster), which establish lifelong social bonds between breeding pairs, also display distress and motivational shifts during periods of prolonged social loss, providing a model to investigate these behavioral and molecular changes at a mechanistic level. Here, a novel odor preference test was used to assess social vs non-social odor investigation, and a sucrose preference test was used to assess non-social, reward-driven motivation. Females that lost a male partner investigated partner- and food-associated cues significantly more than females that lost a female cagemate or remained intact with a male partner. However, females experiencing the loss of a male partner did not change investigation of stranger-associated cues. Western blotting revealed significant increases of dopamine receptor type 1 (DRD1) and oxytocin receptor protein content in specific brain regions in response to the loss of distinct social relationships. Such effects included an increase in DRD1 in the medial preoptic area of the hypothalamus (mPOA) in females experiencing loss of a male partner compared to all other conditions. Pharmacological antagonism of DRD1 in the mPOA blocked the loss-associated increase of investigation of the partner odor but did not affect investigation of food or stranger odors. This reveals a novel dopamine-mediated mechanism for partner-seeking behavior during periods of partner loss in female prairie voles.

Valproate Administration to Adult 5xFAD Mice Upregulates Expression of Neprilysin and Improves Olfaction and Memory.

It is well known that the development of neurodegeneration, and especially Alzheimer's disease (AD), is often accompanied by impaired olfaction which precedes memory loss. A neuropeptidase neprilysin (NEP)-a principal amyloid-degrading enzyme in the brain-was also shown to be involved in olfactory signalling. Previously we have demonstrated that 5xFAD mice develop olfactory deficit by the age of 6months which correlated with reduced NEP expression in the brain areas involved in olfactory signalling. The aim of this study was to analyse the effect of administration of a histone deacetylase inhibitor, valproic acid (VA), to adult 5xFAD mice on their olfaction and memory as well as on brain morphology and NEP expression in the parietal cortex (PC) and hippocampus (Hip). The data obtained demonstrated that administration of VA to 7-month-old mice (200mg/kg of body weight) for 28days resulted in improvement of their memory in the Morris water maze as well as olfaction in the odor preference and food search tests. This correlated with increased expression of NEP in the PC and Hip as well as a reduced number of amyloid plaques in these brain areas. This strongly suggests that NEP can be considered an important therapeutic target not only in AD but also in olfactory loss.

Evaluation of Social Odor Preference and Social Communication with the Same- and Opposite-Sex Conspecifics in Male Mice

Evaluation of Social Odor Preference and Social Communication with the Same- and Opposite-Sex Conspecifics in Male Mice

Exploring the dynamic adult hard ticks-camel-pathogens interaction.

Ticks are obligatory hematophagous arachnids, serving as vectors for a wide array of pathogens that can be transmitted to animals and humans. The ability of ticks to acquire and transmit various pathogens depends on their attraction to quality reservoir hosts and the survival of the pathogens in ticks' gut and other tissues. However, the complex dynamics of tick-pathogen interaction and host-seeking behavior remain understudied. This investigation revealed notable variation in tick preference for domestic animals, with camel being the most preferred host. Moreover, our spatial analysis of tick attachment sites showed nostrils are the most preferred sites by various tick species. Our epidemiology data showed variation in the pathogens harbored by camel (host) and vector (Hyalomma rufipes), demonstrating the camel's efficiency as reservoir host and ticks' vector competence for various pathogens. With our behavioral experiment using H. rufipes and its preferred host's (camel) breath and body signature odors, we identified novel attractants for H. rufipes, thus offering new avenues for combating tick-borne diseases. Overall, our study presents novel insights into how multiple factors shape tick-host-pathogen interaction.

Differences in odor preferences of glass eels of two sympatric anguillid eels, the Japanese eel Anguilla japonica and the Indo-Pacificeel A. marmorata.

Water-choice experiments were conducted using glass eels of Anguilla japonica and A. marmorata, which coexist in subtropical East Asian rivers. The results of the present study, together with those of previous water-choice experiments, suggest that salinity enhances the odor preferences of glass eels. Compared to A. marmorata glass eels, A. japonica glass eels were more strongly attracted to water collected from a leaf detritus-accumulating backwater area than to normal river water under the same salinity conditions. These results suggest that interspecific differences in odor preferences may facilitate their habitat segregation.

A Case Study on the Odor Preferences and Influencing Factors in Chinese Residential Environments

Research on odor preference is needed to improve indoor environment quality. There-fore, to create a better odor environment in the living space, it is necessary to determine the common characteristics of odor preferences in the living environment for individuals with a similar cultural background. In this study, representative odors that are found in Chinese living spaces were selected and the odor preferences and individual traits were examined using online surveys. A total of 1236 valid responses were collected and the factors affecting odor preferences were assessed, including social, geographic, and behavioral attributes, using correlation and descriptive analysis. The results revealed that gender, age, occupation, income, mode, and frequency were correlated with odor preference characteristics in the living environment and were the primary factors for the odor preference characteristics. Further analysis revealed that the odor preferences across the gender, age, income, and frequency groups were consistent with the trend for the overall characteristics. The results of the study showed that there were significant differences in odor preferences in the living environment across occupations and living patterns. Different occupational groups showed different characteristics in odor preferences, while the complexity of living patterns and the frequency of odor exposure also had a significant impact on odor preferences. These research findings will enable us to develop customized fragrance solutions based on specific olfactory preferences related to gender, age, occupation, income level, and lifestyle. Integrating the study conclusions into the spatial layout, selection of decorative materials, and ventilation design of residential spaces has practical significance for creating living environments that better meet the needs of residents.

Taste enhances the ability to express a preference for a congruent odor in rats.

Foods that make up a typical diet are characterized by a rich set of sensory qualities that are perceived through multiple different modalities. It is well known that multisensory aspects of food are integrated to create our perception of flavor, which in turn affects our behavioral responses to food. However, the principles underlying multisensory integration of flavor-related sensory signals and how they inform perceptual judgments remain poorly understood, partly due to lack of control over flavor experience in human subjects. Here, we used rats as a model to overcome this limitation and tested the hypothesis that taste can enhance discriminability of retronasal odor cues. In a series of two-bottle tests, animals chose between two odorized solutions after learning to associate one of the odors with saccharin. When odors were highly similar, animals showed little preference for the saccharin-associated odor. When adding saccharin to both bottles-rendering one of the solutions' congruent-animals' preference for the saccharin-associated odor was significantly enhanced. No effect of taste was observed when using dissimilar odor pairs or novel taste stimuli. These findings suggest that congruent taste stimuli selectively enhance odor identity representations, aiding in the discriminability of perceptually similar flavors. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

A GnRH neuronal population in the olfactory bulb translates socially relevant odors into reproductive behavior in male mice.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons regulate fertility and integrate hormonal status with environmental cues to ensure reproductive success. Here we show that GnRH neurons in the olfactory bulb (GnRHOB) of adult mice can mediate social recognition. Specifically, we show that GnRHOB neurons extend neurites into the vomeronasal organ and olfactory epithelium and project to the median eminence. GnRHOB neurons in males express vomeronasal and olfactory receptors, are activated by female odors and mediate gonadotropin release in response to female urine. Male preference for female odors required the presence and activation of GnRHOB neurons, was impaired after genetic inhibition or ablation of these cells and relied on GnRH signaling in the posterodorsal medial amygdala. GnRH receptor expression in amygdala kisspeptin neurons appear to be required for GnRHOB neurons' actions on male mounting behavior. Taken together, these results establish GnRHOB neurons as regulating fertility, sex recognition and mating in male mice.

Effect of dietary phospholipid on the behavior in C57BL/6J mice

Nowadays phospholipids are widely used as hepatoprotective, neuroprotective and anti-stress drugs, as well as the dietary supplements. Besides, lecithin consisting up to 70% of the phospholipids mixture: phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidic acid, is the often component of food production as an emulsifier. Dose of these biologically active substances in the modern human diet could be quite high. Previously we have shown that chronic intestinal inflammation in Muc2-knockout mice induces behavioral changes along with the significant increase in the content of phospholipids in intestinal epithelial cells, particularly, phosphatidylcholine, phosphatidylserine and phosphatidic acid. Here we investigate the effects of long-term administration of a mixture of these phospholipids, as well as the effects of long-term administration of soy lecithin on the behavioral patterns in laboratory mice. Animals long-term taken a phospholipid mixture shows no normally observed preference towards females in the two intruders test (with female and male). In the social odor preference test, they also did not distinguish female and male odors, while non-social odors discrimination preserved. In addition, we identified a decrease in anxiety, obsessive traits, and schizophrenia-like behavior traits in these animals. Soy lecithin supplementation had similar effects on social behavior and compulsive traits, and increased aggression in males. Thus, long-term perinatal administration of either mixture of phospholipids (phosphatidylcholine, phosphatidylserine and phosphatidic acid) or soy lecithin can influence various aspects of behavior in mice.

Nutrient Composition, Physical Characteristics and Sensory Quality of Spinach-Enriched Wheat Bread.

Food innovation that utilises agricultural waste while enhancing nutritional value is important for waste valorisation and consumer health. This study investigated incorporating spinach (Spinacia oleracea), as a model leafy agricultural waste, into wheat bread. We analysed the nutrient content, colour, texture, sensory attributes and purchase/consume intention ratings. Adding 10-40% spinach (w/w) yielded loaves with similar heights but significantly different colour and texture (p < 0.05) from white bread. Increasing spinach decreased total carbohydrates (including starch) while significantly increasing other nutrients (protein, fibre, iron, magnesium, potassium, zinc, calcium, vitamins A, C, E, folate, niacin, pyridoxine, nitrate/nitrite and polyphenols) (p < 0.05). Spinach addition increased bread porosity, linked to higher pasting parameters (peak, trough, breakdown, final and setback viscosity) with reduced pasting time and temperature. Texture analysis resulted in decreased hardness, chewiness, gumminess and firmness while increasing cohesiveness, with maximum resilience at 20% spinach enrichment. Sensory analysis with 21 untrained panellists revealed decreased visual appeal, less preferred taste, odour and overall liking (p < 0.05) with increasing spinach, with no significant difference in texture acceptance, but the 20% enrichment had comparable acceptance to white bread. Enriching staple foods like bread with leafy vegetable waste offers a promising approach for increasing daily vegetable intake.

The evolution of olfactory sensitivity, preferences, and behavioral responses in Mexican cavefish is influenced by fish personality.

Animals are adapted to their natural habitats and lifestyles. Their brains perceive the external world via their sensory systems, compute information together with that of internal states and autonomous activity, and generate appropriate behavioral outputs. However, how do these processes evolve across evolution? Here, focusing on the sense of olfaction, we have studied the evolution in olfactory sensitivity, preferences, and behavioral responses to six different food-related amino acid odors in the two eco-morphs of the fish Astyanax mexicanus. To this end, we have developed a high-throughput behavioral setup and pipeline of quantitative and qualitative behavior analysis, and we have tested 489 six-week-old Astyanax larvae. The blind, dark-adapted morphs of the species showed markedly distinct basal swimming patterns and behavioral responses to odors, higher olfactory sensitivity, and a strong preference for alanine, as compared to their river-dwelling eyed conspecifics. In addition, we discovered that fish have an individual 'swimming personality', and that this personality influences their capability to respond efficiently to odors and find the source. Importantly, the personality traits that favored significant responses to odors were different in surface fish and cavefish. Moreover, the responses displayed by second-generation cave × surface F2 hybrids suggested that olfactory-driven behavior and olfactory sensitivity is a quantitative genetic trait. Our findings show that olfactory processing has rapidly evolved in cavefish at several levels: detection threshold, odor preference, and foraging behavior strategy. Cavefish is therefore an outstanding model to understand the genetic, molecular, and neurophysiological basis of sensory specialization in response to environmental change.

The evolution of olfactory sensitivity, preferences, and behavioral responses in Mexican cavefish is influenced by fish personality

Animals are adapted to their natural habitats and lifestyles. Their brains perceive the external world via their sensory systems, compute information together with that of internal states and autonomous activity, and generate appropriate behavioral outputs. However, how do these processes evolve across evolution? Here, focusing on the sense of olfaction, we have studied the evolution in olfactory sensitivity, preferences, and behavioral responses to six different food-related amino acid odors in the two eco-morphs of the fish Astyanax mexicanus. To this end, we have developed a high-throughput behavioral setup and pipeline of quantitative and qualitative behavior analysis, and we have tested 489 six-week-old Astyanax larvae. The blind, dark-adapted morphs of the species showed markedly distinct basal swimming patterns and behavioral responses to odors, higher olfactory sensitivity, and a strong preference for alanine, as compared to their river-dwelling eyed conspecifics. In addition, we discovered that fish have an individual ‘swimming personality’, and that this personality influences their capability to respond efficiently to odors and find the source. Importantly, the personality traits that favored significant responses to odors were different in surface fish and cavefish. Moreover, the responses displayed by second-generation cave × surface F2 hybrids suggested that olfactory-driven behavior and olfactory sensitivity is a quantitative genetic trait. Our findings show that olfactory processing has rapidly evolved in cavefish at several levels: detection threshold, odor preference, and foraging behavior strategy. Cavefish is therefore an outstanding model to understand the genetic, molecular, and neurophysiological basis of sensory specialization in response to environmental change.

Investigation of the preference of marlin Kajikia audax sashimi with different lipid contents through sensory evaluation

Identifying the sensory properties of fish consumers is important for providing their preferred seafood. Odor, flavor, texture, and appearance affected the sensory preference for fish. Moreover, several compounds are involved in sensory preference. This study focused on lipids that affect preference for seafood and examined the lipid content preference in marlin Kajikia audax sashimi. First, lipid contents and fatty acid compositions of different individual sizes and body parts of marlin were compared. Next, the preference for overall, taste, texture, odor, aftertaste, and lipid content in marlin sashimi taken from different parts of the body with different amounts of lipids was investigated using the paired preference method. Then the relationship of lipid content preference with other preferences were also evaluated using the Chi-square test. The crude lipid of big-sized marlin (51.1–55.1 kg) was 9.5%−13.2%, and the crude lipid of small-sized marlin (23.5–30.0 kg) was 0.8%−1.2%. The dorsal parts of big-sized marlin had lipid contents in the anterior parts higher than those in the posterior parts (p &amp;lt; 0.05). Whereas no differences were observed in the fatty acid composition of different body parts. The lipid content preference for the anterior dorsal part (high lipid part) was higher than that for the posterior dorsal part (lower lipid part) (p &amp;lt; 0.05). However, no difference in overall preference was observed. Additionally, the relationship between lipid content preference and other preference were indicated that the high lipid content parts preferred group significantly preferred the high lipid content parts at overall and taste evaluation (p &amp;lt; 0.01). On the other hand, the low lipid content parts preferred groups showed opposite evaluation. Therefore, the lipid content was associated with the preference for marlin sashimi and be classified into two groups: one prefers high lipid sashimi and the other prefers low lipid sashimi.

Is the perception of odour pleasantness shared across cultures and ecological conditions? Evidence from Amazonia, East Africa, New Guinea, Malaysia and Poland.

What makes an odour pleasant or unpleasant? The inherent properties of the constituent chemical compounds, or the nose of the beholder, driven by idiosyncratic differences and culture-specific learning? Here, 582 individuals, including Tanzanian Hadza hunter-gatherers, Amazonian Tsimane' horticulturalists, Yali from the Papuan highlands and two industrialized populations (Poles, Malaysians), rated the pleasantness of 15 odour samples. We find considerable similarities in odour assessments across cultures, but our data do not fully support a claim regarding the universality of smell preferences. Despite cross-cultural similarities in olfactory assessments, probably driven by odour properties, we suggest that odour availability in ecological and cultural niches bears an undeniable effect on human odour preferences.

A mixture design approach to develop new starter formulation for Lben: Key aroma compounds, physical, chemical and sensory properties of the product

The study investigated the evolution of the physicochemical and sensory properties of Lben fermented milk inoculated with different starter formulations. The aim was to determine the optimal starter culture formula for Lben production using different combinations of four strains, including three strains of Lactococcus lactis subsp. lactis with strain codes A, E and F and one strain of Leuconostoc mesenteroides subsp. mesenteroides with strain code C. While individual strains had previously demonstrated significant technological and organoleptic properties their interaction in mixtures had not been explored. In the study, a response surface methodology (mixture design approach) was applied to evaluate the effects of the interactions between strains on the physicochemical, antioxidant, volatile, and sensory properties of Lben, a fermented milk. In addition, product optimization using ridge analysis was performed to determine the ideal strain mixture formulation based on the sensory properties of Lben. The optimization goal for odor, taste, consistency, and overall preference was set to maximize their values. A high desirability score of 0.832 was achieved with the following percentage distribution: 34.39% for L. lactis E, 42.38% for L. lactis A, 10% for L. lactis F, and 13.23% for Leuc. mesenteroides C.

Nocturnal exposure to a preferred ambient scent does not affect dream emotionality or post-sleep core affect valence in young adults

Emotions experienced within sleep mentation (dreaming) affect mental functioning in waking life. There have been attempts at enhancing dream emotions using olfactory stimulation. Odors readily acquire affective value, but to profoundly influence emotional processing, they should bear personal significance for the perceiver rather than be generally pleasant. The main objective of the present sleep laboratory study was to examine whether prolonged nocturnal exposure to self-selected, preferred ambient room odor while asleep influences emotional aspects of sleep mentation and valence of post-sleep core affect. We asked twenty healthy participants (12 males, mean age 25 ± 4 years) to pick a commercially available scented room diffuser cartridge that most readily evoked positively valenced mental associations. In weekly intervals, the participants attended three sessions. After the adaptation visit, they were administered the odor exposure and odorless control condition in a balanced order. Participants were awakened five minutes into the first rapid eye movement (REM) stage that took place after 2:30 a.m. and, if they had been dreaming, they were asked to rate their mental sleep experience for pleasantness, emotional charge, and magnitude of positive and negative emotions and also to evaluate their post-sleep core affect valence. With rs < 0.20, no practically or statistically significant differences existed between exposure and control in any outcome measures. We conclude that in young, healthy participants, the practical value of olfactory stimulation with self-selected preferred scents for enhancement of dream emotions and post-sleep core affect valence is very limited.

Haemolymph transfusions transfer heritable learned novel odour preferences to naive larvae of Bicyclus anynana butterflies.

The mechanisms whereby environmental experiences of parents are transmitted to their offspring to impact their behaviour and fitness are poorly understood. Previously, we showed that naive Bicyclus anynana butterfly larvae, whose parents fed on a normal plant feed but coated with a novel odour, inherited an acquired preference towards that odour, which had initially elicited avoidance in the naive parents. Here, we performed simple haemolymph transfusions from odour-fed and control-fed larvae to naive larval recipients. We found that larvae injected with haemolymph from odour-fed donors stopped avoiding the novel odour, and their naive offspring preferred the odour more, compared to the offspring of larvae injected with control haemolymph. These results indicate that factors in the haemolymph, potentially the odour molecule itself, play an important role in odour learning and preference transmission across generations. Furthermore, this mechanism of odour preference inheritance, mediated by the haemolymph, bypasses the peripheral odour-sensing mechanisms taking place in the antennae, mouthparts or legs, and may mediate food plant switching and diversification in Lepidoptera or more broadly across insects.

Low-dose aspirin increases olfactory sensitivity in association with enhanced neurogenesis and reduced activity of AChE in the experimental aging mice

This study examined the effect of aspirin on olfactory discrimination and neurogenesis in experimental aging mice. The results from the buried food test (BFT) and odour preference test (OPT) indicated that aspirin treatment enhanced the olfactory functions in the experimental animals. The immunohistochemical assessment revealed increased amounts of doublecortin (DCX)-positive immature neurons and bromodeoxyuridine (BrdU)/neuronal nuclei (NeuN) double-positive new neurons in the olfactory bulb (OB) of aspirin-treated animals compared to the control group. Besides, aspirin treatment resulted in a decreased number of ionized calcium-binding adaptor molecule (Iba)-1 positive microglia, a main cellular element of neuroinflammation in the brain compared to the control group. In addition, the increased activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in OB of the aspirin-treated mice were evident. Acetylcholinesterase (AChE) is a key enzyme that hydrolyses acetylcholine (ACh), an important neurotransmitter, involved in cognition, and olfaction. While the enhanced activity of AChE has been linked to the severity of dementia and OB defects, the biochemical assessments indicated reduced activity of AChE in OB-derived homogenates of the aspirin-treated experimental animals than that of the control group. Taken together, this study validates the proneurogenic, cholinergic, and anti-neuroinflammatory properties of aspirin in the OB which can be considered in boosting neural regeneration and management of olfactory deficits in aging and various disorders.