Olfaction

Skin-Integrated Wireless Odor Message Delivery Electronics for the Deaf-blind

Deaf-blindness limits daily human activities, especially interactive modes of audio and visual perception. Although the developed standards have been verified as alternative communication methods, they are uncommon to the nondisabled due to the complicated learning process and inefficiency in terms of communicating distance and throughput. Therefore, the development of communication techniques employing innate sensory abilities including olfaction related to the cerebral limbic system processing emotions, memories, and recognition has been suggested for reducing the training level and increasing communication efficiency. Here, a skin-integrated and wireless olfactory interface system exploiting arrays of miniaturized odor generators (OGs) based on melting/solidifying odorous wax to release smell is introduced for establishing an advanced communication system between deaf-blind and non-deaf-blind. By optimizing the structure design of the OGs, each OG device is as small as 0.24 cm3 (length × width × height of 11 mm × 10 mm × 2.2 mm), enabling integration of up to 8 OGs on the epidermis between nose and lip for direct and rapid olfactory drive with a weight of only 24.56 g. By generating single or mixed odors, different linked messages could be delivered to a user within a short period in a wireless and programmable way. By adopting the olfactory interface message delivery system, the recognition rates for the messages have been improved 1.5 times that of the touch-based method, while the response times were immensely decreased 4 times. Thus, the presented wearable olfactory interface system exhibits great potential as an alternative message delivery method for the deaf-blind.

A brief treatment for veterans with PTSD: an open-label case-series study

Introduction

Despite the positive outcomes observed in numerous individuals undergoing trauma-focused psychotherapy for PTSD, veterans with this condition experience notably diminished advantages from such therapeutic interventions in comparison to non-military populations.

Methods

In a preliminary study we investigated the efficacy of an innovative treatment approach in a small sample of veterans (n = 7). Recognizing that accessing and targeting trauma memory in veterans with PTSD may be more challenging compared to other patient populations, we employed unique and personalized retrieval cues that engaged multiple senses and were connected to the context of their trauma. This was followed by a session focused on memory reconsolidation, which incorporated both psychological techniques (i.e., imagery rescripting) and a pharmacological component (i.e., 40 mg of propranolol).

Results

The findings from this small-scale case series cautiously indicate that this brief intervention, typically consisting of only one or two treatment sessions, shows promise in producing significant effects on symptoms of PTSD, distress and quality of life.This is particularly noteworthy given the complex symptomatology experienced by the veterans in this study.

Conclusion

To summarize, there are grounds for optimism regarding this brief treatment of combat-related PTSD. It appears that the potential for positive outcomes is far greater than commonly believed, as demonstrated by the encouraging results of this pilot study.

Seed amplification assay of nasal swab extracts for accurate and non-invasive molecular diagnosis of neurodegenerative diseases

Nasal swabs are non-invasive testing methods for detecting diseases by collecting samples from the nasal cavity or nasopharynx. Dysosmia is regarded as an early sign of coronavirus disease 2019 (COVID-19), and nasal swabs are the gold standard for the detection. By nasal swabs, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acids can be cyclically amplified and detected using real-time reverse transcriptase-polymerase chain reaction after sampling. Similarly, olfactory dysfunction precedes the onset of typical clinical manifestations by several years in prion diseases and other neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. In neurodegenerative diseases, nasal swab tests are currently being explored using seed amplification assay (SAA) of pathogenic misfolded proteins, such as prion, α-synuclein, and tau. These misfolded proteins can serve as templates for the conformational change of other copies from the native form into the same misfolded form in a prion-like manner. SAA for misfolded prion-like proteins from nasal swab extracts has been developed, conceptually analogous to PCR, showing high sensitivity and specificity for molecular diagnosis of degenerative diseases even in the prodromal stage. Cyclic amplification assay of nasal swab extracts is an attractive and feasible method for accurate and non-invasive detection of trace amount of pathogenic substances for screening and diagnosis of neurodegenerative disease.

Examining the Influence of Chemosensation on Laryngeal Health and Disorders

Inhaled airborne stimuli are associated with laryngeal disorders affecting respiration. Clinically, several themes emerged from the literature that point to specific gaps in the understanding and management of these disorders. There is wide variation in the types of airborne stimuli that trigger symptoms, lack of standardization in provocation challenge testing using airborne stimuli, and vague reporting of laryngeal symptoms. Scientifically, evidence exists outside the field of voice science that could prove useful to implement among patients with impaired laryngeal-respiration. To expand this area of expertise, here we provide a thematic overview of relevant evidence and methodological tools from the discipline of chemosensory sciences. This review provides distinctions across the three chemosensory systems of olfaction, trigeminal chemesthesis, and gustation, guidance on selecting and delivering common chemosensory stimuli for clinical testing, and methods of quantifying sensory experiences using principles of human psychophysics. Investigating the science of chemosensation reveals that laryngeal responses to inhaled airborne stimuli have explanations involving physiological mechanisms as well as higher cognitive processing. Fortunately, these findings are consistent with current pharmacological and nonpharmacological interventions for impaired laryngeal-respiration. Based on the close relationships among inhaled airborne stimuli, respiration, and laryngeal function, we propose that new perspectives from chemosensory sciences offer opportunities to improve patient care and target areas of future research.

Emotional memory in the lab: Using the Trier Social Stress Test to induce a sensory-rich and personally meaningful episodic experience

A myriad of clinical theories places emotional memory or mental representations at the root of mental disorders. Various cognitive-behavioural interventions are based on the assumption that targeting the underlying emotional memory is the working mechanism of treatment efficacy. To test the assumptions about the role of emotional memory in the development, maintenance, and treatment of mental disorders, we first need to establish ecologically valid paradigms that can induce emotional memory in the lab. For this, we used the Trier Social Stress Test (TSST), a standardized protocol to elicit social distress, paired with a neutral unfamiliar ambient odour, to create a sensory-rich and personally meaningful episodic experience. Seven days later, participants (N = 132) reactivated the memory of the TSST with the aid of auditory, olfactory, and visual retrieval cues, during which their heart rate and self-reported affective responses were collected. Although increases in heart rate were only observed during encoding, and not at retrieval, self-report ratings showed that cues which directly referred to the aversive experience evoked more negative valence, arousal, and feelings of lack of control during memory reactivation compared to control cues across sensory modalities. These findings are indicative of successful memory induction and corroborate the utility of ambient odours as retrieval aids. Moreover, the self-reported response to the reactivated emotional memory correlated with individual differences in indices of (social) anxiety and depression. Thereby, we provide preliminary evidence of the translational significance of this paradigm that offers potential for being a model to induce ecologically valid emotional memory in the lab.

Unraveling the universality of chemical fear communication: evidence from behavioral, genetic, and chemical analyses

Abundant evidence indicates that humans can communicate threat-related information to conspecifics through their body odors. However, prior research has been primarily conducted on Western (WEIRD) samples. In this study, we aimed to investigate whether threat-related information can be transmitted by individuals of East Asian descent who carry a single-nucleotide polymorphism (SNP) 538G → A in the ABCC11 gene, which significantly reduces (noticeable) body odor. To examine this, we recruited 18 self-identified male East Asian AA-homozygotes and 18 self-identified male Western individuals who were carriers of the functional G-allele. We collected samples of their fear-related and neutral body odors. Subsequently, we conducted a double-blind behavioral experiment in which we presented these samples to 69 self-identified female participants of Western Caucasian and East Asian backgrounds. The participants were asked to rate faces that were morphed between expressions of fear and disgust. Notably, despite the "odorless" phenotypical expression of the ABCC11-mutation in East Asians, their fear odor caused a perceptual fear bias in both East Asian and Caucasian receivers. This finding leaves open the possibility of universal fear chemosignaling. Additionally, we conducted exploratory chemical analysis to gain initial insights into the chemical composition of the body odors presented. In a subsequent pre-registered behavioral study (N = 33), we found that exposure to hexadecanoic acid, an abundant compound in the fear and neutral body odor samples, was sufficient to reproduce the observed behavioral effects. While exploratory, these findings provide insight into how specific chemical components can drive chemical fear communication.

Anatomy and dietary specialization influence sensory behaviour among sympatric primates

Senses form the interface between animals and environments, and provide a window into the ecology of past and present species. However, research on sensory behaviours by wild frugivores is sparse. Here, we examine fruit assessment by three sympatric primates (Alouatta palliata, Ateles geoffroyi and Cebus imitator) to test the hypothesis that dietary and sensory specialization shape foraging behaviours. Ateles and Cebus groups are comprised of dichromats and trichromats, while all Alouatta are trichomats. We use anatomical proxies to examine smell, taste and manual touch, and opsin genotyping to assess colour vision. We find that the frugivorous spider monkeys (Ateles geoffroyi) sniff fruits most often, omnivorous capuchins (Cebus imitator), the species with the highest manual dexterity, use manual touch most often, and that main olfactory bulb volume is a better predictor of sniffing behaviour than nasal turbinate surface area. We also identify an interaction between colour vision phenotype and use of other senses. Controlling for species, dichromats sniff and bite fruits more often than trichromats, and trichromats use manual touch to evaluate cryptic fruits more often than dichromats. Our findings reveal new relationships among dietary specialization, anatomical variation and foraging behaviour, and promote understanding of sensory system evolution.

Gustatory dysfunction in patients with olfactory dysfunction and the associated factors

BACKGROUND

Little is known about the occurrence of gustatory dysfunction (GD) in relation to different aetiologies of olfactory dysfunction (OD) as assessed by psychophysical chemosensory tests. The aim of this study was to analyse gustatory function in patients with OD and to investigate clinical factors associated with GD.

METHODS

A total of 742 individuals who underwent both olfactory and gustatory function tests at a tertiary medical centre from November 2019 to March 2021 were retrospectively enrolled. Olfactory and gustatory function were assessed by the YSK olfactory and gustatory function tests, respectively. Patients with OD were classified into four groups according to the aetiology: sinonasal disease, post-infection OD (PIOD), post-traumatic OD (PTOD), and others. Secondary outcomes included age, sex, smoking history, and alcohol history.

RESULTS

Among the 488 patients with OD, 93 (19.1%) showed GD and 395 (80.9%) had normal gustatory function. Only 25 (9.8%) among 254 individuals with normosmia showed GD. Analyses of these frequencies revealed a significant association between OD and GD. In addition, the taste score was significantly lower in patients with OD than individuals with normosmia. The frequency of GD was significantly higher in patients with PTOD (53.6%) than in those with OD of other aetiologies (sinonasal disease, 6.7%; PIOD, 13.0%; others, 24.4%). In the multivariate analysis, age ≥55 years and PTOD were associated with a high frequency of GD among patients with OD.

CONCLUSIONS

The current study show that GD is significantly associated with OD. In particular, GD is more common in patients with PTOD than in those with OD of other aetiologies.

Less is more: Removing a modality of an expected olfactory-visual stimulation enhances brain activation

In recent years, multisensory integration of visual and olfactory stimuli has extensively been explored resulting in the identification of responsible brain areas. As the experimental designs of previous research often include alternating presentations of unimodal and bimodal stimuli, the conditions cannot be regarded as completely independent. This could lead to effects of an expected but surprisingly missing sensory modality. In our experiment, we used a common functional magnetic resonance imaging (fMRI) study design with alternating strong unimodal and bimodal olfactory-visual food stimuli, in addition to a slight overhang of the bimodal stimuli in an effort to examine the effects of removing a visual or olfactory congruent stimulus for older people (41-83 years). Our results suggest that the processing of olfactory and visual stimuli stays intact over a wide age-range and that the utilization of strong stimuli does not lead to superadditive multisensory integration in accordance with the principle of inverse effectiveness. However, our results demonstrate that the removal of a stimulus modality leads to an activation of additional brain areas. For example, when the visual stimulus modality is missing, the right posterior superior temporal gyrus shows higher activation, whereas the removal of the olfactory stimulus modality leads to higher activation in the amygdala/hippocampus and the postcentral gyrus. These brain areas are related to attention, memory, and the search of the missing stimulus. Consequently, careful attention must be paid to the design of a valid, multimodal sensory experiment while also controlling for cognitive expectancy effects that might confound multimodal results.

Olfactory function in congenital cytomegalovirus infection: a prospective study

Congenital cytomegalovirus (CMV) infection leads to olfactory bulb lesions in the fetus, yet little is known about its impact on olfaction after birth. Here, we have assessed in a prospective study conducted on children in two French hospitals from 2016 to 2019, infection severity and olfactory performance after congenital CMV infection. Children with congenital CMV infection aged 3 to 10 years and healthy controls (CTL) matched for age and sex to CMV children symptomatic at birth (sCMV) were enrolled. Olfactory discrimination was assessed using mono-odorants and binary mixtures. Data were analyzed for 54 children with PCR-confirmed congenital CMV infection, including 34 sCMV (median [IQR] age, 6 [5-8] years; 19 [55.9%] male), and 20 CMV asymptomatic at birth (aCMV, median [IQR] age, 4 [3-6] years; 12 [60.0%] male). sCMV were compared to 34 CTL children. Olfactory scores in CMV-infected children were independent from vestibular deficit and hearing loss. The olfactory score was efficient to discriminate between CTL and sCMV for children > 6 years (area under the receiver-operating characteristic curve (AUC, 0.85; P = 0.0006), but not for children < 7 years. For children > 6 years, the proportion of children with total olfactory score < 4 differed between sCMV and CTL groups (91.2% and 18.7%, P < 0.001), but not between aCMV and age-matched healthy control groups.   Conclusion: Congenital CMV infection is associated with reduced olfactory performance in children with infection symptoms at birth.   Clinical trial registration: NCT02782988 (registration date: May 26, 2016). What is Known: •Congenital cytomegalovirus infection leads to olfactory bulb lesions in the fetus, yet little is known about its impact on olfaction after birth. •Depending on neonatal clinical presentation, children are either categorized as having a symptomatic or asymptomatic infection at birth. What is New: •Congenital cytomegalovirus infection is associated with reduced olfactory performance in children with infection symptoms at birth.

Olfaction in the Multisensory Processing of Faces: A Narrative Review of the Influence of Human Body Odors

A recent body of research has emerged regarding the interactions between olfaction and other sensory channels to process social information. The current review examines the influence of body odors on face perception, a core component of human social cognition. First, we review studies reporting how body odors interact with the perception of invariant facial information (i.e., identity, sex, attractiveness, trustworthiness, and dominance). Although we mainly focus on the influence of body odors based on axillary odor, we also review findings about specific steroids present in axillary sweat (i.e., androstenone, androstenol, androstadienone, and estratetraenol). We next survey the literature showing body odor influences on the perception of transient face properties, notably in discussing the role of body odors in facilitating or hindering the perception of emotional facial expression, in relation to competing frameworks of emotions. Finally, we discuss the developmental origins of these olfaction-to-vision influences, as an emerging literature indicates that odor cues strongly influence face perception in infants. Body odors with a high social relevance such as the odor emanating from the mother have a widespread influence on various aspects of face perception in infancy, including categorization of faces among other objects, face scanning behavior, or facial expression perception. We conclude by suggesting that the weight of olfaction might be especially strong in infancy, shaping social perception, especially in slow-maturing senses such as vision, and that this early tutoring function of olfaction spans all developmental stages to disambiguate a complex social environment by conveying key information for social interactions until adulthood.

Odours as context cues of emotional memories - The role of semantic relatedness

Odours constitute effective context cues, facilitating memory retrieval. Identifying factors which modulate the effectiveness of olfactory context cues can advance the understanding of processes underlying this effect. We hypothesized that the interplay of subjective stress and semantic relatedness between the odour and the learning material would modulate the effectiveness of an olfactory context cue. We further explored the effect of the odorant Hedione, which is a ligand for a putative human pheromone receptor (VN1R1). To this end, 120 participants watched a video of a stressful episode in which visual objects were present, that were either manipulated in the video (central objects) or not (peripheral objects). Participants rated their subjective stress afterwards. After 24 h, recognition and spatial memory of the objects in the video were tested. Ambient during encoding and recall was an odour related to the episode, an unrelated odour, Hedione or no odour. As a result, we observed a narrowing of recognition memory with increased subjective stress elicited by the video - but only if a semantically related odour was ambient. Moreover, higher subjective stress predicted enhanced spatial memory in the no odour condition, but not in presence of a semantically related or unrelated odour. When exposed to Hedione, higher subjective stress predicted impaired recognition and spatial memory of peripheral objects. Our findings stress the importance of considering semantic relatedness between the olfactory context and the encoded episode when applying odours as context cues for emotional or stressful memories.

Multimodal learning of pheromone locations

Memorizing pheromonal locations is critical for many mammalian species as it involves finding mates and avoiding competitors. In rodents, pheromonal information is perceived by the main and accessory olfactory systems. However, the role of somatosensation in context-dependent learning and memorizing of pheromone locations remains unexplored. We addressed this problem by training female mice on a multimodal task to locate pheromones by sampling volatiles emanating from male urine through the orifices of varying dimensions or shapes that are sensed by their vibrissae. In this novel pheromone location assay, female mice’ preference toward male urine scent decayed over time when they were permitted to explore pheromones vs neutral stimuli, water. On training them for the associations involving olfactory and whisker systems, it was established that they were able to memorize the location of opposite sex pheromones, when tested 15 days later. This memory was not formed either when the somatosensory inputs through whisker pad were blocked or when the pheromonal cues were replaced with that of same sex. The association between olfactory and somatosensory systems was further confirmed by the enhanced expression of the activity-regulated cytoskeleton protein. Furthermore, the activation of main olfactory bulb circuitry by pheromone volatiles did not cause any modulation in learning and memorizing non-pheromonal volatiles. Our study thus provides the evidence for associations formed between different sensory modalities facilitating the long-term memory formation relevant to social and reproductive behaviors.

Disgusting odours affect the characteristics of the Adaptive Force in contrast to neutral and pleasant odours

The olfactomotor system is especially investigated by examining the sniffing in reaction to olfactory stimuli. The motor output of respiratory-independent muscles was seldomly considered regarding possible influences of smells. The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces in a holding manner and was suggested to be more vulnerable to possible interfering stimuli due to the underlying complex control processes. The aim of this pilot study was to measure the effects of olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odours. The reaction force and the limb position were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations by perceiving disgusting odours compared to pleasant or neutral odours (p < 0.001). The adaptive holding capacity seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length tension control and by an earlier onset of mutual oscillations during an external force increase. This highlights the strong connection of olfaction and motor control also regarding respiratory-independent muscles.

Perception of Social Odor and Gender-Related Differences Investigated Through the Use of Transfer Entropy and Embodied Medium

The perception of putative pheromones or social odors (PPSO) in humans is a widely debated topic because the published results seem ambiguous. Our research aimed to evaluate how cross-modal processing of PPSO and gender voice can affect the behavioral and psychophysiological states of the subject during a listening task with a bodily contact medium, and how these effects could be gender related. Before the experimental session, three embodied media, were exposed to volatilized estratetraenol (Estr), 5α-androst-16-en-3 α-ol (Andr), and Vaseline oil. The experimental session consisted in listening to a story that were transmitted, with a male or female voice, by the communicative medium via a Bluetooth system during a listening task, recorded through 64-active channel electroencephalography (EEG). The sense of co-presence and social presence, elicited by the medium, showed how the established relationship with the medium was gender dependent and modulated by the PPSO. In particular, Andr induced greater responses related to co-presence. The gender of the participants was related to the co-presence desire, where women imagined higher medium co-presence than men. EEG findings seemed to be more responsive to the PPSO–gender voice interaction, than behavioral results. The mismatch between female PPSO and male voice elicited the greatest cortical flow of information. In the case of the Andr–male voice condition, the trained model appeared to assign more relevance to the flow of information to the right frontotemporal regions (involved in odor recognition memory and social behavior). The Estr–male voice condition showed activation of the bilateral frontoparietal network, which is linked to cognitive control, cognitive flexibility, and auditory consciousness. The model appears to distinguish the dissonance condition linked to Andr matched with a female voice: it highlights a flow of information to the right occipital lobe and to the frontal pole. The PPSO could influence the co-presence judgements and EEG response. The results seem suggest that could be an implicit pattern linked to PPSO-related gender differences and gender voice.

Long-Term Quality of Life after Endoscopic Pituitary Adenoma Surgery with Nasoseptal Flap Reconstruction

INTRODUCTION

Endoscopic endonasal transsphenoidal surgery (EETS) on the pituitary gland is considered safe and efficacious. The nasoseptal flap (NSF) is sometimes used to prevent or repair postoperative cerebrospinal fluid (CSF) leaks. Few investigators have quantified long-term quality-of-life (QOL) outcomes regarding sinonasal measures after EETS, with or without involvement of the NSF. This study assesses whether the septal flap affects sinonasal QOL outcomes for patients receiving EETS for pituitary adenoma.

METHODS AND MATERIALS

This is a retrospective study of patients who underwent EETS between 2013 and 2018. A total of 62 adults completed the Sinonasal Outcome Test-22 (SNOT-22) at least one year after the surgery. Outcome measures were compared between patients who underwent EETS with and without septal flap reconstruction.

RESULTS

For the entire cohort, there were 14 patients (22.6%) who had septal flap reconstruction and 48 patients (77.4%) who did not. Patient demographics, tumor characteristics, surgical outcomes, and duration between surgery and completion of the questionnaire were similar for both groups. The mean SNOT-22 scores in the no reconstruction (NR) group and the nasoseptal flap reconstruction (NSFR) group were similar (P=0.9). In terms of SNOT-22 subdomains (rhinologic symptoms, extranasal rhinologic symptoms, ear/facial symptoms, psychological dysfunction, and sleep dysfunction), no significant differences were found when comparing the groups.

CONCLUSION

As compared with no reconstructive involvement, NSF utilization does not affect the QOL and nasal symptoms of patients undergoing EETS.

Sexually dimorphic effects of prolactin treatment on the onset of puberty and olfactory function in mice

The onset of puberty is associated with the psychophysiological maturation of the adolescent to an adult capable of reproduction when olfactory signals play an important role. This period begins with the secretion of the gonadotropin-releasing hormone (GnRH) from GnRH neurons within the hypothalamus. This is regulated by kisspeptin neurons that express high levels of transmembrane prolactin receptors (PRLR) that bind to and are activated by prolactin (PRL). The elevated levels of serum PRL found during lactation, or caused by chronic PRL infusion, decreases the secretion of gonadotropins and kisspeptin and compromised the estrous cyclicity and the ovulation. In the present work, we aimed to evaluate the effects of either increased or decreased PRL circulating levels within the peripubertal murine brain by administration of PRL or treatment with cabergoline (Cab) respectively. We showed that either treatment delayed the onset of puberty in females, but not in males. This was associated with the augmentation of the PRL receptor (Prlr) mRNA expression in the arcuate nucleus and decreased Kiss1 expression in the anteroventral periventricular zone. Then, during adulthood, we assessed the activation of the mitral and granular cells of the main (MOB) and accessory olfactory bulb (AOB) by cFos immunoreactivity (ir) after the exposure to soiled bedding of the opposite sex. In the MOB, the PRL treatment promoted an increased cFos-ir of the mitral cells of males and females. In the granular cells of male of either treatment an augmented activation was observed. In the AOB, an impaired cFos-ir was observed in PRL and Cab treated females after exposure to male soiled bedding. However, in males, only Cab impaired its activation. No effects were observed in the AOB-mitral cells. In conclusion, our results demonstrate that PRL contributes to pubertal development and maturation of the MOB-AOB during the murine juvenile period in a sex-dependent way.

Comparative Effects of Repetitive Odor Identification and Odor Memory Tasks on Olfactory Engagement in Older Populations - A Pilot fMRI Study

OBJECTIVE

This study evaluated human Blood Oxygen Level-Dependent (BOLD) responses in primary and higher-order olfactory regions of older adults, using odor memory and odor identification tasks. The goal was to determine which olfactory and memory regions of interest are more strongly engaged in older populations comparing these two odor training tasks.

METHODS

Twelve adults 55-75 years old (75% females) without intranasal or major neurological disorders performed repetitive odor memory and identification tasks using a 3-tesla magnetic resonance scanner. Odors were presented intermittently at 10-second bursts separated by 20-second intervals of odorless air. Paired t-tests were used to compare differences in the degree of activation between odor identification and odor memory tasks within individuals. An FDR cluster-level correction of p<0.05 was used for multiplicity of tests (with a cluster-defining threshold set at p<0.01 and 10 voxels).

RESULTS

Odor identification compared to memory (ie, odor identification > odor memory) contrasts had several areas of significant activation, including many of the classical olfactory brain regions as well as the hippocampus. The opposite contrast (odor memory > odor identification) included the piriform cortex, though this was not significant. Both tasks equally activated the piriform cortex, and thus when the two tasks are compared to each other this area of activation appears to be either absent (OI > OM) or only weakly observed (OM > OI).

CONCLUSION

These findings from a predominantly African American sample suggest that odor identification tasks may be more potent than memory tasks in targeted olfactory engagement in older populations. Furthermore, repetitive odor identification significantly engaged the hippocampus - a region relevant to Alzheimer's disease - more significantly than did the odor memory task. If validated in larger studies, this result could have important implications in the design of olfactory training paradigms.

Long-term olfactory dysfunction after single-nostril endoscopic transnasal transsphenoidal pituitary adenoma surgery

BACKGROUND

Over the past decade, the endoscopic transnasal transsphenoidal approach for pituitary adenomas has been widely adopted among neurosurgeons. However, olfactory disturbances have been observed after this procedure, and few studies on long-term (>6 mo) olfactory disturbance after endoscopic transnasal transsphenoidal pituitary adenoma surgery have been conducted. Although we perform minimally invasive endoscopic surgery, some patients continue to experience hyposmia, with some even experience long-term hyposmia. This impairment results in a considerable loss in quality of life. We present a series of patients who underwent minimally invasive single-nostril TSS for pituitary adenoma, including evaluation of their olfactory function. We further investigated the related risk factors for long-term olfactory dysfunction.

METHODS

One hundred sixty-one consecutive patients who met the study criteria underwent the single-nostril endoscopic transsphenoidal approach by the senior author. The Smell Diskettes Olfaction Test was used to evaluate olfactory function.

RESULTS

Postoperative olfactory disturbance in patients treated with endoscopic transnasal TSS is frequent. Of the study population, 67.1% of the patients were hyposmic or anosmic and 14.9% had long-term olfactory dysfunction. We also performed multivariate logistic regression analysis to compare the characteristics of patients with long-term olfactory dysfunction. Nasal symptoms (odds ratio [OR], 6.77) and smoking (OR, 14.77) were associated with long-term olfactory dysfunction after transnasal TSS.

CONCLUSIONS

Significant disturbances in olfactory performance occur after single-nostril transnasal TSS for pituitary adenoma. Furthermore, preoperative nasal disease and smoking appear to be risk factors for long-term olfactory dysfunction. Physicians should address clinical findings related to olfactory function and provide appropriate care.

More Than Smell-COVID-19 Is Associated With Severe Impairment of Smell, Taste, and Chemesthesis

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, and generally lacked quantitative measurements. Here, we report the development, implementation and initial results of a multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, 8 other, ages 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change ±100) revealed a mean reduction of smell (-79.7 ± 28.7, mean ± SD), taste (-69.0 ± 32.6), and chemesthetic (-37.3 ± 36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis. The multimodal impact of COVID-19 and lack of perceived nasal obstruction suggest that SARS-CoV-2 infection may disrupt sensory-neural mechanisms.

Food, Eating, and the Gastrointestinal Tract

Food ingestion induces a metered response of the digestive system. Initially, the upper digestive system reacts to process and extract meal substrates. Later, meal residues not absorbed in the small bowel, pass into the colon and activate the metabolism of resident microbiota. Food consumption also induces sensations that arise before ingestion (e.g., anticipatory reward), during ingestion (e.g., gustation), and most importantly, after the meal (i.e., the postprandial experience). The postprandial experience involves homeostatic sensations (satiety, fullness) with a hedonic dimension (digestive well-being, mood). The factors that determine the postprandial experience are poorly understood, despite their potential role in personalized diets and healthy eating habits. Current data suggest that the characteristics of the meal (amount, palatability, composition), the activity of the digestive system (suited processing), and the receptivity of the eater (influenced by multiple conditioning factors) may be important in this context.

Bio-Inspired Strategies for Improving the Selectivity and Sensitivity of Artificial Noses: A Review

Artificial noses are broad-spectrum multisensors dedicated to the detection of volatile organic compounds (VOCs). Despite great recent progress, they still suffer from a lack of sensitivity and selectivity. We will review, in a systemic way, the biomimetic strategies for improving these performance criteria, including the design of sensing materials, their immobilization on the sensing surface, the sampling of VOCs, the choice of a transduction method, and the data processing. This reflection could help address new applications in domains where high-performance artificial noses are required such as public security and safety, environment, industry, or healthcare.

Field-testing olfactory ability to understand human olfactory ecology

OBJECTIVES

We know little about human olfactory ability in natural settings because current knowledge derives from lab-based studies using nonrepresentative samples of convenience. The primary objective was to use a validated lab tool, the five-item odor identification test, to assess variation in olfactory ability in different environments.

METHODS

Using the five-item test, we conducted two repeated measures experiments that assessed participant ability to correctly identify an odor source in different odor environments. We also examined consistency in odor labelling due to documented potential bias from idiosyncrasies in odor terms.

RESULTS

We found no variation in olfactory ability due to environment, but this may be due to methodological biases. First, subjective bias results from idiosyncratic differences in participant labelling and researcher coding of answer correctness. Second, better ability to learn odors may provide an advantage to women. Third, reducing positive female learning bias by analyzing consistency in response (regardless of correct odor source identification) results in no sex differences but fails to assess the functional aspect of olfactory ability (naming the correct odor source). Fourth, functional olfactory ability is significantly better in women, especially in food-rich odor environments.

CONCLUSIONS

Environment was not a significant factor in olfactory ability in this study but that result may be confounded by methodological biases. We do not recommend odor identification as a field tool. Functional olfactory ability exhibits a sex-based pattern but consistency in recognizing the same odor does not. Food-rich odors may enhance olfactory ability in females. We discuss evolutionary and ecological implications of superior female functional olfactory ability relative to food foraging activity.

Clinical practice guidelines for the management of olfactory dysfunction - Secondary publication

OBJECTIVE

To provide an evidence-based recommendation for the management of olfactory dysfunction in accordance with the consensus reached by the Subcommittee of the Japanese Clinical Practice Guideline for olfactory dysfunction in the Japanese Rhinologic Society.

METHODS

Seven clinical questions (CQs) regarding the management of olfactory dysfunction were formulated by the subcommittee of the Japanese Clinical Practice Guideline for olfactory dysfunction. We searched the literature published between April 1990 and September 2014 using PubMed, the Cochrane Library, and Ichushi Web databases. The main search terms were "smell disorder," "olfactory dysfunction," "olfactory loss," "olfactory disturbance," "olfactory impairments," "olfaction disorder," "smell disorder," "anosmia," "cacosmia," and "dysosmia." Based on the results of the literature review and the expert opinion of the Subcommittee, 4 levels of recommendation, from A-strongly recommended to D-not recommended, were adopted for the management of olfactory dysfunction.

RESULTS

Both oral and locally administered corticosteroids have been strongly recommended for patients with olfactory dysfunction due to chronic rhinosinusitis. Nasal steroid spray and antihistamine drugs have been moderately recommended for patients with allergic rhinitis. Although no drugs have been deemed to be truly effective for post-viral olfactory dysfunction by randomized-controlled trials (RCTs) or placebo-controlled trials, olfactory training using odorants has been reported to be effective for improving olfactory function. There is considerable evidence that olfactory testing is useful for differential diagnosis, prediction of disease progression, and early detection of cognitive decline in neurodegenerative diseases.

CONCLUSION

The Clinical Practice Guideline has developed recommendations for the management of various aspects of olfactory dysfunction.

Olfactory Event-Related Potentials and Exhaled Organic Volatile Compounds: The Slow Link Between Olfactory Perception and Breath Metabolic Response. A Pilot Study on Phenylethyl Alcohol and Vaseline Oil

Olfactory processing starts with the breath and elicits neuronal, metabolic and cortical responses. This process can be investigated centrally via the Olfactory Event-Related Potentials (OERPs) and peripherally via exhaled Volatile Organic Compounds (VOCs). Despite this, the relationship between OERPs (i.e., N1 and Late Positive Component LPC) and exhaled VOCs has not been investigated enough. The aim of this research is to study OERPs and VOCs connection to two different stimuli: phenylethyl alcohol (PEA) and Vaseline Oil (VO). Fifteen healthy subjects performed a perceptual olfactory task with PEA as a smell target stimulus and VO as a neutral stimulus. The results suggest that OERPs and VOCs distributions follow the same amplitude trend and that PEA is highly arousing in both psychophysiological measures. PEA shows ampler and faster N1, a component related to the sensorial aspect of the stimulus. The N1 topographic localization is different between PEA and VO: PEA stimulus evokes greater N1 in the left centroparietal site. LPC, a component elicited by the perceptual characteristic of the stimulus, shows faster latency in the Frontal lobe and decreased amplitude in the Central and Parietal lobe elicited by the PEA smell. Moreover, the delayed time between the onset of N1-LPC and the onset of VOCs seems to be about 3 s. This delay could be identified as the internal metabolic time in which the odorous stimulus, once perceived at the cortical level, is metabolized and subsequently exhaled. Furthermore, the VO stimulus does not allocate the attentive, perceptive and metabolic resource as with PEA.

Olfactory Function is Affected in Patients with Cirrhosis Depending on the Severity of Hepatic Encephalopathy

INTRODUCTION AND AIM

Olfactory functions are altered to a variable degree by chronic liver disease. Few studies including only small populations of patients emphasized the possibility of hepatic encephalopathy (HE) influencing olfactory nervous tasks. So far, no study has explicitly focused on olfactory function depending on the severity of HE as assessed by objective diagnostic procedures. Thus we performed a study using the "Sniffin' Sticks" test system, critical flicker-fusion frequency (CFF) and clinical West Haven criteria.

MATERIAL AND METHODS

54 cirrhotic patients with liver cirrhosis were included. Furthermore, 43 adult volunteers participating as a non-cirrhotic control group. Olfactory testing was performed using the "Sniffin' Stick" test battery (Burghart Medizintechnik, Wedel, Germany) which renders a widely-used tool both in clinical and research settings for the assessment of olfactory threshold, odor identification and discrimination. Several complications of cirrhosis were diagnosed by reference methods. Statistical analysis of cirrhosis-associated complications and their relation to olfactory function was performed. Assessment of HE and classification of different stages were performed according to clinical criteria (West- Haven criteria) and according to CFF, which was determined using a portable analyzer.

RESULTS

Olfactory function was significantly reduced in cirrhotic patients (in 61.1%) compared to controls (p &lt; 0.001). Among cirrhotics patients, the prevalence of olfactory deficits (hyposmia, anosmia) increased with the severity of HE as assessed by CFF and clinical criteria (p = 0.008 and p = 0.097, respectively). No correlation was observed between olfactory deficits and severity of liver disease as assessed by Child-Pugh-Score, etiology of cirrhosis and complications of cirrhosis such as ascites and portal venous hypertension.

CONCLUSIONS

Olfactory testing serves as a screening tool for HE and may facilitate grading of HE-severity.

Mitral cells and the glucagon-like peptide 1 receptor: The sweet smell of success?

The olfactory bulb (OB) is often affected at very early stages of neurodegenerative disorders, in the so-called "prodromal" phase. In Parkinson's disease (PD), olfactory disturbances appear years before motor symptoms arise. Additionally, pathological alpha-synuclein aggregates are found in olfactory regions before spreading to other areas of the brain. Being positioned at the frontier between the brain and a potentially hostile environment, could explain the particular vulnerability of the OB. Mitral cells (MCs), the principal projecting neurons of the olfactory system, are involved in the pathogenesis and in the prion-like progression of PD. They are affected by Lewy pathology and are thought to contribute to the axonal transport of misfolded alpha-synuclein to other regions of the brain. Here, we first describe the main markers reported to distinguish MCs from other olfactory neurons. We focus on the glucagon-like peptide 1 receptor (GLP-1R), a membrane protein specifically expressed in MCs. After summarizing OB pathology, we explore the idea of targeting specifically MCs with GLP-1 or its analogues. Exenatide has shown great promise as a neuroprotective and neurorestorative agent and has been used in a clinical trial for clinical PD. Since GLP-1R activation has the ability to mitigate many facets of prodromal PD pathology, we postulate that once a robust biomarker is in place that is capable of identifying individuals in the prodromal phase of PD, homing in on GLP-1R could assist in deferring, or eradicating to a significant degree, the clinical manifestation of this debilitating human disorder.

Biogastronomy: Factors that determine the biological response to meal ingestion

BACKGROUND

The biological response to a meal includes physiological changes, primarily related to the digestive process, and a sensory experience, involving sensations related to the homeostatic control of food consumption, eg, satiety and fullness, with a hedonic dimension, ie associated with changes in digestive well-being and mood. The responses to a meal include a series of events before, during and after ingestion. While much attention has been paid to the events before and during ingestion, relatively little is known about the postprandial sensations, which are key to the gastronomical experience.

PURPOSE

The aim of this narrative review is to provide a comprehensive overview and to define the framework to investigate the factors that determine the postprandial experience. Based on a series of proof-of-concept studies and related information, we propose that the biological responses to a meal depend on the characteristics of the meal, primarily its palatability and composition, and the responsiveness of the guest, which may be influenced by multiple previous and concurrent conditioning factors. This information provides the scientific backbone to the development of personalized gastronomy.

Odours and incontinence: What does the nose know?

The fear of producing malodours that can be detected by others is a daily cause of anxiety for millions of people with incontinence. For many, the risk-whether real or imagined-that leaked waste products will be detectable by odour is sufficiently concerning to result in limitations on many types of activities. However, worry about personal odours can sensitise our olfactory system and cause us to be more aware of odours that may otherwise not be perceptible. In addition, heightened olfactory attention can often lead to odour misattributions, such as when we erroneously identify our body as the source of an odour that may simply be present in the environment. Odours produced by our bodies (endogenous odours) do enjoy a greater access to emotional brain centers and are processed faster than general odours. Here we provide examples from both everyday life and laboratory studies to explain how and why the olfactory system is unique among our sensory systems and how this knowledge can provide insights to our concerns about smell and incontinence and inform the development of products and solutions for incontinence.

Office Procedures for Quantitative Assessment of Olfactory Function

Background

Despite the importance of the sense of smell for establishing the flavor of foods and beverages, as well as protecting against environmental dangers, this primary sensory system is commonly ignored by the rhinologist.

Methods

In this article basic issues related to practical measurement of olfactory function in the clinic are described and examples of the application of the two most common paradigms for such measurement—odor identification and detection–are presented. A listing is made of the 27 olfactory tests currently used clinically, along with their strengths and weaknesses. A brief review of common nasosinus-related disorders for which quantitative olfactory testing has been performed is provided.

Results

Although many psychophysical tests are available for quantifying olfactory loss, it is apparent that a number are limited in terms of practicality, sensitivity, and reliability. In general, sensitivity and reliability are positively correlated with test length. Given the strengths of the more reliable forced-choice pyschophysical tests and the limitations of electrophysiological tests, the common distinction between “subjective” and “objective” tests is misleading and should not be used. Complete recovery of olfactory function, as measured quantitatively, rarely follows surgical or medical interventions in patients with rhinosinusitis.

Conclusion

Given the availability of practical clinical olfactory tests, the modern rhinologist can easily quantify cranial nerve (CN) I function. The application of such tests has led to a new understanding of the effects of nasal disease on olfactory function. Except in cases of total or near-total nasal obstruction, olfactory and airway patency measures usually are unrelated, in accord with the concept that rhinosinusitis primarily influences olfactory function by apoptotic pathological changes within the olfactory neuroepithelium.

Mechanical and phytochemical protection mechanisms of Calligonum comosum in arid deserts

Unlike animals, plants are sessile organisms, lacking circulating antibodies and specialized immune cells and are exposed to various harsh environmental conditions that make them at risk of being attacked by different pathogens and herbivores. Plants produce chemo-signals to respond to the surroundings and be able to distinguish between harmless and harmful signals. In this study, the production of phytochemicals as plant signaling mechanisms and their defensive roles in disease resistance and repelling herbivores are examined in Calligonum comosum. C. comosum is a leafless standalone perennial shrub widespread in sand dunes. The plant has the ability to survive the drastic environmental conditions of the arid/ hyperarid deserts of the Arabia. Structural anatomy and phytochemicals analyses were used to identify both mechanical and chemical defensive mechanisms in C. comosum. Microscopy-based investigations indicated that stems of this species developed hard structures in its outer layers including sclerenchyma and cluster crystals of calcium oxalate (CaOx). Sclerenchyma and CaOx are difficult to be eaten by herbivores and insects and can harm their mouthparts. On the other hand, the plant developed both short-distance (local) and long-distance (systematic over limited sphere) phytochemicals-producing cells located at its outer regions that is surrounding the inner nutrient-rich vascular system (VS). Local chemical was represented by phenolic idioblasts that were released in response to plant cutting. Systematic chemical was represented by toxic volatile oil containing ~50% benzaldehyde derivative (cuminaldehyde). The oil caused strong killing effect on both mammalian cells and microbial pathogens via either direct addition or indirect exposure to its vapor. The plants lost the oil content and allowed fungal growth once cut and dried. The localization of both defensive mechanisms to the outer region of the plant seemed to protect the inner nutrient-rich VS and hence maintained the plant survival. Surprisingly, in relation to traditional folklore use as medicine, local people use only green parts of the plant and only during the winter, where the plant found devoid of volatile oil and phenolic idioblasts. Moreover, it turns into recommendations for local people to avoid any health problems caused by the plant supply.

A Pilot Study of Reduced Olfactory Bulb Volume as a Marker of PTSD in Childhood Trauma-Exposed Adult HIV-Infected Patients

Evidence suggests that olfactory bulb (OB), a key structure in odor processing, may also be involved in mechanisms of traumatic stress. In animals, chronic stress reduces OB plasticity, and olfactory bulbectomy results in stress-enhanced startle reflex and autonomic dysregulation. However, OB morphometry has not been adequately studied in the development of stress disorders following childhood trauma in humans. The researchers conducted a pilot study evaluating the relationships between OB volume, childhood trauma, and lifetime posttraumatic stress disorder (PTSD) in a sample of 16 HIV-positive individuals, 13 of whom were exposed to childhood trauma of 9 developed PTSD. Participants were recruited from a larger cohort of inner city-dwelling HIV-positive populations in Washington, DC. Mean OB volumes were significantly reduced when PTSD and non-PTSD groups were compared, p = .019, as well as when trauma-exposed PTSD-positive and trauma-exposed PTSD-negative groups were compared, p = .008. No significant difference was observed when trauma-exposed and nonexposed participants were compared. The association between PTSD and right OB volume remained strong p = 0.002 after adjusting for group differences in sex, age, depression, hippocampal volume, and total intracranial volume. Because this study is limited by small sample size, further elucidation of relationships between OB, trauma, and PTSD should be investigated in larger cross-sectional and prospective studies and in diverse cohorts.

(-)-Linalool influence on the cerebral blood flow in healthy male volunteers revealed by three-dimensional pseudo-continuous arterial spin labeling

BACKGROUND

Although aromatherapy is widely used, the pharmacology of the essential oils remains undiscovered.

AIM

The present study assessed the effect of (-)-linalool, the main contained material of lavender, on the brain function.

MATERIALS AND METHODS

Healthy male volunteers calculated the regional cerebral blood flow (CBF) before and after inhalation of (-)-linalool, and CBF changes were evaluated.

RESULTS

There were significant CBF reductions in the right superior temporal gyrus to insula, anterior cingulate cortex after inhalation.

CONCLUSIONS

The previous study detected the regulatory influence of (-)-linalool on the glutamatergic transmission. The effect of (-)-linalool on the ACC and insula would cause the sedative and anxiolytic activity.

Perception of odors and tastes in autism spectrum disorders: A systematic review of assessments

Olfaction and gustation are major sensory functions implied in processing environmental stimuli. Some evidences suggest that loss of olfactory function is an early biomarker for neurodegenerative disorders and atypical processing of odor and taste stimuli is present in several neurodevelopmental disorders, notably in Autism Spectrum Disorders (ASD). In this paper, we conducted a systematic review investigating the assessments of olfaction and gustation with psychophysics methods in individuals with ASD. Pubmed, PMC and Sciencedirect were scrutinized for relevant literature published from 1970 to 2015. In this review, fourteen papers met our inclusion criteria. They were analyzed critically in order to evaluate the occurrence of olfactory and gustatory dysfunction in ASD, as well as to report the methods used to assess olfaction and gustation in such conditions. Regarding to these two senses, the overall number of studies is low. Most of studies show significant difference regarding to odor or taste identification but not for detection threshold. Overall, odor rating through pleasantness, intensity and familiarity do not differ significantly between control and individuals with ASD. The current evidences can suggest the presence of olfactory and gustatory dysfunction in ASD. Therefore, our analysis show a heterogeneity of findings. This is due to several methodological limitations such as the tools used or population studied. Understanding these disorders could help to shed light on other atypical behavior in this population such as feeding or social behavior. Autism Res 2017, 0: 000-000. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1045-1057. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Memory for objects and startle responsivity in the immediate aftermath of exposure to the Trier Social Stress Test

Previously, we observed enhanced long-term memory for objects used (central objects) by committee members in the Trier Social Stress Test (TSST) on the next day. In addition, startle responsivity was increased. However, response specificity to an odour involved in the stressful episode was lacking and recognition memory for the odour was poor. In the current experiments, immediate effects of the stressor on memory and startle responsivity were investigated. We hypothesised memory for central objects of the stressful episode and startle response specificity to an odour ambient during the TSST to be enhanced shortly after it, in contrast to the control condition (friendly TSST). Further, memory for this odour was also assumed to be increased in the stress group. We tested 70 male (35) and female participants using the TSST involving objects and an ambient odour. After stress induction, a startle paradigm including olfactory and visual stimuli was conducted. Indeed, memory for central objects was significantly enhanced in immediate aftermath of the stressor. Startle responsivity increased at a trend level, particularly with regard to the odour involved in the stressful episode. Moreover, the stress group descriptively tended towards a better recognition of the odour involved. The study shows that stress enhances memory for central aspects of a stressful situation before consolidation processes come into play. In addition, results preliminarily suggest that the impact of stress on startle responsivity increases in strength but decreases in specificity during the first 24h after stress exposure.

Review: Sporadic Parkinson's disease: development and distribution of α-synuclein pathology

The development of α-synuclein immunoreactive aggregates in selectively vulnerable neuronal types of the human central, peripheral, and enteric nervous systems is crucial for the pathogenesis of sporadic Parkinson's disease. The presence of these lesions persists into the end phase of the disease, a process that is not subject to remission. The initial induction of α-synuclein misfolding and subsequent aggregation probably occurs in the olfactory bulb and/or the enteric nervous system. Each of these sites is exposed to potentially hostile environmental factors. Once formed, the aggregates appear to be capable of propagating trans-synaptically from nerve cell to nerve cell in a virtually self-promoting pathological process. A regional distribution pattern of aggregated α-synuclein emerges that entails the involvement of only a few types of susceptible and axonally interconnected projection neurons within the human nervous system. One major route of disease progression may originate in the enteric nervous system and retrogradely reach the dorsal motor nucleus of the vagal nerve in the lower brainstem. From there, the disease process proceeds chiefly in a caudo-rostral direction through visceromotor and somatomotor brainstem centres to the midbrain, forebrain, and cerebral cortex. Spinal cord centres may become involved by means of descending projections from involved lower brainstem nuclei as well as by sympathetic projections connecting the enteric nervous system with postganglionic peripheral ganglia and preganglionic nuclei of the spinal cord. The development of experimental cellular and animal models is helping to explain the mechanisms of how abnormal α-synuclein can undergo aggregation and how transmission along axonal connectivities can occur, thereby encouraging the initiation of potential disease-modifying therapeutic strategies for sporadic Parkinson's disease.

Back on the scent: the olfactory system in CNS demyelinating diseases

Olfactory dysfunction is recognised across an ever broadening spectrum of neuropsychiatric conditions including central nervous system (CNS) demyelinating diseases such as multiple sclerosis (MS) and neuromyelitis optica (NMO). In this review, we unravel the striking evidence highlighting how olfactory loss is a common clinical feature in MS and NMO. We provide an overview of the supportive psychophysical, electrophysiological, radiological and pathological data that point to the anatomical substrate of olfactory deficits in these diseases. The pattern of underlying pathology affecting the olfactory system is shown to be complex, involving multiple structures that are affected in different ways throughout the course of the disease. This review is the first to synthesise the expanding body of literature on the topic, provides novel insight into the way in which the olfactory system is affected in CNS demyelinating diseases, and raises intriguing questions about the role of this system in the pathogenesis of these diseases.

Comprehensive Postoperative Management After Endoscopic Skull Base Surgery

To maximize outcomes from endoscopic skull base surgery, careful early postoperative management is critically important. Standardized postoperative regimens are lacking. The type of reconstruction and presence and type of cerebrospinal fluid leak dictate management. If a leak is encountered intraoperatively, patients should avoid maneuvers that increase intracranial pressures for at least 1 month. Early postoperative care focuses on minimizing and managing nasal crusting. This article reviews the evidence in the literature on postoperative management, complications, and quality of life after surgery, and outlines our experience in the management of patients after endoscopic skull base surgery.

Transcriptional regulatory network during development in the olfactory epithelium

Regeneration, a process of reconstitution of the entire tissue, occurs throughout life in the olfactory epithelium (OE). Regeneration of OE consists of several stages: proliferation of progenitors, cell fate determination between neuronal and non-neuronal lineages, their differentiation and maturation. How the differentiated cell types that comprise the OE are regenerated, is one of the central questions in olfactory developmental neurobiology. The past decade has witnessed considerable progress regarding the regulation of transcription factors (TFs) involved in the remarkable regenerative potential of OE. Here, we review current state of knowledge of the transcriptional regulatory networks that are powerful modulators of the acquisition and maintenance of developmental stages during regeneration in the OE. Advance in our understanding of regeneration will not only shed light on the basic principles of adult plasticity of cell identity, but may also lead to new approaches for using stem cells and reprogramming after injury or degenerative neurological diseases.

Brainstem-mediated sniffing and respiratory modulation during odor stimulation

The trigeminal and olfactory systems interact during sensory processing of odor. Here, we investigate odor-evoked modulations of brainstem respiratory networks in a decerebrated perfused brainstem preparation of rat with intact olfactory bulbs. Intranasal application of non-trigeminal odors (rose) did not evoke respiratory modulation in absence of cortico-limbic circuits. Conversely, trigeminal odors such as menthol or lavender evoked robust respiratory modulations via direct activation of preserved brainstem circuits. Trigeminal odors consistently triggered short phrenic nerve bursts (fictive sniff), and the strong trigeminal odor menthol also triggered a slowing of phrenic nerve frequency. Phrenic and vagal nerve recordings reveal that fictive sniffs transiently interrupted odor evoked tonic postinspiratory vagal discharge. This motor pattern is significantly different from normal (eupneic) respiratory activity. In conclusion, we show for the first time the direct involvement of brainstem circuits in primary odor processing to evoke protective sniffs and respiratory modulation in the complete absence of forebrain commands.

Experience shapes our odor perception but depends on the initial perceptual processing of the stimulus

The questions of whether configural and elemental perceptions are competitive or exclusive perceptual processes and whether they rely on independent or dependent mechanisms are poorly understood. To examine these questions, we modified perceptual experience through preexposure to mixed or single odors and measured the resulting variation in the levels of configural and elemental perception of target odor mixtures. We used target mixtures that were spontaneously processed in a configural or an elemental manner. The AB binary mixture spontaneously involved the configural perception of a pineapple odor, whereas component A smelled like strawberry and component B smelled like caramel. The CD mixture produced the elemental perceptions of banana (C) and smoky (D) odors. Perceptual experience was manipulated through repeated exposure to either a mixture (AB or CD) or the components (A and B or C and D). The odor typicality rating data recorded after exposure revealed different influences of experience on odor mixtures and single-component perception, depending both on the type of exposure (components or mixture) and the mixture's initial perceptual property (configural or elemental). Although preexposure to A and B decreased the pineapple typicality of the configural AB mixture, preexposure to AB did not modify its odor quality. In contrast, preexposure to the CD elemental mixture induced a quality transfer between the components. These results emphasize the relative plasticity of odor mixture perception, which is prone to experience-induced modulations but depends on the stimulus's initial perceptual properties, suggesting that configural and elemental forms of odor mixture perception rely on rather independent processes.

Higher Body Mass Index Is Associated with Subjective Olfactory Dysfunction

BACKGROUND

Morbidly obese patients demonstrate altered olfactory acuity. There has been no study directly assessing Body Mass Index (BMI) in patients with olfactory dysfunction. Our purpose was to compare BMI in a group of patients with subjective olfactory dysfunction to those without subjective olfactory complaints.

METHODS

Retrospective matched case-control study. Sixty patients who presented to a tertiary care otolaryngology center with subjective smell dysfunction over one year were identified. Neoplastic and obstructive etiologies were excluded. Demographics, BMI, and smoking status were reviewed. Sixty age, gender, and race matched control patients were selected for comparison. Chi-square testing was used.

RESULTS

48 out of 60 patients (80%) in the olfactory dysfunction group fell into the overweight or obese categories, compared to 36 out of 60 patients (60%) in the control group. There was a statistically significant difference between the olfactory dysfunction and control groups for this stratified BMI (p = 0.0168).  

CONCLUSION

This study suggests high BMI is associated with olfactory dysfunction. Prospective clinical research should examine this further to determine if increasing BMI may be a risk factor in olfactory loss and to elucidate what role olfactory loss may play in diet and feeding habits of obese patients.

Functional and morphological olfactory bulb modifications in mice after vanadium inhalation

Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases.

Cross-Cultural Administration of an Odor Discrimination Test

Olfactory sensitivity can be evaluated by various tests, with "Sniffin' Sticks" test (SST) being one of the most popular. SST consists of tests for odor threshold, discrimination, and identification. It seems relatively straightforward to administer threshold tests in different groups and societies and it has been shown that odor identification tests requires special adaptation before they can be administered to various populations. However, few studies have investigated the application of an odor discrimination task in various regions/cultures. In the present study, we compared the discrimination scores of 169 Polish people with the scores of 99 Tsimane', Bolivian Amerindians. The Tsimane' participants scored very low in the discrimination task, despite their general high olfactory sensitivity. This result suggests that when a discrimination task is chosen as the form of olfactory testing, some additional variables need to be controlled. We suggest three sources of low scores of our participants-their cognitive profile, the cultural background, i.e., little knowledge of the odors used in the discrimination test and problems associated with testing environment.

Short-Term Quality-of-Life Changes after Endoscopic Pituitary Surgery Rated with SNOT-22

Objective Little data exist on short-term quality-of-life (QOL) outcomes, specifically sinonasal measures, after endoscopic pituitary surgery. Design Prospective case series assessed sinonasal QOL before and after the transnasal endoscopic approach to the sella with resection of nasal cavity and sinus tissues. Setting/Participants/Main Outcome Measures A total of 39 adults scheduled to undergo resection for a pituitary mass preoperatively completed the Sinonasal Outcome Test-22 (SNOT-22). Rating various QOL issues, testing repeated postoperatively at 1 month by 37 patients and 3 months by 35 patients, was analyzed (paired Student t test). Results SNOT-22 scores (5-point scale; total: 110) averaged 23.4 preoperatively and 27.6 at 1 month but had significantly improved to 16.2 at 3 months (p = 0.03). Emotional well-being parameters (e.g., sadness, frustration, concentration, productivity, fatigue) significantly improved 3 months postoperatively (p < 0.05). Physiologic parameters (e.g., olfaction, obstruction, postnasal drainage) that had worsened at 1 month (< 0.05) then normalized at 3 months. Conclusion Total ratings for sinonasal QOL shows that SNOT scores were comparable between preoperative and 1-month testing but were improved significantly at 3 months. Individual questions showed marked improvement in emotional well-being and temporary physiologic changes after surgery. Our findings give surgeons information about what patients can expect immediately after transnasal endoscopic pituitary surgery.