Article

Olfactory system and emotion: Common substrates

If you want to read the PDF, try requesting it from the authors.

Abstract

THE AIM OF THE REVIEW: A large number of studies suggest a close relationship between olfactory and affective information processing. Odors can modulate mood, cognition, and behavior. The aim of this article is to summarize the comparative anatomy of central olfactory pathways and centers involved in emotional analysis, in order to shed light on the relationship between the two systems. ANATOMY OF THE OLFACTORY SYSTEM: Odorant contact with the primary olfactory neurons is the starting point of olfactory transduction. The glomerulus of the olfactory bulb is the only relay between the peripheral and central olfactory system. Olfactory information is conducted to the secondary olfactory structures, notably the piriform cortex. The tertiary olfactory structures are the thalamus, hypothalamus, amygdala, hippocampus, orbitofrontal cortex and insular cortex. THE IMPACT OF ODORS ON AFFECTIVE STATES: Quality of life is commonly impaired in dysosmic patients. There have, however, been few publications on this topic. EMOTION AND OLFACTION: COMMON BRAIN PATHWAYS: There are brain structures common to emotion and odor processing. The present review focuses on such structures: amygdala, hippocampus, insula, anterior cingulate cortex and orbitofrontal cortex. The physiology and anatomy of each of these systems is described and discussed.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Olfactory stimulants predominantly activate the piriform cortex, insular cortex, amygdala whereas chemosensory trigeminal stimuli, in addition to these areas, also activate the thalamus and substantia nigra ( Joshi et al., 2021 ;Albrecht et al., 2010 ). The olfactory system is related to complex brain functions like emotions or memory ( Soudry et al., 2011 ). These brain functions are mediated by white matter connections between the many "olfactory areas " and higher cognitive processing centers. ...
... More recently, using a constrained spherical deconvolution (CSD) diffusion model Milardi et al. (2017) could visualize the OT directly projecting to the piriform cortex, the entorhinal cortex and the amygdala and furthermore to the orbitofrontal cortex. Fiber tracking within the olfactory system is complicated as the system is intimately connected with other brain regions, e.g., thalamus, cerebellum, and insula ( Soudry et al., 2011 ). Another complication is that some regions that are directly involved in olfaction, such as piriform cortex or the entorhinal cortex, are structurally difficult to delineate. ...
... the orbitofrontal cortex has close relations with the thalamus. However, when it comes to connections between the piriform cortex and the thalamus, not much is known ( Soudry et al., 2011 ). It may be that the thalamus functions as a relay center providing a link between olfactory processing streams from various brain areas, similar to the amygdala, the nucleus accumbens, the anterior cingulate or the somatosensory system ( Courtiol and Wilson, 2015 ) or as in rats, that there is a direct connection between the piriform cortex and the thalamus. ...
Article
Full-text available
Odorous sensations are based on trigeminal and olfactory perceptions. Both trigeminal and olfactory stimuli generate overlapping as well as distinctive activations in the olfactory cortex including the piriform cortex. Orbitofrontal cortex (OFC), an integrative center for all senses, is directly activated in the presence of olfactory stimulations. In contrast, the thalamus, a very important midbrain structure, is not directly activated in the presence of odors, but rather acts as a relay for portions of olfactory information between primary olfactory cortex and higher-order processing centers. The aims of the study were (1) to examine the number of streamlines between the piriform cortex and the OFC and also between the piriform cortex and the thalamus and (2) to explore potential correlations between these streamlines and trigeminal and olfactory chemosensory perceptions. Thirty-eight healthy subjects were recruited for the study and underwent diffusion MRI using a 3T MRI scanner with 67 diffusion directions. ROIs were adapted from two studies looking into olfaction in terms of functional and structural properties of the olfactory system. The “waytotal number” was used which corresponds to number of streamlines between two regions of interests. We found the number of streamlines between the piriform cortex and the thalamus to be higher in the left hemisphere, whereas the number of streamlines between the piriform cortex and the OFC were higher in the right hemisphere. We also found streamlines between the piriform cortex and the thalamus to be positively correlated with the intensity of irritating (trigeminal) odors. On the other hand, streamlines between the piriform cortex and the OFC were correlated with the threshold scores for these trigeminal odors. This is the first studying the correlations between streamlines and olfactory scores using tractography. Results suggest that different chemosensory stimuli are processed through different networks in the chemosensory system involving the thalamus.
... In sensory science, flavor is defined as the ''biological response to chemical [stimuli] by the senses [that is] interpreted by the brain in the context of human experience'' (Heymann et al. 1993). Chemical stimuli are comprised of molecules that bind to either taste receptors on the tongue to produce sweet, sour, salty, bitter, and umami flavors; to oral trigeminal nerve endings that detect astringency or pungency (Roper and Chaudhari 2017); or to aroma receptors in the back of the throat and nasal cavity (Soudry et al. 2011). Aroma, or odor, is the sensation caused by the action of volatile compounds on the olfactory system (Soudry et al. 2011); importantly, these compounds interact rather than act additively to produce perceived aroma (Wang and Seymour 2017). ...
... Chemical stimuli are comprised of molecules that bind to either taste receptors on the tongue to produce sweet, sour, salty, bitter, and umami flavors; to oral trigeminal nerve endings that detect astringency or pungency (Roper and Chaudhari 2017); or to aroma receptors in the back of the throat and nasal cavity (Soudry et al. 2011). Aroma, or odor, is the sensation caused by the action of volatile compounds on the olfactory system (Soudry et al. 2011); importantly, these compounds interact rather than act additively to produce perceived aroma (Wang and Seymour 2017). Flavor perception varies by individual due to variation in number, assortment, and sensitivity of sensory receptors (Klee and Tieman 2018), which can depend on both genetics and habitual diet (Tesileanu 2019). ...
... Flavor perception varies by individual due to variation in number, assortment, and sensitivity of sensory receptors (Klee and Tieman 2018), which can depend on both genetics and habitual diet (Tesileanu 2019). Signals from all activated flavor receptors are processed by the brain; aroma signals are first associated with memories and emotions (Soudry et al. 2011), and then sensory signals are integrated with environmental, historical, and socio-cultural information to create a unified experience of sensation and preference (Lahne 2016). ...
Article
Full-text available
Participatory plant breeding and rapid sensory evaluation are effective techniques for organic cultivar development. Table beet is an important crop for organic growers, and geosmin, a volatile compound which confers earthy aroma, has been suggested as the attribute around which hedonic liking of beet is organized. Open pollinated table beet populations with diverse pigmentation and low (LGC) or high (HGC) geosmin concentration served as starting materials for the first PPB effort in table beet. This project sought to develop consumer-accepted specialty beet cultivars for organic systems and to gauge consumer perception of and preference for geosmin concentration in non-laboratory conditions. LGC and HGC initial populations were significantly different in mean geosmin concentration but not mean TDS. LGC populations diverged significantly in geosmin concentration over two cycles of selection for hedonic liking, due to drift rather than selection. PPB yielded cultivars ‘Evansville Ember’, ‘Snowglobe’, ‘Blushing Not Bashful’, ‘Evansville Orbit’, and ‘Moving Target’. Cultivar novelty and market development were strengthened by chef input and association with a publicly funded seed system development group. Geosmin concentration was not the central determinant of hedonic liking or perceived earthy flavor in table beet. Earthiness was inconsistently associated with geosmin concentration and hedonic liking. Sweetness and bitterness were positively and negatively correlated with liking, respectively, although sweetness was not associated with variation in TDS. Cultivars with a broad range of geosmin concentration were well accepted by consumers, and manipulating expectation—via appearance—may be as powerful as manipulating flavor compounds in influencing liking of table beet.
... Olfactory information passes through the rst central-nervous relay, the olfactory bulb, and is further conducted to the primary olfactory cortex, which then projects to the amygdala, hippocampus, anterior cingulate cortex, insula and orbitofrontal cortex [2;25]. These areas are at the same time involved in many affective functions such as emotional processing and modulation, autonomic regulation included [25]. The volume of the olfactory bulb, a highly plastic structure that sends inhibitory projections to the amygdala, was demonstrated to be reduced in the case of depressed patients [22] and can be generally treated as a biological vulnerability factor for the occurrence and/or maintenance of depression [7]. ...
... The volume of the olfactory bulb, a highly plastic structure that sends inhibitory projections to the amygdala, was demonstrated to be reduced in the case of depressed patients [22] and can be generally treated as a biological vulnerability factor for the occurrence and/or maintenance of depression [7]. Likewise, both the amygdala, a structure responsible for processing aversive stimuli and detection of emotional signals [25] and the hippocampus, a neuroplastic temporal lobe structure responsible for both consolidating and providing an emotional context to memories [25], are identi ed as primary neurobiological structures involved in the pathophysiology of depression [26][27][28]. ...
... The volume of the olfactory bulb, a highly plastic structure that sends inhibitory projections to the amygdala, was demonstrated to be reduced in the case of depressed patients [22] and can be generally treated as a biological vulnerability factor for the occurrence and/or maintenance of depression [7]. Likewise, both the amygdala, a structure responsible for processing aversive stimuli and detection of emotional signals [25] and the hippocampus, a neuroplastic temporal lobe structure responsible for both consolidating and providing an emotional context to memories [25], are identi ed as primary neurobiological structures involved in the pathophysiology of depression [26][27][28]. ...
Preprint
Full-text available
Olfactory loss is associated with symptoms of depression. The present study, conducted on a large cohort of mostly dysosmic patients, aimed to investigate whether improvement in olfactory performance would correspond with a decrease in depression severity and, if so, to what extent. In 171 participants, we assessed olfactory function and severity of depression before and after an average interval of 11 months, with many patients improving in function. Separate analyses were conducted for a) the whole group of patients and b) the group of dysosmic patients in both classic and Bayesian ways. Student t-test demonstrates that the whole sample improved consistently, especially within the group of dysosmic patients in terms of odor identification, and the dysosmic group also improved in terms of odor threshold and olfactory functions in general. Pearson correlation showed that the increase in olfactory functions corresponded with the decrease in depression severity, particularly in dysosmic patients. To conclude, the present study results indicate that symptoms of depression change with olfactory functions in general and odor identification in particular.
... The intimate relationship between the sense of smell and emotions arises in the brain substrates shared between these two cognitive processes [1]. Indeed, once the olfactory information reaches the piriform cortex (PC) (i.e., the primary olfactory cortex), it is then projected to a variety of cortical and subcortical regions involved in memory and emotion. ...
... where the first level analysis (2) allows to infer single subject connectivity parameters θ (1) i of the DCM Γ(.) from the EEG measurements Y i . Here, any uninteresting known effect (e.g., the signal mean) is modeled by a general linear model (GLM) with design matrix X 0 and parameters β i , whereas the observation noise is modeled as residuals ε (1) . The second level analysis (1) gives an estimate of the group level parameters θ (2) by modeling the first-level parameters θ (1) with a GLM having design matrix X. ...
... where the group level parameter distribution p(θ (2) |θ (1) ) is obtained from the average over models m of the second-level GLMs parameters distribution p(θ (2) |θ (1) , m), weighted by their model posterior probability p(m|θ (1) ). Such weightedaverage gives the parameters which best explain the effect of odor valence on connectivity changes. ...
Conference Paper
Full-text available
Olfaction and emotions share common networks in the brain. However, little is known on how the emotional content of odors modulate dynamically the cortico-cortical interactions within these networks. In this preliminary study, we investigated the effect of odor valence on effective connectivity through the use of Dynamic Causal Modeling (DCM). We recorded electroencephalographic (EEG) data from healthy subjects performing a passive odor task of odorants with different valence. Once defined a fully-connected a priori network comprising the pyriform cortex (PC), orbitofrontal cortex (OFC), and entorhinal cortex (EC), we tested the modulatory effect of odor valence on their causal interactions at the group level using the parametric empirical bayes (PEB) framework. Results show that both pleasant and the unpleasant odors have an inhibitory effect on the connection from EC to PC, whereas we did not observe any effect for the neutral odor. Moreover, the odor with positive valence has a stronger influence on connectivity dynamics compared to the negative odor. Although preliminary, our results suggest that odor valence can modulate brain connectivity.
... The cerebellum as well as the ventrolateral thalamus are, inter alia, involved in olfaction 2,14,44 and both structures are relevant for adaptive motor control. Additionally, olfaction and emotion are evolutionarily strongly coupled [45][46][47] . The effect of emotions on motor control are secured, e.g., by the role of the hippocampus 48 and the amygdala 8 . ...
... Olfactory stimuli are processed by different regions as mentioned above. The piriform cortex and the limbic system (amygdala, hippocampus) 5,6 have to be highlighted because of their close connection to olfaction, emotions and motor control [45][46][47]102,103 . Especially with perception of pleasant or disgusting odours, we assume the occurrence of positive or negative emotions, respectively, as was suggested by several authors 1,8,9,16 . ...
Article
Full-text available
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.
... The cerebellum as well as the ventrolateral thalamus are, inter alia, involved in olfaction 2,14,44 and both structures are relevant for adaptive motor control. Additionally, olfaction and emotion are evolutionarily strongly coupled [45][46][47] . The effect of emotions on motor control are secured, e.g., by the role of the hippocampus 48 and the amygdala 8 . ...
... Olfactory stimuli are processed by different regions as mentioned above. The piriform cortex and the limbic system (amygdala, hippocampus) 5,6 have to be highlighted because of their close connection to olfaction, emotions and motor control [45][46][47]102,103 . Especially with perception of pleasant or disgusting odours, we assume the occurrence of positive or negative emotions, respectively, as was suggested by several authors 1,8,9,16 . ...
Article
Full-text available
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.
... Via the olfactory nerve, odor information is sent to the olfactory bulb and the brain. The amygdala and hippocampus, which process odor information, are also part of the limbic system and thus responsible for emotion regulation [67,68]. Through this connection, it is believed that odors can regulate mood and behavior [67]. ...
... The amygdala and hippocampus, which process odor information, are also part of the limbic system and thus responsible for emotion regulation [67,68]. Through this connection, it is believed that odors can regulate mood and behavior [67]. Consequently, air pollution particles might affect the olfactory pathway and also modulate emotion regulation. ...
Article
Full-text available
Background Recent studies showed that air pollution might play a role in the etiology of mental disorders. In this study we evaluated the association between air pollution and mental and self-rated health and the possible mediating effect of physical activity in this association. Methods In 2008, 2013 and 2018 the Belgian Health Interview Survey (BHIS) enrolled 16,455 participants who completed following mental health dimensions: psychological distress, suboptimal vitality, suicidal ideation, and depressive and generalized anxiety disorder and self-rated health. Annual exposure to nitrogen dioxide (NO 2 ), particulate matter ≤ 2.5 µm (PM 2.5 ) and black carbon (BC) were estimated at the participants’ residence by a high resolution spatiotemporal model. Multivariate logistic regressions were carried out taking into account a priori selected covariates. Results Long-term exposure to PM 2.5 , BC and NO 2 averaged 14.5, 1.4, and 21.8 µg/m ³ , respectively. An interquartile range (IQR) increment in PM 2.5 exposure was associated with higher odds of suboptimal vitality (OR = 1.27; 95% CI: 1.13, 1.42), poor self-rated health (OR = 1.20; 95% CI: 1.09, 1.32) and depressive disorder (OR = 1.19; 95% CI: 1.00, 1.41). Secondly, an association was found between BC exposure and higher odds of poor self-rated health and depressive and generalized anxiety disorder and between NO 2 exposure and higher odds of psychological distress, suboptimal vitality and poor self-rated health. No association was found between long-term ambient air pollution and suicidal ideation or severe psychological distress. The mediation analysis suggested that between 15.2% (PM 2.5 -generalized anxiety disorder) and 40.1% (NO 2 -poor self-rated health) of the association may be mediated by a difference in physical activity. Conclusions Long-term exposure to PM 2.5 , BC or NO 2 was adversely associated with multiple mental health dimensions and self-rated health and part of the association was mediated by physical activity. Our results suggest that policies aiming to reduce air pollution levels could also reduce the burden of mental health disorders in Belgium.
... The chemical senses (olfaction and taste) have also received attention in depression research and may provide some of the most interesting insights into the linkage between sensory function and mood. Olfaction is unique from other sensory modalities, in that olfactory inputs largely bypass thalamic relays and have nearly direct projections to brain centers that are implicated in emotional regulation and possibly mood state (Soudry et al. 2011). This direct access to limbic brain centers may be a vestige of the evolutionary importance of chemosensory function for the detection and response to threat, reproductive opportunities, and approach/avoidance of food sources. ...
... The hippocampus and the amygdala, which receive dense projections carrying information from the olfactory system, play a key role in the regulation of emotional learning and memory (Soudry et al. 2011). These structures have been reliably shown to be affected in depression (Yao et al. 2020) which could explain some alterations in the cognitive aspects of olfactory perception, including identification, olfactory learning, or memory during depression (Lemogne et al. 2006). ...
Article
Links between olfactory sensory function and affect have been well established. A robust literature exists in both humans and animals showing that disrupting olfaction sensory function can elicit disordered mood state, including serve as a model of depression. Despite this, considerably less is known regarding the directionality and neural basis of this relationship, e.g. whether disruptions in sensory function precede and contribute to altered mood or if altered mood state precipitates changes in olfactory perception. Further, the neural basis of altered olfactory function in depression remains unclear. In conjunction with clinical studies, animal models represent a valuable tool to understand the relationship between altered mood and olfactory sensory function. Here, we review the relevant literature assessing olfactory performance in depression in humans and in rodent models of depressive-like behavioral states. Rodents allow for detailed characterization of alterations in olfactory perception, manipulation of experiential events that elicit depressive-like phenotypes, and allow for interrogation of potential predictive markers of disease and the cellular basis of olfactory impairments associated with depressive-like phenotypes. We synthesize these findings to identify paths forward to investigate and understand the complex interplay between depression and olfactory sensory function.
... Patients felt alone and isolated (14)(15) and were relieved to find the support of the online community. Some were frustrated with a lack of understanding from others (16) and responses from their physicians, who seemed uninterested (17)(18) and lacked treatment options. Many reported a decline in their mental health (19)(20)(21)(22)(23), and one member was surprised that loss of smell could have such an impact on their mental health (24). ...
... • Theme 1 confirms that the negative emotional and mental health impacts of smell dysfunction, already described in the literature [8,9,18,19], are prominent in those experiencing parosmia and phantosmia. ...
Article
Full-text available
Background The impact of qualitative olfactory disorders is underestimated. Parosmia, the distorted perception of familiar odors, and phantosmia, the experience of odors in the absence of a stimulus, can arise following postinfectious anosmia, and the incidences of both have increased substantially since the outbreak of COVID-19. Objective The aims of this study are to explore the symptoms and sequalae of postinfectious olfactory dysfunction syndrome using unstructured and unsolicited threads from social media, and to articulate the perspectives and concerns of patients affected by these debilitating olfactory disorders. Methods A thematic analysis and content analysis of posts in the AbScent Parosmia and Phantosmia Support group on Facebook was conducted between June and December 2020. Results In this paper, we identify a novel symptom, olfactory perseveration, which is a triggered, identifiable, and usually unpleasant olfactory percept that persists in the absence of an ongoing stimulus. We also observe fluctuations in the intensity and duration of symptoms of parosmia, phantosmia, and olfactory perseveration. In addition, we identify a group of the most common items (coffee, meat, onion, and toothpaste) that trigger distortions; however, people have difficulty describing these distortions, using words associated with disgust and revulsion. The emotional aspect of living with qualitative olfactory dysfunction was evident and highlighted the detrimental impact on mental health. Conclusions Qualitative and unsolicited data acquired from social media has provided useful insights into the patient experience of parosmia and phantosmia, which can inform rehabilitation strategies and ongoing research into understanding the molecular triggers associated with parosmic distortions and research into patient benefit.
... The sense of smell, one of the most primitive human sensory modalities, is closely related to emotions [1]. Processing of emotions and smell share neuroanatomical commonalities, including the amygdala, insula, anterior cingulate cortex, and orbitofrontal cortex [2]. Apathy and smell dysfunction (SD) are both prevalent in people with Parkinson's disease (PD) [3]. ...
... The sense of smell in humans has been linked to emotions and associated behavior through an evolutionary mechanism [7]. The brain circuitry associated with apathy shares a neuroanatomical pathway with olfaction [2]. Clinically, a relationship between apathy and smell has been shown to exist in patients with probable Alzheimer's disease. ...
Article
Background Apathy remains a disabling symptom in Parkinson's disease (PD) with limited therapeutic success. Processing of emotions and smell share neuroanatomical and evolutionary pathways. Objective To explore the association of apathy with smell dysfunction (SD) in early PD. Methods We analyzed patients with de-novo PD, with follow-up of at least 5 years from the Parkinson's Progression Markers Initiative. SD and apathy were defined using University of Pennsylvania Smell Identification Test and MDS-UPDRS part 1A. Odds ratios were calculated between apathy and olfaction groups. Kaplan-Meier survival analysis was grouped by presence/ absence of smell dysfunction. The Log Rank test was used to compare time to apathy. Results We found no association between presence of apathy in patients with and without SD (OR 1.01 [0.49–2.08]). There was no significant difference between PD patients with and without SD in time to apathy (p = 0.72). Conclusions SD does not portend greater risk of apathy in PD.
... Research has shown that unpleasant odours are perceived faster (Bensafi et al. 2002), and are processed earlier in the brain (Croy et al. 2013b) than pleasant odours. As compared to other sensory modalities, olfaction seems to be more closely connected to areas of the brain that are traditionally involved in emotional reactivity, as it has direct connections with the limbic system (Soudry et al. 2011; and see Walliczek-Dworschak and Hummel 2017, Figure 2). The olfactory system, differently from other senses, projects ipsilaterally, and most fibres bypass the thalamus and project directly into the amygdala, piriform cortex, and entorhinal cortex (Gottfried 2006). ...
... Although the authors attribute the differences between to possible habituation or to time-dependent effects that could be at play in study one, future better-powered replication studies are warranted. Taken together, these results stack up in favour of a functional connection between olfaction and disgust (Soudry et al. 2011;Stevenson 2010). ...
... Mental clouding might affect olfactory function through several mechanisms, particularly during the phase of identification and discrimination of the odors [40,41]; the temporary loss of memory could interfere with the identification of the perceived smell, with consequent diagnosis of anosmia due to poor scores in the Sniffin' test [9]. On the other hand, due to anatomical connections between olfactory bulbs and frontal cortex (trough pyriform cortex), the inflammation of the frontal lobe might also affect the orbitofrontal cortex, amygdala, hypothalamus, insula, entorhinal cortex, and hippocampus, areas involved in emotion and memory [42,43]. In addition, the connection between a negative emotion and the smelled odors during the test might be responsible for the parosmia referred by the patients [12]. ...
Article
Full-text available
Background: Smell alteration and cognitive impairment are common features of the Long-COVID Syndrome. Mental clouding, often described as brain fog might affect smell by al-tering recollection of odors or through a share mechanism of neuroinflammation. We investigated mental clouding, headache, and cognitive function in adult patients with persistent COVID-19 olfactory dysfunction. Methods: This multi-center cross-sectional study enrolled 152 adults with self-reported olfactory dysfunction from 3 tertiary centers specialized in COVID-19 olfactory disorders. Inclusion criteria were smell alteration after COVID-19 persisting over 6 months from infection. Exclusion criteria included smell alteration, headache, or memory problems prior to COVID-19 infection. The patients were evaluated by olfactometry, nasal endoscopy, headache scale, cognitive assessment, Mini Mental State Examination (MMSE) and self-reported measures. Smell dysfunction was stratified and classified based on olfactory deficit severity and presence of olfactory distortion (parosmia, cacosmia). Data on smell disorder, mental clouding, MMSE, and headache were analyzed to assess correlations. Results: Among the 152 patients studied, fif-ty (32.8 %) presented with anosmia, 25 (16.4 %) with hyposmia (Figure 1), 10 (6.6%) with paros-mia/cacosmia, and 58 patients (38.2%) with a combination of hyposmia and parosmia; 7 (4.6%) patients suffered from headache exclusively and two (1.4%) had headache and mental clouding as their primary symptom. Headache was reported by 76 (50%) patients, and mental clouding by 71 (46.7%). The patients reporting headache, mental clouding, or both had significantly increased risk of suffering from anosmia and/or hyposmia when compared with their counterparts without these neurological symptoms. No patients had reduced MMSE scores. Conclusion: In our cohort of adult patients with post-COVID-19, smell alterations persisting over 6 months, cognitive im-pairment and headache were associated with more severe olfactory loss, consistent with neuroin-flammatory mechanisms mediating a variety of Long-COVID symptoms.
... The same pattern of diagnosis by sex effects was observed in the olfactory cortex. Besides its key role in olfaction, this structure was found to be involved in emotional regulation (78). The presence of physiological sexual dimorphism on the area is not surprising, since literature evidence reports sex-related differences in olfactory ability and related pathways (79,80), although there is no specific evidence regarding the olfactory cortex itself (79,81). ...
Article
Full-text available
Major Depressive Disorder (MDD) is a disabling illness affecting more than 5% of the elderly population. Higher female prevalence and sex-specific symptomatology have been observed, suggesting that biologically-determined dimensions might affect the disease onset and outcome. Rumination and executive dysfunction characterize adult-onset MDD, but sex differences in these domains and in the related brain mechanisms are still largely unexplored. The present pilot study aimed to explore any interactions between adult-onset MDD and sex on brain morphology and brain function during a Go/No-Go paradigm. We hypothesized to detect diagnosis by sex effects on brain regions involved in self-referential processes and cognitive control. Twenty-four subjects, 12 healthy (HC) (mean age 68.7 y, 7 females and 5 males) and 12 affected by adult-onset MDD (mean age 66.5 y, 5 females and 7 males), underwent clinical evaluations and a 3T magnetic resonance imaging (MRI) session. Diagnosis and diagnosis by sex effects were assessed on regional gray matter (GM) volumes and task-related functional MRI (fMRI) activations. The GM volume analyses showed diagnosis effects in left mid frontal cortex ( p < 0.01), and diagnosis by sex effects in orbitofrontal, olfactory, and calcarine regions ( p < 0.05). The Go/No-Go fMRI analyses showed MDD effects on fMRI activations in left precuneus and right lingual gyrus, and diagnosis by sex effects on fMRI activations in right parahippocampal gyrus and right calcarine cortex ( p < 0.001, ≥ 40 voxels). Our exploratory results suggest the presence of sex-specific brain correlates of adult-onset MDD–especially in regions involved in attention processing and in the brain default mode–potentially supporting cognitive and symptom differences between sexes.
... Dans ce cadre, un contact entre une/des molécules odorantes et un système olfactif peut potentiellement provoquer une/des sensations mais ce processus ne s'arrête pas là, car ces sensations peuvent se transformer en émotions telles que : la peur, la joie par le fait que notre esprit va ajouter à ces sensations le « j'aime »,/ « j'aime pas ». De plus, notre nez est directement relié à la partie du cerveau qui contrôle la réponse émotionnelle (Soudry et al. 2011, Quercia et al. 2016. Pour comprendre ce mécanisme nous devons faire appel à la neurophysiologie qui décrit la façon dont est traitée l'information olfactive : d'abord par le système limbique (une des parties du cerveau la plus vieille du point de vue de l'évolution), et ensuite par les parties du néocortex, spécialement dans l'hémisphère droit. ...
... 6) Cognitive System Assignment: In order to calculate the integration coefficient for each node of the network, based on previous literature, 28 regions of interest (ROIs) involved in olfactory perception, emotion and reward processing were selected [17], [18], [19], [20]. Based on literature evidence on their predominant function, these ROIs were assigned to one system, out of the 3 possible systems: olfactory, emotion and reward. ...
Conference Paper
Olfactory hedonic perception involves complex interplay among an ensemble of neurocognitive systems implicated in sensory, affective and reward processing. However, the mechanisms of these inter-system interactions have yet to be well-characterized. Here, we employ directed functional connectivity networks estimated from source-localized EEG to uncover how brain regions across the olfactory, emotion and reward systems integrate organically into cross-system communities. Using the integration coefficient, a graph theoretic measure, we quantified the effect of exposure to fragrance stimuli of different hedonic values (high vs low pleasantness levels) on inter-systems interactions. Our analysis focused on beta band activity (13-30 Hz), which is known to facilitate integration of cortical areas involved in sensory perception. Higher-pleasantness stimuli induced elevated integration for the reward system, but not for the emotion and olfactory systems. Furthermore, the nodes of reward system showed more outward connections to the emotion and olfactory systems than inward connections from the respective systems. These results suggest the centrality of the reward system-supported by beta oscillations-in actively coordinating multi-system interactivity to give rise to hedonic experiences during olfactory perception.
... Scholars have therefore observed that the lack of a stable lexicon of olfaction might be due to the relatively poor neural connections between those areas devoted to language processing and the sub-cortical limbic structures (Burdach 1988; see Olofsson and Gottfried 2015, for a neurocognitive framework for olfactory language). The above evidence supports the link between olfaction and emotions, as certain cerebral substrates are, in fact, common to both emotional and olfactory processing, such as the amygdala, hippocampus, insula, and anterior cingulate cortex (Soudry et al. 2011). These areas are variously connected to instinctive behaviours that are necessary for survival, emotional regulation, and memory. ...
Chapter
Odour-sound correspondences provide some of the most fascinating and intriguing examples of crossmodal associations, in part, because it is unclear from where exactly they originate. Although frequently used as similes, or figures of speech, in both literature and poetry, such smell-sound correspondences have recently started to attract the attention of experimental researchers too. To date, the findings clearly demonstrate that the majority of non-synaesthetic individuals associate orthonasally-presented odours with various different sound properties, e.g., pitch, instrument type, and timbre, in a non-random manner. What is more, these auditory-olfactory associations exhibit a number of features that are common to other crossmodal associations, such as their consistency over time, and their bidirectionality. However, the psychological mechanism(s) underpinning these associations in the general population remain(s) unclear, with a number of distinct hypotheses having been put forward over the years. In this chapter, we consider auditory-olfactory associations in art and science, focusing on poetry, music composition, and performance. First, we provide examples of the use of auditory-olfactory synaesthetic metaphors in poetry, from William Shakespeare through to Romanticism, illustrating how crossmodal associations have appeared in literature for centuries. Then, we move on to focus on music composition and performance, describing a number of examples where auditory stimuli have been purposely matched with crossmodally corresponding olfactory and/or visual stimuli. Considering the scientific study of smell-sound correspondences, we review the key psychophysical studies demonstrating that, beyond the artistic context, robust and non-random crossmodal associations are also triggered in the majority of the general population. We discuss a number of hypotheses that have been put forward over the years to account for such associations, focusing on the idea that certain correspondences between olfactory and auditory stimuli are mediated by the emotional character of the component stimuli.
... Paired OBs are the first stations in the olfactory pathway that transduce odorant information from olfactory neuron receptors to the primary olfactory cortex i.e. the piriform cortex of the brain (2). This processed information is then transferred to several brain areas, such as the orbitofrontal cortex, amygdala, hypothalamus, insula, ent orhinal cortex, and hippocampus (3). Main OB functions are organized into four groups: odour distinction, enhancing odour detection, removing some background odours, and letting upper brain regions modify detection and discrimination of odours (4). ...
Article
Full-text available
The Olfactory bulb is a crucial structure involved in olfaction that is located in the ventral anterior of the forebrain. Due to physiological and anatomical connection between olfactory and emotion processing networks, olfactory dysfunction is seen in some psychiatric disorders. Strong evidences suggest that olfactory bulb volume can mirror olfactory system function. Due to this correlation, there has been an interest to investigate the possible correlation between reduction of olfactory bulb volume and some neuropsychiatric disorders. Nowadays, mental disorders are mostly diagnosed according to behavioural symptoms. Gradual progression of mental disorders and delayed onset of behavioral symptoms have increased the importance of finding objective biomarkers. Such biomarkers can improve treatment outcome, accuracy of diagnosis, and prognosis. It is hypothesized that the reduction of olfactory bulb volume could be a biomarker for some disorders. In this article, we reviewed studies on the association of olfactory bulb volume with depression, Alzheimer’s disease, Parkinson’s disease, migraine, and multiple sclerosis.
... The olfactory bulb (OB) processes information and sends it to other parts of the central nervous system after complex signal encoding and transmission (Martines-Marcos, 2009). The primary (piriform cortex, olfactory nucleus and tubercle, amygdala, and entorhinal cortex) and secondary (hippocampus, hypothalamus, thalamus, orbitofrontal cortex, and cerebellum) olfactory regions are responsible for olfaction, emotion, mood, cognition, and many other processes (Soudry et al., 2011;Zhou et al., 2019). In MDD, neuronal and glial degeneration have been reported in the frontolimbic brain regions, such as the prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex, amygdala, and hippocampus (Bremner et al., 2000). ...
Article
Full-text available
Olfactory disorders may be observed together with cognitive impairment in patients with major depressive disorder (MDD). This study compared olfactory performances between patients with MDD and healthy controls and investigated the relationship between olfactory performance and subjective cognitive impairment in these patients. This study included 52 patients diagnosed with MDD and 46 healthy controls. The participants were evaluated in terms of their olfactory capacities (threshold, discrimination, and identification), subjective cognitive impairment, and depression. Although the olfactory threshold (OT) and olfactory discrimination scores were lower in patients with MDD compared with those in the control group, their olfactory identification scores did not differ significantly. OT was negatively correlated with subjective cognitive impairment and may serve as a determinant for subjective cognitive changes. Consequently, patients with MDD had lower olfactory performances compared with healthy controls. Finally, OT may be a component of subjective cognitive impairment in MDD.
... Olfactory dysfunction could also be disease-specific as suggested in a comparative study between bipolar, depressive and schizophrenic patients (Li et al., 2021). However, some brain areas such as amygdala, hippocampus, insula, anterior cingulate cortex and orbitofrontal cortex, involved in the above-mentioned psychiatric disordersespecially mood disorders -are linked to the olfactory system in relation to odor hedonic perception (e.g., Soudry et al., 2011). This relationship warrants further experimental studies on odor pleasantness ratings. ...
Article
Full-text available
Odor hedonic evaluation (pleasant/unpleasant) is considered as the first and one of the most prominent dimension in odor perception. While sex differences in human olfaction have been extensively explored, gender effect in hedonic perception appears to be less considered. However, a number of studies have included comparisons between men and women, using different types of measurements (psychophysical, psychophysiological,…). This overview presents experimental works with non-specific and body odors separately presented as well as experimental studies comparing healthy participants vs patients with psychiatric disorders. Contrary to sensitivity, identification or discrimination, the overall literature tends to prove that no so clear differences occur in odor hedonic judgment between men and women. On the whole, gender effect appears more marked for body than non-specific odors and is almost never reported in psychiatric diseases. These findings are discussed in relation to the processes classically implied in pleasantness rating and emotional processes.
... In light of the above, The Linguistics of Olfaction can be seen as a benchmark in the exploration of olfactory language, and thus of olfaction itself, an often downplayed sensory modality that is deeply connected with our cognitive activities (Holley 1999: 180-181), emotions (Soundry et al. 2011), and memories (Strauch et al. 2019). Consequently, it contributes to the expanding field of sensory linguistics (cf. ...
... Accordingly, anatomical studies uncovered overlapping brain regions that are involved in both olfactory processing and the etiology of depression, and thus are implicated in a bidirectional relationship between olfaction and depression. These brain structures are mainly the hippocampus, the amygdala, the orbitofrontal cortex, the cingulate cortex, the insula, and the thalamus [69,70]. Therefore, the strong link between olfaction and depression, as well as the anatomical overlap and shared neural connections between the olfactory and limbic systems, allow us to hypothesize that the olfactory impairments observed in our animal model might be influenced from depressive effects and reduced hippocampal neuroplasticity induced by chronic thinner inhalation. ...
Article
Volatile solvents exposure can result in various behavioral impairments that have been partly associated to altered adult hippocampal neurogenesis. Despite recent evidence supporting this association, few studies have been devoted to examine the impact on olfactory functioning and olfactory bulb (OB) neurogenesis, although olfactory system is directly in contact with volatile molecules. Thus, this study was designed to evaluate in adult mice the potential modifications of the olfactory functioning after acute (1 day), subchronic (6 weeks) and chronic (12 weeks) exposure to thinner vapor at both behavioral and cellular levels. Firstly, behavioral evaluations showed that chronic thinner exposure impacts on odor detection ability of treated mice but does not affect mice ability to efficiently discriminate between two different odors. Moreover, chronic thinner exposure produces impairment in the olfactory-mediated associative memory. Secondly, analysis of the effects of thinner exposure in the subventricular zone (SVZ) of the lateral ventricle and in the OB revealed that thinner treatments do not induce apoptosis nor glial activation. Thirdly, immunohistochemical quantification of different markers of adult olfactory neurogenesis showed that inhalant treatments do not change the number of proliferating progenitors in the SVZ and the rostral migratory stream (RMS), as well as the number of newborn cells reaching and integrating in the OB circuitry. Altogether, our data highlight that the impaired olfactory performances in chronically-exposed mice are not associated to an alteration of adult neurogenesis in the SVZ-OB system.
... Among these, the piriform cortex (PC), i.e., the primary olfactory cortex, is a deep structure in the brain. Moreover, other structures involved in olfaction, such as the amygdala (AM) and hippocampus (HIP) are even deeper [75,76,77]. Accordingly, the activity recorded with EEG is more likely to derive from projections of these brain areas onto the cortex rather than from their direct activation. ...
Article
Objective: The emotional response to olfactory stimuli implies the activation of a complex cascade of events triggered by structures lying in the limbic system. However, little is known about how this activation is projected up to cerebral cortex and how different cortical areas dynamically interact each other. Approach: In this study, we acquired EEG from human participants performing a passive odor-perception task with odorants conveying positive, neutral and negative valence. A novel methodological pipeline integrating global Field Power (GFP), Independent Component Analysis (ICA), dipole source localization was applied to estimate effective connectivity in the challenging scenario of single-trial low-synchronized stimulation. Main results: We identified the brain network and the neural paths, elicited at different frequency bands, i.e., θ (4-7Hz), α (8-12 Hz) and β (13-30Hz), involved in odor valence processing. This brain network includes the orbitofrontal cortex (OFC), the cingulate gyrus (CgG), the superior temporal gyrus (STG), the posterior cingulate cortex/precuneus (PCC/PCu) and the parahippocampal gyrus (PHG). It was analyzed using a time-varying multivariate autoregressive model to resolve time-frequency causal interactions. Specifically, the OFC acts as the main node for odor perception and evaluation of pleasant and unpleasant stimuli, whereas no specific path was observed for a neutral stimulus. Significance: The results introduce new evidences on the role of the OFC during hedonic perception and underpin its specificity during the odor valence assessment. Our findings suggest that, after the odor onset different, bidirectional interactions occur between the OFC and other brain regions associated with emotion recognition/categorization and memory according to the stimulus valence. This outcome unveils how the hedonic olfactory network dynamically changes based on odor valence.
... (vi). The close anatomic relationships between the systems deployed for olfaction and for emotion [44] account for the important links found between these two functions [45][46][47][48][49]. More than any other sensory modality, olfaction is like emotion in attributing positive (appetitive) or negative (aversive) valence to the environment. ...
Article
Full-text available
Electronic nose (E-nose) devices represent one of the most trailblazing innovations in current technological research, since mimicking the functioning of the biological sense of smell has always represented a fascinating challenge for technological development applied to life sciences and beyond. Sensor array tools are right now used in a plethora of applications, including, but not limited to, (bio-)medical, environmental, and food industry related. In particular, the food industry has seen a significant rise in the application of technological tools for determining the quality of edibles, progressively replacing human panelists, therefore changing the whole quality control chain in the field. To this end, the present review, conducted on PubMed, Science Direct and Web of Science, screening papers published between January 2010 and May 2021, sought to investigate the current trends in the usage of human panels and sensorized tools (E-nose and similar) in the food industry, comparing the performances between the two different approaches. In particular, the focus was mainly addressed towards the stability and shelf life assessment of olive oil, the main constituent of the renowned “Mediterranean diet”, and nowadays appreciated in cuisines from all around the world. The obtained results demonstrate that, despite the satisfying performances of both approaches, the best strategy merges the potentialities of human sensory panels and technological sensor arrays, (i.e., E-nose somewhat supported by E-tongue and/or E-eye). The current investigation can be used as a reference for future guidance towards the choice between human panelists and sensorized tools, to the benefit of food manufacturers.
... The results of this study were also supported by brain science research. Odour and emotional brain studies have found that smells have the same effects on the brain as emotions, and that a smell (especially aroma) stimulus may activate the insula, anterior cingulate and orbitofrontal cortex, which are the areas closely related to emotions (Soudrya et al., 2011). In this study, the effect of aromatic odours on academic emotional improvement may also be due to the fact that teenagers are more sensitive to odours (Larsson et al., 2009). ...
Article
Full-text available
This study investigated the influence of ambient aroma on the academic emotions experienced by middle school students in a practical educational environment. The study was conducted with pre‐ and post‐test experimental design upon subjects in three parallel classes (n = 109) in grade two of a junior school in China. These classes were randomly assigned to one of three experimental conditions (no aroma, daily aroma or aroma every other day). The academic emotions of the students were measured twice using the Adolescent Academic Emotion Questionnaire, once before and once 8 weeks after the use of aromatherapy. Comparison of the change in ratings from baseline to post‐test showed that compared to the control class; joy, hope, positive high‐arousal academic emotion and relaxation were significantly higher in ambient aroma conditions, and anger and negative high‐arousal academic emotion in these conditions were significantly lower. The results suggest that the ambient aroma of sweet orange essential oil can mitigate the reduction in positive academic emotion and improve negative academic emotion in school students over time.
... Moreover, anxiety and olfaction may have common cerebral substrates. Earlier studies have reported a close relationship between olfactory and emotional processing, as they share a common brain pathway (31). The hippocampus (32) and amygdala (33) in the primary olfactory cortex, as well as the insula (34) and the orbitofrontal cortex (35) in the secondary olfactory cortices, may play key roles in encoding, learning, and regulating emotions, especially negative emotions such as sadness, unhappiness, and rage (33). ...
Article
Full-text available
Background Olfactory hallucination refers to olfactory perception in the absence of chemical stimuli. Although it has been associated with many neurological and psychotic disorders, it has rarely been reported as the first and only symptom in patients with anxiety disorder, and its treatment remains inadequate. Case summary A 66-year-old woman who had been experiencing gradually worsening olfactory hallucinations for almost 4 years was diagnosed with generalized anxiety disorder. Olfactory hallucination disappeared after treatment with anti-anxiety drugs. Conclusion Olfactory hallucination can be the first and only symptom in patients with anxiety disorder and may be effectively treated with anti-anxiety medication. In fact, it can precede the diagnosis of anxiety disorder by several years.
... Finally, given the tight relationship between olfaction and emotions (Soudry et al., 2011), emotional competence was assessed through the measure of alexithymia levels. Participants completed the Bermond-Vorst Alexithymia Questionnaire, form B (BVAQ-B; Bermond and Oosterveld, 1994) which consists of 20 items rated on a 5-point scale with total scores ranging from 20 to 100; participants with a score above 53 are considered alexithymic. ...
Article
Background Diminished olfactory functioning has been reported in depression, whereas evidence in anxiety disorders is still controversial. Olfactory meta-cognitive abilities (i.e., olfactory awareness, imagery and reactivity, and the importance of odors) are essential in shaping olfaction. Few studies examined these meta-cognitive abilities in relation to depressive, anxiety, and social anxiety symptoms, and none of them considered the awareness of social odors (i.e., body odors). Methods This pre-registered study examined the relationship between olfactory meta-cognitive abilities and symptoms of depression, general anxiety, and social anxiety in 429 individuals. Self-report measures of symptoms of depression, general anxiety, and social anxiety, along with self-report olfactory meta-cognitive scales, were collected using an online survey. Results Linear regression analyses revealed that olfactory awareness and importance of common odors were significantly directly predicted by symptoms of general anxiety, while affective importance to odors was negatively predicted by symptoms of depression. Regarding social odors, higher symptoms of depression and lower symptoms of social anxiety predicted increased awareness. Limitations Higher prevalence of women and narrow age range of the participants. Depressive and anxiety symptoms were assessed only with self-report questionnaires. Conclusions Symptoms of anxiety seem to be associated with higher levels of common odor awareness, corroborating the importance of olfactory functions in anxiety. In addition, results on social odors seem to reflect dysfunctional social behaviour that characterized symptoms of depression and social anxiety. Hence, the assessment of meta-cognitive abilities may represent a useful tool in the prevention and assessment of depressive, anxiety, and social anxiety symptoms.
... To the best of our knowledge, no previous studies have examined the spatiotemporal dynamics of odor representations in the whole brain during this period. Spatially, the regions shown to represent odor information in the current study are known to be involved in odor processing in general (51), the hedonic aspect of odors (52), and odor identification (53), as well as having functional connectivity with the POA (15). The dominance of the right hemisphere seen in our results ( Fig. 4 and SI Appendix, Fig. S5) was also consistent with a meta-analysis of human neuroimaging studies on odor hedonic judgment (54,55). ...
Article
Significance To elucidate when and where in the brain different aspects of odor perception emerge, we decoded odors from an electroencephalogram and associated the results with perception and source activities. The odor information was decoded 100 ms after odor onset at the earliest, with its signal sources estimated in and around the olfactory areas. The neural representation of odor unpleasantness emerged 300 ms after odor onset, followed by pleasantness and perceived quality at 500 ms. During this time, brain regions representing odor information spread rapidly from the olfactory areas to regions associated with emotional, semantic, and memory processing. The results suggested that odor perception emerges through computations in these areas, with different perceptual aspects having different spatiotemporal dynamics.
... There is no doubt that odor is also an important factor for indoor air environment [32][33][34]. In light of the revelation that the olfactory system is directly connected to the limbic structures which are known to control a human being's mood and memory [35][36][37], the psychological and physiological effects of odor have been studied in various fields recently [38][39][40]. Unlike other indoor environmental factors such as indoor temperature and CO 2 concentration, there is a preference for odor. ...
Article
Full-text available
Indoor environment has an appreciable impact on occupants' mood, health and performance. Among numerous indoor environmental components, indoor air quality is often considered to be one of the most crucial ones. While odor is a decisive factor for evaluating perceived indoor air quality, its effects - particularly the positive effects of pleasant aromas - on human responses and performance have yet to be revealed. In this study, experiments were conducted to investigate the effect of indoor aroma on students' mood and learning performance. Participants comprised 76 university students and they performed two learning tasks under one of the four odor conditions: “control (aromaless)”, “rosemary”, “lemon”, and “peppermint.” First, the way in which students sense the indoor aroma in a study space was investigated using several mood scales, including odor intensity, pleasantness, preference, acceptability, and impression. Second, the influence of indoor aroma on learning and memory performance was quantitatively assessed using a reading task and a verbal memory task. Lastly, the impacts of odor preference on subjective evaluation and performance were explored. This experiment showed that subjective evaluations were significantly different before and after olfactory adaptation, particularly in the rosemary condition. Of all three aroma conditions, the lemon aroma had the highest preference and led to the highest scores in the memory task. Although the significant impact of indoor aroma on learning performance was not detected, our results indicated that pleasant aroma has the potential to enhance students’ mood and learning performance.
... However, smells travel directly to the limbic system that houses the amygdala, where we process emotions, and the hippocampus, where our learning and memory formations occur (Firestein 2001). This strong connection between smells and our emotions can be observed by the manifestation of depressive episodes following the development of olfactory disorders (Soudry et al. 2011). Similarly, olfactory-based memories can induce a powerful emotional response when triggered (Tischler and Clapp 2020). ...
Article
Full-text available
The link between nature and human wellbeing is well established. However, few studies go beyond considering the visual and auditory underpinnings of this relationship, even though engaging with nature is a multisensory experience. While research linking smell to wellbeing exists, it focuses predominantly on smells as a source of nuisance/offence. Smells clearly have a prominent influence, but a significant knowledge gap remains in the nexus of nature, smell, and wellbeing. Here, we examine how smells experienced in woodlands contribute to wellbeing across four seasons. We show that smells are associated with multiple wellbeing domains, both positively and negatively. They are linked to memories, and specific ecological characteristics and processes over space/time. By making the link between the spatiotemporal variability in biodiversity and wellbeing explicit, we unearth a new line of enquiry. Overall, the multisensory experience must be considered by researchers, practitioners, policy-makers and planners looking to improve wellbeing through nature.
... It is therefore conceivable that CORT-induced prolonged distress reinforce the anorexic action of this basal ganglia-like network, and that PEA inhalation may act like a silencing agent in order to relieve the inhibition on food intake. It is well documented that olfactory processing involves a large number of strongly interconnected brain regions that incorporate complex overlapping networks [86], thus creating functional interactions between neural circuits controlling emotional and feeding processes [98][99][100][101]. Therefore, it cannot be excluded that the OB neural activity changes could originate from a differential action of centrifugal systems [102,103] occurring upon CORT administration and PEA exposure. ...
Preprint
Full-text available
Chronic distress-induced hypothalamic-pituitary-adrenal axis deregulations have been associated with the development of neuropsychiatric disorders such as anxiety and depression. Currently available drugs treating such pathological conditions have limited efficacy and diverse side effects, revealing the need of new safer strategies. Aromatic plant-based compounds are largely used in herbal medicine due to their therapeutic properties on mood, physiology, and general well-being. The purpose of this study was to investigate the effects of 2-phenylethyl alcohol (PEA), one of the pharmacologically active constituents of rose essential oil, on chronic corticosterone (CORT)-induced behavioral and neurobiological changes in female mice. Animals followed a prolonged PEA inhalation exposure (30 min per day) for 15 consecutive days prior to behavioral evaluation with open-field, forced swim and novelty-suppressed feeding tests. CORT treatment induced an anxio-depressive-like phenotype, evidenced by a reduced locomotor activity in the open-field, and an increased latency to feed in the novelty-suppressed feeding paradigms. To elucidate the neural correlates of our behavioral results, cerebral cFos expression analysis was further performed to provide a global map of neuronal activity. The altered feeding behavior was accompanied by a significant decrease in the number of cFos-positive cells in the olfactory bulb, and altered brain connectivity as shown by cross-correlation-based network analysis. CORT-induced behavioral and neurobiological alterations were reversed by prolonged PEA inhalation, suggesting a therapeutic action that allows regulating the activity of neural circuits involved in sensory, emotional and feeding behaviors. These findings might contribute to better understand the therapeutic potential of PEA on anxio-depressive symptoms.
... der Bulbus olfactorius, entorhinaler und piriformer Cortex, sowie übergeordnete Zentren wie z.B. Hippocampus und orbitofrontaler Cortex (OFC) (Moessnang et al., 2011, Soudry et al., 2011. Es bestehen zudem relevante Verbindungen zwischen limbischem und olfaktorischem System (Ille et al., 2015). ...
Thesis
Hintergrund und Ziele Neben den motorischen Symptomen sind nicht-motorische Symptome (NMS) des idiopathischen Parkinson-Syndroms (IPS) in den letzten Jahren zunehmend in den Fokus gerückt (Pont-Sunyer et al., 2015, Pfeiffer, 2016). Anhedonie, die Unfähigkeit Freude und Lust zu empfinden, ist ein häufiges NMS (46%) bei IPS Patienten (Lemke et al., 2005), welches auch unabhängig von einer Depression (Isella et al., 2003, Spalletta et al., 2013) auftreten kann. Wir konnten im Rahmen einer “proof-of-principle“ Studie zeigen, dass Patienten mit IPS ihnen präsentierte Gerüche weniger un-/angenehm beurteilten und somit eine Reduktion des affektiven Beurteilungsspektrums vorlag, selbst nachdem für Hyposmie kontrolliert wurde. Zudem zeigte sich eine Korrelation mit der durch validierte Fragebögen erfassten Anhedonie, jedoch nicht mit einer Depression (Mrochen et al., 2016). Da die unabhängige Erfassung von Anhedonie und Depression unter Berücksichtigung der Vorgaben des DSM-V (American-Psychiatric-Association, 2013) durch Überlappung mit somatischen Symptomen des IPS möglicherweise verfälscht wird, könnte eine akkurate, fragebögenunabhängige Erfassung der Anhedonie bei IPS Patienten einen Beitrag zu einer zielgerichteten Diagnostik und Therapie der NMS leisten. In dieser Studie soll, zusätzlich zur Evaluation olfaktorischer Stimuli, die affektive Wahrnehmung von akustischen und visuellen Reizen beim IPS untersucht werden. 3 Folgende Hypothesen werden überprüft: 1. Hypothese: Beim IPS liegt eine multisensorische Störung der affektiven Wahrnehmung vor. 2. Hypothese: Die affektive Evaluation sensorischer Stimuli korreliert mit psychometrischen Fragebögen der Anhedonie. 3. Hypothese: Ein eingeschränktes affektives Beurteilungsvermögen kann beim IPS unabhängig von depressiven Symptomen auftreten. Methoden Die Diagnose eines IPS erfolgte anhand der Leitlinie der Deutschen Gesellschaft für Neurologie (DGN) (DGN, 2016) in Anlehnung an die Kriterien der „UK Parkinson's Disease Society Brain Bank“ (Hughes et al., 1992) und der Movement Disorder Society (MDS) (Postuma et al., 2015). Alle Patienten wurden mit dem Teil III der Unified Parkinson´s Disease Rating Scale (UPDRS-III) (Goetz et al., 2008, Martinez-Martin et al., 2013) und der Hoehn und Yahr (H&Y)-Skala (Hoehn and Yahr, 1967, Goetz et al., 2004) bezüglich motorischer Symptome und Erkrankungsstadium beurteilt. Kontrollen wurden eingeschlossen, wenn kein Anhalt für Symptome eines prodromalen IPS bestand (Berg et al., 2015). Es erfolgte die Bestimmung von Hörschwelle, Nah- und Fernvisus. Der kognitive Status wurde durch das Montreal Cognitive Assessment (MoCA) (Nasreddine et al., 2005) erfasst. Mittels 16-er Sniffin Sticks® Identifikationstest (Sniffin ID) (Sniffin ID Test ©, Burghart Messtechnik, Deutschland) wurde eine Einordnung in hyposmisch bzw. normosmisch vorgenommen (Hummel et al., 2007). Beck Depression Inventory (BDI) (Aaron T. Beck 1988), Snaith-Hamilton-Pleasure-Scale D (SHAPS-D) (Franz et al., 1998), Temporal Experience of Pleasure Scale (TEPS) (Gard et al., 2006) und Starkstein Apathie Skala (SAS) (Starkstein et al., 1992b) wurden zur Erfassung depressiver Symptome (BDI), der Anhedonie (SHAPS und TEPS) und Apathie (SAS) herangezogen. Zur Erfassung der subjektiven affektiven Wahrnehmung wurden drei verschiedene Testserien mit jeweils 22 Stimuli durchlaufen. Die Bewertung bezüglich affektiver Valenz, d.h. Kategorisierung eines Stimulus als positiv bzw. negativ, erfolgte separat für jeden Reiz auf einer 9-stufigen Skala (-4 ≙ „äußerst unangenehm“ bis +4 ≙ „äußerst angenehm“). Wichtig war zudem das „Arousal“, welches es erlaubt, Stimuli bezüglich deren Ausmaß emotionaler Erregung in einem Spektrum von „entspannt“ bis „aufgeregt“ einzuordnen. Dies wurde bei visuellen und akustischen Stimuli auf einer 11- stufigen Skala (0 ≙ „ruhig/entspannt“ bis 10 ≙ „aufgeregt“) bewertet. Bei den Gerüchen wurde analog eine Einstufung der Geruchsintensität vorgenommen (0 ≙ „sehr schwach“ bis 10 ≙ „sehr stark“). Ergebnisse Nach Berücksichtigung der Ein- und Ausschlusskriterien gingen 62 Probanden (30 Patienten und 32 Kontrollen) in die aktuelle Arbeit ein. Demographische Parameter, wie Alter und Geschlecht zeigten keine Unterschiede zwischen den Gruppen. Hörschwelle, Nah- und Fernvisus, kognitive Funktion (MoCA) und Anhedonie (TEPS [CON/ANT]; SHAPS) und Apathie (SAS) unterschieden sich ebenfalls 4 nicht. IPS-Patienten zeigten erwartungsgemäß ein höheres Maß an depressiven Symptomen, sowie eine Hyposmie. 6 von 22 Bildern, 8 von 22 Tönen und 18 von 22 Gerüchen wurden bezüglich ihrer affektiven Valenz signifikant unterschiedlich bewertet. Insbesondere Stimuli am negativen und positiven Ende des abgebildeten affektiven Spektrums wurden signifikant weniger ausgeprägt bewertet. Als Folge ergaben sich signifikante Unterschiede für die absolute affektive Valenz der jeweiligen Sinnesmodalität. Die Resultate der anhedoniespezifischen Fragebögen (TEPS CON, TEPS ANT und SHAPS) korrelierten ausschließlich mit den absoluten Werten der visuellen affektiven Evaluation, während zwischen BDI und absoluten affektiven Werten keinerlei Korrelation vorlag. Schlussfolgerung Die erste Hypothese, dass bei IPS-Patienten ein multisensorisches Defizit bei der affektiven Wahrnehmung sensorischer Stimuli vorliegt, konnte angenommen werden. Die zweite Hypothese konnte nur für das visuelle System angenommen werden, die Ergebnisse der psychometrischen Fragebögen SHAPS und TEPS korrelierten lediglich mit dem absoluten visuellen Punktwert. Eine Korrelation mit der Evaluation olfaktorischer Stimuli (Mrochen et al., 2016) konnte nicht repliziert werden. Die affektive Bewertung akustischer Stimuli erreichte kein Signifikanzniveau, wenngleich mit größerer Gruppenstärke, insbesondere für TEPS und TEPS CON, signifikante Korrelationen zu vermuten sind. Mögliche Ursachen könnten die kleine Studienpopulation und die geringere Prävalenz einer durch SHAPS und TEPS erfassten Anhedonie im untersuchten Studienkollektiv sein. Eine unterschiedliche Bewertung der Stimuli war nicht durch eine höhere Prävalenz an depressiven Symptomen unter den der IPS-Patienten begründet. So bestanden weiterhin signifikante Unterschiede in der affektiven Evaluation nachdem für die Resultate des BDI kontrolliert wurde, so dass die dritte Hypothese angenommen werden konnte. Zukünftige Studien sollten überprüfen, ob 1) der Beginn einer dopaminergen Therapie, bspw. bei de novo IPS-Patienten, die affektive Wahrnehmung verändert, 2) die affektive Wahrnehmung mit motorischen Fluktuationen korreliert, 3) die eingeschränkte affektive Wahrnehmung in einer größeren Kohorte mit einer höheren Anzahl apathischer / anhedoner Patienten signifikant mit diesen Symptomen korreliert, 4) die in der aktuellen Studie untersuchten Probanden im Verlauf eine Apathie / Anhedonie entwickeln, welche mit den Resultaten in dieser Studie übereinstimmt und 5) funktionelle Bildgebung nutzen, um dysfunktionale neuroanatomische Korrelate der defizitären affektiven sensorischen Wahrnehmung zu identifizieren.
... There is no clear consensus about the definition of emotion, in part, because it can be defined based on its affective domain, as well as on its behavioral aspects that guide how biological agents act and respond to the environment (Soudry et al., 2011). It has been hypothesized that emotions evolved to drive behaviors that promote homeostatic processes, explaining why an emotional experience depends on the processing of interoceptive signals (Pace-Schott et al., 2019). ...
Article
Full-text available
Biological agents are context-dependent systems that exhibit behavioral flexibility. The internal and external information agents process, their actions, and emotions are all grounded in the context within which they are situated. However, in the field of cognitive robotics, the concept of context is far from being clear with most studies making little to no reference to it. The aim of this paper is to provide an interpretation of the notion of context and its core elements based on different studies in natural agents, and how these core contextual elements have been modeled in cognitive robotics, to introduce a new hypothesis about the interactions between these contextual elements. Here, global context is categorized as agent-related, environmental, and task-related context. The interaction of their core elements, allows agents to first select self-relevant tasks depending on their current needs, or for learning and mastering their environment through exploration. Second, to perform a task and continuously monitor its performance. Third, to abandon a task in case its execution is not going as expected. Here, the monitoring of prediction error, the difference between sensorimotor predictions and incoming sensory information, is at the core of behavioral flexibility during situated action cycles. Additionally, monitoring prediction error dynamics and its comparison with the expected reduction rate should indicate the agent its overall performance on executing the task. Sensitivity to performance evokes emotions that function as the driving element for autonomous behavior which, at the same time, depends on the processing of the interacting core elements. Taking all these into account, an interactionist model of contexts and their core elements is proposed. The model is embodied, affective, and situated, by means of the processing of the agent-related and environmental core contextual elements. Additionally, it is grounded in the processing of the task-related context and the associated situated action cycles during task execution. Finally, the model proposed here aims to guide how artificial agents should process the core contextual elements of the agent-related and environmental context to give rise to the task-related context, allowing agents to autonomously select a task, its planning, execution, and monitoring for behavioral flexibility.
... Such effects of smell have been explained by neural correlates involving an overlapping of anatomical substrates. For example, the amygdala, hippocampus, hypothalamus and thalamus (parts of the brain that regulate our emotions and memories) can be activated by scents [72]. Additionally, activation of the orbitofrontal cortex (area of the brain linked to our decision making behavior) has been found to be activated by pleasant (rostral area) and unpleasant (lateral area) scents [88]. ...
Article
Previous research has shown the influence of smell on emotions, memories, and body image. However, most of this work has taken place in laboratory settings and little is known about the influence of smell in real-world environments. In this paper, we present novel insights gained from a field study investigating the emotional effect of smell on memories and body image. Taking inspiration from the cultural design probes approach, we designed QuintEssence, a probe package that includes three scents and materials to complete three tasks over a period of four weeks. Here, we describe the design of QuintEssence and the main findings based on the outcomes of the three tasks and a final individual interview. The findings show similar results between participants based on the scent. For example, with cinnamon, participants experienced feelings of warmth, coziness, happiness, and relaxation; they recalled blurred memories of past moments about themselves and reported a general feeling of being calm and peaceful towards their bodies. Our findings open up new design spaces for multisensory experiences and inspire future qualitative explorations beyond laboratory boundaries.
... It is therefore conceivable that CORT-induced prolonged distress reinforce the anorexic action of this basal ganglia-like network, and that PEA inhalation may act like a silencing agent in order to relieve the inhibition on food intake. It is well documented that olfactory processing involves a large number of strongly interconnected brain regions that incorporate complex overlapping networks [86], thus creating functional interactions between neural circuits controlling emotional and feeding processes [98][99][100][101]. Therefore, it cannot be excluded that the OB neural activity changes could originate from a differential action of centrifugal systems [102,103] occurring upon CORT administration and PEA exposure. ...
Article
Full-text available
Chronic distress-induced hypothalamic-pituitary-adrenal axis deregulations have been associated with the development of neuropsychiatric disorders such as anxiety and depression. Currently available drugs treating such pathological conditions have limited efficacy and diverse side effects, revealing the need of new safer strategies. Aromatic plant-based compounds are largely used in herbal medicine due to their therapeutic properties on mood, physiology, and general well-being. The purpose of this study was to investigate the effects of 2-phenylethyl alcohol (PEA), one of the pharmacologically active constituents of rose essential oil, on chronic corticosterone (CORT)-induced behavioral and neurobiological changes in female mice. Animals followed a prolonged PEA inhalation exposure (30 min per day) for 15 consecutive days prior to behavioral evaluation with open-field, forced swim and novelty-suppressed feeding tests. CORT treatment induced an anxio-depressive-like phenotype, evidenced by a reduced locomotor activity in the open-field, and an increased latency to feed in the novelty-suppressed feeding paradigms. To elucidate the neural correlates of our behavioral results, immunohistochemistry was further performed to provide a global map of neural activity based on cerebral cFos expression. The altered feeding behavior was accompanied by a significant decrease in the number of cFos-positive cells in the olfactory bulb, and altered functional brain connectivity as shown by cross-correlation-based network analysis. CORT-induced behavioral and neurobiological alterations were reversed by prolonged PEA inhalation, suggesting a therapeutic action that allows regulating the activity of neural circuits involved in sensory, emotional and feeding behaviors. These findings might contribute to better understand the therapeutic potential of PEA on anxio-depressive symptoms.
Article
Chronic stress causes the abnormality of olfactory bulb (OB) in both anxiety and depression, however, the unique and common neurobiological underpinnings are still poorly understood. Previously, we built the three groups by chronic mild stress (CMS), depression-susceptible (Dep-Sus): with depression-like behavior, anxiety-susceptible (Anx-Sus): with anxiety-like behavior and insusceptible (Insus): without depression- and anxiety-like behaviors. To continuously explore the protein expression changes in these three groups, comparative quantitative proteomics analysis was conducted on the rat OB as crucial part of the olfactory system. Next, bioinformatics analyses were implemented whereas protein expressions were independently analyzed by parallel reaction monitoring (PRM) or Western blot (WB). The OB-proteome analysis identified totally 133 differentially expressed proteins as a CMS response. These deregulated proteins were involved in multiple functions and significant pathways potentially correlated with phenotypes of maladaptive behavior of depression or anxiety as well as adaptive behavior, and hence might act as potential candidate protein targets. The subsequent PRM-based or WB-based analyses showed that changes in Nefl, Mtmr7 and Tk2; Prkaca, Coa3, Cox6c2, Lamc1 and Tubal3; and Pabpn1, Nme3, Sos1 and Lum were uniquely associated with Dep-Sus, Anx-Sus, and Insus groups, respectively. These phenotype-specific deregulated proteins were primarily involved in multiple metabolic and signaling pathways, suggesting that the identical CMS differently impacted the olfactory protein regulation system and biological processes. To sum up, our present data as a useful proteomics underpinning provided the common and distinct molecular insights into the biochemical understanding of OB dysfunction underlying susceptibility and resiliency to chronic-stress-induced anxiety or depression.
Article
Objectives: In this study, we aimed to evaluate the clinical significance of osmophobia and its effect on quality of life in people with migraine. Methods: A total of 145 people with migraine were included in this cross-sectional study. Patients were evaluated with the migraine data form, the Migraine 24-Hour Quality of Life Questionnaire (24-HrMQoLQ), the Migraine Disability Assessment Scale (MIDAS), the Patient Health Questionnaire-9 (PHQ-9), the Insomnia Severity Index (ISI), the Generalized Anxiety Disorder-7 (GAD-7), the Allodynia Symptom Checklist (ASC), and the Fatigue Severity Scale (FSS). To evaluate the presence of osmophobia retrospectively, a semi-structured interview was conducted with the patients by the neurologist. Results: The mean 24-Hr-MQoLQ of patients with osmophobia was significantly lower than those without osmophobia. The decrease in the 24-Hr-MQoLQ was statistically significant in the areas of feeling and concerns and social functionality. The mean of the MIDAS scale was higher significantly in patients with osmophobia than those without osmophobia. In addition, the mean ISI, PHQ-9, FSS and ASC scores of patients with osmophobia were statistically significantly higher than those without osmophobia. Conclusions: Both 24-h and 3-month quality of life of people with migraine with osmophobia were more affected than those without osmophobia. At the same manner, insomnia, depression, fatigue and allodynia were observed at higher rates in people with migraine with osmophobia than in migraine without osmophobia. Osmophobia, which is one of the specific symptoms that distinguishes migraine from other headache disorders, deserves further and multifaceted investigation.
Article
Full-text available
Empathy is significantly influenced by the identification of others' emotions. In a recent study, we have found increased activation in the anterior insular cortex (aIns) that could be attributed to affect sharing rather than perceptual saliency, when seeing another person genuinely experiencing pain as opposed to merely acting to be in pain. In that prior study, effective connectivity between aIns and the right supramarginal gyrus (rSMG) was revealed to represent what another person really feels. In the present study, we used a similar paradigm to investigate the corresponding neural signatures in the domain of empathy for disgust - with participants seeing others genuinely sniffing unpleasant odors as compared to pretending to smell something disgusting (in fact the disgust expressions in both conditions were acted for reasons of experimental control). Consistent with the previous findings on pain, we found stronger activations in aIns associated with affect sharing for genuine disgust (inferred) compared with pretended disgust. However, instead of rSMG we found engagement of the olfactory cortex. Using dynamic causal modeling (DCM), we estimated the neural dynamics of aIns and the olfactory cortex between the genuine and pretended conditions. This revealed an increased excitatory modulatory effect for genuine disgust compared to pretended disgust. For genuine disgust only, brain-to-behavior regression analyses highlighted a link between the observed modulatory effect and a few empathic traits. Altogether, the current findings complement and expand our previous work, by showing that perceptual saliency alone does not explain responses in the insular cortex. Moreover, it reveals that different brain networks are implicated in a modality-specific way when sharing the affective experiences associated with pain vs. disgust.
Article
Lewy body disorders are characterized by oxidative damage to DNA and inclusions rich in aggregated forms of α-synuclein. Among other roles, apurinic/apyrimidinic endonuclease 1 (APE1) repairs oxidative DNA damage, and APE1 polymorphisms have been linked to cases of Lewy body disorders. However, the link between APE1 and α-synuclein is unexplored. We report that knockdown or inhibition of APE1 amplified inclusion formation in primary hippocampal cultures challenged with preformed α-synuclein fibrils. Fibril infusions into the mouse olfactory bulb/anterior olfactory nucleus (OB/AON) elicited a modest decrease in APE1 expression in the brains of male mice but an increase in females. Similarly, men with Lewy body disorders displayed lower APE1 expression in the OB and amygdala compared to women. Preformed fibril infusions of the mouse OB/AON induced more robust base excision repair of DNA lesions in females than males. No fibril-mediated loss of APE1 expression was observed in male mice when the antioxidant N-acetylcysteine was added to their diet. These findings reveal a potential sex-biased link between α-synucleinopathy and APE1 in mice and humans. Further studies are warranted to determine how this multifunctional protein modifies α-synuclein inclusions and, conversely, how α-synucleinopathy and biological sex interact to modify APE1.
Article
Full-text available
Purpose Obesity among elderly consumers precipitates undesirable health outcomes. This study aims to investigate the effects of environmental cues on food intake of elderly consumers in an aged-care facility. Design/methodology/approach A longitudinal study conducted over 17 weeks in situ within an aged-care facility with 31 residents investigated how auditory (soothing music), olfactory (floral-scented candle) and visual (infographic on health benefits of the main meal component) cues influenced food intake quantity during a meal, while accounting for portion size effect (PSE). Findings Analysing the cross-sectional results of individual treatments and rounds did not reveal any consistent patterns in the influence of the three environmental cues. Longitudinal analyses, however, showed that the presence of auditory and olfactory cues significantly increased food intake, but the visual cue did not. Moreover, PSE was strong. Research limitations/implications Extending research into environmental factors from a commercial to a health-care setting, this study demonstrates how the presence of auditory and olfactory, but not cognitive cues, increased food intake behaviour among elderly consumers. It also shows that a cross-sectional approach to such studies would have yielded inconclusive or even misleading findings. Merely serving more would also lead to higher food intake amount. Practical implications Environmental factors should be a part of health-care providers’ arsenal to manage obesity. They are practical and relatively inexpensive to implement across different health-care settings. However, the same environmental factors would have opposite desired-effects with normal or underweight residents, and hence, aged-care facilities need to separate the dining experience (or mealtime) of obese and other residents. Quantity served should also be moderated to discourage overeating. Originality/value While studies into managing obesity, particularly among older adults, have mainly focused on techniques such as pharmacotherapy treatments with drugs, dietary management or even lifestyle change, less attention has been given to the influence of environmental cues. This study, executed in situ within an aged-care facility, provided evidence of the importance of considering the impact of environmental factors on food intake to help reduce obesity.
Article
Background: The prevalence of olfactory impairment in patients with Parkinson's disease (PD) is 50-90%, and therefore, olfactory dysfunction is one of the most prevalent non-motor symptoms (NMSs) in patients with PD. Numerous studies have evaluated the association between motor and non-motor symptoms and olfactory dysfunction in PD. Aim: In this study, we investigated the relationship between olfactory dysfunction, which is measured using the UPSIT test, with other motor and non-motor symptoms separately in three motor subtypes of PD, including tremor dominant (TD), postural instability and gait difficulty (PIGD), and indeterminate and healthy subjects. Methods: We recruited 487 early-stage PD patients (43 PIGD, 406 TD, and 38 indeterminate) and healthy controls (HCs) (n = 197) from the Parkinson Progression Markers Initiative (PPMI). All participants completed motor and non-motor tests at baseline visit and after 4 years of follow-up. Subjects underwent common PD scaling tests. Results: Olfactory dysfunction was significantly correlated with declined motor functions only in the TD subtype. Also, significant correlations were noticed between olfactory dysfunction and speed-attention processing and executive function in the HCs as well. Finally, no significant or meaningful association was observed in the PIGD and indeterminate subtype. Anosmia and hyposmia subjects in the TD group had the worse motor and non-motor scores compared to normosmia subjects after 4 years. Conclusion: Olfactory dysfunction was significantly correlated with declined motor functions in the TD subtype. This is indicating that olfactory dysfunction may be an early motor and non-motor biomarker only in the TD subtype. However, it is possible that the involvement of olfactory function in other subtypes is not strong enough to make it a useful marker of diseases progression.
Article
In recent years, the Icelandic dairy product skyr has been transformed from an everyday staple to a national food heritage. Skyr is high in protein and low in fat, and its nutritional value accounts for its international success. However, the domestic and international marketing of skyr glide effortlessly from medieval literature to modern healthy living in promoting skyr as a unique, wholesome, and authentic product: heritage food and Iceland's “secret to healthy living.” In this article, we explore how skyr has been recontextualized as heritage through the cultural staging of skyr-making and through branding efforts. It was not until skyr had become a standardized export commodity that people began to fear that action was needed to protect the traditional way of skyr-making. Picking up on the trend of “heritagization,” pioneered by Slow Food (which added skyr to its “Ark of Taste”) and by small farmers catering to tourists, industrial skyr producers have come around to narrating the cultural history of skyr, employing heritage branding to carve out a unique place within the global dairy-scape. We untangle the messy relationships between the local and the global in such heritage efforts by examining how global trends and markets influence people at local levels, impacting the way they think about and act on their own cultural forms, and how the local level, in turn, impacts global flows under the sign of heritage.
Article
Full-text available
Olfactory loss is associated with symptoms of depression. The present study, conducted on a large cohort of mostly dysosmic patients, aimed to investigate whether improvement in olfactory performance would correspond with a decrease in depression severity. In 171 participants (157 dysosmic), we assessed olfactory function and severity of depression before and after an average interval of 11 months, with many patients showing improvement in olfactory function. Separate analyses were conducted for (a) the whole group of patients and (b) the group of dysosmic patients using both classic and Bayesian approaches. For odor identification, Student t test demonstrated that the whole sample improved consistently, especially within the group of dysosmic patients. The dysosmic group also improved in odor threshold and overall olfactory function. Pearson correlation showed that an increase in olfactory function was associated with a decrease in depression severity, particularly in dysosmic patients. To conclude, the present results indicate that symptoms of depression change with olfactory function in general and odor identification in particular.
Article
Full-text available
There is growing awareness that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, even in its mild or moderate respiratory forms, can include long-term neuropsychological deficits. Standardized neuropsychological, psychiatric, neurological, and olfactory tests were administered to 45 patients 236.51 ± 22.54 days after hospital discharge following severe, moderate, or mild respiratory severity from SARS-CoV-2 infection (severe = intensive care unit hospitalization, moderate = conventional hospitalization, mild = no hospitalization). Deficits were found in all domains of cognition, and the prevalence of psychiatric symptoms was relatively high in the three groups. The severe infection group performed more poorly on long-term episodic memory tests and exhibited greater anosognosia than did the other two groups. Those with moderate infection had poorer emotion recognition, which was positively correlated with persistent olfactory dysfunction. Individuals with mild infection were more stressed, anxious, and depressed. The data support the hypothesis that the virus targets the central nervous system (notably the limbic system) and the notion that there are different neuropsychological phenotypes.
Article
The human sense of smell and the ability to detect and distinguish odors allows for the extraction of valuable information from the environment, thereby driving human behavior. Not only can the sense of smell help to monitor the safety of inhaled air, but it can also help to evaluate the edibility of food. Therefore, in an effort to further our understanding of the human sense of smell, the aim of this meta-analysis was to provide the scientific community with activation probability maps of the functional anatomy of the olfactory system, in addition to separate activation maps for specific odor categories (pleasant, food, and aversive odors). The activation likelihood estimation (ALE) method was utilized to quantify all relevant and available data to perform a formal statistical analysis on the inter-study concordance of various odor categories. A total of 81 studies (108 contrasts, 1053 foci) fulfilled our inclusion criteria. Significant ALE peaks were observed in all odor categories in brain areas typically associated with the functional neuroanatomy of olfaction including the piriform cortex, amygdala, insula, and orbitofrontal cortex, amongst others. Additional contrast analyses indicate clear differences in neural activation patterns between odor categories.
Article
Full-text available
While philosophers of perception develop representational theories of olfactory experiences, there are doubts regarding whether features of olfactory perception can be accommodated within the representationalist framework. In particular, it is argued that the function of olfaction is not to represent stimuli but rather to evaluate it. The article claims that the major representational accounts of olfaction have problems in accommodating the evaluative aspects of olfactory phenomenology. However, an alternative position, named ‘olfactory evaluativism’, is proposed which is free of these problems and may serve as a foundation for further developments of representational approach to olfactory experiences.
Article
With urbanization, pandemic isolation, and exploration of deep-space and deep-sea, human beings will inevitably face the situation of long-term living and working in small spaces, which has negative impacts on people's mental health and cognitive performance. One of the solutions to these problems is to introduce biophilic design, in which plants are often the momentous elements. But research quantifying psychophysiological and cognitive benefits of edible plants is sparse. This inter-group study chose strawberry, a typical favorite fruit, to explore the impact of the biophilic environment with edible plants on health and cognition in small spaces. A subjective evaluation + electrophysiology + salivary secretion analysis method was adopted to discuss the mechanisms operating between biophilic environment and human psychophysiological and cognitive feedback, and reveal the laws of interaction between them. The results indicated that subjective emotions were significantly improved, and high-frequency power of heart rate variability (HRV), the power of alpha and beta brainwaves were increased, while heart rate, saliva cortisol, α-amylase and IL-1β were reduced in the biophilic environment with strawberry plants. Moreover, the results highlighted an improvement in cognitive performance by introducing strawberry plants into small space. Correlation analysis revealed that vigor was significantly negatively correlated with melatonin and response time, while histidine was positively correlated with mood disturbance and response time. Overall, these findings shed light on the positive regulation of biophilic environment with edible plants on people's emotion and cognition.
Article
Background Electroconvulsive therapy (ECT) efficacy is hypothesized to depend on induction of molecular and cellular events that trigger neuronal plasticity. Investigating how electroconvulsive seizures (ECS) impact plasticity in animal models can help inform our understanding of basic mechanisms by which ECT relieves symptoms of depression. ECS-induced plasticity is associated with differential expression of unique isoforms encoding the neurotrophin, brain-derived neurotrophic factor (BDNF). Hypothesis We hypothesized that cells expressing the Bdnf exon 1-containing isoform are important for ECS-induced structural plasticity in the piriform cortex, a highly epileptogenic region that is responsive to ECS. Methods We selectively labeled Bdnf exon 1-expressing neurons in mouse piriform cortex using Cre recombinase dependent on GFP technology (CRE-DOG). We then quantified changes in dendrite morphology and density of Bdnf exon 1-expressing neurons. Results Loss of promoter I-derived BDNF caused changes in spine density and morphology in Bdnf exon 1-expressing neurons following ECS. Conclusions Promoter I-derived Bdnf is required for ECS-induced dendritic structural plasticity in Bdnf exon 1-expressing neurons.
Article
Full-text available
Several studies have found reduced hippocampal volume in patients with unipolar depression, but discrepancies exist. The authors performed a systematic review and meta-analysis of volumetric studies of the hippocampus in patients with mood disorders. Studies of hippocampal volume in unipolar and bipolar patients were identified. A meta-analysis of the 12 studies of unipolar depression fulfilling specific criteria was performed. The sample comprised 351 patients and 279 healthy subjects. The studies were highly heterogeneous regarding age and gender distribution, age at onset of the disorder, average number of episodes, and responsiveness to treatment, but the pooled effect size of depression was significant in both hemispheres for the unipolar patients. The weighted average showed a reduction of hippocampal volume of 8% on the left side and 10% on the right side. The causes of the heterogeneity were analyzed, and a meta-regression showed that the total number of depressive episodes was significantly correlated to right but not left hippocampal volume reduction. Hippocampal volume is reduced in patients with unipolar depression, maybe as a consequence of repeated periods of major depressive disorder. Bipolar patients did not seem to show a reduction in hippocampal volume, but this has been much less investigated.
Article
Full-text available
Decision-making about affective value may occur after the reward value of a stimulus is represented and may involve different brain areas to those involved in decision-making about the physical properties of stimuli, such as intensity. In an fMRI study, we delivered two odors separated by a delay, with instructions on different trials to decide which odor was more pleasant or more intense or to rate the pleasantness and intensity of the second odor without making a decision. The fMRI signals in the medial prefrontal cortex area 10 (medial PFC) and in regions to which it projects, including the anterior cingulate cortex (ACC) and insula, were higher when decisions were being made compared with ratings, implicating these regions in decision-making. Decision-making about affective value was related to larger signals in the dorsal part of medial area 10 and the agranular insula, whereas decisions about intensity were related to larger activations in the dorsolateral prefrontal cortex (dorsolateral PFC), ventral premotor cortex, and anterior insula. For comparison, the mid orbitofrontal cortex (OFC) had activations related not to decision-making but to subjective pleasantness ratings, providing a continuous representation of affective value. In contrast, areas such as medial area 10 and the ACC are implicated in reaching a decision in which a binary outcome is produced.
Article
Full-text available
Electrophysiologic and lesion studies of animals increasingly implicate the amygdala in aspects of emotional processing. Yet, the functions of the human amygdala remain poorly understood. To examine the contributions of the amygdala and other limbic and paralimbic regions to emotional processing, we exposed healthy subjects to aversive olfactory stimuli while measuring regional cerebral blood flow (rCBF) with positron emission tomography. Exposure to a highly aversive odorant produced strong rCBF increases in both amygdalae and in the left orbitofrontal cortex. Exposure to less aversive odorants produced rCBF increases in the orbitofrontal cortex but not in the amygdala. Change of rCBF within the left amygdala and the left OFC was highly intercorrelated, indicating a strong functional interaction between these brain regions. Furthermore, the activity within the left amygdala was associated significantly with subjective ratings of perceived aversiveness. These findings provide evidence that the human amygdala participates in the hedonic or emotional processing of olfactory stimuli.
Article
Full-text available
Odors can elicit a range of behaviors and emotions. Our purpose was to identify regional activation of the human cerebral cortex in response to pleasant (positive hedonic value) and unpleasant (negative hedonic value) odors. Thirteen neurologically normal adults underwent functional MR imaging of frontal and anterior temporal brain regions with a gradient-echo echo-planar technique. Eleven candidate regions of interest (ROIs) were identified on the first half of the data set based on t-map comparisons of signal intensities during administration of clementine (pleasant odor), isovaleric acid (unpleasant odor), and clear air (control odor). These ROIs were applied to the second half of the data set, and the number of voxels activated with the odorants was compared with the number of voxels activated during clear air trials, using independent t-tests. Clementine activated five cortical areas: Brodmann's area (BA) 8, BA 32 (lateralized to left), BA 46/9, BA 6 (lateralized to right), and the insula. Isovaleric acid activated four of the five regions without lateralization; no BA 8 activity was seen. Clementine produced more activity than isovaleric acid in the left insula, and isovaleric acid produced more activity than clementine in the left BA 6. No activation was detected in the orbitofrontal cortex or in the medial temporal lobes. Subjects rated clementine, isovaleric acid, and clear air as being pleasant, unpleasant, and neutral, respectively. Activation in frontal regions may represent brain processes linked to olfactory networks. There may be regional specialization based on odorant hedonic values.
Article
Full-text available
Individuals differ in the extent to which they experience negative mood states over time. To explore the relationship between individual differences in negative affect (NA) and brain activity, we asked healthy subjects participating in positron-emission tomography scans to rate the extent to which they had experienced NA terms during the month before scanning. In two independent samples of subjects, resting regional cerebral blood flow within the ventromedial prefrontal cortex (VMPFC) correlated with ratings of NA. The finding converges with recent evidence implicating the VMPFC in emotional and autonomic processing. Moreover, it demonstrates that variability in basal VMPFC activity across subjects is related to individual differences in subjective emotional experience.
Article
Full-text available
Odorant-binding proteins (OBPs) are small abundant extracellular proteins belonging to the lipocalin superfamily. They are thought to participate in perireceptor events of odor detection by carrying, deactivating, and/or selecting odorant molecules. Putative human OBP genes (hOBP) have recently been described [Lacazette et al. (2000) Hum. Mol. Genet. 9, 289-301], but the presence of the corresponding proteins remained to be established in the human olfactory mucus. This paper reports the first evidence of such expression in the mucus covering the olfactory cleft, where the sensory olfactory epithelium is located. On the contrary, hOBPs were not observed in the nasal mucus covering the septum and the lower turbinate. To demonstrate the odorant binding activity of these proteins, a corresponding recombinant protein variant, hOBP(IIa)(alpha), was secreted by the yeast Pichia pastoris and thoroughly characterized. It appears as a monomer with one disulfide bond located between C59 and C151, a conservative feature of all other vertebrate OBPs. By measuring the displacement of several fluorescent probes, we show that hOBP(IIa)(alpha) is able to bind numerous odorants of diverse chemical structures, with a higher affinity for aldehydes and large fatty acids. A computed 3D model of hOBP(IIa)(alpha) is proposed and reveals that two lysyl residues of the binding pocket may account for the increased affinity for aldehydes. The relatively limited specificity of hOBP(IIa)(alpha) suggests that other human OBPs are expected to take into account the large diversity of odorant molecules.
Article
Full-text available
Affective experience has been described in terms of two primary dimensions: intensity and valence. In the human brain, it is intrinsically difficult to dissociate the neural coding of these affective dimensions for visual and auditory stimuli, but such dissociation is more readily achieved in olfaction, where intensity and valence can be manipulated independently. Using event-related functional magnetic resonance imaging (fMRI), we found amygdala activation to be associated with intensity, and not valence, of odors. Activity in regions of orbitofrontal cortex, in contrast, were associated with valence independent of intensity. These findings show that distinct olfactory regions subserve the analysis of the degree and quality of olfactory stimulation, suggesting that the affective representations of intensity and valence draw upon dissociable neural substrates.
Article
Full-text available
A neuroimaging study examined the neural correlates of social exclusion and tested the hypothesis that the brain bases of social pain are similar to those of physical pain. Participants were scanned while playing a virtual ball-tossing game in which they were ultimately excluded. Paralleling results from physical pain studies, the anterior cingulate cortex (ACC) was more active during exclusion than during inclusion and correlated positively with self-reported distress. Right ventral prefrontal cortex (RVPFC) was active during exclusion and correlated negatively with self-reported distress. ACC changes mediated the RVPFC-distress correlation, suggesting that RVPFC regulates the distress of social exclusion by disrupting ACC activity.
Article
Full-text available
Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.
Article
Full-text available
Depression is associated with interpersonal difficulties related to abnormalities in affective facial processing. To map brain systems activated by sad facial affect processing in patients with depression and to identify brain functional correlates of antidepressant treatment and symptomatic response. Two groups underwent scanning twice using functional magnetic resonance imaging (fMRI) during an 8-week period. The event-related fMRI paradigm entailed incidental affect recognition of facial stimuli morphed to express discriminable intensities of sadness. Participants were recruited by advertisement from the local population; depressed subjects were treated as outpatients. We matched 19 medication-free, acutely symptomatic patients satisfying DSM-IV criteria for unipolar major depressive disorder by age, sex, and IQ with 19 healthy volunteers. Intervention After the baseline assessment, patients received fluoxetine hydrochloride, 20 mg/d, for 8 weeks. Average activation (capacity) and differential response to variable affective intensity (dynamic range) were estimated in each fMRI time series. We used analysis of variance to identify brain regions that demonstrated a main effect of group (depressed vs healthy subjects) and a group x time interaction (attributable to antidepressant treatment). Change in brain activation associated with reduction of depressive symptoms in the patient group was identified by means of regression analysis. Permutation tests were used for inference. Over time, depressed subjects showed reduced capacity for activation in the left amygdala, ventral striatum, and frontoparietal cortex and a negatively correlated increase of dynamic range in the prefrontal cortex. Symptomatic improvement was associated with reduction of dynamic range in the pregenual cingulate cortex, ventral striatum, and cerebellum. Antidepressant treatment reduces left limbic, subcortical, and neocortical capacity for activation in depressed subjects and increases the dynamic range of the left prefrontal cortex. Changes in anterior cingulate function associated with symptomatic improvement indicate that fMRI may be a useful surrogate marker of antidepressant treatment response.
Article
Full-text available
The amygdala was more responsive to fearful (larger) eye whites than to happy (smaller) eye whites presented in a masking paradigm that mitigated subjects' awareness of their presence and aberrant nature. These data demonstrate that the amygdala is responsive to elements of.
Article
Full-text available
The question of the self has intrigued philosophers and psychologists for a long time. More recently, distinct concepts of self have also been suggested in neuroscience. However, the exact relationship between these concepts and neural processing across different brain regions remains unclear. This article reviews neuroimaging studies comparing neural correlates during processing of stimuli related to the self with those of non-self-referential stimuli. All studies revealed activation in the medial regions of our brains' cortex during self-related stimuli. The activation in these so-called cortical midline structures (CMS) occurred across all functional domains (e.g., verbal, spatial, emotional, and facial). Cluster and factor analyses indicate functional specialization into ventral, dorsal, and posterior CMS remaining independent of domains. Taken together, our results suggest that self-referential processing is mediated by cortical midline structures. Since the CMS are densely and reciprocally connected to subcortical midline regions, we advocate an integrated cortical-subcortical midline system underlying human self. We conclude that self-referential processing in CMS constitutes the core of our self and is critical for elaborating experiential feelings of self, uniting several distinct concepts evident in current neuroscience.
Article
Full-text available
Emotions have a strong influence on the perception of visual and auditory stimuli. Only little is known about the relation between emotional stimulation and olfactory functions. The present study investigated the relationship between the presentation of affective pictures, olfactory functions, and sex. Olfactory performance was assessed in 32 subjects (16 male). Olfactory sensitivity was significantly reduced following unpleasant picture presentation for all subjects and following pleasant picture presentation for male subjects only. Pleasantness and intensity ratings of a neutral suprathreshold odor were related to the valence of the pictures: After unpleasant picture presentation, the odor was rated as less pleasant and more intense, whereas viewing positive pictures induced a significant increase in reported odor pleasantness. We conclude that inducing a negative emotional state reduces olfactory sensitivity. A relation to functional deviations within the primary olfactory cortices is discussed.
Article
Full-text available
Many affective stimuli are hedonically complex mixtures containing both pleasant and unpleasant components. To investigate whether the brain represents the overall affective value of such complex stimuli, or the affective value of the different components simultaneously, we used functional magnetic resonance imaging to measure brain activations to a pleasant odor (jasmine), an unpleasant odor (indole), and a mixture of the two that was pleasant. In brain regions that represented the pleasantness of the odors such as the medial orbitofrontal cortex (as shown by activations that correlated with the pleasantness ratings), the mixture produced activations of similar magnitude to the pleasant jasmine, but very different from the unpleasant indole. These regions thus emphasize the pleasant aspects of the mixture. In contrast, in regions representing the unpleasantness of odors such as the dorsal anterior cingulate and midorbitofrontal cortex the mixture produced activations that were relatively further from the pleasant component jasmine and closer to the indole. These regions thus emphasize the unpleasant aspects of the mixture. Thus mixtures that are found pleasant can have components that are separately pleasant and unpleasant, and the brain can separately and simultaneously represent the positive and negative hedonic value of a complex affective stimulus that contains both pleasant and unpleasant olfactory components. This type of representation may be important for affective decision making in the brain in that separate representations of different affective components of the same sensory stimulus may provide the inputs for making a decision about whether to choose the stimulus or not.
Article
Full-text available
Laboratory studies have shown a significant influence of certain fragrances on affective as well as cognitive states in humans. The aim of the current study was to measure the relationship between complex, natural odors and affective states, that is, calmness, alertness, and mood, in the field. In 4 experiments, the emotional impact, intensity, and hedonics of complex, natural plant odors were assessed in 32 healthy human subjects and compared with control conditions involving a similar outdoor environment without the tested fragrant plants. In all experiments, the selected fragrances were evaluated as more intense than the odors in the control conditions but pleasantness ratings differed only in 2 of the 4 experiments. The fragrances improved subjective ratings of calmness, alertness, and mood depending on the sequence of the conditions but independent of visual features of the environment. In contrast, a fifth experiment which tested the influence of natural and artificial pleasant odors and an artificial unpleasant odor on calmness, alertness, and mood in 22 subjects showed that the unpleasant odor impaired these affective states in humans independent of the order of presentation. On the other hand, no effects of the pleasant odors on mood and calmness were observed in this experiment.
Article
Individuals differ in the extent to which they experience negative mood states over time. To explore the relationship between individual differences in negative affect (NA) and brain activity, we asked healthy subjects participating in positron-emission tomography scans to rate the extent to which they had experienced NA terms during the month before scanning. In two independent samples of subjects, resting regional cerebral blood flow within the ventromedial prefrontal cortex (VMPFC) correlated with ratings of NA. The finding converges with recent evidence implicating the VMPFC in emotional and autonomic processing. Moreover, it demonstrates that variability in basal VMPFC activity across subjects is related to individual differences in subjective emotional experience.
Article
We propose a general hypothesis that integrates affective and cognitive processing with neuroanatomy to explain anxiety pronenes. The premise is that individuals who are prone to anxiety show an altered interoceptive prediction signal, i.e., manifest augmented detection of the difference between the observed and expected body state. As a consequence, the increased prediction signal of a prospective aversive body state triggers an increase in anxious affect, worrisome thoughts and other avoidance behaviors. The anterior insula is proposed to play a key role in this process. Further testing of this model--which should include investigation of genetic and environmental influences--may lead to the development of novel treatments that attenuate this altered interoceptive prediction signal in patients with anxiety disorders.
Article
The aims of this study on the human olfactory bulb were two. First morphometry of the bulbs revealed marked declines during aging in the numbers of mitral cells and glomeruli, the bulb's principal integrative and relay elements. Numbers of glomeruli and mitral cells in each bulb of the young adult human were found to be approximately 8,000 and 40,000, respectively; these numbers declined steadily with age at an approximate rate of 10% per decade, so that in the ninth and tenth decades less than 30% of these elements remain in place. Such a marked decline with aging is suggested to underlie in part the decline in olfactory abilities (odor detection and identification) of humans with aging. In a separate study a systematic search for presence of an accessory olfactory bulb in the adult and aging bulbs was undertaken. No positive evidence for such an organized formation was found in the various regions of the adult bulbs of different age groups. The implications of these negative findings for the recent theories on human vomeronasal function and pheromonal perception are discussed.
Article
We report here a series of 118 patients (79% women) who developed dysomia after acute rhinitis. Mean age was 59 years. Mean follow-up after the initial rhinal episode was 36 months. The dominant olfactory disorder was anosmia (71% of the patients) and dysgeusia in 71%. The prognosis of anosmia was poor as it persisted in 50% of the patients. Six patients (5%) recovered normal olfaction after a delay of 11 months. Partial recovery was observed in 45% of the patients with a mean 14-month delay. Recovery of olfaction was thus observed within the first year. Parosmia was also frequent (59% of the patients). In two out of three cases, parosmia persisted. Improvement generally occurred during the first 18 months. These olfactory disorders have an impact on the patients' psychic equilibrim since a depressive syndrome was observed in 60% of the cases.
Article
Olfactory perception is characterized by interpersonal variability. Although gender has been identified as a potential influencing factor, currently little is known about its effect on perceived hedonicity of individual odorants. This study assessed gender differences in emotional appraisal of 3 odorants (eugenol, vanillin, and hydrogen sulfide [H(2)S]), presented to 25 healthy subjects (13 males, 12 females) in a blocked design. Standardized scales rating valence and judgments of emotional experience were used for stimulus evaluation. Results indicate ambiguous pleasantness ratings for eugenol as well as stronger responses to vanillin odorant in female subjects; furthermore, in emotional experience ratings, the effect of eugenol was found to be gender dependent, evoking more positive and less negative emotions in female subjects than in males. The gender dependence of the mood response to eugenol necessitates reconsideration of this odorant as a reliable gender independent olfactory stimulus for studies on olfaction and emotion.
Article
Smell and taste disorders are common in the general population, yet little is known about their nature or cause. This article describes a study of 750 patients with complaints of abnormal smell or taste perception from the University of Pennsylvania Smell and Taste Center, Philadelphia. Major findings suggest that: chemosensory dysfunction influences quality of life; complaints of taste loss usually reflect loss of smell function; upper respiratory infection, head trauma, and chronic nasal and paranasal sinus disease are the most common causes of the diminution of the sense of smell, with head trauma having the greatest loss; depression frequently accompanies chemosensory distortion; low body weight accompanies burning mouth syndrome; estrogens protect against loss of the sense of smell in postmenopausal women; zinc therapy may provide no benefit to patients with chemosensory dysfunction; and thyroid hormone function is associated with oral sensory distortion. The findings are discussed in relation to management of patients with chemosensory disturbances.
Article
Observers in both literate and preliterate cultures chose the predicted emotion for photographs of the face, although agreement was higher in the literate samples. These findings suggest that the pan-cultural element in facial displays of emotion is the association between facial muscular movements and discrete primary emotions, although cultures may still differ in what evokes an emotion, in rules for controlling the display of emotion, and in behavioral consequences.
Article
Adult humans are capable of remembering prior events by mentally traveling back in time to re-experience those events. In this review, the authors discuss this and other related capabilities, considering evidence from such diverse sources as brain imaging, neuropsychological experiments, clinical observations, and developmental psychology. The evidence supports a preliminary theory of episodic remembering, which holds that the prefrontal cortex plays a critical, supervisory role in empowering healthy adults with autonoetic consciousness-the capacity to mentally represent and become aware of subjective experiences in the past, present, and future. When a rememberer mentally travels back in subjective time to re-experience his or her personal past, the result is an act of retrieval from episodic memory.
Article
Our goal was to use functional MRI (fMRI) to measure brain activation in response to olfactory stimuli. fMRI brain scans were obtained in 17 normal subjects (9 men, 8 women) using-multislice FLASH MRI in response to three olfactory stimuli (pyridine, menthone, amyl acetate) in three coronal brain sections selected from anterior to posterior temporal brain regions. Activation images were derived using correlation analysis, and ratios of areas of brain activated to total brain areas were calculated. Activation was present in each section in all subjects. Subjective estimation of vapor intensity followed relative vapor pressure of stimuli presented (pyridine > amyl acetate > menthone) and were similar for both men and women. However, brain activation did not follow subjective responsiveness order but rather pyridine > menthone > amyl acetate, a pattern demonstrated by both men and women. Brain activation in women was consistently lower than in men for all vapors in all brain sections, although regions of activation did not differ. Activation occurred in regions previously recognized as associated with olfactory stimulation, including orbitofrontal and entorhinal cortex; however, extensive regions within frontal cortex including cingulate gyrus were also activated. Brain regions activated to odors considered pleasant or unpleasant did not differ. The techniques used in this study demonstrated that brain activation to olfactory stimuli could be measured quantitatively such that differences between groups of subjects (in this case men and women) could be compared. Although localization of brain activation was not the major thrust of this study, activation to olfactory stimuli was found not only in brain regions previously associated with processing of olfactory information but also in several other areas of frontal cortex, in cingulate gyrus, and in several components of the limbic system. This is the first study in which activation in human brain parenchyma of normal humans to olfactory stimuli has been quantitated by fMRI.
Article
The somatic marker hypothesis provides a systems-level neuroanatomical and cognitive framework for decision making and the influence on it by emotion. The key idea of this hypothesis is that decision making is a process that is influenced by marker signals that arise in bioregulatory processes, including those that express themselves in emotions and feelings. This influence can occur at multiple levels of operation, some of which occur consciously and some of which occur non-consciously. Here we review studies that confirm various predictions from the hypothesis. The orbitofrontal cortex represents one critical structure in a neural system subserving decision making. Decision making is not mediated by the orbitofrontal cortex alone, but arises from large-scale systems that include other cortical and subcortical components. Such structures include the amygdala, the somatosensory/insular cortices and the peripheral nervous system. Here we focus only on the role of the orbitofrontal cortex in decision making and emotional processing, and the relationship between emotion, decision making and other cognitive functions of the frontal lobe, namely working memory.
Article
Olfactory disorders in Alzheimer's disease and Parkinson's disease have been the topic of a large body of work over the last decades. Work devoted to olfactory disorders in Alzheimer's disease includes over 300 papers providing clinical and fundamental data. Anatomy studies in Alzheimer's disease have demonstrated a specific concentration of lesions in peripheral and central olfactory structures (senile plaques, neurofibrillary degeneration) as well as lesions in layers II and III of the entorhinal cortex. These neuropathological findings led to the development of the hypothesis that olfactory disorders in Alzheimer's disease would result from a toxic process. Observed olfactory deficits involve both identification and recognition of odors and detection thresholds. Nevertheless, patients with Alzheimer's disease rarely consult for sensorial deficits as the other signs of the disease predominate. Neuropathology data on the olfactory system are much more sparse in Parkinson's disease. Lewy bodies suggestive of Parkinson's disease have been observed in the olfactory bulb and pathways, but, unlike Alzheimer's disease, the olfactory disorders appear to be stable, changing little over time, as opposed to the evolution of neurological symptoms and cognition impairment. Clinicians should be aware that olfactory disorders are an integral part of Alzheimer's disease and Parkinson's disease. Screening for sensorial impairment however is a secondary objective in the context of these neurodegenerative diseases.