The Laryngoscope Volume 126, Issue 5, pages E174–E178, May 2015
Trigeminal sensation (TS) within the nasal cavity is important for the perception of nasal airflow. The objective of this study is to examine whether impaired TS contributes to the sensation of nasal obstruction in patients with chronic rhinosinusitis (CRS).
Pain June 2016 - Volume 157 - Issue 6 - p 1279–1285
In response to recent publications from pain neuroimaging experiments, there has been a debate about the existence of a primary pain region in the brain. Yet, there are few meta-analyses providing assessments of the minimum cerebral denominators of pain. Here, we used a statistical meta-analysis method, called activation likelihood estimation, to define (1) core brain regions activated by pain per se, irrelevant of pain modality, paradigm, or participants and (2) activation likelihood estimation commonalities and differences between patients with chronic pain and healthy individuals.
European Journal of Neuroscience Volume 43, Issue 8, pages 997–1005, April 2015
Burning mouth syndrome (BMS) is characterized by a burning sensation in the mouth, usually in the absence of clinical and laboratory findings. Latest findings indicate that BMS could result from neuropathic trigeminal conditions. While many investigations have focused on the periphery, very few have examined possible central dysfunctions. To highlight changes of the central system of subjects with BMS, we analysed the grey matter concentration in 12 subjects using voxel-based morphometry.
Clinical Neurology & Neurosurgery January 2016 Volume 140, Pages 68–75
Traumatic brain injury (TBI) represents a significant public health problem and is associated with a high rate of mortality and morbidity. Although TBI is amongst the most common causes of olfactory dysfunction the relationship between injury severity and olfactory problems has not yet been investigated with validated and standardized methods in the first days following the TBI.
Social Cognitive and Affective Neuroscience v.10(4); 2015 Apr PMC4381235
Brain reward systems mediate liking and wanting for food reward. Here, we explore the differential involvement of the following structures for these two components: the ventral and dorsal striatopallidal area, orbitofrontal cortex (OFC), anterior insula and anterior cingulate. Twelve healthy female participants were asked to rate pleasantness (liking of food and non-food odors) and the desire to eat (wanting of odor-evoked food) during event-related functional magnetic resonance imaging (fMRI).
Brain Injury Volume 29, Issue 7-8, 2015
Background: Concussions exert persistent effects on asymptomatic athletes, especially women. Among chief mechanisms of concussion recovery are alterations of neuronal plasticity. Olfactory function, often impaired following a concussion, greatly involves plasticity and, therefore, appears as a good candidate to study the deleterious effects of concussions. The BDNF Val66Met polymorphism (BDNFMet), which reduces availability of BDNF in the brain, has surprisingly been associated with better recovery following concussion.
PLoS One v.10(3); 2015 PMC4361644
Intranasal trigeminal sensations are important in everyday life of human beings, as they play a governing role in protecting the airways from harm. Trigeminal sensations arise from the binding of a ligand to various sub-types of transient receptor potential (TRP) channels located on mucosal branches of the trigeminal nerve. Which underlying neural networks are involved in the processing of various trigeminal inputs is still unknown.
Brain Injury Volume 29, Issue 6, 2015
Objective: To study the acute relationship between olfactory function and traumatic brain injury (TBI), cognitive functions and outcome.
Chemical Senses Volume 40, Issue 1 Pp. 61-69
The trigeminal system is a chemical sense allowing for the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack a thorough understanding of the trigeminal processing of mixtures. We, therefore, investigated trigeminal perception using mixtures of 3 relatively receptor-specific agonists together with one control odor in different proportions to determine basic perceptual dimensions of trigeminal perception.
Nature Methods 11, 629–632 (2014)
We found that exposure of mice and rats to male but not female experimenters produces pain inhibition. Male-related stimuli induced a robust physiological stress response that results in stress-induced analgesia. This effect could be replicated with T-shirts worn by men, bedding material from gonadally intact and unfamiliar male mammals, and presentation of compounds secreted from the human axilla. Experimenter sex can thus affect apparent baseline responses in behavioral testing.
Frontiers in Psychology 2013; 4: 786.
Although most odorants we encounter in daily life are mixtures of several chemical substances, we still lack significant information on how we perceive and how the brain processes mixtures of odorants. We aimed to investigate the processing of odor mixtures using behavioral measures and functional magnetic resonance imaging (fMRI). The odor mixture contained a target odor (ambroxan) in a concentration at which it could be perceived by half of the subjects (sensitive group); the other half could not perceive the odor (insensitive group).
Chemical Senses Volume 39, Issue 2 Pp. 167-175.
Past research has shown that odor perception can be affected by how we label odors. The aim of this study was to expand on previous work by investigating the impact of labels on edibility, pleasantness, and intensity ratings as well as on reaction times when detecting labeled odors. We tested 50 subjects. Five odorants were administered, each with a positive and a negative label. Participants had to detect odors as fast as possible and then rate their edibility, pleasantness, and intensity.
Cerebral Cortex Volume 23, Issue 10 Pp. 2448-2456
While recent studies suggest an important role of higher order olfactory brain areas for basic olfactory performance, the extent to which cortical and peripheral neural markers account for separate portions of the variability in olfactory perceptual acuity is still unclear. We addressed this question by correlating voxel-based morphometry data from 90 healthy adults with olfactory performance measures.
Frontiers in Psychology 2013; 4: 597.
Studies in non-human mammals have identified olfactory signals as prime mediators of mother-infant bonding and they have been linked with maternal attitudes and behavior in our own species as well. However, although the neuronal network processing infant cues has been studied for visual and auditory signals; to date, no such information exists for chemosensory signals. We contrasted the cerebral activity underlying the processing of infant odor properties in 15 women newly given birth for the first time and 15 women not given birth while smelling the body odor of unfamiliar 2 day-old newborn infants.
NeuroImage Volume 83, December 2013, Pages 1074–1080
Olfactory function in healthy people correlates with structural features of both the olfactory bulb and higher order olfactory processing areas, but we do not yet know how congenital anosmia affects these latter structures. In order to examine this question closer, we acquired T1 weighted magnetic resonance images from 17 subjects with congenital anosmia and from 17 age- and sex-matched controls. We compared white and gray matter volumes as well as cortical thickness between both groups.
Frontiers in Human Neuroscience 2012; 6: 288.
Higher order sensory processing follows a general subdivision into a ventral and a dorsal stream for visual, auditory, and tactile information. Object identification is processed in temporal structures (ventral stream), whereas object localization leads to activation of parietal structures (dorsal stream). To examine whether the chemical senses demonstrate a similar dissociation, we investigated odor identification and odor localization in 16 healthy young subjects using functional MRI.
Chemical Senses Volume 38, Issue 7 Pp. 577-584
Anxiety can either impair or enhance performance depending on the context. Increased sensitivity to threat seems to be an important feature of sensory processing in anxiety since anxious individuals tend to be more attentive to threatening visual stimuli. Evidence of anxiety effects in olfaction is rare; though alterations of olfactory performance in psychiatric patients and some effects of trait and state anxiety on olfactory performance have been reported.
Perception March 2013 42: 341-355
The autism spectrum (AS) is characterised by enhanced perception in vision and audition, described by the enhanced perceptual functioning (EPF) model. This model predicts enhanced low-level (discrimination of psychophysical dimensions), and mid- and high-level (pattern detection and identification) perception. The EPF model is here tested for olfaction by investigating olfactory function in autistic and Asperger participants.
Neuroscience Volume 238, 15 May 2013, Pages 82–86
Although significant progress has been made over the last decades, the chemical senses remain less well explored than vision or audition. One method to assess participants’ ability to identify or localize odors consists in the application of dichotomous stimuli (e.g., left- and right-sided stimulation). In this study we aimed to explore localization and identification mechanisms by investigating whether response times and response accuracy were correlated, with the aim of establishing the pertinence of response times as an additional measure for assessment of the olfactory function.
Behavioural Brain Research Volume 231, Issue 1, 16 May 2012, Pages 60–74
Impaired sense of smell is one of the earliest clinical features in both Alzheimer's disease (AD) and Parkinson's disease (PD). A meta-analysis was performed on articles obtained from the PubMed database in order to determine what aspects of olfaction are affected in these two diseases. By applying strict criteria, we included a total of 81 studies meeting the following criteria: (1) patients had a clinical diagnosis of AD or PD; (2) patients were compared to a healthy control group; (3) patients and controls were age-matched; (4) olfactory function was assessed by means of a psychophysical olfactory test; (5) mean and standard deviation were reported.
American Journal of Rhinology & Allergy, Volume 26, Number 3, May/June 2012, pp. 222-226(5)
Moderate to severe traumatic brain injuries (TBIs) commonly lead to olfactory dysfunction; it is, however, unclear whether and to what degree mild TBI such as concussions, which are common sports injuries, affect olfactory function. We therefore aimed to evaluate smell function in athletes who sustained one or more sport concussions in a cross-sectional design.
Neuroscience Letters Volume 506, Issue 2, 11 January 2012, Pages 188–192
Cross-modal interactions between vision, audition and touch have been extensively studied in the last decade. However, our understanding of how the chemical senses interact with other sensory modalities remains relatively scarce. We performed a cued auditory localization paradigm in healthy young adults by measuring reaction times to monaural auditory stimuli after subjects had been cued by unilateral olfactory stimuli, mixed olfactory/trigeminal stimuli or somatosensory stimuli. As expected, all cuing conditions led to enhanced performances in auditory localization.
Chemical Senses Volume 37, Issue 4 Pp. 371-378
Taste, smell, and chemical irritation (so-called trigeminal sensation) combine in our daily experience to produce the supramodal sensation of flavor, are processed by partly overlapping neural mechanisms, and show functional interconnectivity in experiments. Given their collaboration in flavor formation and the well-established connections between these senses, it is plausible that polymodal detection mechanisms might contribute to individual differences in measured sensitivity.
Neuroscience 2011 Aug 25; 189: 377–383
The intranasal trigeminal system is a third chemical sense in addition to olfaction and gustation. As opposed to smell and taste, we still lack knowledge on the relationship between receptor binding and perception for the trigeminal system. We therefore investigated the sensitivity of the intranasal trigeminal system towards agonists of the trigeminal receptors TRPM8 and TRPA1 by assessing subjects’ ability to identify which nostril has been stimulated in a monorhinal stimulation design.
Chemical Senses Volume 36, Issue 4 Pp. 405-410
When an odorant is presented to one side of the nose and air to the other, the ability to localize which side received the odorant depends upon trigeminal nerve stimulation. It has been shown that performance on this lateralization task increases as stimulus concentration increases. In this study, we determined the influences of stimulus volume and sex on the ability to localize each of 8 odorants presented at neat concentrations: anethole, geraniol, limonene, linalool, menthol, methyl salicyclate, phenyl ethanol, and vanillin.
Human Brain Mapping 2011 Mar; 32(3): 450–460.
Chemosensory-based communication is a vital signaling tool in most species, and evidence has recently emerged in support of the notion that humans also use social chemosignals (so-called pheromones) to communicate. An ongoing controversy does exist, however, concerning the receptor organ through which these chemicals are processed.
Neuroscience Letters Volume 478, Issue 2, 5 July 2010, Pages 102–106
Odor stimuli presented to one nostril can only be localised if they additionally activate the trigeminal nerve's chemosensitive fibers. In this study we aimed to investigate characteristics in the localisation of unilateral trigeminal, olfactory and somatosensory nasal stimuli.
Biological Psychology Volume 84, Issue 2, May 2010, Pages 313–317
Dissociating between ‘good’ or ‘bad’ odors is arguable of crucial value for human survival, since unpleasant odors often signal danger. Therefore, negative odors demand a faster response in order to quickly avoid or move away from negative situations. We know from other sensory systems that this effect is most evident for stimuli from ecologically-relevant categories. In the olfactory system the classification of odors into the food or non-food category is of eminent importance.
The Laryngoscope Volume 120, Issue 8, pages 1707–1713, August 2010
Parosmia and phantosmia relate to distorted odor perceptions. Little is known about their clinical significance. Measuring phantosmia and parosmia is still not possible. Today, assessment of parosmia or phantosmia relies mainly upon the patient's interview and the physician's experience. Therefore, we investigated the clinical usefulness of four structured questions in comparison to the patient's history regarding their accuracy in terms of the presence of odor distortions.
Experimental Brain Research February 2010, Volume 201, Issue 1, pp 1-11
We investigated associations between olfactory function and gray matter thickness in 46 healthy young subjects by means of an automated technique for measuring cortical thickness. We used an extended version of the Sniffin’ Sticks test to assess olfactory function, including odor threshold, concentration discrimination, quality discrimination, and odor identification.
Neuroscience Letters Volume 468, Issue 3, 14 January 2010, Pages 259–263
Next to olfaction and gustation, the trigeminal system represents a third chemosensory system. These senses are interconnected; a loss of olfactory function also leads to a reduced sensitivity in the trigeminal chemosensory system. However, most studies so far focused on comparing trigeminal sensitivity to suprathreshold stimuli; much less data is available with regard to trigeminal sensitivity in the perithreshold range. Therefore we assessed detection thresholds for CO2, a relatively pure trigeminal stimulus in controls and in patients with olfactory dysfunction (OD).
Chemical Senses Volume 34, Issue 2 Pp. 139-144
For humans, the localization of an odorant seems only possible if the odorant also stimulates the trigeminal nerve. There is, however, some evidence that active sniffing may affect this ability and facilitate the localization of pure odorants. Therefore, we tested the ability of 40 subjects to localize a pure odorant and a mixed olfactory/trigeminal stimulus under 2 stimulation conditions: either odors were blown into the subjects’ nostrils (passive) or subjects had to actively sniff the odors (active).
Food Chemistry Volume 106, Issue 4, 15 February 2008, Pages 1385–1392
In this study two aspects of the influence of water on flavour retention were evaluated. The first part of the study was focused on the influence of dehydration and subsequent reconstitution of mandarin juices, which was examined by headspace Proton Transfer Reaction Mass Spectrometry. The different treatments were discriminated by their mass spectra with help of Principal Component Analysis. The second part of the study concerned intranasal volatile flavour retention during food consumption. Volatile flavour concentrations were measured at four intranasal locations in nine subjects during consumption of custard desserts. Differences between the locations indicated various degrees of retention of volatile flavour compounds by the watery mucous in the nasal tract.
Chemosensory Perception March 2008, Volume 1, Issue 1, pp 9-15
Retronasal olfaction gives us information important not only for the well-being by detecting dangerous substances but also provides a basis for the pleasures of eating and drinking. However, odors presented via the retronasal route appear to evoke different sensations compared to orthonasal presentation. In this study, we differentially stimulated anterior and posterior parts of the subjects’ nasal cavity with odors. Subjects were able to tell retronasal and orthonasal smelling apart; the ability of doing so seemed to be linked to but could not completely be explained by the degree to which the odorant stimulated the trigeminal nerve. Furthermore, we examined whether food and nonfood odors were perceived as differently pleasant, depending on the presentation site. In fact, some but not all nonfood odors were described as less pleasant when they were delivered retronasally. In conclusion, the present results clearly suggest that there are differences between sensations produced by presenting odors through the retronasal or the orthonasal route, which bears significance for both basic and applied research.
Neuroscience Volume 149, Issue 1, 12 October 2007, Pages 223–231
Most odorants, in addition to the olfactory system, also activate the intranasal trigeminal system. Recent studies have shown that pure trigeminal stimulation activates somatosensory regions as well as regions traditionally thought of as primary olfactory areas. As a main aim of this study we wished to a) ascertain which brain regions are responsive to an “artificially” bimodal odor composed of a trigeminal (CO2) and an olfactory stimulant (phenyl ethyl alcohol, PEA) and b) determine if presenting CO2 and PEA simultaneously activates different brain regions than when presenting them individually.
Behavioural Brain Research Volume 185, Issue 1, 11 December 2007, Pages 59–64
Aim was to investigate differences in the central-nervous processing of gustatory stimuli between normogeusic subjects and patients with taste disorders. Twelve subjects with normal gustatory function and eight patients suffering from hypo- to ageusia underwent one fMRI run each in a 1.5 T scanner where they received liquid gustatory stimuli. fMRI analyses were performed by means of SPM2. Across all participants clusters of activated voxels were mainly found in orbitofrontal and insular regions of interest. Even those patients who did not perceive any stimuli showed some activation of gustatory centers. Group comparisons revealed higher activation of the insular and orbitofrontal cortices in patients compared to the group of healthy subjects. While further studies are needed, this finding may be interpreted in terms of enhanced neuronal recruitment due to functional impairment in patients with gustatory loss. It may ultimately prove useful in terms of the prognostic evaluation of individual patients.
Brain Research Volume 1139, 30 March 2007, Pages 235–244
The intranasal trigeminal system is involved in the perception of odors. To investigate the cerebral processing of sensory information from the trigeminal nerve in detail we studied subjects with and without olfactory function using functional magnetic resonance imaging. A normosmic group (n = 12) was compared with a group of anosmic subjects (n = 11). For trigeminal stimulation gaseous CO2 was used.
Chemical Senses Volume 32, Issue 4 Pp. 343-353.
Although numerous functional magnetic resonance imaging (FMRI) studies have been performed on the processing of olfactory information, the intranasal trigeminal system so far has not received much attention. In the present study, we sought to delineate the neural correlates of trigeminal stimulation using carbon dioxide (CO2) presented to the left or right nostril.
Clinical Neurophysiology March 2007Volume 118, Issue 3, Pages 696–701
Odor perception does not simply consist in hierarchical processing from transduction to a single “true” cerebral representation. Odor sensation may be modulated by available sensory information during encoding. The present study set out to examine whether the presence of a pure trigeminal stimulus during odor encoding may modulate odor perception at both behavioral and cortical levels.
Cerebral Cortex Volume 17, Issue 10 Pp. 2268-2275
The olfactory and the trigeminal systems have a close relationship. Most odorants also stimulate the trigeminal nerve. Further, subjects with no sense of smell exhibit a decreased trigeminal sensitivity with unclear underlying mechanisms. Previous studies indicated that single stages of trigeminal processing may differently be affected by olfactory loss.
Cerebral Cortex Volume 17, Issue 2 Pp. 370-377
Most odorants not only stimulate olfactory receptor neurons but also activate the intranasal trigeminal nerve. The simultaneous activation of the olfactory and the trigeminal system leads to an interaction in the brain. Therefore, assessment of the trigeminal impact of odorants may be difficult in subjects with a normal sense of smell.
American Journal of Rhinology, Volume 20, Number 4, July-August 2006, pp. 485-486(2)
Background: Smell and taste disorders are among the side effects of chemo- and radiotherapy. Although direct radionecrosis of the salivary glands and the taste buds might explain the chemosensory problems after radiotherapy, the olfactory and gustatory complaints seen after chemotherapy remain unexplained. The patients reporting olfactory symptoms rarely complain about qualitative olfactory disorders such as parosmia or phantosmia. Quantitative olfactory loss such as anosmia and hyposmia seem to be more frequent.
Neuroscience Volume 142, Issue 2, 13 October 2006, Pages 541–546
Humans with olfactory loss have been found to exhibit a decreased sensitivity of the chemosensory trigeminal system. It is not clear, whether the reduced trigeminal sensitivity is restricted to the chemosensitive properties of the trigeminal nerve, or whether it reflects a general decrease of trigeminal sensitivity which is also found for cutaneous afferents.
Journal of Agricultural Food and Chemistry, 2006, 54 (15), pp 5509–5515
To assess the influence of orthonasal and retronasal stimulation on cross-modal interactions between texture and flavor perception of food, a series of experiments have been conducted. Healthy human subjects were exposed to strawberry aroma pulses delivered by a computer-controlled stimulator based on air dilution olfactometry. Just prior to exposure to the aroma, the human subjects consumed water, custard, or protein gels with different textures without any added aroma. The aroma was delivered as a sequence of aroma pulses, in either an orthonasal or a retronasal fashion.
The Laryngoscope Volume 116, Issue 8, pages 1520–1522, August 2006
The trigeminal and olfactory nerves share overlapping innervation areas in the nasal cavity and seem to work in an interactive way. Loss of olfactory function leads to a decreased trigeminal sensitivity, as shown in anosmic subjects. To report the impact of disturbed trigeminal sensitivity on the olfactory function, we present a patient with unilateral loss of trigeminal function resulting from a meningeoma. Thresholds to a selective olfactory stimulus were elevated by a factor of 64 on the affected side. Recordings of event-related potentials in response to olfactory stimuli showed a significantly reduced response on the affected side. This report indicates that loss of trigeminal function may affect the sense of smell.
Journal of Psychiatry Neuroscience 2006 Jul; 31(4): 263–270.
Some patients with bipolar disorder experience mood episodes following emotional life events, whereas others do not. There is evidence that orbitofrontal hypoactivity may be related to this, because the orbitofrontal cortex is involved in the regulation of emotional and behavioural responses to external events. The close anatomical and functional connection between the orbitofrontal cortex and olfactory processing suggests that patients with bipolar disorder and heightened emotional reactivity may exhibit altered olfactory function compared with patients with bipolar disorder who do not exhibit this sensitivity.
Arch Otolaryngol Head Neck Surg. 2006;132(3):265-269. doi:10.1001/archotol.132.3.265.
To investigate the outcome of olfactory function in patients with olfactory loss following infections of the upper respiratory tract (post-URTI) or head trauma.
Rhinology Volume: 44 - Issue: 2 Firstpage: 135 - Lastpage: 139
We investigated whether olfactory dysfunction following infections of the upper respiratory tract (post-URTI) has an incidence matching the seasonality of URTIs.
International Journal of Psychophysiology Volume 62, Issue 1, October 2006, Pages 24–29
Although different parameters are known to alter the shape of olfactory event related potentials (ERP), ERP parameters are generally thought to be independent from stimulus duration. Evidence from recent studies investigating trigeminal ERP indicates that this may not be true. Aim of the present study was to investigate the relationship of stimulus duration and ERP.
Acta Oto-Laryngologica Volume 126, Issue 1, 2006 Pp.101-103
The nature of qualitative olfactory disorders such as phantosmia and parosmia is a matter of debate. Parosmia and phantosmia mainly occur in combination with post-traumatic or post-infectious olfactory loss. Rare causes of these disorders such as brain tumors, side-effects of drugs, paraneoplastic syndromes, psychiatric disorders or intracerebral haemorrhage have been reported. Parosmias are distorted sensations of smell elicited by an odor, whereas phantosmias persist permanently or occur without the presence of an odor source. Phantosmias differ widely in terms of their nature. In contrast, parosmias always seem to be unpleasant. We report the case of a female with post-infectious hyposmia who reported a pleasant parosmia to selected odorants. We have called this rare clinical presentation euosmia.
Chemical Senses Volume 31, Issue 1Pp. 27-31
Following up on recent observations in patients with nasal polyposis (NP), the present study aimed to investigate whether a mechanical obstruction of the anterior olfactory cleft (OC) would produce differential effects on orthonasal and retronasal olfactory functions. To this end, we studied 33 healthy subjects in a randomized trial. Sponges with high content of saline were either placed in the OC or on the respiratory epithelium, such that this was blinded to both subject and observer.
Arch Otolaryngol Head Neck Surg. 2005;131(11):977-981
To investigate differences between orthonasal and retronasal olfaction in patients with loss of the sense of smell without taste complaints.
Chemical Senses Volume 30, Issue 7Pp. 575-582
The odorants emanating from the oral cavity during eating and drinking reach the olfactory mucosa via the pharynx (retronasal olfaction). It is unclear which variables influence the perception of intraorally applied substances. The aim of the present study was to determine the temporal profiles of volatile odor concentrations at different locations in the nasal cavity during consumption of liquid and solid custard samples using proton transfer reaction mass spectrometry.
International Journal of Psychophysiology Volume 57, Issue 3, September 2005, Pages 181–186
The aim of the study was to address sex-related hemispheric differences in trigeminal event-related potentials while controlling for the subjects' olfactory sensitivity. Event-related potentials to lateralized stimulation using the trigeminal stimulant CO2 were recorded in 28 healthy young subjects (16 women). There was no sex-related difference in olfactory sensitivity. Results indicated a sex-differentiated response to trigeminally induced pain. Women were found to have generally higher amplitudes and shorter latencies of the late positive component than men. Moreover, men and women exhibited different hemispheric activations in that women expressed shorter latencies over the left hemisphere than men. The pronounced sex-related difference of the late positive component suggests a cognitive/emotional impact on the processing of intranasal pain as indicated by others.
Environmental Toxicology and Pharmacology Volume 19, Issue 3, May 2005, Pages 575–580
The trigeminal chemosensory system responds to irritation of the nasal cavity. Despite its dominant role as a sentinel in protecting the respiratory tract from harmful substances and its involvement in the perception of odorous substances, it has received relatively little attention compared to the olfactory system.
The Laryngoscope Volume 115, Issue 6, pages 1124–1127, June 2005
Changes of gustatory function after ear surgery have been studied extensively. However, little is known on the influence of repeated/chronic inflammation within the middle ear on taste.
European Archives of Oto-Rhino-Laryngology and Head & Neck March 2005, Volume 262, Issue 3, pp 231-235
The objective of the present study was to investigate the hypothesis that subjects with parosmia suffer more in their daily life than patients who experience only quantitative olfactory loss. Two hundred five outpatients of the Smell and Taste Clinic and 25 healthy controls were included.
Movement Disorders Volume 19, Issue 10, pages 1196–1202, October 2004
Olfactory loss is among the early signs of Parkinson's disease (PD). We investigated whether “idiopathic” olfactory dysfunction might relate to signs of nigral degeneration. Olfactory tests were combined with transcranial sonography of the substantia nigra and single photon emission computed tomography (SPECT) imaging.
Neuroscience Letters Volume 362, Issue 1, 13 May 2004, Pages 65–69
There is evidence that functionally different areas can be distinguished within the nasal mucosa with regard to stimulation site and stimulus properties. The aim of the present study was the comparison of electrophysiological and psychophysical measures obtained in response to mechanical and chemosomatosensory stimulation of two different regions of the nasal mucosa.
European Archives of Oto-Rhino-Laryngology and Head & Neck August 2004, Volume 261, Issue 7, pp 411-415
Many patients with olfactory dysfunction not only experience quantitative reduction of olfactory function, but also suffer from distorted olfactory sensations. This qualitative dysfunction is referred to as parosmia (also called “troposmia”) or phantosmia, with the major difference that distorted olfactory sensations are experienced in the presence or absence of an odor, respectively. Our clinical observations corroborate the literature in terms of a general underestimation of the incidence of olfactory distortions. Based on selected cases we try to show that olfactory distortions exhibit a large variance in their clinical appearance. Further, emphasis is placed on the fact that only a detailed and directed history of the patient can provide cues to the correct diagnosis.
Brain Research Volume 987, Issue 2, 17 October 2003, Pages 201–206
Compared to younger subjects, older people have a reduced sensitivity of the intranasal trigeminal system which responds to irritation of the nasal cavity. It is unclear whether the cause of this difference relates to age-dependent changes in the periphery of the system. The aim of the present study was the comparison of intranasal trigeminal thresholds assessed through electrophysiological measurements in eight young (four women, four men; mean age 25 years) and eight older subjects (four women, four men; mean age 62 years).
Journal of Clinical Neurophysiology February 2003 - Volume 20 - Issue 1 - p 80–86
Few data are available on the relation of EEG‐derived trigeminal event‐related potentials (ERPs) to stimulus duration or stimulus concentration. Thus, the aim of this study was to analyze the relation between ERP components and both stimulus duration and stimulus concentration. Twenty healthy young subjects participated.
Toxicology Letters Volumes 140–141, 11 April 2003, Pages 273–280
The present investigation aimed to compare trigeminal nasal function of anosmic and hyposmic patients to healthy controls. Further, we aimed to study effects of age and gender on trigeminally mediated sensations following intranasal chemosensory stimulation. Participants were 35 patients with olfactory dysfunction (n=13: functional anosmia; n=22: hyposmia; age 28–69 years, mean age 56 years). Their results were compared with 17 normosmic subjects (28–82 years, mean 52 years).
American Journal of Rhinology, Volume 16, Number 5, September-October 2002, pp. 275-279(5)
Patients with chronic renal failure (CRF) show a high prevalence of poor nutritional state so that dietary treatment becomes a significant part of the therapeutic regimen. Because smell plays an important role in nutrition, this study aimed to investigate olfactory function in CRF patients.
Rhinology Volume: 40 - Issue: 3 Firstpage: 129 - Lastpage: 134
We investigated whe--ther di-rhi-nal ol-fac-tory thresholds differ from mo---no--rhinal ones. Experiments 1 and 2 investigated butanol, Experiment 3 phenylethylalcohol. In experiments 2 and 3 pen-like odor dispensing devices were used, in Experiment 1 odors were presented in glass bottles. Participants were in excellent health (Experiment 1: 14 female [f], 15 m [m], mean age [ma] 24 years; Experiment 2: 12 f, 19 m, ma 24 years; Experiment 3: 19 f, 19 m, ma 32 years). Thresholds were assessed for left, right, and both nostrils. No significant difference was found between dirhinal results and results for the best of two nostrils. Apart from this, thresholds were found to improve with repeated testing. In conclusion, using two odorants with different techniques of administration in studies performed at different sites, the present results indicated that there is no major difference between odor detection thresholds obtained for the best and both nostrils.
HNO December 2014, Volume 62, Issue 12, pp 846-852
Die Ursprünge des Geruchssinns liegen in der Wahrnehmung von Umgebungsmolekülen und reichen bis zu einzelligen Lebensformen wie Bakterien zurück. Gerüche liefern uns eine große Vielzahl von Informationen über die chemische Zusammensetzung unserer Umgebung. Der Geruchssinn trägt bei Menschen und Tieren zur Orientierung und Warnung bei Gefahren bei, beeinflusst die Wahl des Sexualpartners, kontrolliert die Nahrungsaufnahme und hat letztendlich Einfluss auf die gesamte Gefühlswelt und unser Sozialverhalten.
Progress in Brain Research, Vol. 191
In this review, we describe crossmodal plasticity following sensory loss in three parts, with each section focusing on one sensory system. We summarize a wide range of studies showing that sensory loss may lead, depending of the affected sensory system, to functional changes in other, primarily not affected senses, which range from heightened to lowered abilities. In the first part, the effects of blindness on mainly audition and touch are described.
Brain Res Rev. 2010 Mar; 62(2): 183.
Almost every odor we encounter in daily life has the capacity to produce a trigeminal sensation. Surprisingly, few functional imaging studies exploring human neuronal correlates of intranasal trigeminal function exist, and results are to some degree inconsistent. We utilized activation likelihood estimation (ALE), a quantitative voxel-based meta-analysis tool, to analyze functional imaging data (fMRI/PET) following intranasal trigeminal stimulation with carbon dioxide (CO2), a stimulus known to exclusively activate the trigeminal system.
Annals of the New York Academy of Sciences Volume 1170, International Symposium on Olfaction and Taste pages 190–195, July 2009
Although numerous fMRI studies have been performed on the processing of olfactory information, the intranasal trigeminal system so far has not received much attention. In a pilot study stimulants were presented within a constantly flowing airstream birhinally to activate the olfactory (phenylethyl alcohol, H2S) or the trigeminal (CO2) nerves. Both olfactory and trigeminal stimulation activated the ventral insular cortex. Intranasal trigeminal stimulation additionally led to an activation of the midbrain, superior temporal gyrus, anterior caudate nucleus, and the dorsolateral orbitofrontal cortex.
International Journal of Psychophysiology Volume 65, Issue 3, September 2007, Pages 177–18
The intranasal trigeminal and the olfactory system are intimately connected. There is evidence showing that acquired olfactory loss leads to reduced trigeminal sensitivity due to the lack of a central–nervous interaction. Both, the orbitofrontal cortex and the rostral insula appear to be of significance in the amplification of trigeminal input which is missing in patients with olfactory loss. On peripheral levels, however, adaptive mechanisms seem to produce an increase in the trigeminal responsiveness of patients with hyposmia or anosmia.
Flavour and Fragrance Journal Vol 21 Issue 1
Orthonasal or retronasal presentation of certain odours in everyday life, such as cheese or fish, evokes different responses. To study this phenomenon, stimulation techniques were developed to allow ortho- or retronasal presentation of chemosensory stimuli. Based on this technique, several studies were performed to investigate: (a) the subjects' ratings of stimulus intensity, hedonic characteristics of the stimuli, and stimulus quality; (b) the peripherally obtained electro-olfactogram; (c) EEG-derived olfactory event-related potentials; and (d) cerebral activation using functional magnetic resonance imaging; additional experiments investigated (e) the differential sensitivity of the nasal mucosa to trigeminal stimuli; and finally (f) clinical observations were obtained from patients with nasal polyposis with regard to ortho- or retronasal presentation of chemosensory stimuli. Summarizing these results, the studies indicate that there are perceptual differences in relation to ortho- and retronasal stimulus presentation.