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Abstracts

Crossmodal olfactory-visual integration in humans

Jessica Albrecht1, jessica.albrecht@me.com; Valentin Schriever2, valentin.schriever@mac.com; Eva C. Alden1, ealden@monell.org; Johan N. Lundström1,3,4, jlundstrom@monell.org

1Monell Center, Cognitive Neuroimaging Laboratory, Philadelphia, USA; 2University of Göttingen, Department of Neurophysiology and Cellular Biophysics, Göttingen, Germany; 3University of Pennsylvania, Department of Psychology, Philadelphia, USA; 4Karolinska Institute, Department of Clinical Neuroscience, Stockholm, Sweden

In our everyday lives we are faced with multisensory rather than pure unisensory experiences. It has been shown that stimulation of more than one sensory modality enhances behavioral variables and modulates cognitive brain processes. The largest perceptual effects occur when the stimuli are congruent in their spatial and temporal presentation, but also a congruent semantic context is of importance. During a first experiment we assessed the effects of congruent and incongruent visual stimuli on olfactory sensitivity and perceptual ratings and in a second experiment we obtained electrophysiological (ERP) data during olfactory-visual stimulation. In Experiment 1, we used a within-subjects 2 x 3 design to measure olfactory thresholds for two odors while subjects viewed the image of either an empty screen, or an image congruent or incongruent to the odor. In addition, we acquired olfactory intensity and pleasantness ratings for each of the six conditions. In Experiment 2, we measured visual and olfactory ERPs related to each of the six conditions. Experiment 1 demonstrated that odor detection threshold and ratings of odor intensity were not modulated by visual congruency; however, congruent visual stimuli significantly enhanced odor pleasantness ratings for both odors in comparison to either blank or incongruent visual stimulation. ERP data from Experiment 2 is currently being evaluated and will be presented. Results from Experiment 1 suggest that peripheral olfactory functions are not modulated by visual stimuli, whereas higher-order cognitive olfactory processes are influenced by a congruent visual stimulus.

Acknowledgements: Supported by start-up funds from the Monell Center awarded to JNL and a DAAD postdoctoral fellowship D/08/40252 awarded to JA.

 

The Neural Architecture of Autobiographical Odor-Evoked Memories

Artin Arshamian1,2, Emilia Iannilli2 , Johan Willander1, Jonas Persson3,Han-seok Seo2, & Thomas Hummel2,  Maria Larsson1

1Gösta Ekman Laboratory, Department of Psychology, Stockholm University, Sweden; 2Department of Otorhinolaryngology, University of Dresden Medical School, Germany; 3Department of Psychology, Stockholm University, Sweden; artin.arshamian@psychology.su.se

Autobiographical memory (AM) refers to the ability to remember past events from one’s life. Both behavioral and neuroimaging research on autobiographical memory has mainly focused on memory recollections generated by verbal cues. The overall aim of this study was to investigate the neural correlates of olfactory evoked memories, and how these may differ from AMs evoked by the verbal referents of the cue odors. Furthermore, potential remoteness effects of the retrieved memories on neural activity were investigated. Following a pre-selection procedure, eighteen participants (age range: 20-28 years) with specified spontaneous evoked olfactory AMs were included. During scanning, subjects were presented with both the target odor and its verbal referent and instructed to retrieve the respective target memory. As control tasks, participants were asked to passively smell a non-memory evoking odor and to visually perceive its verbal referent. Preliminary analyses indicate that olfactory evoked memories overall produced less activation than verbally evoked memories. In congruence with previous work, verbally triggered memories produced a substantial frontal activity including the right dorsolateral prefrontal cortex, and prefrontal cortex. In contrast, retrieval of olfactory evoked memories was primarily localized to limbic structures (e.g., hippocampus, anterior cingulate). Interestingly, in contrast to retrieval of older AM, recollection of more recent AMs was related to higher activity in the left hippocampus. In conclusion, the overall findings from the present study favor the notion that verbal cues initiate a strategically driven retrieval process, whereas olfactory stimuli produce a more automatic and direct retrieval process.

 

Olfactory learning during sleep

Anat Arzi, Limor Shedlesky Anton Plotkin, Aharon Weissbrod and Noam Sobel

Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76110, Israel. anat.arzi@gmail.com

Sleep is a state of relatively suspended sensory and motor activity. Sleep is distinguished from quiet wakefulness in part by decreased reactions to external stimuli. However, evidence suggests that external stimuli, mainly auditory, are nevertheless processed during sleep. Olfaction may offer unique insight into sensory processing during sleep, in that it entails an implicit sensorymotor measure of stimulus content, namely sniffing. During wake, sniffs are truncated in response to either intense or unpleasant odorants. Previous work suggested that odorants presented during sleep don’t wake, but do modify respiratory patterns.

Here we used measures of sniffing during sleep to ask three independent questions:

1. Is odorant pleasantness processed in sleep?

2. Can odors presented during sleep condition a response generated during sleep?

3. Can odors presented during sleep condition a response generated in later wake?

We recorded the following physiological measurements from 34 subjects: electroencephalogram, electrooculogram, electromyogram, electrocardiogram, blood oxygenation, and nasal respiration. Subjects wore a small nasal mask where we could deliver odorants at a flow rate of 3 LPM in a controlled fashion, with no non-olfactory cues as to odorant onset and offset.

During sleep, partial conditioning between odor and sound was generated at a ratio of 2:1. On each Conditioning trial (two thirds of all trials), an auditory stimulus was triggered by an inhalation, and was followed by an olfactory stimulus. We used two auditory stimuli (pure tones of 1200 Hz or 400 Hz, duration = 1 sec), each paired with one of two olfactory stimuli (the pleasant odor of deodorant or the unpleasant odor of rotten fish (duration = 3 sec). About half an hour after the subjects woke up they were tested for a conditioned response: three auditory stimuli were presented, 1200Hz, 400Hz and a new tone of 800Hz that was not present during the night (8 repetitions each), while nasal respiration was recorded.

As to the first question, we found that odor pleasantness influenced respiratory patterns in sleep in a manner similar to wake: unpleasant odorants were followed by truncated respirations. As to the second question, we found that sounds paired with pleasant or unpleasant odorants later induced dissociable respiratory responses during sleep, even in the absence of odor. This suggests learning during sleep. Finally, regarding the third question, our data suggests that odor-sound pairings learned during sleep are then retained during wake.

 

Varying the mode of sniffing alters intra-nasal odorant concentrations

Jonathan Beauchamp1, Mandy Scheibe2, Thomas Hummel2 and Andrea Buettner1,3jonathan.beauchamp@ivv.fraunhofer.de

1Fraunhofer IVV, Sensory Analytics, Freising, Germany; 2University of Dresden,Department of Otorhinolaryngology, Dresden, Germany; 3University of Erlangen-Nuremberg, Department of Chemistry and Pharmacy, Erlangen, Germany

In the early 1980s Laing showed that optimum odour perception is achieved with just a single sniff. Today, almost three decades later, there is still a great deal of uncertainty as to what is actually happening to the odorant molecules inside the nose. We have investigated intra-nasal odorant concentrations at the nostril and olfactory cleft using proton-transfer-reaction mass spectrometry (PTR-MS). By asking subjects to alter their mode of sniffing it was possible to monitor in real-time absolute odorant intensities according to inhalation performance.

 

Determinants of inter-individual variability in odor hedonic perception

Chakirian A, Chastrette M, Rouby C, and Bensafi M

CNRS and University of Lyon, France; bensafi@olfac.univ-lyon1.fr

In humans, odors are usually first described by their hedonic character.  Such hedonic appreciation can vary significantly between individuals for a particular odor whereas for other chemical stimuli there seems to be an agreement between subjects.  Here we will present psychophysical data showing that such hedonic variability is correlated with both physicochemical parameters and semantic descriptors.

 

Olfactory fat detection in human subjects

Sanne Boesveldt1,2, Eva C. Alden1, Johan N. Lundström1,3,4; sanne.boesveldt@wur.nl

1Monell Chemical Senses Center, Philadelphia, USA; 2Division of Human Nutrition, Wageningen University, Wageningen, the Netherlands; 3University of Pennsylvania, Department of Psychology, Philadelphia, USA; 4Karolinska Institute, Department of Clinical Neuroscience, Stockholm, Sweden

In Western diet, about 40% of daily caloric intake is lipids, despite the fact that the recommended level is at least 10% lower. This high-fat supply greatly contributes to the prevalence of obesity and associated diseases. The desire to consume high volumes of fat is thought to originate from an evolutionary pressure to horde calories where fat is among the few energy sources that we can store over a longer time period. Indeed, recent data has shown that the human oral cavity contains a taste receptor for lipids that is specifically tuned to recognize fatty acids (FAs). From an ecological perspective however, it would make more sense for both humans and rodents to be able to detect the fat content of food from a distance rather than being forced to put a potential toxic substance in your mouth for evaluation: We hypothesized that humans can detect fat content by our sense of smell.

We assessed subjects’ ability to discriminate between three different milk samples containing varying percentages of milk fat (skim 0.125%, fat 2.8%, and medium, consisting of a 50/50 mixture of the skim and fat, equaling 1.46%). Based on a three-alternative, forced-choice odor discrimination test, repeated 9 times per triplet (attaining a chance level of 3), blindfolded subjects (n=32) were significantly able to discriminate the skim milk from medium (mean 4.25), as well as skim milk from fat milk (mean 5.72). However, subjects were unable to discriminate the medium milk from fat milk (mean 3.34). We further ascertained that discrimination was based solely on odor quality by removing trials where discrimination was reportedly based on intensity differences. In conclusion, these data demonstrate that humans have a functional olfactory detection system for fat with a seeming ability of discrimination between grades of fat content.

Acknowledgements: Supported by start-up funds from the Monell Chemical Senses Center awarded to JNL. We would like to thank FrieslandCampina for providing us with the milk powder samples.

 

Sexually dimorphic hypothalamic responses to steroid compound androstadienone – an fMRI study

Sarah M. Burke1, Johannes Gerber2, Dick Veltman3, Thomas Hummel4, Julie Bakker156

1: Department of Medical Psychology, VU university medical center, Amsterdam, The Netherlands; 2: Department of Neuroradiology, University of Dresden Medical School, Dresden, Germany; 3: Department of Psychiatry, VU university medical center, Amsterdam, The Netherlands; 4: Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany; 5: GIGA Neuroscience, University of Liege, Belgium; 6: Netherlands Institute for Neuroscience, Amsterdam, The Netherlands; s.burke@vumc.nl

The steroid 4,16-androstadien-3-one (androstadienone), a derivative of testosterone, is found mainly in male sweat and has been attributed to have pheromonal properties. Thus, exposure to androstadienone has been found to elevate mood and autonomic responses in women, but not in men. Furthermore, using positron emission tomography (PET) it was shown that androstadienone elicits a sex-specific hypothalamic response in heterosexual female subjects when exposed to the crystalline form of the steroid, whereas men only exhibit activation in brain areas related to general odor processing. The aim of the present study was to determine whether androstadienone, in more biologically relevant concentrations, would also induce a sexually dimorphic activation in the hypothalamus. In addition, we used functional magnetic resonance imaging since it offers better temporal resolution than PET and subsequently will extend our understanding of how androstadienone may be processed in the brain. A total of 21 women and 16 men (mean age 24,65 +/- 5,44 years), all right-handed and heterosexual, participated. Women used no oral contraceptives and were tested during the second or third week of their menstrual cycle to control for any fluctuations in ovarian hormone levels. Three different concentrations of androstadienone diluted in propylene glycol (10mmol “high”, 0.1mmol “medium,” and 0.001mmol “low”) were delivered to the subjects’ nostrils by means of an air-dilution olfactometer. Statistical analysis of the fMRI data revealed a significant “gender” by “odor concentration” interaction. When exposed to the highest androstadienone concentration (10mmol) women showed a significant hypothalamic response (p=0.012, corrected) in comparison to men, which is in agreement with previous PET studies. By contrast, the “medium” and “low” androstadienone concentrations, which are more biologically relevant, revealed a significant hypothalamic activation in men compared to women (p=0.005 and p=0.013 respectively, corrected). These results thus show that androstadienone can activate the hypothalamus in both men and women and that sex differences in hypothalamic activation depend on the concentration of androstadienone.

Acknowledgements: This study is supported by a VICI grant from the Netherlands Science Foundation (NWO). Julie Bakker is a research associate of the FNRS

 

Helicobacter pylori infection and smell-taste distortion: a case report

Maria Paola Cecchini1, Camilla Pellegrini2, Maria Antonietta Bassetto1, Francesco Osculati3, Andrea Sbarbati1, Marcolini L4, and Lucia De Franceschi2

Dep. of 1N. N. M. M. Sciences, Anatomy and Histology Section and 2 Medicine,  University of Verona, Italy; 3IRCCS Centro Neurolesi “Bonino Pulejo”, Messina, Italy; 4 Dep. of Pathology and Diagnostics, Policlinico GB Rossi, University of Verona, Italy; mmariapaola@gmail.com

Helicobacter pylori (H-P) is the causative agent of worldwide distributed infection of the mucous membranes of stomach possibly involved in severe complications such as gastric ulcer, carcinoma or MALT-lymphoma. H-P has also been found in dental plaque, saliva and lingual site. Up to date, taste or olfaction disorders related to  H-P infections have never been reported. In literature revision we found two papers referring to a sour taste sensation during H-P infection. Here, we report the case of a 24-years-old Ghanaian woman with H-P gastric infection associated with olfaction and taste distortion (cacosmia and hypo-cacogeusia). We performed a diagnostic work-up including chemistries, complete blood count, abdomen x-ray, ultrasound, head computed tomography (CT) and gastroscopy. We documented an H-P infection and we carried out the Sniffin’Sticks Extended test, the taste evaluation with four over threshold spray solutions and a detailed gustatory sensitivity test (Taste Strips) which indicated an hypogeusia and highlighteda specific difficulty in discrimination between bitter and acid taste. This chemosensory distortion associated to nausea made the meal moment very difficult and impaired the normal diet with patient weight loss (almost 12 kg in two years). One month and half after H-P eradication, the patient was clinically re-evaluated and we found the dissapearance of the bad olfactory sensation while  the cacogeusia (a sort of bitter bad taste, in particular while eating) was present only few times in a week. The taste performance,  revealed by test scoring, improved even if sometimes a misinterpretation of the taste bitter and acid hold over. Studies in animal models suggest that changes in taste perception may related to infections damaging taste buds. Based on this case we believe that a taste evaluation might be important in a dyspeptic clinical picture in both pre and post diagnostic phase when H-P infection is  suspected. Further studies need to be carried out in a large patient population to understand the possible connection between H-P infection and smell-taste distortion.

 

A behavioural odour-similarity “space” in larval Drosophila

Chen Yi-chun, Mishra Dushyant, Schmitt Linda, Michael Schmuker, Gerber Bertram

Department of Neurobiology and Genetics, University of Würzburg, Biocenter Am Hubland, D-97074 Würzburg, Germany; chen.yi-chun@biozentrum.uni-wuerzburg.de

To provide a behaviour-based estimate of odour similarity in larval Drosophila, we use four recognition-type experiments: (i) We train larvae to associate an odour with food, and then test whether they would regard another odour as the same as the trained one. (ii) We train larvae to associate an odour with food, and test whether they prefer the trained odour against a novel, non-trained one. (iii) We train larvae differentially to associate one odour with food, but not the other one, and test whether they prefer the rewarded against the non-rewarded odour. (iv) In an experiment like (iii), we test the larvae after a 30min-break. This yields a combined, task-independent estimate of perceived difference between odour-pairs. Comparing these perceived differences to published measures of physico-chemical difference reveals a weak correlation. A notable exception are 3-octanol and benzaldehyde, which are distinct in published accounts of chemical similarity, and in terms of their published sensory representation, but nevertheless are consistently regarded as the most similar of the ten odour pairs employed. It thus appears as if at least some aspects of olfactory perception are 'computed' in post-receptor circuits on the basis of sensory signals, rather than being immediately given by them.

 

Trigeminal modulation of olfactory reception

Philipp Daiber and Frank Möhrlen

Universität Heidelberg, Abteilung für Molekulare Physiologie, Heidelberg, Germany; philipp.daiber@arcor.de, Frank Möhrlen, moehrlen@uni-hd.de

The olfactory system and the trigeminal system have traditionally been regarded as two separate sensory modalities that serve either odor detection or the perception of pain. However, both the olfactory epithelium and the olfactory bulb are innervated by neurosecretory fibers of the trigeminal system. Moreover, only few odorants stimulate the olfactory system exclusively (e.g. phenylethyl alcohol, PEA). All others also activate the somatosensory trigeminal nerve. Functional interactions between the two systems have been demonstrated in psychophysical studies but the molecular basis of this interaction remains unknown. When stimulated, the trigeminal system secretes substance P (SP) and CGRP. Here we ask the question whether these neuropeptides might be involved in modulation of olfactory receptor neurons.

We established the presence of the receptors for SP (neurokinin 1, NK 1) and CGRP (calcitonin receptor like receptor, CRLR, and CGRP-Receptor component protein,CGRP-RCP) on mRNA and protein levels in rat olfactory receptor neurons (ORNs). The receptors are localized at various sites of the ORN, but very prominently in olfactory cilia. To illuminate a possible modulatory effect, we used EOGs (electro-olfactograms). We examined the sensory response to the odorant (phenylethyl alcohol, PEA), which does not co-stimulate the trigeminal system. We also studied the response to an odorant with mild trigeminal stimulation (isoamyl acetate, IAA), as well as the response to the irritant allyl isothiocyanate (AIC). We also examined how the trigeminal peptides SP and CGRP affected the EOG evoked by PEA stimulation. Our data show that trigeminal stimulation severely alters the dose-response relation of the EOG. Moreover, the trigeminal neuropeptides display distinct effects on the olfactory response: While SP potentiates the odor response, CGRP has an excitatory effect on its own. These results point to a direct modulatory impact of the trigeminal system on ORNs.

 

Evidence for ventral and dorsal streams in the chemical senses

Johannes Frasnelli

frasnelli@yahoo.com

Basic sensory processing occurs in the primary and secondary sensory regions of the brain, which are distinct for the different sensory systems. Higher order processing, however, seems to follow a general subdivision into a ventral and a dorsal stream. Object identification in the visual, auditory and tactile senses is processed in temporal structures (ventral stream), whereas object localization leads to activation of parietal structures (dorsal stream).  A series of behavioral and imaging studies will be presented, in which object localization and object identification was studied using volatile compounds with olfactory and trigeminal properties, i.e., mixed olfactory-trigeminal stimuli. Object localization was assessed as the ability to detect which nostril was stimulated in a monorhinal presentation; object identification was tested by asking the subject to name the volatile compound.  The results of these studies suggest that higher order chemosensory processing shares with other sensory systems a general subdivision into a ventral and a dorsal processing stream for higher order processing.

 

Infant Olfactory Event-Related Potentials

Góis-Eanes, M.*, Cruz, S.*, Schuster, B.**, Gonçalves, O.*, Sampaio, A.*

*Neuropsychophysiology Lab, School of Psychology, University of Minho, Portugal ** Department of Otorhinolaryngology, University of Dresden Medical School, Germany;maria.gois@gmail.com

Objective: The aim of this study was to identify electrophysiological responses of around one-month-old infants when presented with olfactory stimuli. These stimuli were offered in three different intensities and we looked for the appearance of olfactory event-related potentials (OERP) for each stimuli intensity.

Background: Since the birth, the neonate is able to respond with specific behaviors to different stimuli that surround him. She may cry when facing an aversive stimulus, shows aversion facial expressions when presented with odors that were previously considered as unpleasant and, likewise, is able to crawl to follow the mother´s breast odor. Behavioral preference signals, such as head turning, when a pleasant olfactory stimuli is presented, can also be observed. These evidences can demonstrate that the olfactory function develops from the first years of life and that at birth this function is already operational, producing behavioral and psychophysiological responses in the newborn.

Method: Sixty-one newborns were recruited at the Obstetric and Pediatric services of Woman’s, Children’s and Adolescent’s Department of Hospital Pedro Hispano, in Matosinhos, Portugal. From the total recruited, thirteen appeared in the hospital and thirteen circa one-month old infants participated in the study. OERP’s were registered with a total of 12 caucasian newborns (6 female, 6 male) because, due to technical issues in the registry, the data for one infant was lost. The infants aged between 23 to 41 days. All infants were full-term with birth weight between 2620g to 4270g and normal Apgar score. To elicit OERP, monomodal chemosensory nasal stimulation was performed using an Olfactometer OM2s (Burghart Instruments, Wedel, Germany). This was achieved by embedding chemical stimuli of 200 ms duration in a constantly flowing air stream (5 l/min) applied to the nasal mucosa by an enteral feeding tube inserted approximately 5mm into the nostril beyond the nasal valve area and fixed to the nose with Mefix adhesive. For the olfactory stimulation Phenyl Ethyl Alcohol Rose-like Odor was used (PEA, 10 30 and 50% v/v; Sigma, Deisenhofen, Germany), offered in three different sequences.

Results: At the present moment, the data analysis is still an ongoing process and because of that there are no results to present. But, being such an ambitious project and using methodologies that are quite new with such young infants we can, however, conclude that collecting the data using the procedures reported above is a doable process and that it is possible to offer the olfactory stimuli the way we did.

 

Clinical Windows into the Basic Neuroscience of Human Olfaction
Jay Gottfried

j-gottfried@northwestern.edu
Clinical studies of neurological patients can usefully serve as Nature's "lesion models" of olfactory processing, helping to inform and constrain basic models of olfactory perception. In this talk I will discuss our recent work in patients with traumatic brain injury, Alzheimer's Disease, and Primary Progressive Aphasia, to illustrate how patient-based investigations that combine psychophysical and neuroimaging approaches have expanded our neuroscientific understanding of odor awareness, odor coding, and odor semantics in the human brain.

 

Burning Mouth Syndrome (BMS) and Taste

Miriam Grushka

Department of Oral Medicine & Orofacial Pain, Toronto; mgrushka@yahoo.com

This talk will review the common characteristics and recently proposed etiologies of BMS including the relationship of BMS to disturbances of taste.   A brief review of current management strategies will also be presented.

 

Ambient urban odors evoke basic emotions

Elisabeth Lingg1, Sandra Weber2, Eva Heuberger1,3

1 University of Vienna, Department of Clinical Pharmacy and Diagnostics, Vienna, Austria; 2 University of California, San Diego, Department of Cognitive Science, La Jolla, California, USA; 3 Saarland University, Pharmaceutical Biology, Saarbruecken, Germany; e.heuberger@mx.uni-saarland.de

Fragrances, such as plant odors, have been shown to evoke autonomic response patterns associated with Ekman’s basic emotions happiness, surprise, anger, fear, sadness and disgust. The present study evaluated the potency of ambient odors connoted with an urban environment to evoke basic emotions by testing whether such odors elicit emotion specific autonomic response patterns and cognitive associations. Synthetic mixtures representing the odors of disinfectant, candles / bees wax, summer air, burnt smell, vomit, mustiness and odorless water as a control were presented five times in random order to 30 healthy, non-smoking human subjects with intact sense of smell while physiological parameters, i.e., skin temperature, skin conductance, breathing rate, forearm muscle activity, blink rate, heart rate and heart rate variability, were recorded. Subjects also rated the odors in terms of pleasantness and intensity and gave cognitive associations with the basic emotions. The results showed that the amplitude of the skin conductance response (SCR) varied as a function of odor presentation. Burnt smell and vomit elicited significantly stronger SCRs than summer air. Also, a correlation was revealed between SCR amplitude and hedonic odor valence indicating that SCR amplitude increased with odor unpleasantness. However, no emotion specific patterns of autonomic activity were identified. The analysis of the cognitive associations between odors and basic emotions showed that candles / bees wax and summer air were specifically associated with happiness whereas burnt smell and vomit were associated with disgust. Our findings suggest that city odors may evoke specific cognitive associations of basic emotions and that autonomic activity elicited by such odors is related to odor hedonics but not necessarily emotion specific.

Acknowledgements: Financial support by Vienna Science and Technology Fund (grant no. CI06 009) is greatly acknowledged.

 

The depth of the olfactory sulcus is an indicator of congenital anosmia

Huart C1,2, Meusel T3, Gerber J4,  Rombaux P1, Hummel T3

1Department of Otorhinolaryngology and 2Institute of Neurosciences, Université Catholique de Louvain, Brussels, Belgium, Clinicien-Chercheur Doctorant FRS-FNRS; Departments of 3Otorhinolaryngology and 4Neuroradiology, Technical University of Dresden Medical School, Dresden, Germany. caro_huart@hotmail.com

In congenital anosmia, the olfactory bulb and olfactory tract can be both aplastic or hypoplastic. In clinical routine they are sometimes difficult to assess. We thus want to investigate morphologic differences of the olfactory sulcus in patients with isolated anosmia (IA) since birth or early childhood in comparison to controls in a large group of subjects; to investigate whether the depth of the olfactory sulcus (OS) indicates IA.

Within the context of a two-center study we investigated 36 IA patients in comparison to 40controls. Imaging was performed with a standard quadrature head coil (1.5 T;T1 and T2-weighted spin echo sequences were used (coronal plane perpendicular to frontal skull base). We assessed olfactory bulb volume by planimetric contouring, and OS depth in the plane of the posterior tangent through the eyeballs (PPTE).

Looking to the OS depth in the PPTE, none of the healthy controls exhibited a depth of less than 8 mm. In IA patients, 10 had an OS deeper than 8 mm, while 26 had OS depth lower than 8 mm. Thus, if we consider an OS depth lower than 8 mm it clearly indicates IA, with a specificity of 1 while the sensitivity is 0.72.

In IA, the OS depth in the PPTE is a useful clinical indicator. Indeed, if it is ≤ 8 mm, it clearly indicates IA, with a specificity of 1. If it is deeper, the measure does not clearly predict IA.

 

OLAF, a Sniffin' Sticks test software

C. Hummel1, A. Zucco2, E. Iannilli1, B. Landis3, T. Hummel1

1 ENT Dept. of University of Dresden Medical School, 2 University of Padova, Italy 3 Unbiversity of Bern, Switzerland; hummeltc@web.de

The Sniffin‘ Sticks test for the assessment of olfactory threshold, odor identification and discrimination, developed in the 1990s (Kobal, et al. 1996), has become a widely used tool both in clinical and  research settings (Anzinger, et al. 2009; Gudziol and Hummel 2009; Landis, et al. 2005).  Originally pen-and-paper documented, it may now be applied using a  computer program. The Filemaker (Filemaker Pro Advanced 11.0v2 by FileMaker Inc.) based software „OLAF“ guides the examiner through any user defined arrangement of the test battery, stores all data in a database, and offers results sheets to be printed out for convenience. The program is available in four languages – English, French, German, and Italian - which can be toggled by a single mouse click, and is suitable for Windows as well as MacIntosh platforms.

References

Anzinger A, Albrecht J, Kopietz R, Kleemann AM, Schopf V, Demmel M, Schreder T, Eichhorn I, Wiesmann M. (2009): Effects of laserneedle acupuncture on olfactory sensitivity of healthy human subjects: a placebo-controlled, double-blinded, randomized trial. Rhinology 47(2):153-9.

Gudziol V, Hummel T. (2009): The influence of distractors on odor identification. Arch Otolaryngol Head Neck Surg 135(2):143-5.

Kobal G, Hummel T, Sekinger B, Barz S, Roscher S, Wolf S. (1996): "Sniffin' sticks": screening of olfactory performance. Rhinology 34(4):222-6.

Landis BN, Knecht M, Huttenbrink KB, Lacroix JS, Hummel T. (2005): [Clinical aspects of dysosmia and presentation of European Olfactory Test of "sniffin sticks": a review]. J Otolaryngol 34(2):86-92.

 

From subjective to objective electrogustometry

Tomasz Kamiński and Antoni Grzanka

Warsaw University of Technology, The Faculty of Electronics, Warsaw, Poland; Tomasz_Kaminski@aster.pl; A.Grzanka@elka.pw.edu.pl

This work presents the construction of an electrogustometer employing the innovative method of gustatory sense analysis – the bipolar stimulation. It consists in simultaneous placement of the active and the passive electrodes on the surface of the tongue. The stimulation takes place by means of rectangular waveform current. This solution allows for high precision of the examination with low voltage battery power thus providing full security for patients during clinical examinations. This paper presents a construction of the electrodes specially designed for this electrogustometer. The electrodes are positioned on the tongue and the subject may close the mouth during the examination. This increases the comfort both for the examiner and the patient. The paper also presents the results of research employing the bipolar method, the first results of the research employing the new type of electrodes as well as the prospects of the electrogustometer’s development.

 

From manual to automatic subjective electrogustometry

Tomasz Kamiński1, Antoni Grzanka1, Anna Choromańska1,2,

1 Warsaw University of Technology, The Faculty of Electronics, Warsaw, Poland; 2 Department of Electrical Engineering, Columbia University in the City of New York, USA; Tomasz_Kaminski@aster.pl, A.Grzanka@elka.pw.edu.pl, aec2163@columbia.edu

Electrogustometry is a simple and fast method of taste examination. The so-far used electrogustometers applied the stimulus usually by means of the electric direct current through the unipolar stimulation method. The active electrode used to be placed on the tongue, the passive electrode was held by the subject’s hand. This study presents electrogustometers constructed on the basis of an innovative examination method – the bipolar simulation. This method assures high precision of the examination, thus a more exact mapping of the tongue surface.  This consists in both the active and the passive electrodes being placed on the tongue. It enables to the decrease the voltage of the circuit and increase the safety of the patient during clinical examination. Three different constructions of electrogustometers have been presented, along with their mode of operation and the results achieved during the gustatory sense examination.

 

Revisiting the myth of the longevity of olfactory memory

Stina Cornell Kärnekull, Fredrik U Jönsson, Johan Willander, & Maria Larsson

Gösta Ekman Laboratory, Department of Psychology, Stockholm University, Sweden; stina.ck@hotmail.com

The relatively few studies that have assessed long-term odor recognition memory indicates little forgetting across time (Engen & Ross, 1973; Lawless, 1978; Lawless & Cain, 1975). This study investigated episodic recognition memory for odors and faces in the long-term as a function of familiarity and identifiability. Eighty-three subjects encoded familiar and unfamiliar odors and faces and memory was assessed at four occasions; immediate, 4, 16 and 64 days after encoding. The results showed that irrespective of modality, memory for familiar stimuli was better than for unfamiliar information. Importantly, there was a significant decline in odor memory that was driven by an increment in false alarm rates over time. This observation indicates that episodic retention of olfactory information is susceptible to the passage of time. The influence of identifiability and familiarity on the obtained forgetting functions will be further discussed.

References: Engen, T., & Ross, B. M. 1973. Long-term memory of odors with and without verbal descriptors. Journal of Experimental Psychology 100: 221-227. Lawless, H. T. 1978.Recognition of common odors, pictures, and simple shapes. Percept Psychophys 24: 493-495. Lawless, H. T., & Cain, W. S. 1975.Recognition memory of odors. Chemical Senses and Flavour 1: 331-337.

Acknowledgment: This study was supported by grants from the Swedish Research Council to ML.

 

Structural and functional alterations in the olfaction system associated with Parkinson Disease

Jochen Klucken1, Carolin Moessnang2, Johannes Kahlis3, Nina Mallog3, Beate Winner4, Gerhard Schuierer3, Mark Greenlee2, Juergen Winkler1

1: Division of Molecular Neurology, University Hospital Erlangen, 2: Institute for Experimental Psychology, University of Regensburg,

3: Institute of Neuroradiology, University of Regensburg, 4: Nikolaus-Fiebiger-Center for Molecular Medicine, University Hospital Erlangen; all Germany; jochen.klucken@uk-erlangen.de

Olfactory deficit is an important premotor symptom in Parkinson’s disease (PD). PD patients are often not aware of their smelling deficiency which requires simple olfactory testing. Indeed, only 50% of PD patients report an olfactory deficit, whereas about 90% have reduced olfaction levels. Neuropathological findings report early degenerative changes in the olfactory bulb (OB) in PD, potentially before the conversion into the motor-stage of the disease. Thus, impaired olfaction and associated neuronal structures might serve as a biomarker to identify subjects with an increased risk to develop PD. We tested the hypothesis that impaired olfaction in PD is based on functional impairment of signal transduction based on degenerated primary olfactory structures (e.g. olfactory bulb and tract) resulting in reduced neuronal activity in associated cortical areas. Using structural MRI we detected a reduced size of the olfactory bulb in PD patients. However, using event-related MR imaging during an odor detection paradigm using air dilution olfactometry we observed a hyperactivation of higher ordered olfactory structures suggesting a compensatory plasticity. Furthermore, primary olfactory structures showed preserved discriminatory ability in contrast to a loss of selectivity in secondary olfactory structures. We identified distinct activation patterns within the disturbed olfactory network in PD consisting both of dysfunctional disinhibition and compensatory up-regulation of neural activity at different levels of olfactory information processing. Our results propose that impairment of olfactory network function is a dynamic process during the course of PD which can serve as diagnostic marker to identify different stages of PD associated neurodegeneration. Measurements of OB volumes may be an additional biomarker in the diagnosis of premotor stages in PD and easily implemented in routine MR imaging procedure in early PD.

 

Genetic influences on age-related olfactory decline

Maria Larsson

Gösta Ekman Laboratory, Department of Psychology, Stockholm University and Stockholm Brain Institute; maria.larsson@psychology.su.se

Scientific evidence indicates large individual differences in olfactory function in old age. The mechanisms are multifactorial and include demographic, environmental, cognitive, and a range of health-related factors. However, knowledge is sparse regarding specific genetic influences underlying individual differences in olfaction. This talk will focus on two genes that have been linked to both the aging process and olfactory function – the brain derived neurotrophic factor (BDNF) val66met and the apolipoprotein E (ApoE). Using longitudinal data (45-80 years) from a large population-based sample, we have found that the BDNF is associated with the rate of age-related olfactory decline such that older homozygote val carriers display a significant decline whereas older met carriers show stability in olfactory function. Our work focusing on the ApoE e4, a risk factor for dementia, indicates that the gene is associated with olfactory processing deficits specifically in the elderly (75-80 years). Interestingly, this deficit is not mediated by cognitive factors or by pre-clinical dementia. Overall, our findings suggest that the BDNF val66met polymorphism and the ApoE gene plays a significant role for the integrity of the olfactory system in non-demented elderly individuals.

 

The flexible olfactory brain

Pierre-Marie Lledo

Laboratory of Perception and Memory, Pasteur Institute, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; Tel: (33) 1 45 68 88 03 — Fax: (33) 1 45 68 83 69 — e-mail: pmlledo@pasteur.fr

The olfactory brain is flexible, from cognitive areas all the way to the peripheral areas in which sensory information is encoded so as to facilitate the subsequent extraction of relevant information. It is becoming increasingly clear that adaptability operates at the level of neural circuits. In the adult olfactory brain, new neurons are constitutively generated throughout life and form an integral part of the normal functional circuitry.

This presentation focuses on the functional issues linked to the neurogenic plasticity of the sense of smell. After outlining the processes of adult neurogenesis in the olfactory system and discussing their regulation by various factors, I will explore the possible functional role of newly formed neurons in the host olfactory circuits. Concentrating exclusively on mammalian systems, I will demonstrate throughout this presentation that adult neurogenesis is a plastic mechanism by which brain performance can be optimized in a changing word.

 

Trigeminal chemosensation in pain research

Jörn Lötsch

pharmazentrum frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; loetsch@em.uni-frankfurt.de

When increasing their strength, trigeminal chemosensory stimuli cross the point of pain threshold. This change toward pain is reflected in specific cerebral activations mainly in the posterior insular cortex, whereas quantitative information about the stimulus strength is processed in brain areas regarded as the "pain matrix" (e.g., insula, primary and secondary somatosensory cortex, amygdala, midcingulate cortex). Trigeminal pain thresholds are not closely correlated with olfactory thresholds but with pain thresholds to mechanical or electrical stimuli, indicating that chemosensation is composed of two distinct systems, which nevertheless seem to share several molecular pathways. The stinging pain sensation produced by short chemosensory trigeminal stimuli consisting of carbon dioxide is transmitted via Adelta and C fibers in the nociceptive system and evokes pain specific peripheral trigeminal signals and cortical potentials. These signals have been repeatedly used to study the pain specificity and dose relationship of drugs of many classical opioid and non-opioid analgesics in human clinical pharmacology. The implications of trigeminal chemosensation in pharmacological and physiological pain will be presented.

 

The Importance of Body Odors: from Neurons to Behavior and Back

Johan N. Lundström

Monell Chemical Senses Center, Philadelphia, PA., and Dept. of Psychology, University of Pennsylvania, Philadelphia, PA.  - jlundstrom@monell.org

Body odors carry informational cues of great importance for individuals across a wide range of species, and signals hidden within the body odor cocktail are known to regulate several key behaviors in animals. For a long time, the notion that humans may be among these species has been outright dismissed. We now know, however, that also humans have unique odor signatures within our body odors that carry information related to his or her genetic makeup, as well as other pertinent information that helps guide our behavior. Data will be presented demonstrating how the signals within our body odors are processed by the brain and how these signals shape our perceptions and actions.

Acknowledgement: JNL is funded by grants from the National Institute for Deafness and Communication Disorders and the Swedish Research Council.

 

Olfactory neuroblastoma: Our ten-year experience

Alberto Macchi°, studiodottormacchi@virgilio.it ;Fabio Ferreli°, fabio_ferreli@yahoo.it ; Luca Volpi^, lucavolpino@libero.it ; Stefania Gallo*, mary_jane@email.it; Paolo Castelnuovo°, paologc@tin.it

° Clinica ORL, Università dell’Insubria, Varese, Ospedale di Circolo e Fondazione Macchi, Varese; ^ Clinica ORL, Università degli Studi di Sassari, Azienda Ospedaliera Universitaria, Sassari; * Clinica ORL, Università degli Studi di Brescia, Spedali Civili, Brescia

The olfactory neuroblastoma is a malignant neuroectodermal tumor thought to originate from the olfactory membrane of the sinonasal tract. It is uncommon, representing approximately 2-3% of sinonasal tract tumours, with a bimodal age distribution. The main presenting symptoms are unilateral nasal obstruction and epistaxis; less common manifestations include anosmia, headache, pain, excessive lacrimation and ocular disturbances. Craniofacial resection followed by radiotherapy is considered the gold standard of the treatment. It is actually recognized the feasibility of the endoscopic endonasal resection, eventually associated to a craniotomic approach, with respect of the oncological criteria of radicality. From 1999 to 2009, 30 patients were treated for olfactory neuroblastoma at the Universitary Hospital of Varese and Brescia (Italy). 27 patients underwent a pure endoscopic endonasal resection, whereas 3 patients were treated with cranioendoscopic technique. Adjuvant radiotherapy was performed in 60% of cases. Overall Survival, Disease Free Survival e Recurrence Free Survival after 5 years are rispectively of 100%, 93,7% ± 6,05% and 75,6% ± 11,0%. Rate of complications is about 16,6%. These results are comparable to the ones reached with the standard craniofacial resection and allow us to carry on our experience in performing the endoscopic technique for the treatment of olfactory neuroblstoma. Larger and longer studies are needed.

Acknowledgements: Castelnuovo P, Bignami M, Delù G, Battaglia P, Bignardi M, Dallan I: Endonasal endoscopic resection and radiotherapy in olfactory neuroblastoma: our experience. Head & Neck Sep;29(9):845-50, 2007.

 

Exploring monomolecular odorants.

Christian Margot

Firmenich, Basel, Switzerland

 

Tracing the temporal dynamics of olfactory processing with EEG source imaging

Christoph M. Michel, Agustina Lascano, Basile N. Landis, and Thomas Hummel

Neuroscience Department, University Medical School, Geneva, Switzerland; christoph.michel@unige.ch

EEG source imaging (ESI) based on distributed inverse solutions of scalp multichannel evoked potentials is a new tool to study the temporal sequence of cortical activation after sensory stimulation in humans. Because of the excellent temporal resolution, ESI provides information on serial versus parallel neuronal processing as well as bottom-up versus top-down information flow. While ESI has been successfully applied to visual, auditory, and somatosensory evoked potentials, olfactory processing has only been studied with functional neuroimaging methods that have no temporal resolution (PET, fMRI). Consequently, brain structures involved in central nervous olfactory processing in humans are well known, but little is known about the temporal sequence of their activation. We will present the basic methodological approach that allows studying the temporal dynamics of information processing with multichannel evoked potentials, and then present a study on 64-channel olfactory evoked potentials to H2S stimuli presented to the left and right nostril in healthy subjects. Four distinct processing steps were identified between 200 and 1000 ms. Activation started ipsilateral to the stimulated nostril in the mesial and lateral temporal cortex, followed by activation of the corresponding structures on the contralateral side and finally by frontal structures. These results suggest that olfactory information in humans is processed first ipsilaterally to the stimulated nostril and then activates the major relays in olfactory information processing in both hemispheres.

 

High-resolution spatio-temporal characterization of olfactory information processing using simultaneous EEG-fMRI

Carolin Mößnang, Christina Regenbogen, Thilo Kellermann, Andreas Finkelmeyer, Ute Habel

Department of Psychiatry and Psychotherapy, RWTH Aachen University, Germany

Study Aims: In contrast to other sensory modalities, human olfaction has rather been neglected in imaging research, presumably arising from methodological difficulties (e.g. susceptibility artifacts in imaging of mediobasal structures, distortion of electrophysiological signals originating from basal brain regions). By applying simultaneous EEG/fMRI imaging, advantages of both imaging techniques can be combined to investigate key processes of olfactory information processing in high temporal and spatial resolution without the trade-offs of a single-technique approach.

Methods: Subjects (n=16) were exposed to visual and olfactory stimuli (neutral or disgusted facial expressions and neutral or unpleasant odors, yielding four different stimulus combinations) while engaging in a perceptual decision task (uni- vs. bimodal stimulus perception). Electrophysiological data were recorded using a 64-channel EEG device (BrainProducts, Gilching, Germany) during fMRI scanning (3T, Siemens Trio, Erlangen, Germany). Odorants were presented in a highly controlled manner using an olfactometer device (OM4, Burghart, Wedel, Germany).

Data Analysis: For fMRI data analysis, individual SPM{T}s were entered into a full factorial, flexible design to reveal robust activation in olfactory and visual brain areas (FWE p<.05). EEG data were preprocessed using various protocols to determine the optimal strategy for artifact reduction. Analysis was subsequently performed in both time and frequency domain in a trial-by-trial manner and averaged across conditions.

Outlook: Further analysis will focus on the integration of both modalities. In EEG-informed fMRI analysis, trial-by-trial parameters extracted from EEG will be incorporated into fMRI data analysis as parametric HRF modulator. In fMRI-informed EEG analysis, fMRI results will be used to determine spatial constraints for source localization analysis in EEG.

 

On the relation between perceived intensity and pleasantness of olfactory stimuli and brain activity observed using functional Magnetic Resonance Imaging (fMRI)

Friedrich  Müller1, Necla Soyak1, Kathrin Kandel1, Bernd Weber2, Jennifer Faber2, Simona Negoias3, Artin Arshamian3, and Thomas Hummel3
1Leuphana University Lueneburg, Institute for Experimental Industrial Psychology; 2University Bonn, Life and Brain GmbH; 3University Dresden, Department of Otorhinolaryngology,  Smell and Taste Clinic; f.mueller@uni-leuphana.de

Objective of this study was to explore the psychophysical relation between i) the quality and intensity of odor stimuli, ii) the perceived intensity and hedonic impression and iii) the relation between stimuli and observable blood oxygen level-dependent (BOLD) signals. Special attention was drawn to the psychological scaling procedures applied. Using the Sniffin`Sticks-Test (SnS) 28 subjects were chosen from primarily 40 persons and served as subjects in fMRI-studies. In a first experimental session they rated the pleasantness of olfactometrically presented H2S and Vanilla-stimuli using a bipolar category anchored visual analogue scale and the intensity of the same stimuli using a Category-Partitioning Scale (CP) containing 5 verbal labels subdivided by 10 numerical steps. From psychophysical functions fitted to these scaling data, for each subject 3 intensity-levels were calculated representing equally perceived intensities: just above perception threshold, weak and strong. In a 2nd sessioneach subject received both odors in these intensities via olfactometer in the operating fMRI firstly for sensory evaluation. Only after sensory evaluation brain activity was recorded. Stimuli were presented randomly to the right nostrils whereby each of the 6 pulsed stimuli (H2S and Vanilla in the individual concentration for low, weak and high intensity) was presented for 20 sec separated by odorless inter-stimulus intervals of 30 sec. For the main effect of odor vs. rest we observed activity in the bilateral insula, bilateral amygdala and the left VLPFC (p<0.001). The intensity ratings correlated with the right amygdala activity (p<0.001). Hedonic ratings were negatively correlated with right amygdala and bilateral insula activity (p<0.001).

Acknowledgements: This study was supported by Symrise AG, Holzminden and by AGIP (Arbeitsgruppe + Geschäftsstelle Innovative Projekte der angewandten Hochschulforschung beim Min. für Wiss. und Kultur Niedersachsen). F.A.-Nr. 2007.786)

 

Does the method of limits reveal subjects’ capability to determine odor thresholds?

Friedrich  Müller and Matthias Metz

Leuphana University Lueneburg, Institute for Experimental Industrial Psychologyf.mueller@uni-leuphana.de

Odor thresholds for butanol were obtained for 50 healthy normosmic students using the Sniffin`Sticks-Test (SnS), as well as the method of limits (ML) in ascending and descending order. The pro­cedures were repeated about 2 weeks later. In addition, performance time was recorded for each method and session and subjects were asked to rate the pleasantness of each odor, as well as the degree of activation required by the task using a category anchored visual analogue scale. For all subjects plausible thresholds could be obtained by the SnS procedure and by the ascending ML. For 22 out of 50 subjects, however, thresholds could not be obtained by the descending ML. Irrespective of presenting a target or blank these subjects reported smelling the target odor throughout the entire test session. Further analysis of the data revealed worse performance and significantly lower retest-reliabilities for those 22 subjects in the ascending ML (r = -0.05; p<0,05; n=22 compared to r = 0.570; p<0.01; n = 28) and the SnS-procedure (r = - 0.105; ns; n = 22 compared to r = 0.651; p<0.001; n = 28) as well. For those subjects who reported plausible odor thresholds in all experimental conditions in the retest, but not in the first test session, the sensitivity for butanol was increased with an increase in activation (r = 0.51; p<0.01; n =28).

 

Training the inter-nostril localization ability of olfactory chemicals 

Simona Negoias1, Oxana Aszmann 1, and Johannes Gerber 2 and Thomas Hummel 1

1 Interdisciplinary Centre for Smell and Taste, University of Dresden Medical School, Dresden, Germany; 2 Departament of Neuroradiology, University of Dresden Medical School, Dresden, Germany; simonanegoias@yahoo.com

In vision and audition, the pair of receptor organs is crucial for spatial orientation and localisation of stimuli in the 3-dimensional environment. Whether the pair of receptor organs in olfaction fulfils the same function of localizing odor sources is not yet clear. Is is widely accepted that mixed trigeminal-olfactory chemicals can be accurately localized when applied passively to one of the nostrils. Chemicals with a predominant olfactory component seem, on the contrary, hard or impossible to localize in passive stimulation procedure. Purpose of this study was to investigate whether the ability of subjects to localize an olfactory stimulus delivered passively to one of the two nostrils would improve under training. Fifty-two healthy, normosmic women aged between 18 and 30 years participated in 6 to 7 sessions. Two groups were created: 27 subjects followed an olfactory lateralisation training protocol using two chemicals known to selectively stimulate the olfactory system (hydrogen sulphide and phenylethylalcolol). The second group performed "brain jogging". Before and after- training subjective intensity and lateralisation ratings were recorded. Additionally electrophysiological parameters after stimulation with the two odorants were recorded at the end of the training. Comparisons between trained and non-trained subjects suggested an improvement of localisation scores in subjects specifically trained for this. Amplitudes N1 and P1N1 were found larger in subjects that performed smell training. Consequently, the ability to localize passively applied olfactory stimuli can be trained; further on training influences the amplitudes of the early oERP components possibly as a result of increased attention towards the olfactory stimuli.

 

Life span cognitive development: Cross-sectional or longitudinal data

Lars-Göran Nilsson

Department of Psychology, Stockholm University and Stockholm Brain Institute; lgn@psychology.su.se

Much research on cognitive development has demonstrated that many cognitive functions reach a peak relatively early in life, whereafter there is a decline in midddle age and old age. Conscious recollection of an experienced event (episodic memory) is one example of such an ability that decreases linearily from the age of about 20 years. All such studies showing this effect are based on cross-sectional data. When instead the analyses are based on longitudinal data a completely different pattern emerges. Episodic memory performance is rather stable up to late middle age and does not start declining until about 70 years of age. The control of confounding factors like cohort effects, re-test effects and attrition effects are essential for the understanding of individual cognitive development throughout life. It is claimed that results based on cross-sectional data largely reflect cohort differences only. Behavioral data and neuroimaging data will be used for illustrating this claim.

 

Assessment of oral trigeminal sensitivity in healthy subjects by electrical stimulation.

Timomi Nin

Hyogo College of Medicine, Department of Otoralyngology, Japan; ninniku245@hotmail.com

Objective: Measurements of oral trigeminal sensitivity have not been established.

This prospective study measured the trigeminal thresholds on the tongue’s surface using an electrical stimulator (ES) and investigated correlations between taste function and trigeminal sensitivity.  

Subjects and Methods: Forty-six healthy volunteers (13 male, 33 female) between the ages of 20 and 45 years participated in this study. For each subject, gustatory function and trigeminal sensitivity were measured using filter paper disc (FPD) and ES (0.2ms stimulus duration, PowerLab 26T, Scope™), respectively. FPD tests the four (sweet, sour, salty, and bitter) taste qualities in five different concentrations. With each test paradigm, 4 regions on the tongue were examined: 1) anterior tongue, approximately 2cm from the center and tip of the tongue and 2) posterior tongue, just in front of circumvallate papillae on the right and left sides. In addition, we statistically analyzed correlations between these regions and findings these tests.

Results: Taste function of all subjects were within normal limits by FPD. On average, trigeminal sensitivity in the anterior regions was rated as significantly lower (right side: Mean (Standard Deviation) =0.67(0.21) mA, left side: 0.66(0.2) mA) than that in the posterior regions (right side: 1.27(0.38) mA, left side: 1.34(0.42) mA). There were positive relationships between the anterior and posterior regions (respectively p<0.001) and between the right and left sides (respectively p<0.05). There were no significant differences between taste function and trigeminal sensitivity except in the left posterior region, in which significant correlation was found between sour taste and trigeminal sensitivity.

Conclusion: ES is useful for measurement of trigeminal thresholds in the oral cavity, especially in the region of the lingual nerve. Further accumulation of clinical data are still needed, for example, measuring the threshold of oral trigeminal sensitivity in patients with Burning Mouth Syndrome, taste disorder and damage to the chorda tympani nerve after middle ear surgery, and other condition.

 

Parosmia and Phantosmia

Steven Nordin

Department of Psychology, Umeå University, SE-901 87 Umeå, Sweden; E-mail: steven.nordin@psy.umu.se

Parosmia (a qualitative odor distortion) and phantosmia (an odor sensation in the absence of an external odorant), collectively referred to as dysosmia, are conditions that in some patients cause more complaints than a loss in odor sensitivity. The purpose of this presentation is to provide a broad understanding for parosmia and phantosmia in terms of their characteristics, assessment, prevalence, etiology and possible pathogenesis. Clinical implications of parosmia and phantosmia are also discussed, that include treatment, consequences for quality of life, and use of coping strategies to deal with these conditions on a daily basis. 


Delayed decrease of pleasantness ratings in congenital anosmia during consumption of a simple food

Lenka Novakova1, Viola Engelhardt2, Jan Havlicek1, Ilona Croy2

1 Department of Anthropology, Faculty of Humanities, Charles University, Husnikova 2075, 158 00 Prague 13, Czech Republic; lenka.novakova@yahoo.com

2Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstraße 74, 01307 Dresden, Germany

Food is evaluated for various attributes. One of the key domains of food evaluation is hedonicity. As food is consumed, its hedonic valence decreases due to prolonged sensory stimulation and hedonic habituation results. The aim of the present study was to investigate food pleasantness ratings during consumption of a simple food in individuals without olfactory experience with food. Fifteen congenital anosmics and fifteen normosmic controls were presented with ten 10g banana slices. Each was visually inspected, then smelled and chewed for ten seconds and subsequently rated for hedonicity on a 21-point scale. The difference in pleasantness ratings between anosmic subjects and controls approached the formal level of significance (p = .06), F(1,28) = 3.70, r = .34. Furthermore, changes in pleasantness over four equally spaced time points were examined, yielding a significant decrease in the control group, but not in anosmic subjects, between the fourth and the seventh measure and between the seventh and the tenth measure, both at p < .01. The results of the present study indicate that olfaction plays a significant role in the hedonic assessment of a simple food over the course of consumption and that the decrease of hedonic valence is less pronounced in congenital anosmia.

 

Congenitally anosmic adults report less maternal care than normosmics - a retrospective questionnaire study

Lenka Novakova1, Jan Havlicek1, and Ilona Croy2

1 Department of Anthropology, Faculty of Humanities, Charles University, Husnikova 2075, 158 00 Prague 13, Czech Republic

2Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstraße 74, 01307 Dresden, Germany

Olfactory cues are known to play a significant role in the social interactions of vertebrates and humans are no exception. Human neonates are able to learn the odor signature of their mothers and to orient towards them. Mothers are more attracted to newborn infant body odors than nonmothers and are able to recognise their infants based on their odors following very little experience with them. This reciprocal olfactory-based communication might substantially assist in the process of mother-infant bonding. However, the effect of chemosensory information in mother-child interactions was rarely studied. One research interest is to study mother-infant bonding in individuals with inborn absence of smell. Thus, the aim of the present study was to investigate the consequences of congenital anosmia for the formation of the mother-infant bond, as assessed retrospectively. Twenty-eight congenitally anosmic patients (18 - 42 years) and twenty-eight normosmic controls (18 - 42 years) participated in the study. They were administered the German versions of the 25-item Parental Bonding Instrument, to assess their recollections of parental care and overprotectiveness during the first sixteen years of life, and the 21-item Beck Depression Inventory to assess depressive symptoms. Statistical analysis revealed a significant difference in the maternal care dimension (F(1,54) = 8.62, p = .005, r = .37), with congenital anosmic participants reporting less marternal care than controls. No difference was found in maternal overprotection, paternal care or overprotection. No correlation between maternal care and the depression score, educational status or age was found. The results of the present study indicate that olfaction plays a crucial role in the formation of the mother-infant bond and that retrospective perception of maternal care may be adversely affected in congenital anosmia.

 

Electrical neuroimaging of processing different tastants in humans
Kathrin Ohla, Julie Hudry & Johannes le Coutre

Nestlé Research Center, Lausanne, SWITZERLAND ; mail@kathrinohla.net

Questions of how in general, and where and when in particular, gustatory percepts are represented in the human brain remain largely unanswered despite decades of research. Electrical neuroimaging of gustatory perception has been hampered by difficulties with stimulus control because recording of event-related brain electrical responses (electroencephalography, EEG) requires temporally precise stimulus presentation to obtain good summation of the signal across trials. This is difficult to achieve with flowing stimuli in solution. Aim of this study was to investigate cortical response patterns of gustatory perception over time. For this, a gustometer, which met the requirements for the recording of event-related responses, was employed to present taste solutions to human volunteers while EEG was recorded. Brain responses to the different tastants were analyzed with respect to their time courses, spatial distributions and neuronal generators.

We present the spatio-temporal brain activation patterns for each tastant, we show overlaps between tastants and point out differential activation. The neuronal generators observed comprise areas previously associated with the processing of taste and food-related stimuli. In particular, the bilateral insular cortices and opercula were involved. The findings are discussed in the framework of current knowledge on gustatory perception in the human brain.

 

An Examination of Behavioral Odor Data in Sensory disabled individuals

Adile Oniz*, Ipek Erdogan, Onur Bayazit, Murat Ozgoren

Dokuz Eylul University, Faculty of Medicine, Dept. of Biophysics, Izmir, Turkey; *adile.oniz@deu.edu.tr

Scope: The aim of this study is to compare odor performance of sensorial disabled individuals (deaf and blind) with healthy individuals.

Method: 41 deaf students (22 female, mean age 14.39±1.24), 40 blind students (17 female, mean age 13.55±1.43) and 52 healthy (24 female, mean age 13.48±1.09) students participated in this study. The odor threshold, odor discrimination and odor identification performances were measured through  Sniffin’ Sticks. Obtained data was evaluated by SPSS 11.0.1 and one-way ANOVA was used for statistical analysis.

Results: Post hoc Scheffe test showed for threshold there were no significant differences between groups (deaf students: 7.40±3.47, blind students: 8.45±3.35, healthy students: 8.00±2.73), for discrimination, healthy students (12.32±1.81) had significantly better performance than deaf students (10.87± 2.29) (p < .05). For identification, both blind students (11.45±1.99) and healthy students (11.96±1.48) had significantly higher points than deaf students (9.87±2.01).  On the contrary there was no difference between blind and healthy students. Total points (TDI) displayed similar to results of identification (blind 31.65 ±5.09, deaf 28.15 ±5.56, healthy 32.30 ±3.86).

Conclusion: This initial field study in the sensory disabled can be used as a template for assessing and designing behavioral as well as objective (i.e. CERP) research studies. 

Acknowledgements: The study is supported by TUBITAK 108S113 and DEU.2008.KB.SAG.019. Authors appreciate support of Burcu Aydin.

 

Bourgeonal olfactory threshold and human capacity of reproduction: A prospective study

Ottaviano Giancarloa; Zuccarello D. b; Marioni G. a; Marchese-Ragona R. a; Staffieri A.a; Foresta C. b

aDepartment of Medical and Surgical Specialties, Section of Otolaryngology, University of  Padova, Padova, Italy; bDepartment of Histology, Microbiology and Medical Biotechnology, University of Padova, Padova, Italy; giancarlo.ottaviano@unipd.it

Introduction. The reproductive success requires the realise of millions of spermatozoa and eggs and is made more efficient by attractans that guide sperm to the eggs. For mammals the number of eggs is quite small. The question of what determines which one of the many candidate spermatozoa will fertilize the egg remains still without answer. Recent investigations have focused on the sperm Bourgeonal receptor which seems to be involved in the human sperm chemotaxis and seems to be a critical component in the fertilization process1. Human olfactory sensitivity to the sperm attractant odorant Burgeonal is still debated2.       

Aims: The present prospective case control study has the purpose to investigate the olfactory sensitivity to Butanol and Burgeonal comparing a group of patients not able to have children despite no alteration of the sperm and a normal fertility of the mate against a control group.

Methods. The present prospective study investigated a group of 7 aldult males (mean age of 40±3,8) not able to have children in the last  5 years despite no alteration of the sperm and a normal fertility of the mate against a control group of 15 adult males (mean age of 27,5±4,8) without sperm alterations and history of fertility problems. The spermatozoa number and vitality were evaluated; the effect of buorgeonal on sperm chemotaxis, the odor threshold both for butanol and for bourgeonal were compared between the two groups.

Preliminary results. The mean total number of spermatozoa did non differ in the two groups (p=0,105), as well as the sperm motility and vitality (p=0,832 and p=0,595, respectively). In both groups, spermatozoa clearly migrated towards bourgeonal (p=0,004 in the control group and p=0,001 in the study group). Nevertheless olfactory threshold for Butanol did not differ between the two groups (p=0,089), the mean olfactory threshold for Burgeonal was 12,6 in the control group and 10,2 in the study group (p=0,01). 

Conclusions. If confirmed by an invastigation based on a larger series, odor threshold for burgeonal could be of great value in studying the male capacity of reproduction.

1Spehr M, Gisselmann G, Poplawski A, Riffel JA, Wetzel CH, Zimmer RK, Hatt H. Identification of a testicular odorant receptor mediating human sperm chemotaxis. Science 2003;299:2054-2058. 2Brodin M, Laska M, Olsson MJ.Odor Interaction between Burgeonal and its antagonist Undecanal. Chem Senses 2009;34:625-630

 

The Chemosensory Responses in Blind, Deaf and Healthy Humans

Murat Ozgoren*, Cagdas Guducu, Adile Oniz

Dokuz Eylul University, Faculty of Medicine, Dept. of Biophysics, Izmir, Turkey; *murat.ozgoren@deu.edu.tr

The current study has the scope of assessing the electrophysiological responses in the sensory disabled (blind and deaf) and healthy humans. The motivation behind the study is to address the neural capacity assignment and usage in the limitation of one sense. In this prospect our group has added olfactory modality to visual, auditory, and tactile modalities, with 64 channel EEG (Neuroscan Synamps 64) using EMISU (Embedded Interactive Stimulus Unit) device. The initial phase has been applied over 13 deaf (7F; mean age 14.6±1.01), 14 blind (5F; mean age 14.43±1.09), and 10 control subjects (4F; mean age 16.6±2.72). Olfactory and trigeminal stimulants were delivered using OM2s as 2-phenylethyl alcohol (PEA) and CO2,respectively. The baseline airflow was adjusted to 8 mL/min, 80% relative humidity and 36 C0. The duration of stimuli was 200 ms and ISI was 25 sec. In order to rule out auditory cues white noise (80 dB) administered through headphones. SCAN 4.0 and sLORETA have been used to assess the responses and localizations.

The preliminary analysis efforts of olfactory and trigeminal were focused on (A) time-amplitude and (B) localization processes.  Accordingly (A) point to three major peaks: N1 as around 350, P1 at around 500 and N2 as around 900 ms.  (B) The sLORETA localizations of CO2 responses were mostly distributed around BA 6,7,11 in controls whereas the responses of deaf also incorporated BA 39 and 40 (more towards auditory cortex). The blind localization showed BA 19 (towards visual cortex) besides BA6, BA7. The three groups also included cingulate gyrus. The grand average PEA responses had sLORETA localization of BA11 for blinds, BA6, 8, 10 for deaf and BA7, 8,9,32 for healthy individuals at this initial stage.

The comparative analysis of chemosensory responses may allow a further understanding of sensory organization and plasticity. Moreover the dynamic responses may allow further functional connectivity insight within the brain using olfactory modality.

Acknowledgements: The study is supported by TUBITAK 108S113 and DEU.2008.KB.SAG.019. Authors appreciate support of Ugras Erdogan and Onur Bayazit. 

 

Factors Associated with Presbyosmia: A Population Approach

Jayant M. Pinto

Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, The University of Chicago, Chicago, IL, USA; jpinto@surgery.bsd.uchicago.edu

 

A new test for qualitative olfactory dysfunction using an extended version of the “Sniffin`Sticks”

B Renner1, S Zapf1, AH Esmi2, I Esfandeyari2, CA Mueller2

1Department of Experimental and Clinical Pharmacology, University of Erlangen-Nürnberg, Erlangen, Germany, 2Department of Otorhinolaryngology, Medical University Vienna, Austria; renner@pharmakologie.uni-erlangen.de

Qualitative olfactory dysfunction (parosmia) represents a common symptom in patients with olfactory disorders. In most cases the hedonic value of the distorted perception is shifted to unpleasant odors. So far the only way to assess parosmia is to ask the patient about their complaints. Therefore, the aim of the study was to create and validate a new test to quantify parosmia. The proposed “Sniffin`Sticks Parosmia Test” (SSPT) consists of an extended version of the odor identification test and a set of paired odorants with opposing hedonic values (pleasant vs. unpleasant). During pretesting healthy subjects had to rate the hedonic and intensity of the well-established “Sniffin`Sticks” identification test kit. In this way eight odorants from the established identification test were found to be acceptable for the new test. In a further step, 24 additional odorants not included in the “Sniffin`Sticks” were presented in the same way in order to offer a broader range of pleasant and unpleasant odors. For the SSPT those odorants with distinct pleasant or unpleasant hedonic values were selected and are currently being tested in patients suffering from parosmia. The newly developed test seems to be suited for clinical routine and studies dealing with qualitative olfactory dysfunction.

 

The olfactory bulb: from basic research to the clinic.
Philippe Rombaux

Cliniques Universitaires Saint Luc, University of Louvain, Brussels, Belgium; philippe.rombaux@uclouvain.be
Since magnetic resonance imaging of the olfactory system became routinely performed, basic informations regarding the volume, the morphology, the plasticity of the olfactory bulb (OB) constantly evolve. Neurogenesis and presence of an olfactory ventricle are probably essential for structural maintenance of the OB circuit. In clinical practice, imaging is indicated to confirm the presence of the OB structure and to rule out any tumoral and/or degenerative lesions. The OB volume is correlated to the remaining olfactory function in many different clinical circumstances both when qualitative and quantitative olfactory dysfunction  exist. Plasticity and increased OB volume have been also demonstrated in humans. Through many imaging case studies, knowledge about the OB will be reviewed during the lecture.

 

Taste disorder and sensory dysfunction after middle ear surgery

Akiko Sakaguchi, Tomomi Nin, Hirokazu Katsura, and Masafumi Sakagami,

Dept. of Otolaryngology, Hyogo College of Medicine, Nishinomiya, Japan; akkocafe5492@yahoo.co.jp

OBJECTIVE:  Patients often complain of taste disorder and tongue numbness after middle ear surgery. Our previous study reported that post operative taste disorder frequently occurred in patients with non-inflammatory disease, however the mechanism of numbness remains unclear (Sone et al., 2001). In the present study, postoperative trigeminal sensation of the tongue was examined by two kinds of objective tests.

SUBJECTS: Twelve patients with non-inflammatory middle ear diseases underwent middle ear surgery between October 2009 and August 2010. Patient consisted of 3 males and 9 females, and their ages ranged from 7 to 70 years (mean 36 years). Subjects with previous ear surgery were excluded. Fifteen healthy subjects served as a control group. They consisted of 8 males and 7 females, and their ages ranged from 27-45 years (mean 34 years).

METHODS: The tactile threshold was assessed with the Sennes-Weinstein sensory test (SW test) and two-point discrimination tests before surgery, 2 days, 14 days and one month after surgery. Taste function was simultaneously assessed with electrogustometry (EGM) (TR-06,R, RION Co., Japan).

RESULTS: Six of 12 patients (50%) complained of taste disorder and 5 of 12 patients (42%) complained of both tongue numbness and taste disorder 2 days after surgery.  On SW test, the average (SD) (Fmg) of the control group was 2.32±0.54 on the right side and 2.46±0.3 on the left side. The average (SD) (Fmg) of 12 patients on the operated side was 2.37±0.59 before surgery, 2.42±0.67 2 days after surgery, 2.37±0.6 14 days after surgery, and 1.91±0.46 one month after surgery. On two-point discrimination tests, the average of the control group was 3±1 on the right side and 4±1 on the left side.  The average (SD) (mm) of 12 patients on the operated side was 3.67±1.5 before surgery, 4.08±1.98 2 days after surgery, 4±1.25 14 days after surgery, and 3±0.96 one month after surgery.  In EGM threshold, the average (SD) (dB) of 12 patients on the operated side was 9.8±15.76 before surgery, 12±13.5 2 days after surgery, 5.42±7.89 14 days after surgery, and 22.8±5 a month after surgery.  There were no significant differences on SW test, two point discrimination tests or EGM although the threshold of each test was elevated after surgery. 

CONCLUSIONS: There findings suggested that injury to the chorda tympani nerve during middle ear surgery induces trigeminal disorder together with taste disorder. Further study is necessary in order to clarify the mechanism of trigeminal disorder.

 

Mammary odor cues and pheromones: a comparative view on infant-directed communication about milk 

Benoist Schaal1,2

1Research Group in Developmental Ethology and Cognitive Psychology, Center for Taste, Smell, and Food Science, CNRS (UMR 6265), 21000 Dijon, France (benoist.schaal@u-bourgogne.fr); 2Dijon-Dresden Laboratory for Taste and Smell (EAL 552 CNRS-Technische Universität Dresden)

Neonatal mammals are exposed to an outstandingly potent selective pressure at birth, and any mean to lessen their effort and accelerate acceptance to orally grasp a nipple and ingest milk can have had advantageous consequences over evolutionary time. Thus, it is essential for mammalian, including human, females to display a biological interface structure that is sensorily conspicuous and executively easy for their newborns. Females’ strategy to increase the conspicuousness of nipples could only exploit the newborns’ most advanced sensory systems, touch and olfaction. Selection has accordingly shaped tactilely and olfactorily conspicuous mammary structures. This evolutionary adjustment has worked either directly by shaping structural features of mammaries or indirectly by mobilizing maternal behavioral propensities to create olfactory traces on them. These predictions will be considered in mammalian cases that have received empirical attention among marsupials, rodents, lagomorphs, ungulates, carnivores and primates. It appears that broadcasting chemical cues and/or signals from the mammae is a pan-mammalian reproductive strategy to pilot neonatal arousal, motivation and attraction to the mother, provide assistance in localizing and orally grasping the mammae, and boost up rapid learning. But the ways by which these chemical cues are produced and assembled on the mammae are both diverse between species and complex within species, offering an excellent opportunity for comparative analyses in chemical communication.

 

Spatio-temporal correlates of taste perception

Ariel Schoenfeld

Ariel.Schoenfeld@med.ovgu.de

Automated odor presentation for odor identification testing

Valentin Schriever1, Samanta Sviana2, and Thomas Hummel3,

1University of Göttingen, Department of Neurophysiology and Cellular Biophysics, Goettingen, Germany; 2Spain; 3Smell & Taste Clinic Department of Otorhinolaryngology University of Dresden Medical School; valentin.schriever@mac.com

Odor identification tests are helpful and widely used instruments for measuring olfactory function. There are many test in use like the UPSIT or the Sniffin’ Sticks testing battery.  So far most test are administered by an experimenter and therefore time consuming. We evaluated an automated odor presentation odor identification test using the aerome® ScentController. Participants performed a ten odor identification test using the automated test as well as an odor identification test administered by an experimenter using the Sniffin’ Sticks. A group of participants repeated the experiment in a second session on another day to test the retest reliability of the two methods.

The results differed significantly between the two methods, with higher scores achieved with the Sniffin’ Sticks odor identification test. This effect was driven by two individual odors. After excluding these odors form the analysis no differences between the two methods could be found. Both methods showed no significant difference in scores obtained during the first and second session.

The automated odor presentation method showed to be a valid option for a self administered olfactory identification test.

 

Olfactory effect on semantic access : Do odors influence children’s verbal fluency ?

Alix Seigneuric 1 2 (alix.seigneuric@u-bourgogne.fr); Karine Durand 1 2 (karine.durant@u-bourgogne.fr); Daniel McCall 3 (dmccall@gettysburg.edu); Tao Jiang 1 2 (tao.jiang@u-bourgogne.fr); Benoist Schaal 1 2 (benoist.schaal@u-bourgogne.fr)

1Centre des Sciences du Goût et de l’Alimentation, UMR6265 CNRS, UMR1324 INRA, Université de Bourgogne, Agrosup Dijon, Dijon, France.2Dijon-Dresden European Laboratories for Taste and Smell, CNRS and Technische Universität Dresden (EAL 549).3Department of Psychology, Gettysburg College, USA

The purpose of this study was to explore whether odors can influence access to semantic memory in children.  In one study with adults, Holland, Hendriks & Aarts (2005) demonstrated that the smell of cleaning fluid can facilitate access to “cleaning” words, even when the odor is not consciously detected. It is unknown, however, whether odors can cue semantic access in children. The current experiment used a semantic verbal fluency task to examine whether exposure to food-related odors facilitated access to semantically congruent words in 5-9-year children.

167 French children participated to the experiment (55 kindergarteners (Mean age=5y6m), 54 second graders (M=7y6m), and 58 third graders (M=9y6m)).  They wore headphones with a microphone attached.  The microphone was positioned so that it was centered beneath the child’s nose, and the foam microphone windscreen was perfumed.  Children were randomly assigned to one of 3 odor groups: Sweet (strawberry odor), Savory (bacon odor) and Unscented. Odorants were equalized for intensity and diluted so as to be detectable but not overly salient. Once the headphones were fitted, children were asked to “name all the things we can eat” in 60 seconds. 

The total number of responses increased with age and there was no effect of odor on the overall quantity of responses.  Children’s responses were coded into 7 categories:  meats, vegetables, savory-other, fruit, sweet-other, cheese and dairy-other.  The variety in children’s responses, measured as the number of different food categories used, increased with age. There was an Age X Odor interaction: the oldest children gave more variety in their responses when an odor was present than when there was no odor.  Children’s responses were then condensed into “savory” words (meats+vegetables+savory-other)  vs “sweet” words (fruits+sweet-other) to examine whether the congruent odors increased the frequency of these global categories.  In general, children had a higher proportion of savory responses than sweet, although this difference diminished with age. The odor had little impact on children’s response categories, with one exception:  seven-year-olds’ who smelled strawberry gave more “sweet” words and fewer “savory” words than those who smelled bacon.  Results suggest an effect of odor on semantic access and are discussed in the context of extant literature on odor encoding and identification.

 

Auditory cues modulate odor pleasantness

Han-Seok Seo, Franziska Lohse, Thomas Hummel

Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany; hanseok94@gmail.com

It is well known that visual or gustatory cues modulate olfactory perception. Indeed, we often perceive odors together with auditory cues in everyday life. For example, while eating or drinking, people experience not only odors through the ortho-/retronasal route, but also sounds evoked by mastication or the drinking process. Nevertheless, surprising little is known about influence of auditory cue on odor perception. This study aimed to determine whether auditory cue can modulate ratings of odor intensity and/or pleasantness. In Experiments 1 and 2, participants received odors in the presence of congruent, incongruent, or neutral sounds. In Experiment 3, participants were presented with odors while listening to pleasant or unpleasant sounds. In Experiments 1 and 2, participants judged the odors as being more pleasant while listening to a congruent sound than while listening to an incongruent sound. In Experiment 3, as the participants preferred the preceding sound, they rated the subsequent odor as being more pleasant. In contrast, the ratings of odor intensity were little or not influenced by the congruency or hedonic valence of auditory cues. In conclusion, the current study presents empirical evidence that auditory cues can modulate odor pleasantness.

 

Olfactory granule cell-specific silencing slows down odor discrimination time in mice

Bhavana Shrivastava1, Ruud Toonen2, Matthijs Verhage2 and Thomas Kuner1

1 Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg; 2 Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam; bhavss4@gmail.com

The granule cells (GCs) of the olfactory bulb (OB) are axonless inhibitory interneurons, which form reciprocal-dendrodendritic synapses with the first order relay neurons (Mitral/Tufted cells, MTC) of the olfactory pathway. It is upon these excitatory relay neurons, that the GCs mediate inhibition at various levels (recurrent/global-lateral/local-lateral inhibition). Our study aims to understand the contribution of GC-mediated inhibition in the OB to odor discrimination behavior. Previously it has been shown that mice require less time to discriminate dissimilar olfactory stimuli (amyl acetate versus ethyl butyrate) compared to discriminating similar stimuli (binary mixtures of these odorants). To assess how the extent of inhibition between GCs and MTC contributes to odor discrimination time, we silenced the GC output and examined odor discrimination behaviour of mice. The two-fold approach adopted to investigate the effects of completely silencing the GC mediated inhibition on the principal olfactory relay neurons, was as follows:

(1) Targeted ablation of the essential presynaptic protein Munc-18-1 was carried out by stereotaxic delivery of r-AAV1/2 expressing Cre recombinase into the GC layer of three week old mice carrying floxed Munc18-1 alleles, thereby generating a highly specific Munc18-1 knockout in GCs of the OB.

(2) Botulinum neurotoxin light chain-A was specifically expressed in the granule cell layer using r-AAV1/2 to selectively cleave the synaptosomal associated protein 25 (SNAP-25) which in turn is an essential component of the SNARE complex that enables synaptic vesicle fusion and neurotransmitter release.

In both cases, olfactory behavioral testing (using a go, no-go operant conditioning paradigm) revealed the pattern that mice with silenced GC output required consistently longer times to discriminate even highly dissimilar odor stimuli than their littermate controls. Besides, the discrimination time for highly similar binary mixtures of odorants remained more than for dissimilar odor-pairs, as has been noted before. No significant difference was apparent in binary mixture discrimination time between the control and silenced GC groups. Thus, these results suggest a pivotal role of GC-mediated inhibition in the OB, even for the discrimination of simple odor stimuli, which was previously unknown.

Acknowledgement: We thank Claudia Kocksch and Michaela Kaiser for expert technical help and virus production. This work was funded by DFG grant Ku-1983/2 (FOR 643).

 

No brain-response to a human chemosignal in congenital anosmia

Sagit Shushan1, 2, Yaara Yeshurun1, Yehuda Roth2, and Noam Sobel1

1Weizmann Institute of Science, Rehovot, Israel; 2Wolfson Medical center, Holon, Israel; sashushan@gmail.com

Non-human chemosignaling is mediated by a combination of several chemosensing subsystems.  For example, rodent social chemosignaling is mediated in part by the vemoronasal system.  The functionality of human chemosensing subsystems beyond the main olfactory system remains poorly understood.  To test for such non-olfactory chemosensing, we set out to use brain imaging in order to measure the brain response to a chemosignal in otherwise congenitally anosmic individuals.  We hypothesized that if human social chemosensing is mediated by subsystems beyond the main olfactory system, than such anosmic individuals should nevertheless display a brain-reesponse to a chemosignal.  We used the sweat-derived compound 4,16-androstadien-3-one (AND), which has been widely considered in the context of human chemosignaling.  An olfactometer delivered 6 blocks of 30 seconds of AND followed by 30 seconds of clean air, with a constant sniffing rate of once every 6 seconds (5 sniffs per block).  We used a 3-Tesla Siemens Tim-Trio scanner, with acquisition parameters of 30 slices, slice thickness=4 mm, gap=0, TR=1500 msec, TE=23.

Group analysis revealed an AND-induced response in the normosmic, but not anosmic subject (p < 0.05).  Those results are consistent with those obtained by Savic et al in conductive anosmia, and together suggest that the human brain response to the chemosignal AND are mediated by the main olfactory system. However, single-subject analysis revealed AND-induced responses in some anosmics. This suggests one of two alternatives: either that AND is processed by another subsystem, or that some diagnosed anosmics are not truly anosmic.

 

Dissimilarity of  blending mixture and components in an olfactory space

CharlotteSinding1,2, Thierry Thomas-Danguin2, Adeline Chambault2, Noelle Béno2, Benoist Schaal1, Gérard Coureaud1.

Centre des Sciences du Goût et de l’Alimentation (CSGA), UMR CNRS/UB/INRA/AgroSup, Developmental Ethology and Cognitive Psychology1, and Flavour Perception Teams2, 21000 Dijon, France; Charlotte.Sinding@dijon.inra.fr

Certain odour mixtures appear processed differently from their components at the glomerular level (Grossman et al. 2008). Such results could support the concept of configural perception of odour mixture, a concept which is much likely to occur in multicomponent mixture (Jinks et al., 2001). In the present study we evaluated whether human subjects perceived a 6 components odour mixture, previously suspected to produce a blending effect in human adults (Le Berre et al. 2008; and in rabbit pups, Sinding et al. ECRO 2010), as different from its components, by an approach representing the olfactory space of a mixture mainly focused on aromatic qualities dissimilarities. Our hypothesis is that the blending, occurring when subjects perceive an odour quality specific to the mixture and not to the components, is represented by a novel quality well separated from each one of the components in an olfactory space. Seventy four human subjects carried out a free-sorting task on 7 stimuli (mixture and the 6 components) delivered in glass bottles. The data were analysed through a non-metric MDS followed by a bootstrap analysis in order to create a map of dissimilarity of the stimuli and confidence ellipses around each stimulus on the map. The results clearly indicated that the mixture was significantly separated from each of its components. Moreover the mixture is not located in the middle of the space and is not surrounded by the components. Thus, the odour perceived by the subjects exposed to the mixture does not appear to result from the summation of components’ qualities or from a “brown” effect created by a mix up of the numerous components. It would result from the perception of a new, unique and distinct odour quality, promoted by the association of the 6 components in specific proportions.

 

Representation of umami and salt taste in the human brain

Singh PB1,3, Iannilli E1, Schuster B1, Gerber J2, Hummel T1

1Smell and Taste Clinic, Department of Otorhinolaryngology, 2Department of Neuroradiology, University of Dresden Medical School, Germany; 3 Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway; p.b.singh@odont.uio.no

The aim of this  fMRI study was two-fold 1) to elucidate the cerebral processing of salt and umami taste and 2)to investigate the laterality of the gustatory system. A total of 24 right handed subjects participated in this study. The salt and umami taste stimuli were presented at suprathreshold concentrations on the lateral ridges of the subjects tongue through a gustometer. The sequence was presented in a session of 6 repetitions on/off -block per stimulus and per side. The BOLD signal (blood oxygenation level dependent) was detected by means of a 1.5 T scanner. fMRI data analysis was implemented in SPM5 (p<0.005 cluster level= 5).The main effect of the tastants was activation in the primary and secondary gustatory cortex. However,  different coordinates of the activated areas were found for the two tastants inside the same brain, suggesting a segregation of the brain areas involved with the tastants. Comparing the two stimuli we found that the positive effect of MSG on NaCl was evidently highlighted in the limbic lobe.On the contrary the positive effect of NaCl on MSG elicited activations in areas more common to taste perception. The conjunction analysis revealed common activated areas for the two tastants in the primary (SI) and secondary (SII) somatosensory cortex, premotor cortex, but also in the secondary taste areas. With regard to lateralization within the gustatory system, the BOLD contrast for the MSG stimulus was significantly bigger on the right side of the brain when the stimulus was presented to the left side as compared to the right side presentation of the stimulus. Moreover the opposite contrast for MSG highlighted only few brain areas including the left orbitofrontal cortex. The contrary appeared when the stimulus was NaCl. This result suggests a contralaterality of the brain response to the MSG stimuli but an ipsilaterality for the NaCl stimuli with a strong and general right sided lateralization of the brain for salt taste perception.

 

Predicting odorant perception and neural activity from odorant structure

Noam Sobel

Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100, Israel; noam.sobel@weizmann.ac.il

Using common methods for dimensionality reduction, we generated a perceptual olfactory space, a physichochemical olfactory space, and a neural olfactory space.  We then uncovered rules that allowed us to predict perception and neural activity from structure alone. 

 

Riech-O-Mat: A small and simple olfactometer for fMRI studies

J.U. Sommer, C. Heiser, B.A.Stuck, T. Hummel

Departments of Otorhinolarnygology, Universities of Mannheim and Dresden, Germany; mail@ulrich-sommer.de

 

Stress-reducing effects from orange odor exposure in humans in an experimental setting

Monique Smeets1, Jasper de Groot1, Annemarie Kaldewaij1, Alexander Toet2, Lorenz van Doornen1

1 Utrecht University, Clinical & Health Psychology, Utrecht, the Netherlands; 2TNO Defence, Security & Safety, Soesterberg, the Netherlands; m.a.m.smeets@uu.nl

While exposure to the essential oil of orange has demonstrated anxiolytic and sedative effects in mice and rats, evidence in humans has so far been less convincing (Toet, Smeets et al., 2010). To investigate the cause-and-effects relation between orange odor and mental stress we conducted a laboratory experiment in which, after an initial relaxation phase, stress was induced in females (N = 68) using the Trier Social Stress Task. The experimental group (n = 34) received exposure to the odor of Brazilian essential oil at low intensity, while the control group received (n = 34) exposure to room air. Subjective (feelings of stress, mood, positive and negative affect) and physiological responses (cortisol level, heart rate, skin conductance, respiratory rate) were registered during a 1.5 hour session. Results showed significant blunting of subjective reports of stress (p = .001) during the stress task in the orange group. This was, however, not reflected in the physiological endpoints, as group differences failed to reach statistical significance. This pattern of results supports a psychological explanation for stress-reducing effects of orange odor in humans rather than a pharmacological explanation.

Reference: Toet, A., Smeets, M.A.M., van Dijk, E., Dijkstra, D., & van den Reijen, L. (2010). Effects of Pleasant Ambient Fragrances on Dental Fear: Comparing Apples and Oranges. Chemosensory Perception, 3, 182-189.

Acknowledgements: Supported by TNO and NWO MAGW-VIDI grant 452-03-334 to M.A.M.S. Orange oil provided by Creative Flavour & Fragrances.

 

 

Sandalwood oil alters facial attractiveness

Iris Stappen1, Martina Hoeferl1, Eva Heuberger1,2

1 University of Vienna, Department of Clinical Pharmacy and Diagnostics, Vienna, Austria; 2 Saarland University, Pharmaceutical Biology, Saarbruecken, Germany; Iris.stappen@univie.ac.at

The influence of two essential oils, New Caledonian Sandalwood oil and Geranium oil, on judgments of facial attractiveness was measured in 50 healthy human subjects (25 males) in a within-subject experiment. In addition physiological, psychological and endocrine effects were recorded. The study focused on the putative aphrodisiac effect of Sandalwood oil. Geranium oil served as an odor control, odorless air was used as an additional control condition. The participants were neither informed of odorants being used in the study nor were they aware of their presence in the experimental chamber. The results showed that both male and female subjects rated the faces presented on a computer screen as being significantly more attractive in the presence of Sandalwood oil than under the influence of Geranium oil or odorless air although both odors were rated as pleasant. Neither compound significantly affected mood, physiological arousal or salivary cortisol level. The findings of the current study suggest that ratings of facial attractiveness may be affected by certain plant odors which are used as aphrodisiacs in some cultures and are not dependent on odor pleasantness alone.

Acknowledgements: Theresa Rameder, Monika Angerer, Sandra Bichl (support in data acquisition and data entry)

 

Hormones as Predictors of Odor Pleasantness?

Sokratis Trellakis a, Cornelia Fischer a, Jens Greve a, Alena Rydleuskaya a, Sefik Tagay b, André Scherag c, Ali E. Canbay d, Thomas K. Hoffmann a, Stephan Lang a, Sven Brandau a

a Department of Otorhinolaryngology, b Department of Psychosomatic Medicine and Psychotherapy, c Institut for Medical Informatics, Biometry and Epidemiology, d Department of Gastroenterology and Hepatology, University of Duisburg-Essen, Essen, Germany; sokratis.trellakis@uk-essen.de

 

Influence of night-time odorant-application on dreams

Vent J, Bornkessel F, Matthies A, Vitinius F, Hellmich M, Hüttenbrink K.-B.

Department of Otorhinolaryngology, Unversity of Cologne; julia.vent@uk-koeln.de

Introduction: Subconscious application of odorants in humans has not yet been thoroughly investigated. In animal models, rose may have a sedating and anxiolytic effect.

Hypothesis and Aim: The effect of rose odorant application on dream activity in depressed patients was assessed. It was hypothesized that dream quality was more pleasant and recall of dream activity was more frequent.

Methods: In cooperation between the department of Otorhinolaryngology, head and neck surgery, and the department of psychosomatic medicine of the university of Cologne medical centre, a randomised, placebo-controlled pilot study investigated the dream activity of 20 normosmic females. They were in-patients suffering from psychosomatic depression aged 18 to 50 years. The influence of night-time rose odorant application on dreams was assessed. A special interval-applicator added rose concentrate to breathing air during inspiration every three minutes. There were three consecutive nights of odorant application, three nights of a wash out phase, as well as three nights of placebo. Two groups were investigated in a cross over design, one starting with placebo, and one with odorant. Every morning after waking up, patients completed a standardized questionnaire about their dreams.

Results: Odorant application was well tolerated, and only one patient dropped out of the study. The dream experience was more positive than before therapy, but there was no significant difference between both groups. The frequency of recalled dreams did not differ between the groups, either.

Discussion: Night-time odorant application may have positive influence on dream experience and frequency in depressed patients. However, this may be partially due to the anti-depressive medication and psychotherapy, too. A larger case series, also including healthy subjects, males and other odorants, is planned for obtaining statistically significant evidence of our hypothesis.



Olfactory dysfunction in patients with Parkinson’s disease is related to gray matter atrophy in regions of the olfactory cortex

Antje Welge-Lüssen1, Elise Wattendorf2, Thomas Hummel3, Birgit Westermann4

1Department of Otorhinolaryngology, University Hospital, University of Basel, Switzerland; 2Anatomy Unit, University of Fribourg, Switzerland; 3Smell and Taste Clinic, University of Dresden Medical School, Dresden, Germany; 4Department of Neurosurgery, University Hospital, University of Basel, Switzerland; awelge@uhbs.ch

Objectives:  It is now widely accepted that early non-motor signs indicate pre-clinical stages of Parkinson’s disease (PD) prior to the onset of motor symptoms. According to recent neuropathological staging concepts, impaired olfaction is assumed to indicate an early pathological process and might be associated with structural changes in primarily non-motor related brain regions.

Subjects and Methods: Early PD patients (n=15, median Hoehn and Yahr stage 1.5), moderately advanced PD (n=12, median Hoehn and Yahr stage 2.5) and age-matched healthy controls (n=17) participated in the study. Olfactory function was assessed in all subjects birhinally using the standardized “Sniffin’ Sticks’’ test battery (Burghart, Germany). A morphometric analysis of magnetic resonance images (voxel-based morphometry [VBM]) was used to investigate gray matter atrophy related to psychophysically measured scores of olfactory function.

Results: In PD patients, but not in controls, cortical atrophy in olfactory-related brain regions correlated specifically with olfactory dysfunction. Positive correlations between olfactory performance and gray matter volume were observed in the right piriform cortex in early PD patients and in the right amygdala in moderately advanced patients.

Discussion:The results provided first evidence that olfactory dysfunction in PD is related to atrophy in olfactory-eloquent regions of the limbic and paralimbic cortex. In addition, olfactory-correlated atrophy in these brain regions is consistent with the assumption that olfactory impairment as an early symptom of PD is likely to be associated with extranigral pathology.

 


Perceptual plasticity in olfaction

Donald A. Wilson

Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, and New York University School of Medicine; Donald.Wilson@nyumc.org

Odor perception is an object-oriented process, involving experience-dependent synthesis of volatile molecular features present into  a single perceptual gestalt, such as “coffee” or “rose”.  The molecular features are recognized by a large set of receptors in the nose, and then converted into complex, odorant-specific spatiotemporal patterns of neural activity in the olfactory bulb.  The primary olfactory (piriform) cortex serves as a pattern recognition device, storing previously experienced patterns through synaptic plasticity, and allowing template matching of new inputs to the stored patterns.  Familiar patterns are more easily discriminated, and thus perceptual learning can occur through odor exposure with a corresponding increase in perceptual acuity.  This pattern recognition process also allow for completion of degraded input patterns (e.g., slight variations due to single component disruption) which contributes to perceptual stability.  New data will be presented showing that different kinds of experience can result in either an increase or decrease in perceptual acuity and pattern recognition by cortical ensembles, leading to either enhanced generalization or enhanced discrimination at the behavioral and neural levels depending on task demands.  Furthermore, given the reliance of odor perception on cortical plasticity and memory, data will be presented suggesting that neuropathology associated with dementia can impair both cortical odor processing and odor perception.  Together, the results provide further support for the critical role of learning and memory in basic odor perception and discrimination.

Acknowledgement: Work presented was funded by grants to D.A.W. from the National Institute for Deafness and Communication Disorders.

 

Olfaction in an animal model of Niemann-Pick disease

Martin Witt, Andreas Wree

Department of Anatomy, University of Rostock Medical School, Rostock, Germany; martin.witt@med.uni-rostock.de

Niemann-Pick disease type C (NPC-1) is a rare genetic neurovisceral lipid storage disease characterized by abnormalities in intracellular cholesterol trafficking. We used a knock-out mouse model (NPC1-/-) to examine the effects of this disorder to morphologically distinct regions of the olfactory system. For histochemistry, we applied antibodies against a series of neuronal and glia marker proteins, proliferation antigens, apoptotic and macrophage markers. Mutant animals present myelin-like deposits in virtually all cells of both the peripheral and central olfactory system. Especially supporting cells of the olfactory epithelium and central glia cells are affected resulting in astrocytosis and microgliosis in the olfactory bulb and other olfactory cortices. Synaptic contacts, unmyelinated olfactory afferents seem less affected. Interestingly, first data suggest that new neurons such as neuroblasts of the subventricular zone and the rostral migratory stream do not contain pathological inclusions. Nevertheless, it is assumed that NPC1-/- animals exhibit severe olfactory deficits.